A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation
Edition: Model Aviation - 1988/07
Page Numbers: 88, 89, 90, 91, 160, 161, 164
A SOUND according Webster sensation produced ears certain vibrations caused surrounding air Noise other hand called sound loud harsh confused kind Human perception sound seems vary individual what may noise person may experienced negatively another Prolonged exposure high-decibel sound levels well documented poten tially leading permanent hearing damage sound produced model aircraft engines can damaging modelers hearing others may closely involved operating engines can also annoying individuals consid erable distance away well aware consequence sound operations close proximity surrounding populated areas controlled loss flying sites has happened repeatedly past comes ever-increasing problem more housing moves area es tablished sites safe secure no pro blem situation can rapidly become crisis L Sign times Art Johnson L Bill Cooper Gold Coast Flyers site Delray Beach FL Big Picture Gold Coast flying site 900 ft Uust beyond parked vehicles location Sound thats 90 dBA 9 ft model barely audible distance loss lease threatened Typically modeling club may invest tween $10000 $15000 flying site no small sum addition untold hours volunteer labor devoted site preparation maintenance seems author would prudent pro tect investment via expedient model sound reduction tend think sound generated model airplanes originates solely operation engines thats fal lacy Other noises example turbulent flow over airframe usually masked engine sound Therefore changing good muffler will itself achieve ade quate sound reduction total propulsion system must treated Sound produced combination things including following a engine exhaust b propeller c engine mechanical noises bearings etc d radiation sound walls engine muffler pipe etc As imputus quiten models heightens manning front lines have come back several good ideas Simple modi fications new products described article will go long way helping average modelers reach 9OdBA 9 ft guide line EDon Lowev/vvvv-vvvvsvvwvvv/vvvv\tvv\VV\ 88 Model Aviation e intake f airframe total sound model produces nonlinear summation above factors condition no matter small measure contributes aggre gate sound footprint model Lets examine sound sources indi vidually Exhaust Engine exhaust noise generated burning fuel its rapid cy clic expansion atmosphere 100% engine efficiency gases would fully expanded atmospheric pressure temperature before escaping mosphere sound production would negligible good muffler compensates some engine inefficiency allowing gases cool expand controlled basis prior release atmo sphere process normally requires certain minimum volume and/or multiple passes Left Soft Lord mounts see text details next step overall noise reduction significantly cut back both mechanical air frame noise Right engines large Quadra 50 can quieted 90 @ 9 rule German-made PST uffler does job compact muffler simple open-chamber rent production quiet enough conse design does job hollow- quently internal baffling required chamber muffler typical cur- reach lower noise levels Some modelers 0 Bill Rudolph got Stik model down 90 dBA using add-on Stinger muffler sysTem have resorted multiple mufflers series get noise down seems work pretty well course anything bolt onto engine exhaust helps sound suppression degree Mufflers guts two bottom Soundmasters available Davis Diesel PO Box 141 Milford CT 06406 203 877-1670 top PST obby Lobby 5614 Franklin Pike Cir cle Brentwood TN 37027 615 373-1444 July 1988 89 Model noise disrupting concert Japanese museum located near Gold Coasts site prompted confrontation Parks Commission clubs willingness compromise hard work