AS WRITE THIS new year starting winter has set modelers around supposed building new airplanes next year could use about three new Speed jobs Id better get busy Control line booming club Tree Town Modelaires has almost doubled size should goodyear Ill try cover variety topics months column help prospective competitors still get letters questions modelers want buy make suitable bellcranks two-line Speed models fliers interested 21 Sport Speed Formula 40 have three four different ways fabricate bellcranks seem work type use just depends much work feel like doing simplest version Perfect #1 bellcrank setthe aluminum large brass center bushingor similar type available several other manufacturers have reduce its size will fit narrow Speed fuselage Refer Figure 1 suggested dimensions critical thing use brass grommet hole leadout cable Solder cable grommet acts like bearing pivots aluminum otherwise rough cable can soon wear enough fail point drop oil pivot points helps too mounting pin bolt should have smooth head prevent abrasion bladder fuel tanksits problem use metal tank Use /t6-inch-diameter pushrod short piece brass tubing glued fuselage about halfway stab prevent buckling can make allowances future removal bellcrank inspection repairs Figures 2 3 handmade bellcranks machined tool other steel use shown Figure 2 make sure use double loop lines guard against failure Put drop oil button lubrication between line bellcrank shown Figure 3 works very well Make sure brass bushing free rotate slot Insert removable shimstock spacer between bushing steel peening rivetsdont force bellcrank lips together disadvantage using bellcrank lines difficult changeit must dismantled Some modelers like round bellcranks have never liked quite large Speed models always have trouble fastening leadout cable bellcrank simple ones Ive illustrated work great People always asking can find inexpensive lathe milling machine can fly Speed such machinery necessary flier decent competitor course equipment would used make venturi spinner backplate commercial engines dont need milling grinding improve seems everyone CONTROL LINE thinks some secret head shape will instantly hop up engine Ive best luck stock heads good engines available now spare parts can ordered items like spinners can purchased several specialty shops want experiment build own engine good tools imperative merely want fly Speed dont bother spending big bucks things dont need Spend time building nicer airplane working better props test-flying SPEED re 1 shows modifications Perfect #1 belicrank set use 21 Sport Speed Formula 40 Brass grommet critical protection against wear Leadout cable soldered grommet Mounting bolt must have smooth head bladder tank used Oil pivot points Figure 2 shows alternate belicrank handmade tool other hardened steel author suggests double loops lines guard against failure drop oil provides lubrication between button line Figure 3 illustrates another belicrank setup used author Spacers placed between bushing steel rivets peened keep bellcrank lips open allow bushing rotate Disadvantage system changing lines impossible unless bellcrank disassembled years hop-up equipment set Swiss files still lot fun flying Speed Too modelers still think some secret place engine can go grinder instantly create monster just aint course have access equipment its lot Jim make parts make own engine certainly necessary competitive Conrinued page 122 May1993 115 Cut off excess e s/s I_ Brass grommet 11/4 - Wing Section Bend up Figure 1 bolt F1 e632 11/a2iisLI Ida0O dia /5 tool steel hardened Figure 2 Brass_ bush ng Line loop 1~ r F use 5/es larger steel rivets 030 slot / steel Figure 3 FF Indoor/Tenny Continued page 114 model characteristic spiral death seem have first time trimmed out could manage meager flight 630 before decided give up frustration wasnt until went Lakehurst Labor Day weekend tried agaln after adding Ultraflim pylon like transformed Chilton s model thought should have fixed prob lems didnt Later Stan suggested put rudder bottom boom move wing over partial turns half torque did nearly eight minutes after climbing 150 feet Stan gave 15-inch-long motor best tan rubber wound 2200 turns model staggered around first began long slow climb about 140 feet dead-sticked 927 immediately tried again 1000 turns broke motor getting dark guess Ill never know since model broken now also Precise joints Stan Chilton uses special fixture cut splices wing spars photo shows fixture open another shows spar place After spar place cut made parallel edge work table 4CL SpeedlLee Continued paqe 115 huve new airplane built try pick highly visible color finish Dayton Buzzin Buzzards have years complete records Speed contests compared stopwatch readings versus airplane color found three recorded times much closer light-colored airplanes dark ones Recorded times bright yellow airplanes consistently close white airplanes second Last fall Paul Gibeault FAI model painted neon orangethe brilliant fluorescent high-visibility paint thin sidewinder-type airplanes very difficult see speeds over 170 mph could easily timed Speed fliers racing modelers have asked what to engines switching high-intro fuel 10% stuff Im really positive what best have theory Im still experimenting should own test-flying see idea has merit ABC engine highperformance engines now fit shape sleeve piston critical parameters maximum speeds running 80% nitro seemed rule tighter better ran engines would squeak piston turned past compression best K&B 40s instance could turned over slowly prop could barely flipped over engine cold okay soon engine warmed up just little indicated coefficient thermal expansion brass sleeve greater high-silicon-alloy piston engines run much hotter high nitro fuels 10% sleeve going expand much reduce drag between piston sleeve reach high rpm piston fit should tight low-nitro fuel Does make sense Compression ratio another confusing issue switch high-nitro low-nitro fuel used run Hustad Roys Rattler high-compression trumpet head close almost touched piston flew high-nitro propylene oxide ignitor fuel Now low-nitro fuel seems engines just cant develop enough power compress air-fuel charge have run squish-band clearances 006 008 012 inch helps increase distance top piston face glow plug have allow engines rev higher rpm regain power Test-flying way find out exactly what engine needs go fast 4122 Model Aviation *
Edition: Model Aviation - 1993/05
