HELICOPTERS Dave Chesney LAST month began review similarities RC helicopters RC airplanes Briefly airplane helicopter forward flght respond control inputs three basic flight controls much same way once youve mastered hovering helicopter progress forward flight things get little easierhut now helicopter flights should begin end transition through hovering flight So now leave airplane cloud dust quickly moves down runway lifts off relentless pursuit forward flight other hand will struggle learn make helicopter lift off hover please dont hover dirty air long fine particles picked up rotor mixed engine exhaust will cover machine excellent abrasive compound Choose flying site care fully use engine air intake filter clean up helicopter after flying As remember last month discussed briefly collective cyclic controls helicopter beginning fixed pitch helicopters remember proper term fixed collective pitch helicopters fixed collective pitch main rotor systems have variable collective pitch mecha nism Yes tail rotor uses collective pitch order vary thrust tail rotor provide yaw control tail rotor collective comparatively simple device since required move both blades collectively negative pitch positive pitch spin Usually instructions given helicopter kit will note approximate neutral pitch setting tail rotor collective hover thrust provided just enough overcome torque Differences main rotor pitch engine speed combinations plus other factors will mean neutral setting will probably never perfectly balance tendency fuselage rotate opposite main rotor tail demands much attention during hover So collective pitch control tail rotor necessary although same result could achieved fixing tail rotor collective varying tail rotor speed see last month although mechanisms vary slightly function variable pitch same See tail rotor sketch example scheme shown has rod running through hollow tail rotor shaft end rod connected bellcrank turn con trolled tail rotor rudder servo other end rod has collective spider cap tured between two collars spider free revolve about control rod yet may pulled pushed Out respect end tail rotor shaft hub tail rotor blades free change pitch since attached blade holders bearing-mounted tail rotor hub inner races bearings attached securely rotor hub blade holders secured Outer bearing races results blade holders blades being free swivel about pitch axes Now 30 Model Aviation remaining step Connect linkage collective spider tail rotor blade holders movement spider will cause blades swivel change pitch collectively tail rotor system fact great example rigid rotor system following example fly-barless rigid rotor main rotor blades attached blade holders mounted via bearings center hub turn attached rigidly shaft blades free swivel about pitch axis See main rotor sketch Note like tail rotor system linkage attached device will transmit linear movement shaft rotor turning instead connecting collective spider linkage connected swaslz plate Movement swash plate up down main shaft transmitted collective pitch change blades Since main rotor must also controlled cyclicly see last month swash plate very special device swash plate assembly consists upper lower section two sections isolated other bearing free turn relation other example another bearing called spherical bearing also part assembly adding spherical bearing swash plate assembly may also tilted relation main shaft assembly slipped onto main rotor shaft may therefore tilt direction move up down shaft rotate shaft linkages main rotor blades attached upper section swash plate left free revolve main rotor system lower section connected via linkages servos control lateral cyclic longitudinal cyclic collective/throttle lower section swash plate free rotateit prevented doing via anti-rotation link order transmit collective pitch changes main rotor swash plate assembly raised lowered main rotor shaft similar movement motion spider tail rotor example unlike spider swash plate can also tilt lower section can tilt upper section can tilt rotate main rotor shaft rotor system So upper section swash plate linkage main rotor pitch-change mechanism rotate main rotor shaft linkage captured guides insure linkage upper section swash plate phase rotor system see main rotor linkage detail sketch raising lowering entire swash plate assembly linkage will transfer movement collective pitch changes rotor blades Additionally through upward downward movement swash plate swash plate may tilt toward azimuth does transmits tilt differential move ment through linkage attached blade Thus get cyclic pitch changes Now have means converting motion swash plate collective cyclic pitch changes main rotor blades Ill again refer example airplane forward flight result adding throttle