Radio Control: Helicopters

SERVO ROTOR PIVOT TO SWASH~MAIN ROTOR PITCH R PIVOT AXISj CH TO FLYBAR PADDLES PUSHROD TO SERVO ROTOR CAGE L0 iO ILL CONTINUE discussion begun February column flybars rotor modifica dons look mixing direct rotor control control servo rotor seems \ SERVO ROTOR FLAPPING CAUSES MAIN ROTOR CYCLIC PITCH CHANGE TO EACH BLADE SKETCH 1 SERVO ROTORCOLLECTIVE CAGE PIVOTS CONTROL ARMON FLYBAR PIVOT AXIS FOR SERVO ROTOR MAIN ROTOR_ _-u PITCH ARM TO ROTOR BLADE PUSHROD TO SERVOCYCLIC PITCH TO PADDLES ROTOR FROM SWASH PLATE SWASHPLATE COLLECTIVE ILEVER DOWN SLOT SHAFT SKETCH 2IN PIVOT AXIS FOR MAIN ROTOR accepted practice some newest ma chines review some things mentioned over past few months regarding rotor blade servo rotor flybar control Ill start again swash plate will recall swash plate device rely transmit motion stationary servos pitch changes main rotor blades some RC Helicopters swash plate used transmit both collective pitch changes cyclic pitch changes directly main rotor blades example given simple two-bladed rigid rotor head swash plate could raised lowered along main rotor shaft give collective pitch yet tilted transmit cyclic changes well simplify things showed example swash plate could used transmit cyclic control flybar servo rotor turn controlled main rotor cyclic SKETCH h Last time found flybar controlled following rate main rotor changing either diameter flybar weight paddles following rate could adjusted faster following rate lengthen flybar lighten paddles slow things down shorten flybar add weight paddles found discussions main rotor systems direct input swash plate pitch arm main rotor blade has advantage very fast response case rigid rotor head very simple linkage swash plate rotor head following rate main rotor controlled primarily weights fixed tip blade mass spinning high rpm could made highly effective gyroscope fact may recall article American RCs rigid rotor Revolution gyroscope could made effective aerodynamic force available would enough overcome gyroscopic properties selection tip weights rigid rotor flybarless Helicopters can criticaltoo much weight too little control too little weight no Continued page 112 SHORT SIDE TO SERVO ROTOR COLLECTIVE CAGE LINK ALSO TRANSMITS COLLECTIVE TO MIR MIXER BELLCRANK PIVOTS ON ATTACHMENT POINT OF M/R PITCH ARM LONG SIDE TO SWASHPLATE LINKAGE TRANSMITS ONLY CYCLIC FULCRUMj CYCLIC IN COLLECTIVE CAGE/SERVO ROTOR CYCLIC COLLECTIVE/ PIVOT FOR COLLECTIVE.CYCLIC OUT AND SERVO ROTOR 1.*PIVOT FOR CYCLIC FROM SWASHPLATE M/R PITCH ARM ATTACH POINT TO CYCLIC SWASHPLATE $*CYCLIC OUT NOTE SHORTER MOMENT ARM ________________FULCRUM FOR CYCLIC FROM SWASHPLATE KCYCLIC IN FROM SWASHPLATE April 1 981 41 Control Helicopters Dave Chosney darker wood such redwood outstanding effect Redwood alone can used carves easily often splinters unwanted direc tion Full-size wooden props commonly made birch light color close-grained take good finish Its hardness makes difficult carve Carving simulated metal propeller such Hamilton Standard requires some extra effort blocks center section hub carved turned lathe cylindrical shape desired diameter After carved same wood prop start half-blade pattern cut cardboard traced onto basswood blank exact length width dimensions hole drilled its precise center engine shaft front view shape cut aug coping saw Pencil guide lines drawn curved outline surfaces indicate desired thickness tapering toward tip material removed front rear surfaces down lines using jigsaw blank now ready hand carving use X-Acto handle number 26 blade special wood carving tools may superior rear surfaces carved flat across corners produce constantly changing pitch hub toward tip Front surfaces carved airfoil section Exact pitch really important since flying prop shape cut saw will determine pitch knife used bring shape its final form very little sanding required bring blades down equal thickness fingertips will tell much eyesight Time spent up point