__________________George M Myers HAPPY NEW YEAR During 10 years Ive writing RT have tested radio systems has rare thing encounter defective unusually-poor-performing system regard less price fact some least expensive sets really have shown best performances Likewise some high est-priced sets have produced worst performances overall spread between best worst has small once discount two three real stinkers know about now Third-order intermodulation inter ference major problem must solved Bill Hershberger Reasoning previous test method may have showing us important differences retested repre sentative group RC systems tempt find better test method Table 1 shows combinations receivers transmitters tested objective find field test anyone could perform would ac curately assess performance field conditions encounter daily As shown test setup sketch New Test Method approximates condition taxiing flying closer interferer control transmitter Test Setup Baseline DcDi CR ContiolReceiverinterference TransmitterTransmitters begin placing Control trans mitter fixed location held person continuously rocks aile Table 1 Test Matrix Receiver TypesTransmitter Types FMFM AMFMPCMSRF Single-Conversion XX Dual-ConversionXXXX PCM e code modulation SRF chable radio frequency ron control terferer set up another fixed loca tion about 200 feet Control Test En gineer walks receiver Control transmit ter toward terferer watching action ofaservo connected aileron channel receiver some point interference will noted Test Engineer puts receiver down point paces off dis tance remaining Interferer Ob viously closer Inter ferer better performance judged up point really isnt much value plac ing receiver tenna right next interference transmitter because dont fly way Five feet tween Interfer ence transmitter receiver tennas about closest distance use field because wingspan taxiing airTable 2 Field TestInterferenceDistances TestReceiver AMSingle-Conversion RC5972799MHZ Test InterferencesBaselineIfeet FrequencyTrenamitter DifferenceFrequency2559109299480 40kHz M135 S-1W M1W 198640kHz MT3TT 40kHzRC48FM139 1115ll Canada20kHzRC51 FM91224 3048 198620kHzRC49 FM811203T56 PRS/MRS Hz7280 AM112148601125 31MRC4OAM1213 142338E RC48IAM FM~691W FM DPRr2T1F Re -- 31M d-order intermodulation interference 20P nd-order product interference PAS/MAS Personal Radio Service/Manufacturers Radio Service pagers etc Table 3 Field Test Summary Control Transmitter Advantage vs Baseline Distances Test Receiver AM Single-Conversion RC50 Beseline Distances ft Type Interference 2090 2550100290480extrepelated Third-Order Intermodulafion AM 11 28 61 77 95 136 d-Order lntermodulatjon FM 11 28 16 19 16 26 smitter Advantage c/Di see test setup sketch Table 4 Field Test Summary Control Transmitter Advantage vs 31M Frequencies Separation Test Receiver AM Single-Conversion RC54 7297 MHz Beseline Distance 200 feet Frequency Separations end_RC Channels Used Test Interferers29 kHz48 kHz1 80 kHz169 kHz RC53 RC52 RC5O RC4S RC5O 6 RC3U AMAM notest AMFM 44I 41 FMFM 26 7 31M d-Order Intermodulation Interference plane couple feet can expect taxi pilot will leave couple feet between wing tip legs someone holding transmitter So must get closer Interferer five feet order complete test show have bit larger margin safety Testing Testing As soon started testing found difficult set up situation receiver antenna would always five feet interferer led us series tests various baselines up 400 feet see Table 2 tested 31M Third-Order Intermodu lation interference dual-conversion dont wish set myself up some kind consumers testing service crystal FM receiver RC52 both Interferers together zero feet separation antennas pointing opposite directions got Interference Distance Di 61 feet moved Interferers away extend baseline five 10 20 feet corresponding distances nearest Interferer 61 60 58 42 Model Aviation ValuesValue of0i M terpretationft 200ft baseline 0 1Intolerable interference 1 2The dangerous range 60 100 2 4Poor Performance 40 66 4 8Mediocre 1965 performance 22 40 8 16Good 1985 performance 2 16 32Excellent 1985 perforresoce Over 32Soperior joterference rejection leon 6 feet So much spreading out reduce 31M didnt help least what considered range interest did rest testing zeroseparation interfering transmitters base base described earlier RT Before writing off benefits sep aration lets take look what get reduce 31M data Table 2 First divided distance Control Transmitter distance Inter ferer MDc/Di yielded multi plier indicates Control Transmitter Advantage terms times farther Control transmitter can receiver Interferer before losing control Without changing anything distance AM receiver kept getting better against AIvI 31M showed literally no improve ment against FM 31M Curious Table 3 shows data also took look 31M caused various frequency spacings Heres what found using different receiver see Table 4 After plotting data studying awhile concluded equallyspaced grouping three RC channels produces 31M resulting inter ferences about equally destructive constant combination AMAM AMFM orFMFM However FM FM always produced worst interfer Table 6 Control Transmitter Advantage M 200-ft Baseline TestGroundReceiverInterference Interference Freq Separation NoCondTypeXntr Type40kHz20kHz10kHz31M 1DryAM SogiAM3562377 ConyFM1655619 FM/PCM 2WetAM SogiAM298522213 ConyFM11352 FM/PCM 3DryAM SogiAM1751133720 ConyFM14511312 FM/PCM 4DryAM SogiAM1451063721 FM1457810 C CM 0 SDryAMOvalAM0 ConyFM11810220 0 FMIPCM 6WetFM SogiAM113932034 ConyFM675213 FM/PCM90II 7DryFM SogiAM113932034 ConyFM11310815 FM/PCM113 8WetFM DualAM113674237 ConyFM675920 FM/PCMC 9DryFM DualAM1136752 37 ConyFM784220 FM/PCME 0 10DryFM DualAM1139308 l31 ConyFM1965221i 0 FM/PCM 11DryFM/PCMAM49024 SogiFM49027633 0 ConyFM/PCM 12WetFM/PCMAM26 I362029 DoalFM2553120 ConyFM/PCM 13DryFM/PCMAM42362629 DualFM25511320 ConyFM/PCM 14DryFM/PCMAM1231014635 DualFM65739023 ConyFM/PCM Notes bad tented twice make sure wax no mistake 31M d-Order Intermodulation Interference ence 31M re sulting 20 kHz spacing twice bad other interval results above suggest ed should standardize 200-foot baseline using zero separa tion between 31M transmitters operat ing 40 kHz other point will report thing terms Control Transmitter Ad vantage because think what looking no such thing total freedom fmm interference enough advantage can fly spite interference Therefore based experi ence reasoning observations per formances field chose interpret multipliers shown Table 5 looked five kinds interference depending available equipment tested over turf types systems gave poorer results grass wet First checked Third-Order Intermodulation 31M because produces interference directly control channel radio frequency inter ference causes trouble such simultaneous operation RC46 RC48 RC5O Next looked Second-Order Prod uct interference 20P kind get Interfering transmitter fre Continued page 131 January1986 43 Table 5 Field Test Results Interpreting Computed Control Transmitter AdvantaNe M See test setup sketch DiM i Before rush out buy something get rid equipment based results consider no statistical significance databecause unique Only two samples type tested because tested what what could borrowwhich explains gaps table Besides took lot time collect data see Make no mistakeits workl Perhaps can fill some gaps tell us results data leads us several conclusions 1 This test method differentiates good poor mediocreperforming equipment 2 All tests show must very careful about RO channels being used vicinitybecause Third-Order Intermodulation interference 31M gets types surprising information come out tests 31M FM transmitters gives worse interference AM transmitters check 31M column Table 6 doesnt seem drop off much distance check Table 3 3 Flying low over other transmittersand taking off landing taxiing out pitswhen controlling plane distance asking trouble because 31M interference practically guaranteed kind RO system case 1985 Nats Pattern turnarounds being made 2O0ofeet awayfrom pilot minimum slant rangefrom plane other flight lines possibly-interfering trans mitters should have kept 2000/26 feet check Table 3 Now tells mel 4 If must fly over/close other transmitters stand close theml Study what Tables 2 3 trying tell about basic idea keep distance equal less potential interferer because doing will give much advantage possible case pitifully small 31M Standing close also gives other guy best chance too 5 FM beats up AM vice versa Surprised sure wasl Retail price 349 Factory direct price 262 0 kits use product yearn research development keep scsi size appearance slot help good people Besle Air Force Base Maryiville California SR71 hase Lockheeds heat representative have exact 1112 scale kit Being ail wood flyabie true scale kit availahie P104 cockpit kit off scale item no can get interior SR-71 yet jan01 heginners kit hut very nice 10 