strict enforcement self-imposed 90 dBA 9 ft rule saved site seeking requires sophisticated design Manufacturers mufflers models need emulate design philosophy automotive industry good example model engine line having mufflers exhibit intelligent application good de sign practices K&B Sportster series stock engines have measured under 90 dBA 9 ft mounted aircraft least two other muffler designs employ ing same principles currently market both Germany Soundmaster series imported Davis Diesel De velopment PSTPC imported Hobby Lobby International also number good muffled tuned pipes market best Hatori Japan imported Fu tuba Corporation America choose tuned pipe certain is muffled variety best will show daylight peered end Propeller assertion may surprise some Im convinced propeller single difficult problematic sound source modelers enoounter Elim inating propeller noise requires lot wiz ardry little cut-and-try design major investigation sponsored Two methods soft engine mounts double firewall mount top will marketed wIth Jimmy Griers Coyote bottom mount example Lord mount using Fox standard radial unit rub ber grommets studs bonded end rubber cylinderhighly effective AMA now under way dual goals first better defining problem second working out design solutions present reduced propeller tip velocity has heen definitively correlated lowered prop lathe second largest contributor models total noise Thinner blades smaller diameter props multiple blades can help reduce factor authors own tests some quieter props available Top bottom Asano DW Yoshioka plastic Robbee plastic MK plastic three-blade Also shown Lowes home brew four-blader Use extreme caution never notch prop hubs deeper one-third thicknese 90 Model Aviation i-nil ijoma TIUSO nis lAID win munier made Bill Cooper scratch-built Hots empty spray can Seemed like Power comes massIve Superligre good idea could make 90 dBAs 3000 second muffler PST educed sound 98 87 dBA PSI i Pc mufflers avaIlable three sizes smallest engine sizes 21 40 medIum sIze fits 40 60 large muffler fits 90 way up 108 sound Experiments have shown keep ing tip velocity below approximately 6500 per sec will meet current FAI re quirement F3A Pattern 98 dBA three meters number will altered somewhat blade tip shape Propeller tip speed can determined simple formula 314 x dia x rpm 60 means 11-in prop turning approximately 11300 rpm produces same noise level 14-in turning about 9000 rpm Remember isolat ing prop noise actual dB level generated aggregate sources sound model Simply employing larger-diameter prop also reducing rpm accomplishes nothing fact maintain rpm reducing pitch larger-diameter prop sound will actu ally increase magic three-bladed four bladed prop design does derive use multiple blades rather simply maintaining engine thrust through use smaller-diameter prop lower tip speed Full-scale aircraft employ multi bladed props because confer some automatic improvement performance provide means absorbing en gine horsepower through prop diameter sufficiently practical also keep land ing gear reasonable length According current knowledge quietest props seem efficient onesa very happy circumstance Again keeping tip velocity down vital taining quietness Blade stiffness us ing thin blades also important factors Sweeping blade leading edge reduces sound too has shown raking back last 10% prop tip helpful very best props have tested Asano Japan unfortunately also expensive Props fabricated very hard woods laminations com posites carbon fiber fiberglass ap pear very advantageous materi als permit stiffness thin-bladed design Nevertheless single effective means suppressing propeller sound get tip velocity down however becomes necessary increase prop pitch order keep airspeed