will less hour carving sanding Have no regrets must discarded because doesnt look right purchased flying propeller can used pattern blade thickness airfoil front view will likely correct nor will portion blade near hub Model flying props usually have sharp unfinished edges near hub seen full-size hub thickness reduced comparison scale prop will have hub thickness nearly double typical store-bought prop three-blade controllable-pitch prop made individual carved blades cemented hub easier carve two-blade prop cutting through center afterward since blade can held carving other hub much time-consuming blades main hub lathe-turned birch dowel individual blade hubs cemented 1200 positions over layout drawing accuracy same drawing can used cementing blades using angular block check ing pitch Finish similar used model Bass needs very little filling because its close grain simulate metal fill auto primer sand smooth surface after complete prop can painted varnished lacquered finish wood prop use clear dope Bob Dolly Wiseher Rt 1 S-221 Lapham Peak Road Delafield WI 53018 RC Helicopters/Chesney Continued page 41 stability flybar appropriately designed main rotor blades need weighted Again flybar controlling following rate main rotor have two gyroscopesthe main rotor servo rotor Since cross right angles pivot axis servo rotor pitch axis main blades parallel due gyroscopic precession servo rotor accounts extra degree stabilitypar ticularly main rotor has upset wind gust both methods controlling main rotor cyclic pitch have advantages Little wonder now Kavan chose control Jet Ranger using both direct input main rotor blades input via flybar way understand early Kavan Jet Ranger used weighted flybarthe paddles aero dynamic dampening came later Kavan married Bell rotor system Hiller servo rotor system applying stub rotors place weights course simple linkage two pushrods swash plate main rotor head became three since cyclic control applied servo rotor see Sketch 1 since swash plate raised lowered servo rotor paddles also changed pitch later device shown sketch added prevent collective changes affecting servo rotor still allowing cyclic changes Meanwhile some other Helicopters pro duced allowed tilting swash plate swash plate did raise lower Continued page 116 Fine Quality Flying Models 98 RUBBER POWER KITS plus Gliders C/L R/C Accessories Books 4 44 MAJESTIC MODELS 3273 West 129th Street Cleveland Ohio 44111 112 Model Aviation Catalog $150 WILLIAMS BROTHERS 1A IBYACCESSORIES RNASCALE SCALE PILOTS E WHEELS CONTROL-LINECYLINDERS ENGINE KITS MACHINE GUN KITS FREE-FLIGHT STIC DISPLAY MODELS SEND $1 FOR COMPLETE ILLUSTRATED CATALOG DEPT MA 181 PAWNEE STREET SAN MARCOS CA 9 /3 , NEW US Y M15COUGARMUSTANG PIETENPOLGIPSY MOTHZERO PIPER CUBGAHAGOBIEMILES M18 ANDRESONDRUINE COMPLETE C#TqtX $100 HARD TO FIND ACCESSORIES KITS AND PLANS FOR RUBBER POWERED MODELS MESA CALIF • Peck-PIyme6s O BOX 2458M 92041 PHONE 714 4698675 o 714 4424638 Ultimate Flying Boat 1Ii MAN WIDGEON MR Gs PRODUCTS 1010 Gratiot Box 161 Marysville MI 48040 THE RISING STAR IN GIANT SCALE ENGINES 4q% 4 K K K K K K K 0 Sealed Points 4 W~PAYSUPRNG ON PRE-PAID ORDER K* K** K K ** K ** Exhaust Manifold Velocity Stack Kits Available * * * * Dealer Inquiries * * Welcome ROUSH MFG P0 Box 251 Sandyville OH 44671 Ph 216/866-9462 216/484-4374 OUR AIM IS TO KEEP SPORT FLYING SPECIALIZING IN OT FF KITS AND ENGINES FOR THE COMPETITOR WE HAVE THE HOT EQUIPMENT a. u1- 44U 2264625 WE BUY OR TMtE OW ENGINES ANt KITS STOP PROP BRAKESWEVE EXPANOEOI ATD Brake Kit no 101 $275SCALE DRAWINGSPHOTOS BOOKLETS FAI CABBrake Kit no 102 $325 BcBrake Kit no 103$375 1 ea size $8503 FAI size $850 used Kit no 102 PA Residents Add 6% Sales TaxREPLA-TECH -INrERNAToNAL K&W ENTERPR ISES 7824 Lexington AveCATALOGS $20048500 MO 5NZ5 Philadelphia Penna 19152VCA 058005 8498 therefore used transmit Collective pitch Commands rotor head Instead either pushrod running inside hollow shaft wire rod running slot along outer