Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE
Edition: Model Aviation - 1978/05
Page Numbers: 38, 39, 40, 41, 42, 43, 44, 96
Less work cheaper carving rubber-model props sturdy blades will spare soul-shattering experience self-destructing props striking ground U Jim OReilly toMake Laminate Three row Coupe Unlimited Wake field Asked about Rev-Up decal author assured us Rev-Ups Jim Finley promises will help climb think OReilly sheds welcome light front-ends HAVE YOU ever tempted try rubber power put off job carving prop past have carved number props became serious competition flying began hit ground under power occasion carved props soul-shattering experience After couple such disas ters near-misses began look better way 1969 built Coupe dHiver magazine plans called sheet balsa blades made up coffee can form blade roots dowel rod huh music wire prop dramatic reduction construction time few problem areas remained thing blade twist did give uniform pitch another hinge an38 Model Aviation Long knife necessary carving wide block knife has built-in template Incidentally note photo conveys impression pitch pic Lew Woolard others Bud Burroughs gles wire hub hinge holes through blade struggle make accurately theory could re place blades fact no way make identical After couple years evolved sys tem answers objec tions Part system borrowed buddies part stumbled onto part invented system less work carving far cheaper Replacement blades truly possible total front end assembly generally lighter carved var iety final bonus discover prop motor airframe new pride joy mismatched may possible salvage repitching prop bending wire hub Try wooden hub As limitations am aware Some rubber fliers feel formed blades will hold shape tends true non-lam inated blades certainly true laminated blades Some people shy away wire hubs difficult build ac curately answer drilled hole form block serves drill jig prop blade also align ment jig forming wire hub Carving Block form block its accurately drilled hole hinge line what sets system apart block may carved pine fir spruce may poured polyester auto body putty plaster Dave Linstrum has published Coupe dHiver built-up form block made balsa sheet strip Actually built-up block adequate forming blades may BLADE PATH FOR ONE REVOLUTION AT INNER SECTION TIP // / ________ IG BLADE PATH UNROLLED AND FLATTENED AT INNER SECTION AT TIP PITCH DISTANCE PROP TRAVELS FORWARD . DISTANCE TRAVELED AROUND IN ONE REVOLUTION INNER SECTION BY TIP L LBLADE ANGLE AT TIP BLADE ANGLE AT INNER SECTION PITCHINCHES1820 22 24 26 28 RADIUS r- INCHES573 637 700 764 628 891 JPCkne LAYOUT BLADE DIAGONAL LINE ON BOTH SIDES OF BLOCK CENTERLINE OF THRUST d Prop Blades rugged enough use jig hub unless reinforced pouring full resin point neednt let carving throw must first decide type prop twist use Helical constant pitch simplest successful models using type twist other explain term see Fig 1 consider 20-in pitch prop propeller turned exactly revolution advanced sections blade twist exactly line airflow its pitch said 20 inches propeller has advanced ex actly 20 inches revolution helical constant pitch prop blade sections have same pitch root tip other hand Schwartzbach prop currently popular style prop has higher pitch root tip done cause air does simply flow straight line through prop speeds up FIG 2 B~----K7-4 TURN BLOCK UPSIDE DOWN AND ACCURATELY SAW THIS LINE CARVE FROM CORNER TO CORNER LEAVING SLIGHT CROWN May1978 39 FIG 3 SCHWARTZBACH PROP FORMBLOCKS DIAMETER XPITCH 175 X22520 X 2422X2724X30 WIDTH 1 HEIGHT WIDTH HEIGHT WIDTH HEIGHT WIDTH HEIGHT RADIUS f @ISOhJ@338w @ISOh @338w @I50h @338w eI50h @338w 29__J_____272322 269635551 31091008882 4154140123112 5201184160145 6251229200180 7301275240214 8352144I 322158282249 875I 389130 9369137323286 10 417122366 139322 II387131359141 12396128 LAYOUT BLADE AND CURVED LINE ON BOTH SIDES OF BLOCK twists flows inward passes through prop disc pitch Schwartzback prop measured 70% blade radius Thus Schwartzback prop 20 inches pitch would actually have pitch 20 inches center 70% out less 20 inches 70% tip small advantage prop effi ciency Schwartzbach pitch used ever work tied up lamin ated Schwartzbach props build sizes because helical props diameter may made block particular