plus simulta neous up elevator right aileron compares helicopter control actions adding throttle collective usually mixed plus simul taneous aft longitudinal cyclic right lateral cyclic Both aircraft would begin accelerated climbing right roll course preceding ex ample over-simplified particularly regard helicopter since lots things going rotor head discussion will continued next month Dave Chesney Rt 9 Box 62 IA Greensboro NC 27409 RC HELICOPTERS AT THE NATS Flying events 1980 National Contest takes place Monday Tuesday August 11-12 Wright Field Dayton OH Write AMA HQ 815 Fifteenth St NW Washington DC 20005 Nats entry form full details please enclose pre-addressed stamped envelope Only late entry Wil mington Air Base possible after July 23 Entry form has details deadline RC HELICOPTER INTEREST SURVEY Mike Mas acting coordinator new RC helicopter special-interest group United Helicopter Association ModelA viation pleased help cause along printing following survey Its purpose enable UHA find out what majority modelers want association UHA being formed accommodate great interest shown among helicopter group form united voice respect new rules regula tions contest activities unite promote help sport model helicopters final results questionnaire will published UHA will include names addresses respondents summary results Mike sends plea anyone whether beginner expert interested prospective modeler please take time fill out form mail CITY CLUB NAMF STATE ZIP_______ PHONE LICThA BSINF~ 0TH E flying helicopter nn9 lop" helicopters now own List types ownedmost-used ones first What type flying like best Sport Fun-fly____________ Contest What transmitter mode fly_______________________________________ Nose tI9 you/have flown conventional RC model planes_________________________ long helicopter fliers area A-i Are able help other helicopter pilots InactivA need help What consider greatest difficulty ' member NRCHA state nijmher What think would fair dues UHA $0______ $2...... $5______ $8______ Other______ Would like see new helicopter nrnnni7tiAn9 Would like see scale helicoptere now own one_____ Would like letter club activity technical information Please tell us what would like see newsletter Please mail completed form THE UNITED HELICOPTER ASSOCIATION c/o Mike Mas PO Box 1172 Altamonte Springs FL 32701 September 1980 31 NI NA lDlc~
Edition: Model Aviation - 1980/09
Page Numbers: 30, 31
HELICOPTERS Dave Chesney LAST month began review similarities RC helicopters RC airplanes Briefly airplane helicopter forward flght respond control inputs three basic flight controls much same way once youve mastered hovering helicopter progress forward flight things get little easierhut now helicopter flights should begin end transition through hovering flight So now leave airplane cloud dust quickly moves down runway lifts off relentless pursuit forward flight other hand will struggle learn make helicopter lift off hover please dont hover dirty air long fine particles picked up rotor mixed engine exhaust will cover machine excellent abrasive compound Choose flying site care fully use engine air intake filter clean up helicopter after flying As remember last month discussed briefly collective cyclic controls helicopter beginning fixed pitch helicopters remember proper term fixed collective pitch helicopters fixed collective pitch main rotor systems have variable collective pitch mecha nism Yes tail rotor uses collective pitch order vary thrust tail rotor provide yaw control tail rotor collective comparatively simple device since required move both blades collectively negative pitch positive pitch spin Usually instructions given helicopter kit will note approximate neutral pitch setting tail rotor collective hover thrust provided just enough overcome torque Differences main rotor pitch engine speed combinations plus other factors will mean neutral setting will probably never perfectly balance tendency fuselage rotate opposite main rotor tail demands much attention during hover So collective pitch control tail rotor necessary although same result could achieved fixing tail rotor collective varying tail rotor speed see last month although mechanisms vary slightly function variable pitch same See tail rotor sketch example scheme shown has rod running through hollow tail rotor shaft end rod connected bellcrank turn con trolled tail rotor rudder servo other end rod has collective spider cap tured between two collars spider free revolve about control rod yet may pulled pushed Out respect end tail rotor shaft hub tail rotor blades free change pitch since attached blade holders bearing-mounted tail rotor hub inner races bearings attached securely rotor hub blade holders secured Outer bearing races results blade holders blades