NEED THAT little extra performance Try procedure reworking props can guarantee effort ex pended will satisfy im proved aircraft engine performance No need go highnitro fuels burn up expensive engines trying get last little bit out Ive using sytem past few years have become believer fact prop can does add immeasurably overall performance airplane engine combination procedure does require fancy pitch machine can done about 20 minutes no special tools will notice anywhere 200 600 rpm gain ground real proof DRAWING 25% TO 300/o HIGH POINT LINE 0 As shown picture drawing high-point line drawn hub tip 25 30% blade chord after blade cross sections reshaped shown two step drawing B Far being just bright idea mod has proved its value field pudding air engine can unload allow prop work should have tried stock props would just about get RC pattern air plane air fly rather sluggishly switch reworked prop no other changes improved over performance airplane immense ly Give try am sure will convinced Lets go over rework step step Top Flite 11-7 Super M Power prop Other brands pitches sizes can used see fit try stick good hard maple-wood props easier work First true up hub area sanding both front rear hub flat true can done placing sheet 80-grit garnet sandpaper flat sur face working hub area back forth over Dont worry about finish prop because will remove anyway After completing step ream prop hole out correct size Notice said ream out drill cause likely will split prop hole Fox makes some excellent ream ers purpose Taper reamers should avoided give true flatsided hole way through hub Now take felt marking pen draw line front face prop 25% 30% leading edge see drawing does have super Continued page 94 Editors Note Jack Aycock has building 35 years has flown RC since 1949 AF fighter pilot Jet flight test officer hobby shop proprietor Retired Sport Scale aM Expert Pattern attends contests has placed President Pikes Peak RC Club AMA CD area vice pres NMPRA-QM February 1 978 31 DRAWING B Note sharp leading trailing edges plus flat surfaces after filing completed blade Section after sandingThe high point has rounded slightly see local hobby dealer WI~E almost Stahl design40 years ago t~p tTA OGA 4 lOBts famous 24 1/2 WWdGSPAN 0% FOR PACKING AND POSTAGE VA NESIDENTS ADD 4% TAX RUBBER & CO2 WINNER AT THE 50th NATS Blot 221/2 WINGSPMI $695 Kioud King Ambivalent Dennyplane Miss Arpiem Brigadeer articles skeleton photo 85% Power house photo accompanying months column Depending model size four spruce spars ranging located approximately 30% 70% chord perpendicular other Fulldepth plywood dihedral joiners placed slotting ribs hacksaw stacks appropriate thickness epoxied flush spars Shear webs 1/16 balsa added grain running vertical alternating front rear spars picture illustrates front spars should always webbed rear set may also webbed model stunted weight factor Additional strength can gained D tube sheeting leading edge ever seems add spanwise strength torsional rigidity has stated times bears repeating wing will no stronger rigid after covered heat-shrink material uncovered wing seems flexible uncovered absolutely should covered shiny stuff full set shear webs still doesnt cure flexibility get out silk pre pared pick up pieces Consider four-spar shear-web tech nique next old-timer Dr D B Mathews 506 South Walnut Greens burg KS 67054 Foam/Evans/Lester continued page 35 will take care problem mean time core isnt too bad ways salvage will discussed next issue Sectioning hot-wire method cut ting has limitation cuts must straight line Wings taper angle either LE TE must cut sections glued together Follow same procedure *108 Spo&te 28 WING8PAN S6 INE MODELS 2820 DORR AVE FAIRFAX VA 22030 Send free brochure section described cutting wing panel tip template inboard section also root template outboard section additional section requires additional template tip section also necessary cut very long wings sections due limitations tension necessary keep wire straight power uniform heating wire Dihedral Angle Cutting sim plest ways cutting dihedral angle two-piece wing raise tip prescribed height height can calcu lated angle given make vertical cut root panel can best done after cutting core core still blank can done before sheeting end-cutting jig after sheeting saw and/or sanding block endcutting jig can also done dihedral-angle cutting template angle-cutting tem plate can attached foam blank nails pressed foam can attached cutting jig see Fig 6 template angle half com plement total desired angle both sections must cut match cross sections joint example tendegree angle required template gle will 900 100/2 850 Regardless method should done systematically avoid cutting angle wrong end wrong direction two-panel wings right left sure top up cut root panel except gull wings cut angle outboard section polyhedral wing sure top up cut outer end tip inboard section root outboard section except gull wings same principles apply core cut complete right left panel sectioned polyhedral angle continued Prop Mod/Aycock continued page 31 exact eyeball part just make sure line both blades same OK now have big black line front prop will become high point wood work begins Select rather rough flat wood rasp starting high point work towards leading edge rasp being careful cut away leading edge just take down rather sharp leading edge satisfied same thing again high point towards trailing edge worrying about curved rounded surface just make flat per drawing B Repeat other blade Round off high point shown drawing tips will get quite thin will no way subtract props efficiency should have pile wood dust front now will make some Using 80-grit again hand sand blades rather smooth finish See said hard maple props work best have done respectable job put prop balancing tool should ball park After little practice will able get right money fact time will balanced closer came out box Finish sand blades 280 wet dry dry course done Notice did take anything off back prop blades Thus did alter basic pitch just added airfoil front finished prop should have quite sharp leading trailing edges Leave raw wood finish nothing please Try procedure prop size now using check engine performance airplane flying have found often can go high er pitch prop engine would lug before will turn now author ity Experiment various sizes pitches until get satisfies air remember prop rework can prove itself air ground tach have questions regard ing prop rework please feel free drop line care magazine will happy answer questions Helicopter/B itner continued page 37 altitude 20-60 meters stay within fly course start finish procedures must checked directing official Timing flight can done several ways will tell what method used four timers located south end four north end 94 Model Aviation
Edition: Model Aviation - 1978/02