build finished product AWESOME Expect speeds over 150 mph 80s parachute option very nice too full 22 picture photo pak availahie real scale huffs Have fun R Hugh Performance Twin Ducted Fan Asrplane Ktt Length 1075 span 558j Gear Tir-gear retract mechanical Weight 18-22 Designed Turbex III Fans44 Channei Radio 48-80 Ducted Fan Engines 1515 785-5550 other parts accessories build repair plane available Call write information needed B-Line Products & Hobbvs e PO Box 1231 s 101 AtkInson St fisansUIa CA 95661 Avaimbie Ieee 1-4 Phuuts peelber Sabre sF-I Crusaders U-i Biselceef balance location building plan placing model onto balanc er Designers choose center gravi ty CG locations because want aircraft have flight qualities de scribed article informa tion about kit change CG location unless experienced builder flier Tail-heavy aircraft tend fly peculiar way. read accident about happen safe bet should have plan out CG position indicated balance aircraft between 2507o 30% wing chord measured wing leading edge aircraft should balance slight nose-down atti tude no fuel fuel tank Freeing hands model rests balancer will allow shift items such radio forward back wards order achieve desired balance point Use balance stand will avoid finger balancing act will end up better-flying aircraft Try youll wonder didnt use balance stand before Build yours today Questions comments may sent PO Box 40 Hanover MI 49241 Take care fly safely tell someone new about model building flying Radio Technique/Myers Continued page 43 quency approximately 455 kHz away Control transmitter frequency like Orange/White 72400 MHz RC54 72870 MHz could problem usually isnt wasnt test sets left out summary looked Personal Radio Service PRS Manufacturers Radio Service MRS channels 10 kHz away RC channels except old ones dead another could problem After looked Canada today same USA 1991 adjacent RC channels are/will 20kHz apart easy have Kraft Synthesizer FM tests special set crystals AM trans mitter Bear mind 31M serious 20 kHz spacing RC50 RC5 1 RC5 2 Finally checked USA today adjacent RC channels 40 kHz apart tools checked AM FM FM/PCM Interferers Table 6 tabulates some results may surprised what see Per haps bit explanation order first thing note tested over turf types systems gave poorer results grass wet Ive tried show effect summary table column take seriously 31Mnone RC System-types does good job rejecting Most interferences glitches have reported can traced 31M particularly associated approach landing Helicopters particularly susceptible effects 31M due field setup way flown ii groups fly today 40 kHz spacing look down colunm get idea various types doing environment Youll see FM sets AMA_ El 0 i5Zzz -o -I 0 CD coJ x U x 0 n 0 -a 0 V CD 0 p C 0 Cn 0 0 01 0 January1986 131 0 Flying Near Airports Careful Free Flight Radio Control flying near airports situation might involve possibility models being vicinity full-scale aircraft operations must avoidedor conducted eliminate dangerous situations Models should flown proximity full-scale aircraft operations unless flyer has someone else him sole purpose watching full-scale aircraft supervising flying 88 prevent accident possibilities PROTECT YOUR RIGHT TO FLYI Safe Flying No Accident A4 TEL FOUR CYCLE ENGINE MOUNTS Cast oluminurrr alloy Ground 90 thrust tine Bsght polish finished Socket cop screws inCluded 600 BOO 1000 1000 1000 1000 1000 1000 1200 1100 1300 No JT-62OS MAX FS 60-75-901300 No JT-64ENVA 60-80-90-120 4C1300 No JI-65SAITO PA 651300 No JT-120 Uridrited 120 1600 No Jf-121 ENYA R 120 PC 1800 No JT-122 OS MAX PS 120 1800 No -123 SAITO PA 120 1800 No Jf-125 Super hgre 25-30001800 DRILLED AND TAPPED 1-20 OS MAX PS 20 No JI-40 Undnhted 21-40 Noll-Af t4PVT2f No JI-42 ENVA 35-40 AC No JI-43 SAITO PA 30 No JIM OS MAX PS 40 No J1-45 SAITO PA 40-45 No 1-46 ENVA 46 AC No JI-49 HP VT 49 No J1-60 Undnhled 60-90 No JI-61 OS MAX PS 61 available hobby shop ORDER DIRECT return UPS shipment John rorone ENGINE TESTING STANDS Steel restraining pins Cast Aluminum ton engine No jrrsr J1-rS2 rA 10 60Grant srze 10 25 1150 0 SIDE MOUNT MUFFLERS PillS CAP 21 CESSNA ISO etc No J-40P.No Jr40P 29-4045 60 15001800 2 EXHAUST EXTINSIONS NEO9STNE METAL-FLEXJr-N56 300 r JIM12 DIA GA350 JT-M34 OIA500JT-N58 OIA00 JT-M78V DIX600JT-N34 GA5 50 Jt-Q34 QUADRA 35 Jt-Z34 ZENOAH G-3B A-IDA ALTEC TED 2000 J1-Q3B QUADRA 25 JI-Q5B QUADRA SO JT-Z3B ZENOAR G-3B JI-M38 MAXI 30 2000 JI-Q SS QUADRA SO Jt-M35 MAXI 30 2000 GIANT ENGINE MUFFLERS Matched engine toil pe extensions mounting bolts included Also avaob4e ATLAS 46 BULLY COBRA EAWASAKI KIORtTZ SACII-DOMLER SUPER TiGRE 2500-3000 MAIL ORDER Please add 250 UPS shipping Check MO VISA MC COD accepted Add 200 extra COD Calil residents odd 8% tax -SEND FOR FREE CATALOGJT-Q3L QUADRA 35 JT-Q5L QUADRA 50 JT-23L ZENOAH G-3B JT-TDR ALTEC TED J1-M3R MAN 30 JTQ3R QUADRA 35 Jt-QSR QUADRA 50 JT-23R ZENOAII G-3B JT-M3L MAXI 30 Jt-Q54 QUADRA 50 JI-M34 MAXi 30 2000 arent improvement over AM sets PCM stuff shows some promise better times can lick 31M problem fly Canada can check 20 kHz column saw generally poorer performance 20 kHz spacing expected Hz column misleading got data using transmitters approxi mately equal power case PRS MRS power can up 400 times larger radios wide open interference Yet Ive noted before havent interference reports traced may save some letter-writing tell used old Ace RC Silver Seven built kit AM single-con version receiver tests Tables 2 3 4 Test 14 Simprop PCM-20 am withholding rest names because dont wish set myself up some kind consumers testing service will say 1984 1985 systems did what always work something out test tell you can donduct interpret own tests Now go has debate going about What 1988 Some folks favor splitting band FM-Only preserve Anything Goes area No doubt data will used support positions both sides argument same time may some will data hand start hunting FM scalps Now play nice boys No matter slice splitting band bound reduce number channels use due 31M problems would counterproductive future discussions FCC position remains wit Keep whole band open forms modulation FM can beand will have bedeveloped resist AM because AMA members wont abandon AM systems until/unless FM sets come market offer clearly superior per formance rejecting forms AM interference including dirt-bike ignition noise high-voltage transmission-line cor ona arcing lightning etc However smart thing now may change AMA Phase-k Plan way minimizes 31M Before closing column must ac knowledge help provided long time friend Bob Aberle collected some equipment spent hours performing tests discussing results Without Bob would have stopped writing column longtime ago also have thank Bill Hershberger has saying years 31M major problem must solved finally listened Bill must also thank Ace RC advertisers sug gesting 200-fcot baseline started us off expedition Kraft Systems providing synthesized RF modules make FM testing easy Tower Hobbies loaned us pair AM transmitters some special crystals made AM testing easier Thanks well friends entrusted us equipment test column has led us some unusual conclusions may stir up small amount controversy invitenay challenge disprove data and/or conclusions orderto will have work harder did will have put some hard test data table Opinions worthless analyses no better assumptions George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 responding advertisers mention read about Model Aviation RC Scale/Wischers Continued page 49 Large flying-type models emphasize realism air rather ground dominant rally dont see visitors creeping around knees examine finely-executed detail ing except few rare models Paul Weigand brought Toledo prize-winner K-W rally TA-size Culver Dart flies very well mildly aerobatic its Quadra 50 engine Toledo winners real ly fly Formed windshields Fastening simple sloping windshields curved direc tion can become battle stiff material fights remain flat Glue alone may hold throughout models life Heat-forming 031-inthick acrylic butyrate sheet takes fight out material fastening becomes simple process However windshield isnt formed shape fits closely gluing job can still quite frustrating preferred process begins paper template paper draped over fuselage windshield frame rough ly marked pencil determine ap proximate outline Fold paper along its centerline check equal shapes both halves cut scissors around outline Fit paper template fuselage satisfactory make sec ond third template until shape correct always folding along its centerline certain equal left right halves have never made paper template correct first time Next step duplicate template 010 litho-plate aluminum Form template bending using large-diameter wood dowels rolling pin kitchen fits fuselage Continued page 136 132 Model Aviation 2000 -4:
Edition: Model Aviation - 1986/01
Page Numbers: 42, 43, 131, 132