up Airspeed generated rpm x pitch reduce rpm must increase pitch has positively demonstrated model engines long-stroke otherwise work very well lower rpm example F3A Pattern fliers now turning 10500 11500 rpm using props pitch ranging 9 12 aircraft performing just well did em ploying former standard 7- 8-in pitch 13000 14000 rpm fly ing much quieter Experiments have dramat ically shown using very quiet muffler fast-turning prop does get job done lowering prop speed necessary effectively quiet sound Most modelers underpitch models faced problem too much load engine simply reduce ACTUAL SIZE 0832 SIMPLE 2-CYCLE MOUNT FOX 60 ENGINENYLON INSERT MOUNT DEPICTED BACKPLRTE [TWUNT _____________________NYLON INSERT FIREUlALL BACK-PLATE SCREWS ALUIIIIAIIIM OR STEEL PS APPROX I/AM THICK HARDWOOD ENaIIIE IIOUNTSNYLON INSERT LOCK HIlTS POSSIBLE 4-CYCLE flOUNT pitch Usually wrong approach general better correction reduce prop diameter either holding pitch actually increasing Another startling revelation fanfare about Electric flight four-stroke engines panacea noise problem shouldnt blind us whole picture compare Electric setup piston engine equipped suitable muffling turning same propeller find prop noise renders former just about noisy latter Most Electrics quiet because low-energy systems contention can operate piston en gines same noise energy levels Electric properly treat piston Continued page 160 July1988 91 both EAA chapters AMA charter clubs exchanging list ings club chapter would like participate activities directed toward youth contact Bob Under wood AMA Technical Director 1810 Sam uel Morse Dr Reston VA 22090 terrific experience About Noise/Lowe Continued page 91 engine does mean anti Electrics great low-energy ap plications Still will never match energy-per-pound ratio piston en gine simply because no known bat tery energy density alcohol gasoline fuel Some years ago involved de velopment RPV using ad vanced lithium hydride very dangerous battery system concert ad vanced motor design around cobalt turned prop same rpm com parable piston engine found RPV system approximately noisy piston engine setup addition RPV netted about 25% energy density piston engine gasoline setup other words Electric system 300 watt hours per pound would operate just 25% duration piston en gine equivalent weight Furthermore Ni-Cd batteries used models have far less energy high-performance lithium hydride batteries tested Four-stroke engines usually credited being quieter two-stroke ones testing has contradicted assumption given rpm primary sound frequency typical four-stroke engine half two-stroke may fact sound pleasant measured dB levels prove comparable fact some Pat tern fliers have shied away four-stroke engines because too noisy Remem ber dB meter scale does compen sate perceived sound lowering its re sponse lower frequencies since tries simulate human response Most four-stroke Pattern fliers using high prop pitch 1112 less diameter reduce rpm noise Four-strokers have mechanical noise addition suspect generate airframe noise due higher vibration Check out prop diameter rpm tip velocity typical four-stroke engine Youll find higher typical two-stroke F3A Pattern ship setup What modeling world needs greater availability high-quality stiff high-pitch props Various measures can taken reduce engine mechanical noisesthose radiated propulsion system surfaces such bearings etcas well sound radiation walls engine muffler pipe forth lack well-quantified data area have seen 2-dR noise re duction replacing noisy bearings new ones 1- 2-dB drop using rub ber sleeve tuned pipe 1-dB reduc tion using filter intake pri mary focus quest sound reduc tion should course having quality muffler getting propeller tip speed down