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Old Oct 15, 2001, 10:49 PM
high-speed freak
opualuan's Avatar
San Jose, CA
Joined Sep 2001
3,863 Posts
4.5x3 pusher prop source

I am scratchbuilding a 36" slowflyer with a friend, using a graupner 6v speed 280 (direct drive) as a pusher. I am having trouble finding a prop to go with this, however. Motocalc seems to favor a 4.5x3... 4.5x 2.75 and 4.75x 3 , and 5x 3.5 seem ok, but not as efficient.

anyone got a source for a prop that will work? anyone have pitch/size info on the e-gull pusher prop or the firebird prop, or for that matter, wingo/soarstar/etc? it needs to have a 2mm mounting hole, or be able to fit on a 2mm prop adapter...

thanks!
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Old Oct 16, 2001, 07:19 AM
Registered User
Thessaloniki, Greece
Joined Mar 2001
105 Posts
Graupner has a direct drive 12x6 cm folding prop in pusher configuration for speed 280 motors: item # 1335.12.6 (L).
Alternative you can use a Paul Gunther push on prop.

good luck
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Old Oct 16, 2001, 02:40 PM
high-speed freak
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San Jose, CA
Joined Sep 2001
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ok, i will simulate the graupner prop, closest I've seen. I went to the graupner site, and did not see the model with the (L) designation. where did you see this model? I guess I'll call graupner up...

I'd prefer folding, plus I don't think the gunther is the right size, slightly too big.
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Old Oct 16, 2001, 09:23 PM
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Walled Lake, MI, USA
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See first prop at the top of the lefthand column:

http://www.hobby-lobby.com/camfold.htm
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Old Oct 16, 2001, 10:47 PM
high-speed freak
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San Jose, CA
Joined Sep 2001
3,863 Posts
I am using a thin airfoil and direct drive speed 280, and the graupner prop just doesn't have enough pitch... it has to be closer to 4.5x3... simulation too far away from this prop and performance suffers big time.
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Old Oct 17, 2001, 08:29 AM
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Walled Lake, MI, USA
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If you prefer folding, there simply are not many options in your size range. Simulations are OK to a point, but field testing beats simulation and bench testing every time. This particular Graupner folder is the only one in that size range that I've seen which is designed for a direct drive Speed 280 and its 2mm shaft. If it were me, I'd buy one for $12 and see how it works. They have them at my LHS for the same price as Hobby Lobby. If it didn't work on this particular aircraft, I'd stash it away for a future DD S280 application.
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Old Oct 17, 2001, 09:46 AM
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Thessaloniki, Greece
Joined Mar 2001
105 Posts
Quote:
Originally posted by opualuan
ok, i will simulate the graupner prop, closest I've seen. I went to the graupner site, and did not see the model with the (L) designation. where did you see this model? I guess I'll call graupner up...

I'd prefer folding, plus I don't think the gunther is the right size, slightly too big.
look at http://gm-racing.de/graupner/neuheit...tschrauben.pdf
or manual go to
http://www.graupner.de in "produkte" then press
"Download der Neuheiten 2001 als .pdf Dateien" then open "Luftschrauben 852kB" pdf archive. There it is in the first page, the folding - pusher speed 280 prop (for Graupner Tipsy I think) side by side with a Gunther. Text in plain German { : ) don't know either but specifications are easy to understand}

regards





http://gm-racing.de/graupner/neuheit...tschrauben.pdf
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