Edition: Model Aviation - 1986/01
Page Numbers: 42, 43, 131, 132
__________________George M Myers HAPPY NEW YEAR During 10 years Ive writing RT have tested radio systems has rare thing encounter defective unusually-poor-performing system regard less price fact some least expensive sets really have shown best performances Likewise some high est-priced sets have produced worst performances overall spread between best worst has small once discount two three real stinkers know about now Third-order intermodulation inter ference major problem must solved Bill Hershberger Reasoning previous test method may have showing us important differences retested repre sentative group RC systems tempt find better test method Table 1 shows combinations receivers transmitters tested objective find field test anyone could perform would ac curately assess performance field conditions encounter daily As shown test setup sketch New Test Method approximates condition taxiing flying closer interferer control transmitter Test Setup Baseline DcDi CR ContiolReceiverinterference TransmitterTransmitters begin placing Control trans mitter fixed location held person continuously rocks aile Table 1 Test Matrix Receiver TypesTransmitter Types FMFM AMFMPCMSRF Single-Conversion XX Dual-ConversionXXXX PCM e code modulation SRF chable radio frequency ron control terferer set up another fixed loca tion about 200 feet Control Test En gineer walks receiver Control transmit ter toward terferer watching action ofaservo connected aileron channel receiver some point interference will noted Test Engineer puts receiver down point paces off dis tance remaining Interferer Ob viously closer Inter ferer better performance judged up point really isnt much value plac ing receiver tenna right next interference transmitter because dont fly way Five feet tween Interfer ence transmitter receiver tennas about closest distance use field because wingspan taxiing airTable 2 Field TestInterferenceDistances TestReceiver AMSingle-Conversion RC5972799MHZ Test InterferencesBaselineIfeet FrequencyTrenamitter DifferenceFrequency2559109299480 40kHz M135 S-1W M1W 198640kHz MT3TT 40kHzRC48FM139 1115ll Canada20kHzRC51 FM91224 3048 198620kHzRC49 FM811203T56 PRS/MRS Hz7280 AM112148601125 31MRC4OAM1213 142338E RC48IAM FM~691W FM DPRr2T1F Re -- 31M d-order intermodulation interference 20P nd-order product interference PAS/MAS Personal Radio Service/Manufacturers Radio Service pagers etc Table 3 Field Test Summary Control Transmitter Advantage vs Baseline Distances Test Receiver AM Single-Conversion RC50 Beseline Distances ft Type Interference 2090 2550100290480extrepelated Third-Order Intermodulafion AM 11 28 61 77 95 136 d-Order lntermodulatjon FM 11 28 16 19 16 26 smitter Advantage c/Di see test setup sketch Table 4 Field Test Summary Control Transmitter Advantage vs 31M Frequencies Separation Test Receiver AM Single-Conversion RC54 7297 MHz Beseline Distance 200 feet Frequency Separations end_RC Channels Used Test Interferers29 kHz48 kHz1 80 kHz169 kHz RC53 RC52 RC5O RC4S RC5O 6 RC3U AMAM notest AMFM 44I 41 FMFM 26 7 31M d-Order Intermodulation Interference plane couple feet can expect taxi pilot will leave couple feet between wing tip legs someone holding transmitter So must get closer Interferer five feet order complete test show have bit larger margin safety Testing Testing As soon started testing found difficult set up situation receiver antenna would always five feet interferer led us series tests various baselines up 400 feet see Table 2 tested 31M Third-Order Intermodu lation interference dual-conversion dont wish set myself up some kind consumers testing service crystal FM receiver RC52 both Interferers together zero feet separation antennas pointing opposite directions got Interference Distance Di 61 feet moved Interferers away extend baseline five 10 20 feet corresponding distances nearest Interferer 61 60 58 42 Model Aviation ValuesValue of0i M terpretationft 200ft baseline 0 1Intolerable interference 1 2The dangerous range 60 100 2 4Poor Performance 40 66 4 8Mediocre 1965 performance 22 40 8 16Good 1985 performance 2 16 32Excellent 1985 perforresoce Over 32Soperior joterference rejection leon 6 feet So much spreading out reduce 31M didnt help least what considered range interest did rest testing zeroseparation interfering transmitters base base described earlier RT Before writing off benefits sep aration lets take look what get reduce 31M data Table 2 First divided distance Control Transmitter distance Inter ferer MDc/Di yielded multi plier indicates Control Transmitter Advantage terms times farther Control transmitter can receiver Interferer before losing control Without changing anything distance AM receiver kept getting better against AIvI 31M showed literally no improve ment against FM 31M Curious Table 3 shows data also took look 31M caused various frequency spacings Heres what found using different receiver see Table 4 After plotting data studying awhile concluded equallyspaced grouping three RC channels produces 31M resulting inter ferences about equally destructive constant combination AMAM AMFM orFMFM However FM FM always produced worst interfer Table 6 Control Transmitter Advantage M 200-ft Baseline TestGroundReceiverInterference Interference Freq Separation NoCondTypeXntr Type40kHz20kHz10kHz31M 1DryAM SogiAM3562377 ConyFM1655619 FM/PCM 2WetAM SogiAM298522213 ConyFM11352 FM/PCM 3DryAM SogiAM1751133720 ConyFM14511312 FM/PCM 4DryAM SogiAM1451063721 FM1457810 C CM 0 SDryAMOvalAM0 ConyFM11810220 0 FMIPCM 6WetFM SogiAM113932034 ConyFM675213 FM/PCM90II 7DryFM SogiAM113932034 ConyFM11310815 FM/PCM113 8WetFM DualAM113674237 ConyFM675920 FM/PCMC 9DryFM DualAM1136752 37 ConyFM784220 FM/PCME 0 10DryFM DualAM1139308 l31 ConyFM1965221i 0 FM/PCM 11DryFM/PCMAM49024 SogiFM49027633 0 ConyFM/PCM 12WetFM/PCMAM26 I362029 DoalFM2553120 ConyFM/PCM 13DryFM/PCMAM42362629 DualFM25511320 ConyFM/PCM 14DryFM/PCMAM1231014635 DualFM65739023 ConyFM/PCM Notes bad tented twice make sure wax no mistake 31M d-Order Intermodulation Interference ence 31M re sulting 20 kHz spacing twice bad other interval results above suggest ed should standardize 200-foot baseline using zero separa tion between 31M transmitters operat ing 40 kHz other point will report thing terms Control Transmitter Ad vantage because think what looking no such thing total freedom fmm interference enough advantage can fly spite interference Therefore based experi ence reasoning observations per formances field chose interpret multipliers shown Table 5 looked five kinds interference depending available equipment tested over turf types systems gave poorer results grass wet First checked Third-Order Intermodulation 31M because produces interference directly control channel radio frequency inter ference causes trouble such simultaneous operation RC46 RC48 RC5O Next looked Second-Order Prod uct interference 20P kind get Interfering transmitter fre Continued page 131 January1986 43 Table 5 Field Test Results Interpreting Computed Control Transmitter AdvantaNe M See test setup sketch DiM i Before rush out buy something get rid equipment based results consider no statistical significance databecause unique Only two samples type tested because tested what what could borrowwhich explains gaps table Besides took lot time collect data see Make no mistakeits workl Perhaps can fill some gaps tell us results data leads us several conclusions 1 This test method differentiates good poor mediocreperforming equipment 2 All tests show must very careful about RO channels being used vicinitybecause Third-Order Intermodulation interference 31M gets types surprising information come out tests 31M FM transmitters gives worse interference AM transmitters check 31M column Table 6 doesnt seem drop off much distance check Table 3 3 Flying low over other transmittersand taking off landing taxiing out pitswhen controlling plane distance asking trouble because 31M interference practically guaranteed kind RO system case 1985 Nats Pattern turnarounds being made 2O0ofeet awayfrom pilot minimum slant rangefrom plane other flight lines possibly-interfering trans mitters should have kept 2000/26 feet check Table 3 Now tells mel 4 If must fly over/close other transmitters stand close theml Study what Tables 2 3 trying tell about basic idea keep distance equal less potential interferer because doing will give much advantage possible case pitifully small 31M Standing close also gives other guy best chance too 5 FM beats up AM vice versa Surprised sure wasl Retail price 349 Factory direct price 262 0 kits use product yearn research development keep scsi size appearance slot help good people Besle Air Force Base Maryiville California SR71 hase Lockheeds heat representative have exact 1112 scale kit Being ail wood flyabie true scale kit availahie P104 cockpit kit off scale item no