ancillary modifications should also considered Airframe noise generated thrash ing single-cylinder model engine design cannot perfectly balanced again well quantified certainly proven source noise some models inherent resistance perfect balance such engines due nonlinear accelera tion forces piston offset connecting rod function rotation addition have torsional vibration created impulsive nature beasta phenomenon makes Perry vibrator fuel pump work well several ways alleviate problem First could go multiple cyl inders However very practical solution would still have torsional vibration although its frequency would crease function number firings per revolution Second could enclose engine exhaust system inside airframean effective strategy far goes still capable eliminating tor sional vibration Third could change well-balanced electric motor Electrics usually operate very smoothly Interest ingly too impulsive systems thus likewise exhibit torsional vibration higher frequency function number poles motor As mat ter fact knowledge everything life impulsive cyclic nature amazing think about far satisfactory solution air frame noise shield engine vibration airframe through use rubber metal isolators Several Pattern fliers have experimenting rubber en gine mounts various kinds have found case noise reduced Secondary perhaps primary bene fits isolation saving radio system failure eliminating incidence fuel foaming has struck down flier Also may prevent breakage loosening pushrod fittings engine mounts RPV project employed vibration isolation engine conse quently experienced no instance elec tronic failure due vibration Certainly worth price effort Isolating engine also removes very high-peak im pulsive loads engine permits much lighter less robust engine mount system Some will argue theyve tried Lord mounts found system wouldnt stay together response setup properly designed First mount systems natural frequency must outside operating frequency range engine harmonics can tear apart usually means very low soft frequency system Second peak loads iso lators must rupture rubber/metal bonds its important choose cor rect isolator task highly em pirical design solution cut try typ ical 60 engine installation uses three four liz- 9A6-in-diameter Lord mounts supporting engine radial mount fashion addition exhaust system pipe must rubber isolated also experiments quiet mufflers have found presence airframe noise testing engine mounted airplane versus testing engine mount significantly lessens noise reduc tion induced muffler air160 Model Aviation THERMAL CHARGER what looking electric sailplane good looks easy build fun fly great perfor mance Thermal Charger fl PRECISION PRODUCTS INC 714 592-5144 510 E Arrow Highway San Dimas CA 91773 FAI RUBBER Sizes 1/4 3/16 1/8 3/32 1/16 042 thick pound box Price *1350 includes 4 oz Slick Lube $1250 no lube Slick costs *1751 Postpaid US via UPS Cal add 6% tax SMALL BOX 114 lb rubber $450 size Orders up $1500 1/4 lb rubber mdse. add $150 UPS Over $15 add 10% CROCKET HOOKS NOW MADE BYFAI SEND $150 PAl Model lupply FOR CATALOG P0 Box 3667 Torrance CA 10610 frame noise has counteracted effective ness mufflers Similarly readings comparing quiet mufflers against noisier ones same rpm have shown insignifi cant differences engines mounted airplanes case air frame noise acts equalizer under mines superiority quieter mufflers Using engine isolation counteract air frame noise own Pattern ship setup has produced profound reduction sound air though testing ground showed small reduction theorize because airframe vibration ground somewhat damped contact earth through holding ship air unrestrained airframe free shake Open-framework film-covered air frames noisy fiberglass fuse lages foam/plastic