pitch provided block long enough contrast Schwartzbach prop say 15-in diameter 20-in pitch will require block 18 inch dia 20 inch pitch will require another actually less work sounds because normally pitch selected prop 12 14 times great diameter can cover entire range Coupe Unlimited per haps three four blocks event select pitch distribution proceed construction both types will covered Fig 2 gives dimensions helical form blocks Fig 3 shows Schwartzbach use Fig 2 take following example lay out 24-in pitch block read radius 764 inches chart ra dius sloped portion block completed will twice wide high Lay out block centerline both bottom top surfaces block Measure block thickness lay out distance t both sides cen terline radius 764 inches shown Fig 2A both top bottom sides block Now draw di agonal lines centerline thrust through points t repeat bottom block Did diagonal lines run off sides block Fig 2A either get wider block 2 6 means carving else plot lines sides block shown Fig 2A equation h pitch X block width radius X 6283 24-in pitch prop 2 4 happens 340 wide height 11 inches radius h 340 11 X 6283 118 inches math problem try flying buddy happens math teacher engineer accountant what ever else fails send desired prop diameter pitch exact dimensions chunk wood along self-addressed stamped envelope Ill send sketch num bers Schwartzbach props select size want plot shown Fig 3 difficulty will probably appear Fig 3 based 2 4 measuring exactly 150 inches high 338 inches wide 40 Model Aviation Farm blocks templates Templates either thin cardboard plywood photocopy blade drawing glued surface Two types blanks shownsee text details 2 4 will likely slightly different width height both Simply multiply numbers width column ra tio block height 150 inches example block actually 148 inches high divide 148 150 obtain 99 Multiply numbers width col umn 99 same way block exactly 338 wide multiply numbers height column ratio block width 338 close width 01 02 inches can ignore step little difference careful backwards block high wide will multiplying number like 98 99 block bigger rather smaller multiplier will like 102 104 either type block has plotted saw Fig 2B Since blade light hobby saw will wander badly turn block upside down saw because its bottom line needs accurate Finally carve block Fig 2C use sharp hunting knife concave back use back blade gage carving complete shown photo leave slight crown because its less work carving down straight line cause want blade camber two schools thought blade camber enough evi dence conclusive believe flat-bottom blades will outperform undercambered blades Ron Roberti Nor man Oklahoma under-camber school thought Ron laminates blades uses narrow strip 1/32 balsa glued face block form camber blade After carving have option sanding finishing form block extra steps necessary can see photos blocks nearly carved little sanding no filling paint ing carving sanding done hole hinge line can drilled use skewed hinge line blade rolls folds ends up less parallel fuselage Theoretically skew angle should half angle widest part blade simply use 100 skew angle its always within degree two far hinge line located prop centerline also important Too close blade will fold back hit fuselage before reaches streamlined position Too far out gap will remain between prop fuselage necessarily bad some fliers feel gives lower drag folded safe locate hinge points half-inch further prop centerline half width fuse lage Refer Fig 4 drilling hole hinge needs skewed 10 degrees both front end views First mark blade centerline block shown Fig 4A mark point representing BLADE CENTERLINE CONNECT MIDPOINTS AT EACH END AS SHOWN HINGE POINT FROM BLADE TEMPLATE NSUPPORT BIT IN NOTCH IN EDGE OF WORK BENCH May1978 41 Farm blocks blade components before laminating perhaps 50 cents worth balsa plywood picture balsa block carved prop blade can run upwards $3 blade hinge point Make up two tern- board tablet backing tape plates 10 degrees 80 degrees 900 block shown Fig 4B Drill hole less 100 stiff material such card- 1/32 larger wire diameter plan use hub Buy long bit dont have drill hole clear through block ruin hole 44 050 CII 00 zz 0N4 NN5 0 LUz 0 0 LUN 0 z LU S10-JI 4LULUrn LU0-JD 0 ma wDO 0 0 LUH I zm H0 4 LUL \W\\ \ LU HH z 0 0 LULU 0-0 z4 -1-I-J m LC 6 E LU z LU H z LU 0 0 42 Model Aviation dont worry can shove birch dowel Hot Stuff place redrill hole As regards accuracy very im portant hinge line skewed ex actly same angle both end front views angle same both views blade tips will meet fold may show separation side view much inch two block drilled checked blade outline should marked block Make blade templates tablet carboard plywood using blade shapes shown Fig 5 Lay template block carefully lining up blade centerline checking see blade correct distance cen ter Mark around template block soft pencil marking pen After cutting piece brass tubing bit longer hole same diam eter ready proceed making front end assembly Making blades blades use layers 1/16 balsa 1/32 birch plywood re inforcements blade root Two layers 1/16 balsa adequate largest props 24-in diameter prop run ning 16 strands inch rubber should probably have third layer 1/16 balsa strength toward blade root made prop two layers 1/16 balsa layer 1/64 birch plywood back side happy results ply did want lie smoothly block furthermore 1/64 plywood adequate rein forcement hinge However can see possibilities materials Coupe use soft medi um balsa medium hard bigger models back layer should least medium hold reasonably sharp leading trailing edges Cut re quired number layers both blades well plywood doublers Cut front doubler outline shown Fig 5 back doublers cut oversize three sides easier balancing cut both back layers same sheet both front layers etc Sand feather edge doublers indicated Fig 5 ready begin laminating first step preform bal sa layers both blades minimize blade untwisting after laminating step optional hurry preforming blade will untwist 2 degrees after laminating Without preforming will untwist much 3 4 degrees minor effect sneaky about drill hole about later However pos sible minimize untwisting Take balsa layers both blades soak hot water little ammonia added Strap whole stack block rubber either let dry bake oven 1750 F laminate blade glue dry balsa layers plywood doublers Titebond A 90 USE THE BLOCK AS JIG FOR THE HUB ASSEMBLY WITHOUT THE SHAFT SOLDERED ON AS YE THE DIHEDRAL ANGLES SHOULD BE EQUAL WHEN HUB IS VIEWED ENDWISE AFTER THE SHAFT IS SOLDERED ON IT SHOULD MAKE 90 ANGLE IN BOTH SIDE AND END VIEWS SIMULTANEOUSLY AS SHOWN ABOVE CHECK BOTH ENDS OF Z HUB ZK equivalent strap onto formblock rubber Make certain stack lies within marked blade outline Either go easy cement protect formblock kitchen plastic Excess cement rear doubler may squeeze out dry blobs out-of-sight back surface haunt later no longer use plastic Instead carefully apply uniform coat Titebond FIG 6 WIRE HUBS 100 RADIUS Z HUB FOR 175 IN DIA PROP IN FIG5 125 IN R HUB FOR 20 IN PROP 138 IN R HUB FOR 22 IN PROP 150 IN R HUB FOR 24 IN PROP will squeeze out edges espe cially careful near feathered edges back doubler dont use oven speed drying others Now drill hole Remove brass tube formblock strap blade rubber outer onehalf blade Observe angle untwist mentioned above Carefully re strain blade left hand May1978 43 Blade assembly strapped block glue dries possible use masking tape elastic bandage instead rubber strip Note ply hub reinforcement piece already place running drill right south-paws standard conversion Apply very light pressure drill restrain blade such remains un twisted drilling procedure will confine inacurracy inner less important part blade Trim off excess edges back doubler carve sand blade airfoil shape shown Fig 5 Cut piece brass bush ing reinforce hinge hole should about /i 7/16 inches length Epoxy Hot Stuff place blades can doped can covered tissue silk Ive done three ways generally use tissue Coupes dope Unlimiteds silk Wakes Hub Assembly hubs shafts use either 1/16 3/32 music wire 1/16 wire good up 14 strands Y4-in FAI rubber pretty torky stuff note Bob Whites Godfather published showing 1/16-in wire hub 16 strands Pirelli cant argue success thus far have used 3/32in wire 16 strands Bend Z hub per plans Fig 6 Bend flat twist skew angle extra bends middle part serve blade stop front blade overhung reason other Outrigger blades meet middle alleged inefficient because inner blade end tends act like additional wingtip Extending inner blade tips nearly gether