being free swivel about pitch axes Now 30 Model Aviation remaining step Connect linkage collective spider tail rotor blade holders movement spider will cause blades swivel change pitch collectively tail rotor system fact great example rigid rotor system following example fly-barless rigid rotor main rotor blades attached blade holders mounted via bearings center hub turn attached rigidly shaft blades free swivel about pitch axis See main rotor sketch Note like tail rotor system linkage attached device will transmit linear movement shaft rotor turning instead connecting collective spider linkage connected swaslz plate Movement swash plate up down main shaft transmitted collective pitch change blades Since main rotor must also controlled cyclicly see last month swash plate very special device swash plate assembly consists upper lower section two sections isolated other bearing free turn relation other example another bearing called spherical bearing also part assembly adding spherical bearing swash plate assembly may also tilted relation main shaft assembly slipped onto main rotor shaft may therefore tilt direction move up down shaft rotate shaft linkages main rotor blades attached upper section swash plate left free revolve main rotor system lower section connected via linkages servos control lateral cyclic longitudinal cyclic collective/throttle lower section swash plate free rotateit prevented doing via anti-rotation link order transmit collective pitch changes main rotor swash plate assembly raised lowered main rotor shaft similar movement motion spider tail rotor example unlike spider swash plate can also tilt lower section can tilt upper section can tilt rotate main rotor shaft rotor system So upper section swash plate linkage main rotor pitch-change mechanism rotate main rotor shaft linkage captured guides insure linkage upper section swash plate phase rotor system see main rotor linkage detail sketch raising lowering entire swash plate assembly linkage will transfer movement collective pitch changes rotor blades Additionally through upward downward movement swash plate swash plate may tilt toward azimuth does transmits tilt differential move ment through linkage attached blade Thus get cyclic pitch changes Now have means converting motion swash plate collective cyclic pitch changes main rotor blades Ill again refer example airplane forward flight result adding throttle plus simulta neous up elevator right aileron compares helicopter control actions adding throttle collective usually mixed plus simul taneous aft longitudinal cyclic right lateral cyclic Both aircraft would begin accelerated climbing right roll course preceding ex ample over-simplified particularly regard helicopter since lots things going rotor head discussion will continued next month Dave Chesney Rt 9 Box 62 IA Greensboro NC 27409 RC HELICOPTERS AT THE NATS Flying events 1980 National Contest takes place Monday Tuesday August 11-12 Wright Field Dayton OH Write AMA HQ 815 Fifteenth St NW Washington DC 20005 Nats entry form full details please enclose pre-addressed stamped envelope Only late entry Wil mington Air Base possible after July 23 Entry form has details deadline RC HELICOPTER INTEREST SURVEY Mike Mas acting coordinator new RC helicopter special-interest group United Helicopter Association ModelA viation pleased help cause along printing following survey Its purpose enable UHA find out what majority modelers want association UHA being formed accommodate great interest shown among helicopter group form united voice respect new rules regula tions contest activities unite promote help sport model helicopters final results questionnaire will published UHA will include names addresses respondents summary results Mike sends plea anyone whether beginner expert interested prospective modeler please take time fill out form mail CITY CLUB NAMF STATE ZIP_______ PHONE LICThA BSINF~ 0TH E flying helicopter nn9 lop" helicopters now own List types ownedmost-used ones first What type flying like best Sport Fun-fly____________ Contest What transmitter mode fly_______________________________________ Nose tI9 you/have flown conventional RC model planes_________________________ long helicopter fliers area A-i Are able help other helicopter pilots InactivA need help What consider greatest difficulty ' member NRCHA state nijmher What think would fair dues UHA $0______ $2...... $5______ $8______ Other______ Would like see new helicopter nrnnni7tiAn9 Would like see scale helicoptere now own one_____ Would like letter club activity technical information Please tell us what would like see newsletter Please mail completed form THE UNITED HELICOPTER ASSOCIATION c/o Mike Mas PO Box 1172 Altamonte Springs FL 32701 September 1980 31 NI NA lDlc~