ready-to-fly air frames pretty good vibration absorbers WE MPY -\VE f StAPLL CLUB% UTWEWRE KNOVI HOVI ID OUR CLUB PPE5lDNV PLYK lo Stock Iomod0e Shipment ZENOAH 0-6237 Cu In$25495 Now Onedro 40 CDI 3-beoing spring storto $14966 Reg Ocodro 40- *12205 Brieghollo flywheel 06 Reg Onedra 40 Pow Aenewhly Only points $6496 OUADRAor ZENOAH REPAIR$1000 plan porte Jim Meeter ERCOUPEPLANS $2396 FULL-KIT $23996 Jim Menno TOMAHAWKPLANS $2395 FULL-KIT 023996 Jim Meeter J-3 KITTENPLANS $2996 FULL-KIT $19696 WE ROBINHOOD 50 KIT$5996 neon $3096 WE ROSINHOOD 96 KIT$13096 note 000001 ZENOAH 023 $16405ZENOAM G3g 96 FLOATS 401/4 conIccorns $2195 oonplete hit $4700 10 WWI WHEELS 6 P/K SprIng Starter 6 PLANS SUPER STEARMAN 14 Godfrey $2895 13TAYLORCRAFTor 13 CUB Nell, $3996 VOLKOPLANE 13 ChIcken Cherlinl 02396 Seroon H402 42 no 0120$ World 5l610rlrge reodeln $4496 Propo oIl clone ER TOP FLITE DYNATHRUST 20% OFF US Onedra FUEL TANKS15 no $600320 0796 FIBERGLASSARROW SHAFTS 5/15 o32 long Sfo$11 95 24 Ho, Sorolon Add 0264 pontoon 00k Check ore JIM MESSERS QUALITY MODEL PRODUCTS VaIMy View Dr Box 43 AIIegaay IVY 14706 Solid balsawood airframes best Vibrating pushrods terrible noise pro ducers other part aircraft such landing gear free rattle must guard against drawing rash con clusions noise testing ground what happens air really counts Probably representative noise test ing would conducted air some distance model Ground test ing meter useful guide can help sort out effects changes might make better ground test would employ rubber suspension airframe allow everything shake case study club has noise problem count yourself fortunate Gold Coast Fliers Delray Beach FL recently faced get quiet get out situation beautiful site lo Continued page 164 0 SPECIALISTS IN CUSTOM COX TEE DEE & REED ENGINE$ 020S 049 051S & 09S ALL CUSTOM & STOCK PARTS AVAILABLE INDIVIDUALLY MANY NEW PARTS FOR OLD DISCONTINUED COX ENGINES COX PROPS & GLOW HEADS COMPETITION ACCESSORIES & CUSTOMIZED K&B ENGINES ALSO COMPLETE LINE OF RACING PARTS - GLO-BEE FIREBALL & K&B PLUGS SOLID LINES RACING WHEELS QUICK FILLS ETC WE ALSO STOCK CARBON FIBER KLOTZ OIL LATEX & SILICONE FUEL TUBING PEN BLADDER MATERIALS & HARDTO-FIND HARDWARE ESPECIALLY 2-56 & 3-48 SIZES COILS CONDENSERS NGK & STITT PLUGS SILK 12 COLORS QUALITY DOPE BRUSHES 5 & 7 LOOP RUBBER BANDS KSB SEELIG & IGNITION TIMERS GAS & DIESEL FUEL TUBING TRANSISTOR IGNITION SYSTEMS RESISTOR HI-TENSION LEADS 1/2A TEXACO PLAYBOY SR KIT 1/2A TEXACO ENGINES & PARTS EVERYTHING YOU NEED FOR OLD TIMER EVENTS July 1988 161 OUR REV-UP INVENTORY AVERAGES OVER 9000 PROPS I! CALL FOR IMMEDIATE SHIPMENT ON VISA OR MASTERCARD OLD TIMER SUPPLIES ORDER BY MAIL OR PHONE 619728-4365 SORRY NO COD VISA & MASTERCARD WELCOME DEALER INQUIRES INVITED MINIMUM MERCHANDISE ORDER $1000 SHIPPING & HANDLING FEE $150 FOR INSURANCE ADD $100 ORDERS SHIPPED WITHIN 24 IIflhIqS fAI oinrniro flfl OL S 4 ns No 591 Focke-WuIf FW 190-A$1350 RO Sport Scale NW II fighter spans 58 uses 35145two-stroke engine Two plan sheets no documentation No 592 ET$475 CL trainer/sportster uses 05 electric power 6-cell battery pack Wingspan 241/2 No 193StIletto CL Stunt model McDonald winner 1976 1980 1982 FAI World Champs.. $375 No 239Blue Birds RC Ken Willards formation plane 4-channel 10/15 power$375 No 262crashmaster CL Crash-proof trainer two sizes15/30 35140 power$125 No 3101930 Fleet Biplane AC Sport Scale 35/40 4-channel Wingspan 56 /s scste Twe sheets$625 No 314Drake II AC Ken Willards flying boot 3-channel 15-power Fly land removable gear$375 No 326Taylor cub AC Don Srolls Schoolyard-Scale fur 048s 2-3 channel Spans 50 in$350 No 332Zephyr AC Small 2-channel glider hand-launch tow thermal slope sealing$200 No 388Laser 200 AC Sport Scale replica