should improve situation worst cant hurt Bend up shaft 900 bend about 5A inch length Take pains get near 900 possible Bind 7 hub shaft together fine iron wire about 010 inch diameter Center shaft hub closely possible Sweatsolder joint Use best rosin core solder can get finish aligning shaping hub put brass bushing back formblock insert end 7 hub shown Fig 6 Rotate hub until shaft forms 900 angle bottom block shown sketch Look also 900 angle end view Note angle other 900 correction later Remove hub insert its other end repeating checks above will able tell dihedral needs twisted 7 hub less will able tell shaft coming off Z hub correct angle Also will able tell Continued page 96 Chemical Milling powder mixed water forms acidic solution concentration easily changed addition either water powdered Ph-minus Add little powAn easy method rem Ovifl der time water mix Check THIS PROCESS simple requires method masking areas should have metal removed weak acid solution process chemical milling also contest proven safe have using FAI speed models several years have problems cracked pans although planes have hit ground hard several times have shaken apart screaming Rossi engines counterbalance one-blade prop attached engine process has numerous applications noteworthy weight conscious fliers FAI Speed Team Racing power Free Flight magnesium en gine mounts used frequently AMA speed fliers also can benefit chemical milling correcting tail heavy airplanes use heavy full pans actual process will describe applied two Darp A-size pans will used control-line World Champs models Step 1 Apply good quality masking tape areas desire have metal removed photo #1 masking tape applied area being accentuated black inked lines Pans material magnesium castings U Charles Lieber Step 2 Dip entire pan molten wax allow wax harden Photo #2 Step 3 sharp razor blade cut through wax surface pan around area marked care fully pull back masking tape area will milled should now free wax other areas should covered wax will protect acid solution photo #3 pan-i has wax stripped away area milled pan-2 still com pletely covered wax Step 4 now ready actual milling Find either glass plastic con tainer object will fit Fill enough water cover area milled go local depart ment store sells poo1 chemicals purchase some Ph-minus solid strength solution placing pan etc solution observe rate reaction bubbles fairly slow rate about right CAU TION make solution too strong will produce enough heat melt wax mask off pan ruin everything Photo #4 shows pan acid solution undergoing good reaction pan has reached desired weight thickness etc remove solution wash off dry remove wax hang pan 2000 F oven dish underneath catch wax will melt off about 10-15 minutes Photo #5 shows two pans after chemical milling removal wax slight roughness surface may noted easily removed 80 grit sandpaper photo #6 shows fin ished product Any questions concerning simple effective process can addressed Charles Lieber 725 Signal Light Road Moorestown NJ 08057 44 ModelAviation Drilling hole hinge Note restraint being applied aft edge blade Hing ing alignment always troublesome article describes procedures accuracy KITS PLANS SSORIES 5417 ME 17 SPAN STOCK NO PP 13 KIT $425 ASK POE OUR KITS AND ACCESSORIES AT YOUR LOCAL DEALER P NOT AVAILABLE AT TOUR DEALRR ORDER DIRRCT ADD 60R POSTAGR BROWN CO-2 ENGINES ENGINES ARE IN STOCK NEW CHARGER AND 5 SIZES OP TANKS BROWN ENGINES MUST BE ORDERED DIRECT PROM PECKPOLYMERS WALNUT SCALE KITS BABY ACE$425 PSANUT SCALE KITS PIPSR J3 CUB$329 PIETENPOL$329 MILES$329 TURBULENT$329 MUSTANG$349 ZERO$349 COUGAR$349 ANDESASON$349 GIPSY MOTH$349 GANAGOBIE$349 SPORT MODEL KITS ONE NITE 28 $475 ONE MITE 16$349 STRINGLESS WONDER$249 PECK BOG$139 KITS S PLANS 0 ACCESSORIES REAL JAPANESE TISSUE-PROPS COMPLETE CATALOG 50 MANY HARD TO PIND ITEMS P 0 BOX 2498 -AMA LA MESA CALIF 92041 PHONE 7141 469-4673 o 7141 4424636 CUSTOM TUNED ENGINES I COMPETITION ACCESSORIES Cox 0491051 SpecialistsPARASOL brochure send 13e stamp Kustom Krattsmanship BrochureMODERNISTIC MODELS Box 2699 Laguna Hilts CA 92653 714 830-5162PO BOX 6974ALBUQ NM 87107 49-cc engine no exception three versions have common dimensions except diameter piston What means could use rear intake crankshaft/front end