Control Line Navy Carrier Dick Perry THE SERIES basics Navy Carrier model ing continues month Aprils column dis cussed three-line control systems handle bellcrank month discussion control systems starts belicrank goes forward engine L-R Products 7787 Archdale Detroit MI 48228 bellcranks described April issue available four configurations Three configurations shown accom panying photograph bellcranks come elevator pushrod either inboard outboard outboard configuration compact appropriate installation narrow fuselages other confined spaces configuration pushrod inside circle offers less-cluttered installa tion since throttle elevator pushrods separated greater distance factor becomes important bellcrank installed throttle arm toward rear model upright inverted designations used describe bellcranks refer configuration ofthe throttle arm relative belicrank mount assumed throttle arm will forward beilcrank mount engine side applications standard counterclockwise installation upright beilcrank would mounted top side bellcrank platform model order have throttle arm toward engine An inverted bellcrank must mounted below bellcrank platform place throttle arm toward engine mounted standard maimer up right top inverted underneath pull throttle lever handle will produce pull throttle pushrod model Before deciding type bellcrankto buy particular model must decide whether pull throttle lever handle will open close throttle engine purely matter personal preference whether pulling throttle lever toward flier opens closes throttle majority Carrier modelers set up control systems throttle open high speed throttle lever pulled toward flier pull open push close configuration allows first finger assist carrying pull model during high-speed flight addition opening throttle comes rather naturally Up elevator should both needed hurry Another factor consider deciding whether install upright inverted bellcrank direction motion required open throttle engine Most throttles have control arms can put variety positions relative throttle barrel feature allows modeler change position throttle arm 1800 reverse direction travel required open throttle front-intake engines also possible rotate carburetor 1800 its mount reverse direction travel usually possible select throttle-arm position maximum con venience engine control installation Select configuration easiest build Although throttle arm bellcrank usually side bellcrank toward engine design model may such would convenientbecause pushrod routing engine tank location etcto have throttle arm rear bellcrank Again either configuration acceptable pick installation easiest summarize four factors consider determining whether use upright inverted bellcrank sake discussion assume standards listed following table apply starting point Mounting Handle Engine Bellcrank Bellcrank above platform Pull open Pull open Throttle arm forward factors particular model same summary above upright bellcrank required change factors list causes change type bellcrank required Therefore no changes two changes four factors changed upright bellcrank needed change three factors change inverted bellcrank appropriate As example ifthe engine characteristics such pull closed throttle other factors remained unchanged inverted bellcrank would needed addition engine change bellcrank mounted under mount upright bellcrank would needed though bellcrank placed under mount What matters combination factors making up total installation L-R bellcranks have total travel throttle arm 1 throw appropriate extending length carba throt tle arm possible match throttle pushrod movement available bellcrank requirements carb An exact match provides smooth accurate con trol engine speed reduces mechan Ical stress carb parts exhaust-slide applications majority commercial carburetors have throttle-arm movement about ismatch throws can put excessive loads carburetor cause potential control problems extremes throttle travel addition mismatch throws increases sensitivity throttle inputs pilot making harder set engine speed precisely opinion easiest way overcome problem throttle travel mismatch extend control arm throttle use /32-in-thlck brass attach extension 0-80 machine screws nuts screws small enough fit intheA6-in holes throttle arm drop glue Loctite prevents screws vibrating loose 0-80 screws nuts common item hobby shops cater model railroading using extended throttle arm carburetor sure new arm remains well clear propeller especially Taipan other brands have blades extend aft propeller hub Next time subject will switch engine speed-control systems also hope resume Mystery Plane feature soon drawing board didnt survive move South Dakota hope have repaired before next column due Richard L Perry 10035 Deadwood Ave Ellsworth AFB SD 57706 June1987 77 Products three-line belicranks come variety configurations suit various needs Elevator pushrods can originate either side crank inboard R out board L difference btween Upright Land Bottom inverted Top belicranks explained column KEEP CL MODELS AWAY FROM POWER LINES