Page Numbers: 115, 122
AS WRITE THIS new year starting winter has set modelers around supposed building new airplanes next year could use about three new Speed jobs Id better get busy Control line booming club Tree Town Modelaires has almost doubled size should goodyear Ill try cover variety topics months column help prospective competitors still get letters questions modelers want buy make suitable bellcranks two-line Speed models fliers interested 21 Sport Speed Formula 40 have three four different ways fabricate bellcranks seem work type use just depends much work feel like doing simplest version Perfect #1 bellcrank setthe aluminum large brass center bushingor similar type available several other manufacturers have reduce its size will fit narrow Speed fuselage Refer Figure 1 suggested dimensions critical thing use brass grommet hole leadout cable Solder cable grommet acts like bearing pivots aluminum otherwise rough cable can soon wear enough fail point drop oil pivot points helps too mounting pin bolt should have smooth head prevent abrasion bladder fuel tanksits problem use metal tank Use /t6-inch-diameter pushrod short piece brass tubing glued fuselage about halfway stab prevent buckling can make allowances future removal bellcrank inspection repairs Figures 2 3 handmade bellcranks machined tool other steel use shown Figure 2 make sure use double loop lines guard against failure Put drop oil button lubrication between line bellcrank shown Figure 3 works very well Make sure brass bushing free rotate slot Insert removable shimstock spacer between bushing steel peening rivetsdont force bellcrank lips together disadvantage using bellcrank lines difficult changeit must dismantled Some modelers like round bellcranks have never liked quite large Speed models always have trouble fastening leadout cable bellcrank simple ones Ive illustrated work great People always asking can find inexpensive lathe milling machine can fly Speed such machinery necessary flier decent competitor course equipment would used make venturi spinner backplate commercial engines dont need milling grinding improve seems everyone CONTROL LINE thinks some secret head shape will instantly hop up engine Ive best luck stock heads good engines available now spare parts can ordered items like spinners can purchased several specialty shops want experiment build own engine good tools imperative merely want fly Speed dont bother spending big bucks things dont need Spend time building nicer airplane working better props test-flying SPEED re 1 shows modifications Perfect #1 belicrank set use 21 Sport Speed Formula 40 Brass grommet critical protection against wear Leadout cable soldered grommet Mounting bolt must have smooth head bladder tank used Oil pivot points Figure 2 shows alternate belicrank handmade tool other hardened steel author suggests double loops lines guard against failure drop oil provides lubrication between button line Figure 3 illustrates another belicrank setup used author Spacers placed between bushing steel rivets peened keep bellcrank lips open allow bushing rotate Disadvantage system changing lines impossible unless bellcrank disassembled years hop-up equipment set Swiss files still lot fun flying Speed Too modelers still think some secret place engine can go grinder instantly create monster just aint course have access equipment its lot Jim make parts make own engine certainly necessary competitive Conrinued page 122 May1993 115 Cut off excess e s/s I_ Brass grommet 11/4 - Wing Section Bend up Figure 1 bolt F1 e632 11/a2iisLI Ida0O dia /5 tool steel hardened Figure 2 Brass_ bush ng Line loop 1~ r F use 5/es larger steel rivets 030 slot / steel Figure 3 FF Indoor/Tenny Continued page 114 model characteristic spiral death seem have first time trimmed out could manage meager flight 630 before decided give up frustration wasnt until went Lakehurst Labor Day weekend tried agaln after adding Ultraflim pylon like transformed Chilton s model thought should have fixed prob lems didnt Later Stan suggested put rudder bottom boom move wing over partial turns half torque did nearly eight minutes after climbing 150 feet Stan gave 15-inch-long motor best tan rubber wound 2200 turns model staggered around first began long slow climb about 140 feet dead-sticked 927 immediately tried again 1000 turns broke motor getting dark guess Ill never know since model broken now also Precise joints Stan Chilton uses special fixture cut splices wing spars photo shows fixture open another shows spar place After spar place cut made parallel edge work table 4CL SpeedlLee Continued paqe 115 huve new airplane built try pick highly visible color finish Dayton Buzzin Buzzards have years complete records Speed contests compared stopwatch readings versus airplane color found three recorded times much closer light-colored airplanes dark ones Recorded times bright yellow airplanes consistently close white airplanes second Last fall Paul Gibeault FAI model painted neon orangethe brilliant fluorescent high-visibility paint thin sidewinder-type airplanes very difficult see speeds over 170 mph could easily timed Speed fliers racing modelers have asked what to engines switching high-intro fuel 10% stuff Im really positive what best have theory Im still experimenting should own test-flying see idea has merit ABC engine highperformance engines now fit shape sleeve piston critical parameters maximum speeds running 80% nitro seemed rule tighter better ran engines would squeak piston turned past compression best K&B 40s instance could turned over slowly prop could barely flipped over engine cold okay soon engine warmed up just little indicated coefficient thermal expansion brass sleeve greater high-silicon-alloy piston engines run much hotter high nitro fuels 10% sleeve going expand much reduce drag between piston sleeve reach high rpm piston fit should tight low-nitro fuel Does make sense Compression ratio another confusing issue switch high-nitro low-nitro fuel used run Hustad Roys Rattler high-compression trumpet head close almost touched piston flew high-nitro propylene oxide ignitor fuel Now low-nitro fuel seems engines just cant develop enough power compress air-fuel charge have run squish-band clearances 006 008 012 inch helps increase distance top piston face glow plug have allow engines rev higher rpm regain power Test-flying way find out exactly what engine needs go fast 4122 Model Aviation *