w M _ Hub assembled before bla Showsdes areecept Striker Plate Itc atta h COflt trailing edge ched Right Side PO rr erO hinge open CGIIIflg St4tsom Indoor models can use variable-pitch VP props increase rubber-motor efficiency U Nick Johnen F longest time Bob DeBatty intrigued idea building variable-pitch VP propeller FiD models knew others tried VP some degree success best knowledge previous designs some problems worked tension rubber motor requiring adjustment whenever different-size motor used Others designs two-position props launched high pitch tension decreased certain amount would switch low pitch nothing between especially good design operated motors torque made smooth transition high low pitch torque decreased Unfortunately too its problems too complicated tended destroy itself Bob still felt torqueactuated design best set work making simple prop would hold up under normal flying conditions project easy oneif easy someone would have done long time ago Eventually prototype built next thing try under competition conditions Bob traveled almost 400 miles join some other Indoor flyers Cow Palace San Francisco Normally great place fly certainly wasnt particular day Just few days before ice show delighted audiences now remained cold damp air wet floor Since meet earn points FAJ team selection modelers flying FiD models half-length motors other half space between motor hooks taken up wooden stick wire setup allows flights reasonable amount time less likelihood destroying model hanging up ceiling good air under 98-foot ceiling models would able make 20-minute flights However conditions times ranged 14 16 minutes Eventually Joe Foster made breakthrough 18minute flight excellent under conditions nowhere near Joes usual performance meantime Bob repaired some damage plane sustained during long ride Southern California competing just wanted try out new prop ready wound motor 90% capacity enough good test risking blown motor flight went off hitch casual observer nothing spectacular about except time stayed up 201/2 minutesa full two minutes anyone else did fully wound motor Most important climbed fifty feet prop turned same rpm throughout flight Bob wasnt merely satisfiedhe ecstatic 76 Model Aviation * ptC~ 8d t1cK proP iUci r Bob DeBattys FiD looks much like other except prop hub light 041 02 prop makes Winner Once worked out obvious very simple mechanism would job little no torque shaft torsion spring closes hinges place blades low pitch rubber wound resulting torque overcomes spring increases pitch amount increase controlled high-pitch control arm tricky part rate change controlled torsion spring spring sketch approximately 11/2 turus 010 music wire may may work specific model Anyone constructing such propeller should anticipate spending some time finding proper amount tension Indoor modeler construction should rather straightforward However certain things must done absolutely right wont work important shaft two ends must perfect alignment prop run true Second tiny solder joint prevents shaft losing its shape motor wound must interfere thrust washer next item requires careful attention hub assembly Various hinging methods tried oldtime thread hinges seemed work best carefully made light strong have no slop test prop Bob made simple setup amounted half motor stick firmly mounted workbench attached rubber motor wound just would flight everything held steady able observe action mechanism during testing Bob saw original torsion spring too strong lighter spring little bit fine-tuning finally gave him what looking sure spring does lose its setting disengages use Once prop flown successfully Bob showed design number West Coast flyers hopes would help move new level performance Bob himself has given up competition As Chicago Aeronut active competitor before WW IL until retired California just few years ago Since has worked improving performance just fun er NOT TO SCALE VP PROP SHAFT 014 MuSIC Wire IIIIII PROP SPAR THREAD HINGE ON LEADING EDGE OF SPAR 511511 TURNS-\ SPRING IN UNHOOKED POSITION S SOLDER 014 WIRE REAR VIEW K HOOK SPRING INTO CROSSBAR ALUMINU STRIKER PLATE NOTE FILLER BLOCK TO TAKE UP GAP FOR PLIERS TO BEND PITCH CONTROL WIRE II SIDE VIEWI March 1994 77 -4-I JL JH __ 01 GRID A ALJMINUM BEA INGS K-SEE_ NOTE 2-HIGH PITCH CONTRO FRONT VIEW N
Edition: Model Aviation - 1994/03