championship Aerobatic flier Uses 40 power 4-5 channel Two sheets$1075 No 414Electric Sparky AC Electric fun flier 35 motor 3-channel RC scaled-op 1939 wbber-power fanorite$050 No 440cavalier AC Old-Timer-like new design has huge wing slow easy flights 35 pwr 3 cfr Two sheets$1725 No 4471/2A Misa America AC Old-Timer Teoaco model 049 glow 2-channels$050 No 454sweet P-30 FE Neat stick-and-hosue Outdoor Robber P-30-class model contest-winner$200 No 457Spectra AC ElecIlic-power 05-size motor uses 3 different wings sport soanog aerobatics$700 No 4804-40 AC Shoulder-wing sport flier 4-cycle 40-size engine 4 channels.. $650 No 465Blue Max II AC Fun-fly sportoter 40-size engines spans 52 Lightweight stwclore$700 No 478Buttercup AC Cute elfin sportoter uses micro 2-ch AC pulse-wdder Spans 2710 02Q/035 power$300 No 490Weekender AC Low-wing sport flier 20-size 4-stroke engine spans 47 in$575 No 506Playmate AC Sport flier 3 AC channels 15125-sloe engines spans 50 $650 No 812Extra 230 AC Slant Scale acrobatic plane spans 0 0 eves Quadra engine Two plan sheets$1650 No 514Henry T AC Sportater 2-3 channel AC spans 52 has adiustable wing flaps$475 No 521comet Jr clipper Plus 35% AC Old-Timer sportoter engine 2-ch AC spans 40 in$650 No 522Sorta Pitta AC Reminder-scale bipe 40160 engines spans 43 Two plan streets$1050 No 525Hi-Tech 2002 AC Canard ducted-fan fur 45 engines spans 39 Two sheets$1000 No 528swallow AC Lightweight hutrioggen 40-sloe four-stroke engines spans 50 $025 No 531TerrIble coupe FF Aubber-powered Coupe ditiver spans 40 contest-winner$475 No 533cessna c-37 AC Schoolyard Scale famous 305 plane 040/10 power 2-cS spuns 42 in$500 No 5341938 challenger AC Tevaco Old-Timer spans 47 049 engine 2-channel AC$550 No 535Atrlx AC AMA Class 0 Sailplane spans 110 uses 4-channel AC system$725 No 539Simitar Slow-Motion 15 AC Tailless fl4ng wing 15 engines spans 60 uses 3-ch ACS350 No 541Parakeet AC Sport biplane 10/25 engines 3-channel AC eAuipment spans 42 in$675 No 544Heron AC Sill Winters sport Electric geared 075 motor 3 AC cb spans 65 in$575 No 549cricket AC Sport scalelike fur 20-sloe two- tour-stroke engine spans 40 in$675 No 554Super Doubler II AC Sport AerohaticsPylon 40/46 four-stroke engine spans 57 in$575 No 555Double Duty AC Basic/advanced trainer 10/15 engines spans either 67 59 Two plan sheets$1075 No 559Low Voltage AC Electric-power sport 035 motor spans 44 in$475 No 561Wild Hare AC TI-motor spurtoter spans 63 uses 25 engines Two plan sheets$900 No 562XB-35 CL Reminder-scale flying wing Somber two engines spans 47 in$575 No 56310 AC AMA Class 8 2-Meter Sailplune bus 780/a-in-span bum wing$725 No 564Thunderbird 60 CL Big competition Stunter Tom Glenn 45161 engines spans 61 in$000 No 585Sea Loon AC Pod-and-boom seaplane 15 power spans 400/a In$675 No 568Avro 560 FF Mini-electnc Scale 23 British ultralight spans 30 in$200 No 569ElectrostreakRC Electric aerobatic plane spans 05 motor$550 No 570Busy See EF Fee Wee-30 plane 02 power spans 30 hay either sheet-balsa built-up surfaces$400 No 571Voyager CL Sorto-Scale A-powered version around-the-world plune spans 46 in$225 No 572TR-280 AC Sport Scale Aerobatic plane 4-stroke 60165 power spans 6610$1100 No 573PInk Lady F-40 CL Bill Wisniewokis Formula 40 Speedster 40 power spuns 27 in$400 No 575ScorpIon 60 AC Fun-fly aerohatic plane 60 power spans 56 in$1150 No 576Serendipityt ndoor EZB record-holder spans 17% in$325 No 577Haiflite CL Combat plane has foam wing spans 30 in$225 No 578Schweizer 1-265 AC Quarter-scale Sailplane npans 125 Two plan sheets$1475 No 579Lockheed P-38 CL Precision Scale WV/ II fighter twin 4Ss spans 55 Fowler flaps etc Three plan sheets$1000 No 580Parnall Pixie FF Rubber Scale golden Age British biplane 112 scale spans 31 