can get interior SR-71 yet jan01 heginners kit hut very nice 10 build finished product AWESOME Expect speeds over 150 mph 80s parachute option very nice too full 22 picture photo pak availahie real scale huffs Have fun R Hugh Performance Twin Ducted Fan Asrplane Ktt Length 1075 span 558j Gear Tir-gear retract mechanical Weight 18-22 Designed Turbex III Fans44 Channei Radio 48-80 Ducted Fan Engines 1515 785-5550 other parts accessories build repair plane available Call write information needed B-Line Products & Hobbvs e PO Box 1231 s 101 AtkInson St fisansUIa CA 95661 Avaimbie Ieee 1-4 Phuuts peelber Sabre sF-I Crusaders U-i Biselceef balance location building plan placing model onto balanc er Designers choose center gravi ty CG locations because want aircraft have flight qualities de scribed article informa tion about kit change CG location unless experienced builder flier Tail-heavy aircraft tend fly peculiar way. read accident about happen safe bet should have plan out CG position indicated balance aircraft between 2507o 30% wing chord measured wing leading edge aircraft should balance slight nose-down atti tude no fuel fuel tank Freeing hands model rests balancer will allow shift items such radio forward back wards order achieve desired balance point Use balance stand will avoid finger balancing act will end up better-flying aircraft Try youll wonder didnt use balance stand before Build yours today Questions comments may sent PO Box 40 Hanover MI 49241 Take care fly safely tell someone new about model building flying Radio Technique/Myers Continued page 43 quency approximately 455 kHz away Control transmitter frequency like Orange/White 72400 MHz RC54 72870 MHz could problem usually isnt wasnt test sets left out summary looked Personal Radio Service PRS Manufacturers Radio Service MRS channels 10 kHz away RC channels except old ones dead another could problem After looked Canada today same USA 1991 adjacent RC channels are/will 20kHz apart easy have Kraft Synthesizer FM tests special set crystals AM trans mitter Bear mind 31M serious 20 kHz spacing RC50 RC5 1 RC5 2 Finally checked USA today adjacent RC channels 40 kHz apart tools checked AM FM FM/PCM Interferers Table 6 tabulates some results may surprised what see Per haps bit explanation order first thing note tested over turf types systems gave poorer results grass wet Ive tried show effect summary table column take seriously 31Mnone RC System-types does good job rejecting Most interferences glitches have reported can traced 31M particularly associated approach landing Helicopters particularly susceptible effects 31M due field setup way flown ii groups fly today 40 kHz spacing look down colunm get idea various types doing environment Youll see FM sets AMA_ El 0 i5Zzz -o -I 0 CD coJ x U x 0 n 0 -a 0 V CD 0 p C 0 Cn 0 0 01 0 January1986 131 0 Flying Near Airports Careful Free Flight Radio Control flying near airports situation might involve possibility models being vicinity full-scale aircraft operations must avoidedor conducted eliminate dangerous situations Models should flown proximity full-scale aircraft operations unless flyer has someone else him sole purpose watching full-scale aircraft supervising flying 88 prevent accident possibilities PROTECT YOUR RIGHT TO FLYI Safe Flying No Accident A4 TEL FOUR CYCLE ENGINE MOUNTS Cast oluminurrr alloy Ground 90 thrust tine Bsght polish finished Socket cop screws inCluded 600 BOO 1000 1000 1000 1000 1000 1000 1200 1100 1300 No JT-62OS MAX FS 60-75-901300 No JT-64ENVA 60-80-90-120 4C1300 No JI-65SAITO PA 651300 No JT-120 Uridrited 120 1600 No Jf-121 ENYA R 120 PC 1800 No JT-122 OS MAX PS 120 1800 No -123 SAITO PA 120 1800 No Jf-125 Super hgre 25-30001800 DRILLED AND TAPPED 1-20 OS MAX PS 20 No JI-40 Undnhted 21-40 Noll-Af t4PVT2f No JI-42 ENVA 35-40 AC No JI-43 SAITO PA 30 No JIM OS MAX PS 40 No J1-45 SAITO PA 40-45 No 1-46 ENVA 46 AC No JI-49 HP VT 49 No J1-60 Undnhled 60-90 No JI-61 OS MAX PS 61 available hobby shop ORDER DIRECT return UPS shipment John rorone ENGINE TESTING STANDS Steel restraining pins Cast Aluminum ton engine No jrrsr J1-rS2 rA 10 60Grant srze 10 25 1150 0 SIDE MOUNT MUFFLERS PillS CAP 21 CESSNA ISO etc No J-40P.No Jr40P 29-4045 60 15001800 2 EXHAUST EXTINSIONS NEO9STNE METAL-FLEXJr-N56 300 r JIM12 DIA GA350 JT-M34 OIA500JT-N58 OIA00 JT-M78V DIX600JT-N34 GA5 50 Jt-Q34 QUADRA 35 Jt-Z34 ZENOAH G-3B A-IDA ALTEC TED 2000 J1-Q3B QUADRA 25 JI-Q5B QUADRA SO JT-Z3B ZENOAR G-3B JI-M38 MAXI 30 2000 JI-Q SS QUADRA SO Jt-M35 MAXI 30 2000 GIANT ENGINE MUFFLERS Matched engine toil pe extensions mounting bolts included Also avaob4e ATLAS 46 BULLY COBRA EAWASAKI KIORtTZ SACII-DOMLER SUPER TiGRE 2500-3000 MAIL ORDER Please add 250 UPS shipping Check MO VISA MC COD accepted Add 200 extra COD Calil residents odd 8% tax -SEND FOR FREE CATALOGJT-Q3L QUADRA 35 JT-Q5L QUADRA 50 JT-23L ZENOAH G-3B JT-TDR ALTEC TED J1-M3R MAN 30 JTQ3R QUADRA 35 Jt-QSR QUADRA 50 JT-23R ZENOAII G-3B JT-M3L MAXI 30 Jt-Q54 QUADRA 50 JI-M34 MAXi 30 2000 arent improvement over AM sets PCM stuff shows some promise better times can lick 31M problem fly Canada can check 20 kHz column saw generally poorer performance 20 kHz spacing expected Hz column misleading got data using transmitters approxi mately equal power case PRS MRS power can up 400 times larger radios wide open interference Yet Ive noted before havent interference reports traced may save some letter-writing tell used old Ace RC Silver Seven built kit AM single-con version receiver tests Tables 2 3 4 Test 14 Simprop PCM-20 am withholding rest names because dont wish set myself up some kind consumers testing service will say 1984 1985 systems did what always work something out test tell you can donduct interpret own tests Now go has debate going about What 1988 Some folks favor splitting band FM-Only preserve Anything Goes area No doubt data will used support positions both sides argument same time may some will data hand start hunting FM scalps Now play nice boys No matter slice splitting band bound reduce number channels use due 31M problems would counterproductive future discussions FCC position remains wit Keep whole band open forms modulation FM can beand will have bedeveloped resist AM because AMA members wont abandon AM systems until/unless FM sets come market offer clearly superior per formance rejecting forms AM interference including dirt-bike ignition noise high-voltage transmission-line cor ona arcing lightning etc However smart thing now may change AMA Phase-k Plan way minimizes 31M Before closing column must ac knowledge help provided long time friend Bob Aberle collected some equipment spent hours performing tests discussing results Without Bob would have stopped writing column longtime ago also have thank Bill Hershberger has saying years 31M major problem must solved finally listened Bill must also thank Ace RC advertisers sug gesting 200-fcot baseline started us off expedition Kraft Systems providing synthesized RF modules make FM testing easy Tower Hobbies loaned us pair AM transmitters some special crystals made AM testing easier Thanks well friends entrusted us equipment test column has led us some unusual conclusions may stir up small amount controversy invitenay challenge disprove data and/or conclusions orderto will have work harder did will have put some hard test data table Opinions worthless analyses no better assumptions George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 responding advertisers mention read about Model Aviation RC Scale/Wischers Continued page 49 Large flying-type models emphasize realism air rather ground dominant rally dont see visitors creeping around knees examine finely-executed detail ing except few rare models Paul Weigand brought Toledo prize-winner K-W rally TA-size Culver Dart flies very well mildly aerobatic its Quadra 50 engine Toledo winners real ly fly Formed windshields Fastening simple sloping windshields curved direc tion can become battle stiff material fights remain flat Glue alone may hold throughout models life Heat-forming 031-inthick acrylic butyrate sheet takes fight out material fastening becomes simple process However windshield isnt formed shape fits closely gluing job can still quite frustrating preferred process begins paper template paper draped over fuselage windshield frame rough ly marked pencil determine ap proximate outline Fold paper along its centerline check equal shapes both halves cut scissors around outline Fit paper template fuselage satisfactory make sec ond third template until shape correct always folding along its centerline certain equal left right halves have never made paper template correct first time Next step duplicate template 010 litho-plate aluminum Form template bending using large-diameter wood dowels rolling pin kitchen fits fuselage Continued page 136 132 Model Aviation 2000 -4:
Edition: Model Aviation - 1986/01