Page Numbers: 76, 77
w M _ Hub assembled before bla Showsdes areecept Striker Plate Itc atta h COflt trailing edge ched Right Side PO rr erO hinge open CGIIIflg St4tsom Indoor models can use variable-pitch VP props increase rubber-motor efficiency U Nick Johnen F longest time Bob DeBatty intrigued idea building variable-pitch VP propeller FiD models knew others tried VP some degree success best knowledge previous designs some problems worked tension rubber motor requiring adjustment whenever different-size motor used Others designs two-position props launched high pitch tension decreased certain amount would switch low pitch nothing between especially good design operated motors torque made smooth transition high low pitch torque decreased Unfortunately too its problems too complicated tended destroy itself Bob still felt torqueactuated design best set work making simple prop would hold up under normal flying conditions project easy oneif easy someone would have done long time ago Eventually prototype built next thing try under competition conditions Bob traveled almost 400 miles join some other Indoor flyers Cow Palace San Francisco Normally great place fly certainly wasnt particular day Just few days before ice show delighted audiences now remained cold damp air wet floor Since meet earn points FAJ team selection modelers flying FiD models half-length motors other half space between motor hooks taken up wooden stick wire setup allows flights reasonable amount time less likelihood destroying model hanging up ceiling good air under 98-foot ceiling models would able make 20-minute flights However conditions times ranged 14 16 minutes Eventually Joe Foster made breakthrough 18minute flight excellent under conditions nowhere near Joes usual performance meantime Bob repaired some damage plane sustained during long ride Southern California competing just wanted try out new prop ready wound motor 90% capacity enough good test risking blown motor flight went off hitch casual observer nothing spectacular about except time stayed up 201/2 minutesa full two minutes anyone else did fully wound motor Most important climbed fifty feet prop turned same rpm throughout flight Bob wasnt merely satisfiedhe ecstatic 76 Model Aviation * ptC~ 8d t1cK proP iUci r Bob DeBattys FiD looks much like other except prop hub light 041 02 prop makes Winner Once worked out obvious very simple mechanism would job little no torque shaft torsion spring closes hinges place blades low pitch rubber wound resulting torque overcomes spring increases pitch amount increase controlled high-pitch control arm tricky part rate change controlled torsion spring spring sketch approximately 11/2 turus 010 music wire may may work specific model Anyone constructing such propeller should anticipate spending some time finding proper amount tension Indoor modeler construction should rather straightforward However certain things must done absolutely right wont work important shaft two ends must perfect alignment prop run true Second tiny solder joint prevents shaft losing its shape motor wound must interfere thrust washer next item requires careful attention hub assembly Various hinging methods tried oldtime thread hinges seemed work best carefully made light strong have no slop test prop Bob made simple setup amounted half motor stick firmly mounted workbench attached rubber motor wound just would flight everything held steady able observe action mechanism during testing Bob saw original torsion spring too strong lighter spring little bit fine-tuning finally gave him what looking sure spring does lose its setting disengages use Once prop flown successfully Bob showed design number West Coast flyers hopes would help move new level performance Bob himself has given up competition As Chicago Aeronut active competitor before WW IL until retired California just few years ago Since has worked improving performance just fun er NOT TO SCALE VP PROP SHAFT 014 MuSIC Wire IIIIII PROP SPAR THREAD HINGE ON LEADING EDGE OF SPAR 511511 TURNS-\ SPRING IN UNHOOKED POSITION S SOLDER 014 WIRE REAR VIEW K HOOK SPRING INTO CROSSBAR ALUMINU STRIKER PLATE NOTE FILLER BLOCK TO TAKE UP GAP FOR PLIERS TO BEND PITCH CONTROL WIRE II SIDE VIEWI March 1994 77 -4-I JL JH __ 01 GRID A ALJMINUM BEA INGS K-SEE_ NOTE 2-HIGH PITCH CONTRO FRONT VIEW N