back door 65 58 case/pis ton/liner have rear rotor 58 have talked John Brodbeck K&B told rear-rotor 58 49 available special order dont expect youll see item advertised distributed through dealers since will small quantity item engine available engine manufacturer rear rotor requirement make legal AMA Slow Rat under new rule So have another engine consider next Slow Rat design 1978 National Championships will back Lake Charles during week July 30 through August 6 us live area quite excited about since Lake Charles friendliest places Nats has years schedule racing quite similar previous years exception will no Mouse Race will sit well Y2A fans history participation doesnt justify flying event year However bring along Mouses ay will flying unofficial Mouse event Tuesday same day FAI Team Race will plenty time space available Trophies will supplied al though writing Im sure will sponsor event enough interest unofficial event perhaps next year will back schedule summarize Open events will Goodyear Monday Rat Thursday Slow Rat Saturday Junior Senior events will held together Goodyear Wednesday Rat Friday morning Slow Rat Friday afternoon mentioned FAI Team Race unofficial Mouse Race Tuesday Rules Change Cycle Some people Ive talking have thinking about possibility longer cycle rules changes current two years felt present cycle period doesnt allow full impact rules felt time initial change proposal deadline has passed Adding year cycle would give competitors two items First stable rules will diminish frequent changes result obsolete equipment Second will chance fly rules longer period fore becomes too late supply needed corrections feeling out would support idea write AMA district VP. Contest Board member Let feelings known W R Lee 3522 Tamarisk Lane Mis souri City TX 77459 Laminated Props/OReilly continued page 44 shaft centered along hub After round checks rebend reposition required solder joint will almost cer tainly break dont worry will resolder easily After resoldering check again see joint didnt slip soldering Install blades hub retain wheel retainers available Carl Goldberg 3/32 wire Goldberg Sig 1/16 wire Pull both blades forward thrust position blade stops will prob ably prevent going way forward Trim blade stops until both blades 906 prop shaft Note placement hinge point behind blade centerline makes props flare higher pitch during power burst possible increase decrease flare trimming blade stops may now complete front end assembly using design choice generally use ordinary ten sioner stop such find major ity contest rubber jobs flying note caution may order flying short-nosed model has blades folded overlap wing leading edge tensioner stop will sometimes disengage yet turn tip will hang up wing lead ing edge other will hang down spoil glide trim Montreal stop usual fix problem will adapt wire hub Bob White/Hank Cole stop described Bob Meusers col umn May 76 Model Aviation may answer am trying version standard tensioner stop small 032 wire hook instead usual stop screw So far has given reliable performance would delighted receive questions comments readers article address 4760 N Battin Wichita KS 67220 FF Duration/Meuser continued page 47 ited Rubber models flown under suddendeath rules flight no-max time limit As January result recent rules change Unlimited Rubber will henceforth forevermore known Mulvihill Event pox Contest Directors magazine wri ters modelers AMA Headquarters personnel ever refer otherwise Well thats pretty long-winded way lead announcement George Perryman won Mulvi-Mulvi event King Orange Internats Mulvi hill-Trophy-winning Great Speckled Bird shown December issue first time GSB has won such contest foggy drizzly George afraid model might climb out-of-sight low-lying clouds wound about 70% maximum turns GSB landed 531 tree top Georges score followed 7-sec intervals Jim Lewis Phil Hartman respectively Phil sponsored event have other good news about Georges GSB professional ethics demands keep awhile chances good will Mulvi-Mulvi event real Memorial Day Classic Taft year provided can get out sack early enough run George allows has new design up sleeve Im sure want know about current designs enough make strong men cry 96 Model Aviation FL WIT* ~#5fR CU3 PU WIN .t WALNUT SCALE