Page Numbers: 42, 43, 131, 132
__________________George M Myers HAPPY NEW YEAR During 10 years Ive writing RT have tested radio systems has rare thing encounter defective unusually-poor-performing system regard less price fact some least expensive sets really have shown best performances Likewise some high est-priced sets have produced worst performances overall spread between best worst has small once discount two three real stinkers know about now Third-order intermodulation inter ference major problem must solved Bill Hershberger Reasoning previous test method may have showing us important differences retested repre sentative group RC systems tempt find better test method Table 1 shows combinations receivers transmitters tested objective find field test anyone could perform would ac curately assess performance field conditions encounter daily As shown test setup sketch New Test Method approximates condition taxiing flying closer interferer control transmitter Test Setup Baseline DcDi CR ContiolReceiverinterference TransmitterTransmitters begin placing Control trans mitter fixed location held person continuously rocks aile Table 1 Test Matrix Receiver TypesTransmitter Types FMFM AMFMPCMSRF Single-Conversion XX Dual-ConversionXXXX PCM e code modulation SRF chable radio frequency ron control terferer set up another fixed loca tion about 200 feet Control Test En gineer walks receiver Control transmit ter toward terferer watching action ofaservo connected aileron channel receiver some point interference will noted Test Engineer puts receiver down point paces off dis tance remaining Interferer Ob viously closer Inter ferer better performance judged up point really isnt much value plac ing receiver tenna right next interference transmitter because dont fly way Five feet tween Interfer ence transmitter receiver tennas about closest distance use field because wingspan taxiing airTable 2 Field TestInterferenceDistances TestReceiver AMSingle-Conversion RC5972799MHZ Test InterferencesBaselineIfeet FrequencyTrenamitter DifferenceFrequency2559109299480 40kHz M135 S-1W M1W 198640kHz MT3TT 40kHzRC48FM139 1115ll Canada20kHzRC51 FM91224 3048 198620kHzRC49 FM811203T56 PRS/MRS Hz7280 AM112148601125 31MRC4OAM1213 142338E RC48IAM FM~691W FM DPRr2T1F Re -- 31M d-order intermodulation interference 20P nd-order product interference PAS/MAS Personal Radio Service/Manufacturers Radio Service pagers etc Table 3 Field Test Summary Control Transmitter Advantage vs Baseline Distances Test Receiver AM Single-Conversion RC50 Beseline Distances ft Type Interference 2090 2550100290480extrepelated Third-Order Intermodulafion AM 11 28 61 77 95 136 d-Order lntermodulatjon FM 11 28 16 19 16 26 smitter Advantage c/Di see test setup sketch Table 4 Field Test Summary Control Transmitter Advantage vs 31M Frequencies Separation Test Receiver AM Single-Conversion RC54 7297 MHz Beseline Distance 200 feet Frequency Separations end_RC Channels Used Test Interferers29 kHz48 kHz1 80 kHz169 kHz RC53 RC52 RC5O RC4S RC5O 6 RC3U AMAM notest AMFM 44I 41 FMFM 26 7 31M d-Order Intermodulation Interference plane couple feet can expect taxi pilot will leave couple feet between wing tip legs someone holding transmitter So must get closer Interferer five feet order complete test show have bit larger margin safety Testing Testing As soon started testing found difficult set up situation receiver antenna would always five feet interferer led us series tests various baselines up 400 feet see Table 2 tested 31M Third-Order Intermodu lation interference dual-conversion dont wish set myself up some kind consumers testing service crystal FM receiver RC52 both Interferers together zero feet separation antennas pointing opposite directions got Interference Distance Di 61 feet moved Interferers away extend baseline five 10 20 feet corresponding distances nearest Interferer 61 60 58 42 Model Aviation ValuesValue of0i M terpretationft 200ft baseline 0 1Intolerable interference 1 2The dangerous range 60 100 2 4Poor Performance 40 66 4 8Mediocre 1965 performance 22 40 8 16Good 1985 performance 2 16 32Excellent 1985 perforresoce Over 32Soperior joterference rejection leon 6 feet So much spreading out reduce 31M didnt help least what considered range interest did rest testing zeroseparation interfering transmitters base base described earlier RT Before writing off benefits sep aration lets take look what get reduce 31M data Table 2 First divided distance Control Transmitter distance Inter ferer MDc/Di yielded multi plier indicates Control Transmitter Advantage terms times farther Control transmitter can receiver Interferer before losing control Without changing anything distance AM receiver kept getting better against AIvI 31M showed literally no improve ment against FM 31M Curious Table 3 shows data also took look 31M caused various frequency spacings Heres what found using different receiver see Table 4 After plotting data studying awhile concluded equallyspaced grouping three RC channels produces 31M resulting inter ferences about equally destructive constant combination AMAM AMFM orFMFM However FM FM always produced worst interfer Table 6 Control Transmitter Advantage M 200-ft Baseline TestGroundReceiverInterference Interference Freq Separation NoCondTypeXntr Type40kHz20kHz10kHz31M 1DryAM SogiAM3562377 ConyFM1655619 FM/PCM 2WetAM SogiAM298522213 ConyFM11352 FM/PCM 3DryAM SogiAM1751133720 ConyFM14511312 FM/PCM 4DryAM SogiAM1451063721 FM1457810 C CM 0 SDryAMOvalAM0 ConyFM11810220 0 FMIPCM 6WetFM SogiAM113932034 ConyFM675213 FM/PCM90II 7DryFM SogiAM113932034 ConyFM11310815 FM/PCM113 8WetFM DualAM113674237 ConyFM675920 FM/PCMC 9DryFM DualAM1136752 37 ConyFM784220 FM/PCME 0 10DryFM DualAM1139308 l31 ConyFM1965221i 0 FM/PCM 11DryFM/PCMAM49024 SogiFM49027633 0 ConyFM/PCM 12WetFM/PCMAM26 I362029 DoalFM2553120 ConyFM/PCM 13DryFM/PCMAM42362629 DualFM25511320 ConyFM/PCM 14DryFM/PCMAM1231014635 DualFM65739023 ConyFM/PCM Notes bad tented twice make sure wax no mistake 31M d-Order Intermodulation Interference ence 31M re sulting 20 kHz spacing twice bad other interval results above suggest ed should standardize 200-foot baseline using zero separa tion between 31M transmitters operat ing 40 kHz other point will report thing terms Control Transmitter Ad vantage because think what looking no such thing total freedom fmm interference enough advantage can fly spite interference Therefore based experi ence reasoning observations per formances field chose interpret multipliers shown Table 5 looked five kinds interference depending available equipment tested over turf types systems gave poorer results grass wet First checked Third-Order Intermodulation 31M because produces interference directly control channel radio frequency inter ference causes trouble such simultaneous operation RC46 RC48 RC5O Next looked Second-Order Prod uct interference 20P kind get Interfering transmitter fre Continued page 131 January1986 43 Table 5 Field Test Results Interpreting Computed Control Transmitter AdvantaNe M See test setup sketch DiM i Before rush out buy something get rid equipment based results consider no statistical significance databecause unique Only two samples type tested because tested what what could borrowwhich explains gaps table Besides took lot time collect data see Make no mistakeits workl Perhaps can fill some gaps tell us results data leads us several conclusions 1 This test method differentiates good poor mediocreperforming equipment 2 All tests show must very careful about RO channels being used vicinitybecause Third-Order Intermodulation interference 31M gets types surprising information come out tests 31M FM transmitters gives worse interference AM transmitters check 31M column Table 6 doesnt seem drop off much distance check Table 3 3 Flying low over other transmittersand taking off landing taxiing out pitswhen controlling plane distance asking trouble because 31M interference practically guaranteed kind RO system case 1985 Nats Pattern turnarounds being made 2O0ofeet awayfrom pilot minimum slant rangefrom plane other flight lines possibly-interfering trans mitters should have kept 2000/26 feet check Table 3 Now tells mel 4 If must fly over/close other transmitters stand close theml Study what Tables 2 3 trying tell about basic idea keep distance equal less potential interferer because doing will give much advantage possible case pitifully small 31M Standing close also gives other guy best chance too 5 FM beats up AM vice versa Surprised sure wasl Retail price 349 Factory direct price 262 0 kits use product yearn research development keep scsi size appearance slot help good people Besle Air Force Base Maryiville California SR71 hase Lockheeds heat representative have exact 1112 scale kit Being ail wood flyabie true scale kit availahie P104 cockpit kit off scale item no