diameter main shaft used Helicopters both cyclic collective pitch available mixed Kavan Jet Ranger see Sketch 2 might recognize example Heliboy beginner head Later Sketch 3 shows mixers added make system comparable Sketch 1 exceptionno other linkage required pre vent collective pitch changes servo rotor since seperate cyclic collective linkages already used So see both direct control servo rotor control may applied main blades little mixer usually set majority authority servo rotor remember Larry Axelson reversed mixer ratio see February column Larry felt shortened flybar Heliboy sluggish slow follow rate mixer change brought things back line thats end line See next month Dave Chesney Rt 9 Box 62 IA Greensboro NC 27409 Bristol Scout/Iltzsch Continued page 44 rigged interplane struts time go ahead cut shape finished interplanes closely possible stub fitting drill through carefully centered the stub area 5/64-in drill Remove wings drill out spar stub ends 7/64-in clear 4-40 bolts Tap 4-40 threads copper wing center section fuselage stubs Put wings 24 cu inch 32 HP BON RPM 6A lbs 3 Ring Pisten Ball Bearings Crank back insert 4-40 x -in bolts through point Fit requiredso wing stubs go out bolt goes through tightens difficulty Control system following description control system general should help clear up some slightly nebulous points various constructions relating control functions Rudderpushrod servo rudder pedal use ball socket links best Locate link rudder pedal close possible point connection control cable otherwise differential rudder will result Run cables rudder pedal under seat Nyrod-covered bearing bar back rudder horns elevator wires run servo arm side arm under bearing bar lower ones run out side fuselage exit points noted plan lower end elevator horn upper cables after leaving bearing bar run over small pulleys Proctor top fuselage top elevator horns small tumbuckle upper cables adjustment per full-scale also desirable have some sort adjustable clevis side servo output arm should give needed adjustment trimming elevators Du-Bro # ill threaded coupler clevis clip will job alleron controls consist bellcrank assembly amidship shown plan Run pushrod side long servo arm side long arms center bellcrank Make up short rods connected short ends bellcrank using ball socket connections out through fuselage side about -in eye formed outside fuselage eyes connected eye-end rods running lower wing aileron bellcranks 2-56 bolts lock nuts top wing cable connects two top aileron bellcranks hook disconnect under center wing center section upper lower allerons con nected cable small tumbuckle bottom end will give some adjustment needed balance ailerons Remember aileron circuit runs contin uous circle example right torn command will pull left aileron down connected upper aileron will also pull down through wire connection upper bellcranks will ralse upper right aileron turn pulls up lower aileron type rigging quite reliable also allows disconnec tion removal wings pairs upsetting fixed rigging parameters Rigging may carried out either before after painting wings Probably best done before dismantled painted final-rigged later Rigging critical take time follow directions listed hereafter should have no difficulty Remember wings stay rigged pairs Field assembly consists plugging wing stubs fixing place 4-40 x -in bolts connecting upper aileron wires affixing drag lines Assemble strut rigging fittings points wings Use Proctor fittings make up own desired flying wires double landing wires single Use Proctor #3C turnbuckles points indicated scale size confirmed factory drawings rigging recommend use Proctor heavy duty rigging wire next step set fuselage level position have incidence gauge highly recommended wing center section should 116 Model Aviation 1 YEAR WARRANTY WARRANTY OR SERVICE WORE CAR RE DORE EV Rouse RIFE OR CT YOUR NEAREST ECRO-EIORITZ PRODUCTS DEALER 4$ 4 PLANES E Erwin Rd BOATS lex 227 CARS - wwart osuoi TRAINS