inS375 No 561Gee Bee Model Y AC Golden Age Racer spans 72 1/s scale 60 power Three plan sheets$1175 No 582Heinkel 100 CL Sport Scale WW II fighter 40 engine spans 61 stracture mostly cardboard Two planabto. $1250 No 583Sporawagon AC Radin-ized sport FF model spans 54 uses 10115 engine$700 No 584Happy Days CL Intermediute trainer/Stunter spans 42 uses 29135 engine$575 No 585Dragonfly FF High-performance P-30 Aubber ship spans 30 weighs 50 grams$400 No 586Snapdragon AC Fun-fly/sportster 25/30 engines spans 45 In. $600 No 587Pilatus Pc-9 CL Profile Scale/Stunter/spmfster spuns 56 uses 29/35 engine5550 No 568Mariah AC Slope-Soaring Sailplane spans 4110 uses 2 AC channels$425 No 589Vickera Welleeley AC Sport Scale WIN II bomber spans 69 uses 49 4-cycle engine Two plan sheets no duc$1250 No 590Bud Line Laser Stunter CL Stunter scalelike spars 63 uses 60 engine Two plan sheets$1050 0 03 0 N N o0 -an 083 U zo 03s 8 - c 00 C0 o C - - to g3e an83 no 83 0 - g3 an83 can tOan 083 00 083 C an83 0 -gcO Oan 30 0 c 83 00 mc U FIAMF 0 STREET CITY c STAF n 0 Circle numbers plans wish order 193 414 490 531 554 568 577 585 239 440 506 533 555 569 578 586 262 447 512 534 559 570 579 587 310 454 514 535 561 571 580 588 314 457 521 539 562 572 581 589 326 460 522 541 563 573 582 590 332 465 525 544 564 575 583 591 386 478 528 549 565 576 584 592 Plan price includes first class postage US delivery Air Mail over 300 miles orders non-US address lease add $25e Air Mail osta e handlin Ian Make check money order payable US funds drawn US bank Model Aviation AMA 1810 Samuel Morse Dr Reston VA 22090 Please allow 3 6 weeks delivery Please prinf carefullyEnclosed $ __________________________________________ AMA No ______________ ZIP About Noise/Lowe Continued page 161 cated county park features picnic facilities Japanese museum time time special events held 900 ft clubs flying site airplanes drowned out music such event recently club threatened expulsion compromise solution reached county both sides agreed AMA suggested standard 90 dBA 9 ft require ment now rigidly enforced search quieter model setups club members have tried things have involved operating re duced horsepower Two-cycle fourcycle engines alike have difficulty meet ing requirement Typical fixes modifi cation existing mufflers adding mufflers series adding plastic fuel tank muffler exhaust proposed Duke Fox adding length rubber hose muf fler using larger and/or higher-pitch props get rpm down now flying lash-up arrangements ST 3000- Quadra 35-powered ships flying ossible also obvious much educa tion solutions problem help industry required need least optionat choice en gine manufacturers quiet muffler need higher-pitch props plastic prop lines now market least up 10-in pitch also need basic under standing vibration-induced noise introduction products market make easier change modeler model airplane can operated reduced sound levels significant reduction horsepower solution properly designed sound two- four-stroke engines meeting 90 dB requirement can still detected 900 ft noise disagreeable Inside building allis quiet dis tance No seems complaining Delray Beachon contrary terested spectators abound Would like live next door un controlled model flying site club site within half-mile neighbors should concerned Remember pre vention far better facing lot irate neighbors once positions established its very hard people change minds summary would like emphasize once again noise reduction involves total package super-quiet muffler ma total answer necessary part solution Dont afraid ex periment Go Radio Shack plunk down 30 bucks indispensable sounc meter get started assure wil] rewarding pleasant experience Ir addition may save flying site hearing 164 Model Aviation