can get interior SR-71 yet jan01 heginners kit hut very nice 10 build finished product AWESOME Expect speeds over 150 mph 80s parachute option very nice too full 22 picture photo pak availahie real scale huffs Have fun R Hugh Performance Twin Ducted Fan Asrplane Ktt Length 1075 span 558j Gear Tir-gear retract mechanical Weight 18-22 Designed Turbex III Fans44 Channei Radio 48-80 Ducted Fan Engines 1515 785-5550 other parts accessories build repair plane available Call write information needed B-Line Products & Hobbvs e PO Box 1231 s 101 AtkInson St fisansUIa CA 95661 Avaimbie Ieee 1-4 Phuuts peelber Sabre sF-I Crusaders U-i Biselceef balance location building plan placing model onto balanc er Designers choose center gravi ty CG locations because want aircraft have flight qualities de scribed article informa tion about kit change CG location unless experienced builder flier Tail-heavy aircraft tend fly peculiar way. read accident about happen safe bet should have plan out CG position indicated balance aircraft between 2507o 30% wing chord measured wing leading edge aircraft should balance slight nose-down atti tude no fuel fuel tank Freeing hands model rests balancer will allow shift items such radio forward back wards order achieve desired balance point Use balance stand will avoid finger balancing act will end up better-flying aircraft Try youll wonder didnt use balance stand before Build yours today Questions comments may sent PO Box 40 Hanover MI 49241 Take care fly safely tell someone new about model building flying Radio Technique/Myers Continued page 43 quency approximately 455 kHz away Control transmitter frequency like Orange/White 72400 MHz RC54 72870 MHz could problem usually isnt wasnt test sets left out summary looked Personal Radio Service PRS Manufacturers Radio Service MRS channels 10 kHz away RC channels except old ones dead another could problem After looked Canada today same USA 1991 adjacent RC channels are/will 20kHz apart easy have Kraft Synthesizer FM tests special set crystals AM trans mitter Bear mind 31M serious 20 kHz spacing RC50 RC5 1 RC5 2 Finally checked USA today adjacent RC channels 40 kHz apart tools checked AM FM FM/PCM Interferers Table 6 tabulates some results may surprised what see Per haps bit explanation order first thing note tested over turf types systems gave poorer results grass wet Ive tried show effect summary table column take seriously 31Mnone RC System-types does good job rejecting Most interferences glitches have reported can traced 31M particularly associated approach landing Helicopters particularly susceptible effects 31M due field setup way flown ii groups fly today 40 kHz spacing look down colunm get idea various types doing environment Youll see FM sets AMA_ El 0 i5Zzz -o -I 0 CD coJ x U x 0 n 0 -a 0 V CD 0 p C 0 Cn 0 0 01 0 January1986 131 0 Flying Near Airports Careful Free Flight Radio Control flying near airports situation might involve possibility models being vicinity full-scale aircraft operations must avoidedor conducted eliminate dangerous situations Models should flown proximity full-scale aircraft operations unless flyer has someone else him sole purpose watching full-scale aircraft supervising flying 88 prevent accident possibilities PROTECT YOUR RIGHT TO FLYI Safe Flying No Accident A4 TEL FOUR CYCLE ENGINE MOUNTS Cast oluminurrr alloy Ground 90 thrust tine Bsght polish finished Socket cop screws inCluded 600 BOO 1000 1000 1000 1000 1000 1000 1200 1100 1300 No JT-62OS MAX FS 60-75-901300 No JT-64ENVA 60-80-90-120 4C1300 No JI-65SAITO PA 651300 No JT-120 Uridrited 120 1600 No Jf-121 ENYA R 120 PC 1800 No JT-122 OS MAX PS 120 1800 No -123 SAITO PA 120 1800 No Jf-125 Super hgre 25-30001800 DRILLED AND TAPPED 1-20 OS MAX PS 20 No JI-40 Undnhted 21-40 Noll-Af t4PVT2f No JI-42 ENVA 35-40 AC No JI-43 SAITO PA 30 No JIM OS MAX PS 40 No J1-45 SAITO PA 40-45 No 1-46 ENVA 46 AC No JI-49 HP VT 49 No J1-60 Undnhled 60-90 No JI-61 OS MAX PS 61 available hobby shop ORDER DIRECT return UPS shipment John rorone ENGINE TESTING STANDS Steel restraining pins Cast Aluminum ton engine No jrrsr J1-rS2 rA 10 60Grant srze 10 25 1150 0 SIDE MOUNT MUFFLERS PillS CAP 21 CESSNA ISO etc No J-40P.No Jr40P 29-4045 60 15001800 2 EXHAUST EXTINSIONS NEO9STNE METAL-FLEXJr-N56 300 r JIM12 DIA GA350 JT-M34 OIA500JT-N58 OIA00 JT-M78V DIX600JT-N34 GA5 50 Jt-Q34 QUADRA 35 Jt-Z34 ZENOAH G-3B A-IDA ALTEC TED 2000 J1-Q3B QUADRA 25 JI-Q5B QUADRA SO JT-Z3B ZENOAR G-3B JI-M38 MAXI 30 2000 JI-Q SS QUADRA SO Jt-M35 MAXI 30 2000 GIANT ENGINE MUFFLERS Matched engine toil pe extensions mounting bolts included Also avaob4e ATLAS 46 BULLY COBRA EAWASAKI KIORtTZ SACII-DOMLER SUPER TiGRE 2500-3000 MAIL ORDER Please add 250 UPS shipping Check MO VISA MC COD accepted Add 200 extra COD Calil residents odd 8% tax -SEND FOR FREE CATALOGJT-Q3L QUADRA 35 JT-Q5L QUADRA 50 JT-23L ZENOAH G-3B JT-TDR ALTEC TED J1-M3R MAN 30 JTQ3R QUADRA 35 Jt-QSR QUADRA 50 JT-23R ZENOAII G-3B JT-M3L MAXI 30 Jt-Q54 QUADRA 50 JI-M34 MAXi 30 2000 arent improvement over AM sets PCM stuff shows some promise better times can lick 31M problem fly Canada can check 20 kHz column saw generally poorer performance 20 kHz spacing expected Hz column misleading got data using transmitters approxi mately equal power case PRS MRS power can up 400 times larger radios wide open interference Yet Ive noted before havent interference reports traced may save some letter-writing tell used old Ace RC Silver Seven built kit AM single-con version receiver tests Tables 2 3 4 Test 14 Simprop PCM-20 am withholding rest names because dont wish set myself up some kind consumers testing service will say 1984 1985 systems did what always work something out test tell you can donduct interpret own tests Now go has debate going about What 1988 Some folks favor splitting band FM-Only preserve Anything Goes area No doubt data will used support positions both sides argument same time may some will data hand start hunting FM scalps Now play nice boys No matter slice splitting band bound reduce number channels use due 31M problems would counterproductive future discussions FCC position remains wit Keep whole band open forms modulation FM can beand will have bedeveloped resist AM because AMA members wont abandon AM systems until/unless FM sets come market offer clearly superior per formance rejecting forms AM interference including dirt-bike ignition noise high-voltage transmission-line cor ona arcing lightning etc However smart thing now may change AMA Phase-k Plan way minimizes 31M Before closing column must ac knowledge help provided long time friend Bob Aberle collected some equipment spent hours performing tests discussing results Without Bob would have stopped writing column longtime ago also have thank Bill Hershberger has saying years 31M major problem must solved finally listened Bill must also thank Ace RC advertisers sug gesting 200-fcot baseline started us off expedition Kraft Systems providing synthesized RF modules make FM testing easy Tower Hobbies loaned us pair AM transmitters some special crystals made AM testing easier Thanks well friends entrusted us equipment test column has led us some unusual conclusions may stir up small amount controversy invitenay challenge disprove data and/or conclusions orderto will have work harder did will have put some hard test data table Opinions worthless analyses no better assumptions George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 responding advertisers mention read about Model Aviation RC Scale/Wischers Continued page 49 Large flying-type models emphasize realism air rather ground dominant rally dont see visitors creeping around knees examine finely-executed detail ing except few rare models Paul Weigand brought Toledo prize-winner K-W rally TA-size Culver Dart flies very well mildly aerobatic its Quadra 50 engine Toledo winners real ly fly Formed windshields Fastening simple sloping windshields curved direc tion can become battle stiff material fights remain flat Glue alone may hold throughout models life Heat-forming 031-inthick acrylic butyrate sheet takes fight out material fastening becomes simple process However windshield isnt formed shape fits closely gluing job can still quite frustrating preferred process begins paper template paper draped over fuselage windshield frame rough ly marked pencil determine ap proximate outline Fold paper along its centerline check equal shapes both halves cut scissors around outline Fit paper template fuselage satisfactory make sec ond third template until shape correct always folding along its centerline certain equal left right halves have never made paper template correct first time Next step duplicate template 010 litho-plate aluminum Form template bending using large-diameter wood dowels rolling pin kitchen fits fuselage Continued page 136 132 Model Aviation 2000 -4:
Edition: Model Aviation - 1986/01