Page Numbers: 31, 94
NEED THAT little extra performance Try procedure reworking props can guarantee effort ex pended will satisfy im proved aircraft engine performance No need go highnitro fuels burn up expensive engines trying get last little bit out Ive using sytem past few years have become believer fact prop can does add immeasurably overall performance airplane engine combination procedure does require fancy pitch machine can done about 20 minutes no special tools will notice anywhere 200 600 rpm gain ground real proof DRAWING 25% TO 300/o HIGH POINT LINE 0 As shown picture drawing high-point line drawn hub tip 25 30% blade chord after blade cross sections reshaped shown two step drawing B Far being just bright idea mod has proved its value field pudding air engine can unload allow prop work should have tried stock props would just about get RC pattern air plane air fly rather sluggishly switch reworked prop no other changes improved over performance airplane immense ly Give try am sure will convinced Lets go over rework step step Top Flite 11-7 Super M Power prop Other brands pitches sizes can used see fit try stick good hard maple-wood props easier work First true up hub area sanding both front rear hub flat true can done placing sheet 80-grit garnet sandpaper flat sur face working hub area back forth over Dont worry about finish prop because will remove anyway After completing step ream prop hole out correct size Notice said ream out drill cause likely will split prop hole Fox makes some excellent ream ers purpose Taper reamers should avoided give true flatsided hole way through hub Now take felt marking pen draw line front face prop 25% 30% leading edge see drawing does have super Continued page 94 Editors Note Jack Aycock has building 35 years has flown RC since 1949 AF fighter pilot Jet flight test officer hobby shop proprietor Retired Sport Scale aM Expert Pattern attends contests has placed President Pikes Peak RC Club AMA CD area vice pres NMPRA-QM February 1 978 31 DRAWING B Note sharp leading trailing edges plus flat surfaces after filing completed blade Section after sandingThe high point has rounded slightly see local hobby dealer WI~E almost Stahl design40 years ago t~p tTA OGA 4 lOBts famous 24 1/2 WWdGSPAN 0% FOR PACKING AND POSTAGE VA NESIDENTS ADD 4% TAX RUBBER & CO2 WINNER AT THE 50th NATS Blot 221/2 WINGSPMI $695 Kioud King Ambivalent Dennyplane Miss Arpiem Brigadeer articles skeleton photo 85% Power house photo accompanying months column Depending model size four spruce spars ranging located approximately 30% 70% chord perpendicular other Fulldepth plywood dihedral joiners placed slotting ribs hacksaw stacks appropriate thickness epoxied flush spars Shear webs 1/16 balsa added grain running vertical alternating front rear spars picture illustrates front spars should always webbed rear set may also webbed model stunted weight factor Additional strength can gained D tube sheeting leading edge ever seems add spanwise strength torsional rigidity has stated times bears repeating wing will no stronger rigid after covered heat-shrink material uncovered wing seems flexible uncovered absolutely should covered shiny stuff full set shear webs still doesnt cure flexibility get out silk pre pared pick up pieces Consider four-spar shear-web tech nique next old-timer Dr D B Mathews 506 South Walnut Greens burg KS 67054 Foam/Evans/Lester continued page 35 will take care problem mean time core isnt too bad ways salvage will discussed next issue Sectioning hot-wire method cut ting has limitation cuts must straight line Wings taper angle either LE TE must cut sections glued together Follow same procedure *108 Spo&te 28 WING8PAN S6 INE MODELS 2820 DORR AVE FAIRFAX VA 22030 Send free brochure section described cutting wing panel tip template inboard section also root template outboard section additional section requires additional template tip section also necessary cut very long wings sections due limitations tension necessary keep wire straight power uniform heating wire Dihedral Angle Cutting sim plest ways cutting dihedral angle two-piece wing raise tip prescribed height height can calcu lated angle given make vertical cut root panel can best done after cutting core core still blank can done before sheeting end-cutting jig after sheeting saw and/or sanding block endcutting jig can also done dihedral-angle cutting template angle-cutting tem plate can attached foam blank nails pressed foam can attached cutting jig see Fig 6 template angle half com plement total desired angle both sections must cut match cross sections joint example tendegree angle required template gle will 900 100/2 850 Regardless method should done systematically avoid cutting angle wrong end wrong direction two-panel wings right left sure top up cut root panel except gull wings cut angle outboard section polyhedral wing sure top up cut outer end tip inboard section root outboard section except gull wings same principles apply core cut complete right left panel sectioned polyhedral angle continued Prop Mod/Aycock continued page 31 exact eyeball part just make sure line both blades same OK now have big black line front prop will become high point wood work begins Select rather rough flat wood rasp starting high point work towards leading edge rasp being careful cut away leading edge just take down rather sharp leading edge satisfied same thing again high point towards trailing edge worrying about curved rounded surface just make flat per drawing B Repeat other blade Round off high point shown drawing tips will get quite thin will no way subtract props efficiency should have pile wood dust front now will make some Using 80-grit again hand sand blades rather smooth finish See said hard maple props work best have done respectable job put prop balancing tool should ball park After little practice will able get right money fact time will balanced closer came out box Finish sand blades 280 wet dry dry course done Notice did take anything off back prop blades Thus did alter basic pitch just added airfoil front finished prop should have quite sharp leading trailing edges Leave raw wood finish nothing please Try procedure prop size now using check engine performance airplane flying have found often can go high er pitch prop engine would lug before will turn now author ity Experiment various sizes pitches until get satisfies air remember prop rework can prove itself air ground tach have questions regard ing prop rework please feel free drop line care magazine will happy answer questions Helicopter/B itner continued page 37 altitude 20-60 meters stay within fly course start finish procedures must checked directing official Timing flight can done several ways will tell what method used four timers located south end four north end 94 Model Aviation