Page Numbers: 42, 43, 131, 132
__________________George M Myers HAPPY NEW YEAR During 10 years Ive writing RT have tested radio systems has rare thing encounter defective unusually-poor-performing system regard less price fact some least expensive sets really have shown best performances Likewise some high est-priced sets have produced worst performances overall spread between best worst has small once discount two three real stinkers know about now Third-order intermodulation inter ference major problem must solved Bill Hershberger Reasoning previous test method may have showing us important differences retested repre sentative group RC systems tempt find better test method Table 1 shows combinations receivers transmitters tested objective find field test anyone could perform would ac curately assess performance field conditions encounter daily As shown test setup sketch New Test Method approximates condition taxiing flying closer interferer control transmitter Test Setup Baseline DcDi CR ContiolReceiverinterference TransmitterTransmitters begin placing Control trans mitter fixed location held person continuously rocks aile Table 1 Test Matrix Receiver TypesTransmitter Types FMFM AMFMPCMSRF Single-Conversion XX Dual-ConversionXXXX PCM e code modulation SRF chable radio frequency ron control terferer set up another fixed loca tion about 200 feet Control Test En gineer walks receiver Control transmit ter toward terferer watching action ofaservo connected aileron channel receiver some point interference will noted Test Engineer puts receiver down point paces off dis tance remaining Interferer Ob viously closer Inter ferer better performance judged up point really isnt much value plac ing receiver tenna right next interference transmitter because dont fly way Five feet tween Interfer ence transmitter receiver tennas about closest distance use field because wingspan taxiing airTable 2 Field TestInterferenceDistances TestReceiver AMSingle-Conversion RC5972799MHZ Test InterferencesBaselineIfeet FrequencyTrenamitter DifferenceFrequency2559109299480 40kHz M135 S-1W M1W 198640kHz MT3TT 40kHzRC48FM139 1115ll Canada20kHzRC51 FM91224 3048 198620kHzRC49 FM811203T56 PRS/MRS Hz7280 AM112148601125 31MRC4OAM1213 142338E RC48IAM FM~691W FM DPRr2T1F Re -- 31M d-order intermodulation interference 20P nd-order product interference PAS/MAS Personal Radio Service/Manufacturers Radio Service pagers etc Table 3 Field Test Summary Control Transmitter Advantage vs Baseline Distances Test Receiver AM Single-Conversion RC50 Beseline Distances ft Type Interference 2090 2550100290480extrepelated Third-Order Intermodulafion AM 11 28 61 77 95 136 d-Order lntermodulatjon FM 11 28 16 19 16 26 smitter Advantage c/Di see test setup sketch Table 4 Field Test Summary Control Transmitter Advantage vs 31M Frequencies Separation Test Receiver AM Single-Conversion RC54 7297 MHz Beseline Distance 200 feet Frequency Separations end_RC Channels Used Test Interferers29 kHz48 kHz1 80 kHz169 kHz RC53 RC52 RC5O RC4S RC5O 6 RC3U AMAM notest AMFM 44I 41 FMFM 26 7 31M d-Order Intermodulation Interference plane couple feet can expect taxi pilot will leave couple feet between wing tip legs someone holding transmitter So must get closer Interferer five feet order complete test show have bit larger margin safety Testing Testing As soon started testing found difficult set up situation receiver antenna would always five feet interferer led us series tests various baselines up 400 feet see Table 2 tested 31M Third-Order Intermodu lation interference dual-conversion dont wish set myself up some kind consumers testing service crystal FM receiver RC52 both Interferers together zero feet separation antennas pointing opposite directions got Interference Distance Di 61 feet moved Interferers away extend baseline five 10 20 feet corresponding distances nearest Interferer 61 60 58 42 Model Aviation ValuesValue of0i M terpretationft 200ft baseline 0 1Intolerable interference 1 2The dangerous range 60 100 2 4Poor Performance 40 66 4 8Mediocre 1965 performance 22 40 8 16Good 1985 performance 2 16 32Excellent 1985 perforresoce Over 32Soperior joterference rejection leon 6 feet So much spreading out reduce 31M didnt help least what considered range interest did rest testing zeroseparation interfering transmitters base base described earlier RT Before writing off benefits sep aration lets take look what get reduce 31M data Table 2 First divided distance Control Transmitter distance Inter ferer MDc/Di yielded multi plier indicates Control Transmitter Advantage terms times farther Control transmitter can receiver Interferer before losing control Without changing anything distance AM receiver kept getting better against AIvI 31M showed literally no improve ment against FM 31M Curious Table 3 shows data also took look 31M caused various frequency spacings Heres what found using different receiver see Table 4 After plotting data studying awhile concluded equallyspaced grouping three RC channels produces 31M resulting inter ferences about equally destructive constant combination AMAM AMFM orFMFM However FM FM always produced worst interfer Table 6 Control Transmitter Advantage M 200-ft Baseline TestGroundReceiverInterference Interference Freq Separation NoCondTypeXntr Type40kHz20kHz10kHz31M 1DryAM SogiAM3562377 ConyFM1655619 FM/PCM 2WetAM SogiAM298522213 ConyFM11352 FM/PCM 3DryAM SogiAM1751133720 ConyFM14511312 FM/PCM 4DryAM SogiAM1451063721 FM1457810 C CM 0 SDryAMOvalAM0 ConyFM11810220 0 FMIPCM 6WetFM SogiAM113932034 ConyFM675213 FM/PCM90II 7DryFM SogiAM113932034 ConyFM11310815 FM/PCM113 8WetFM DualAM113674237 ConyFM675920 FM/PCMC 9DryFM DualAM1136752 37 ConyFM784220 FM/PCME 0 10DryFM DualAM1139308 l31 ConyFM1965221i 0 FM/PCM 11DryFM/PCMAM49024 SogiFM49027633 0 ConyFM/PCM 12WetFM/PCMAM26 I362029 DoalFM2553120 ConyFM/PCM 13DryFM/PCMAM42362629 DualFM25511320 ConyFM/PCM 14DryFM/PCMAM1231014635 DualFM65739023 ConyFM/PCM Notes bad tented twice make sure wax no mistake 31M d-Order Intermodulation Interference ence 31M re sulting 20 kHz spacing twice bad other interval results above suggest ed should standardize 200-foot baseline using zero separa tion between 31M transmitters operat ing 40 kHz other point will report thing terms Control Transmitter Ad vantage because think what looking no such thing total freedom fmm interference enough advantage can fly spite interference Therefore based experi ence reasoning observations per formances field chose interpret multipliers shown Table 5 looked five kinds interference depending available equipment tested over turf types systems gave poorer results grass wet First checked Third-Order Intermodulation 31M because produces interference directly control channel radio frequency inter ference causes trouble such simultaneous operation RC46 RC48 RC5O Next looked Second-Order Prod uct interference 20P kind get Interfering transmitter fre Continued page 131 January1986 43 Table 5 Field Test Results Interpreting Computed Control Transmitter AdvantaNe M See test setup sketch DiM i Before rush out buy something get rid equipment based results consider no statistical significance databecause unique Only two samples type tested because tested what what could borrowwhich explains gaps table Besides took lot time collect data see Make no mistakeits workl Perhaps can fill some gaps tell us results data leads us several conclusions 1 This test method differentiates good poor mediocreperforming equipment 2 All tests show must very careful about RO channels being used vicinitybecause Third-Order Intermodulation interference 31M gets types surprising information come out tests 31M FM transmitters gives worse interference AM transmitters check 31M column Table 6 doesnt seem drop off much distance check Table 3 3 Flying low over other transmittersand taking off landing taxiing out pitswhen controlling plane distance asking trouble because 31M interference practically guaranteed kind RO system case 1985 Nats Pattern turnarounds being made 2O0ofeet awayfrom pilot minimum slant rangefrom plane other flight lines possibly-interfering trans mitters should have kept 2000/26 feet check Table 3 Now tells mel 4 If must fly over/close other transmitters stand close theml Study what Tables 2 3 trying tell about basic idea keep distance equal less potential interferer because doing will give much advantage possible case pitifully small 31M Standing close also gives other guy best chance too 5 FM beats up AM vice versa Surprised sure wasl Retail price 349 Factory direct price 262 0 kits use product yearn research development keep scsi size appearance slot help good people Besle Air Force Base Maryiville California SR71 hase Lockheeds heat representative have exact 1112 scale kit Being ail wood flyabie true scale kit availahie P104 cockpit kit off scale item no can get interior SR-71 yet jan01 heginners kit hut very nice 10 build finished product AWESOME Expect speeds over 150 mph 80s parachute option very nice too full 22 picture photo pak availahie real scale huffs Have fun R Hugh Performance Twin Ducted Fan Asrplane Ktt Length 1075 span 558j Gear Tir-gear retract mechanical Weight 18-22 Designed Turbex III Fans44 Channei Radio 48-80 Ducted Fan Engines 1515 785-5550 other parts accessories build repair plane available Call write information needed B-Line Products & Hobbvs e PO Box 1231 s 101 AtkInson St fisansUIa CA 95661 Avaimbie Ieee 1-4 Phuuts peelber Sabre sF-I Crusaders U-i Biselceef balance location building plan placing model onto balanc er Designers choose center gravi ty CG locations because want aircraft have flight qualities de scribed article informa tion about kit change CG location unless experienced builder flier Tail-heavy aircraft tend fly peculiar way. read accident about happen safe bet should have plan out CG position indicated balance aircraft between 2507o 30% wing chord measured wing leading edge aircraft should balance slight nose-down atti tude no fuel fuel tank Freeing hands model rests balancer will allow shift items such radio forward back wards order achieve desired balance point Use balance stand will avoid finger balancing act will end up better-flying aircraft Try youll wonder didnt use balance stand before Build yours today Questions comments may sent PO Box 40 Hanover MI 49241 Take care fly safely tell someone new about model building flying Radio Technique/Myers Continued page 43 quency approximately 455 kHz away Control transmitter frequency like Orange/White 72400 MHz RC54 72870 MHz could problem usually isnt wasnt test sets left out summary looked Personal Radio Service PRS Manufacturers Radio Service MRS channels 10 kHz away RC channels except old ones dead another could problem After looked Canada today same USA 1991 adjacent RC channels are/will 20kHz apart easy have Kraft Synthesizer FM tests special set crystals AM trans mitter Bear mind 31M serious 20 kHz spacing RC50 RC5 1 RC5 2 Finally checked USA today adjacent RC channels 40 kHz apart tools checked AM FM FM/PCM Interferers Table 6 tabulates some results may surprised what see Per haps bit explanation order first thing note tested over turf types systems gave poorer results grass wet Ive tried show effect summary table column take seriously 31Mnone RC System-types does good job rejecting Most interferences glitches have reported can traced 31M particularly associated approach landing Helicopters particularly susceptible effects 31M due field setup way flown ii groups fly today 40 kHz spacing look down colunm get idea various types doing environment Youll see FM sets AMA_ El 0 i5Zzz -o -I 0 CD coJ x U x 0 n 0 -a 0 V CD 0 p C 0 Cn 0 0 01 0 January1986 131 0 Flying Near Airports Careful Free Flight Radio Control flying near airports situation might involve possibility models being vicinity full-scale aircraft operations must avoidedor conducted eliminate dangerous situations Models should flown proximity full-scale aircraft operations unless flyer has someone else him sole purpose watching full-scale aircraft supervising flying 88 prevent accident possibilities PROTECT YOUR RIGHT TO FLYI Safe Flying No Accident A4 TEL FOUR CYCLE ENGINE MOUNTS Cast oluminurrr alloy Ground 90 thrust tine Bsght polish finished Socket cop screws inCluded 600 BOO 1000 1000 1000 1000 1000 1000 1200 1100 1300 No JT-62OS MAX FS 60-75-901300 No JT-64ENVA 60-80-90-120 4C1300 No JI-65SAITO PA 651300 No JT-120 Uridrited 120 1600 No Jf-121 ENYA R 120 PC 1800 No JT-122 OS MAX PS 120 1800 No -123 SAITO PA 120 1800 No Jf-125 Super hgre 25-30001800 DRILLED AND TAPPED 1-20 OS MAX PS 20 No JI-40 Undnhted 21-40 Noll-Af t4PVT2f No JI-42 ENVA 35-40 AC No JI-43 SAITO PA 30 No JIM OS MAX PS 40 No J1-45 SAITO PA 40-45 No 1-46 ENVA 46 AC No JI-49 HP VT 49 No J1-60 Undnhled 60-90 No JI-61 OS MAX PS 61 available hobby shop ORDER DIRECT return UPS shipment John rorone ENGINE TESTING STANDS Steel restraining pins Cast Aluminum ton engine No jrrsr J1-rS2 rA 10 60Grant srze 10 25 1150 0 SIDE MOUNT MUFFLERS PillS CAP 21 CESSNA ISO etc No J-40P.No Jr40P 29-4045 60 15001800 2 EXHAUST EXTINSIONS NEO9STNE METAL-FLEXJr-N56 300 r JIM12 DIA GA350 JT-M34 OIA500JT-N58 OIA00 JT-M78V DIX600JT-N34 GA5 50 Jt-Q34 QUADRA 35 Jt-Z34 ZENOAH G-3B A-IDA ALTEC TED 2000 J1-Q3B QUADRA 25 JI-Q5B QUADRA SO JT-Z3B ZENOAR G-3B JI-M38 MAXI 30 2000 JI-Q SS QUADRA SO Jt-M35 MAXI 30 2000 GIANT ENGINE MUFFLERS Matched engine toil pe extensions mounting bolts included Also avaob4e ATLAS 46 BULLY COBRA EAWASAKI KIORtTZ SACII-DOMLER SUPER TiGRE 2500-3000 MAIL ORDER Please add 250 UPS shipping Check MO VISA MC COD accepted Add 200 extra COD Calil residents odd 8% tax -SEND FOR FREE CATALOGJT-Q3L QUADRA 35 JT-Q5L QUADRA 50 JT-23L ZENOAH G-3B JT-TDR ALTEC TED J1-M3R MAN 30 JTQ3R QUADRA 35 Jt-QSR QUADRA 50 JT-23R ZENOAII G-3B JT-M3L MAXI 30 Jt-Q54 QUADRA 50 JI-M34 MAXi 30 2000 arent improvement over AM sets PCM stuff shows some promise better times can lick 31M problem fly Canada can check 20 kHz column saw generally poorer performance 20 kHz spacing expected Hz column misleading got data using transmitters approxi mately equal power case PRS MRS power can up 400 times larger radios wide open interference Yet Ive noted before havent interference reports traced may save some letter-writing tell used old Ace RC Silver Seven built kit AM single-con version receiver tests Tables 2 3 4 Test 14 Simprop PCM-20 am withholding rest names because dont wish set myself up some kind consumers testing service will say 1984 1985 systems did what always work something out test tell you can donduct interpret own tests Now go has debate going about What 1988 Some folks favor splitting band FM-Only preserve Anything Goes area No doubt data will used support positions both sides argument same time may some will data hand start hunting FM scalps Now play nice boys No matter slice splitting band bound reduce number channels use due 31M problems would counterproductive future discussions FCC position remains wit Keep whole band open forms modulation FM can beand will have bedeveloped resist AM because AMA members wont abandon AM systems until/unless FM sets come market offer clearly superior per formance rejecting forms AM interference including dirt-bike ignition noise high-voltage transmission-line cor ona arcing lightning etc However smart thing now may change AMA Phase-k Plan way minimizes 31M Before closing column must ac knowledge help provided long time friend Bob Aberle collected some equipment spent hours performing tests discussing results Without Bob would have stopped writing column longtime ago also have thank Bill Hershberger has saying years 31M major problem must solved finally listened Bill must also thank Ace RC advertisers sug gesting 200-fcot baseline started us off expedition Kraft Systems providing synthesized RF modules make FM testing easy Tower Hobbies loaned us pair AM transmitters some special crystals made AM testing easier Thanks well friends entrusted us equipment test column has led us some unusual conclusions may stir up small amount controversy invitenay challenge disprove data and/or conclusions orderto will have work harder did will have put some hard test data table Opinions worthless analyses no better assumptions George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 responding advertisers mention read about Model Aviation RC Scale/Wischers Continued page 49 Large flying-type models emphasize realism air rather ground dominant rally dont see visitors creeping around knees examine finely-executed detail ing except few rare models Paul Weigand brought Toledo prize-winner K-W rally TA-size Culver Dart flies very well mildly aerobatic its Quadra 50 engine Toledo winners real ly fly Formed windshields Fastening simple sloping windshields curved direc tion can become battle stiff material fights remain flat Glue alone may hold throughout models life Heat-forming 031-inthick acrylic butyrate sheet takes fight out material fastening becomes simple process However windshield isnt formed shape fits closely gluing job can still quite frustrating preferred process begins paper template paper draped over fuselage windshield frame rough ly marked pencil determine ap proximate outline Fold paper along its centerline check equal shapes both halves cut scissors around outline Fit paper template fuselage satisfactory make sec ond third template until shape correct always folding along its centerline certain equal left right halves have never made paper template correct first time Next step duplicate template 010 litho-plate aluminum Form template bending using large-diameter wood dowels rolling pin kitchen fits fuselage Continued page 136 132 Model Aviation 2000 -4:
