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Webra Speed 40 Pylon

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Old 03-31-2012, 04:46 PM
  #1
dbacque
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Default Webra Speed 40 Pylon

I'm building a sport/speed plane and a friend just gave me a Webra Speed 40 Pylon engine. The plane will be about 470 sq in, 12% airfoil and probably around 3.25 lbs. It's not going to be as slick as the things you guys fly and I'm not looking for any speed records, just something faster than my fast sport planes.

So the question is what sort of prop range should I start with on this engine and what kind of RPM should I expect? I'm am planning to run it with a pipe.

Thanks,
Dave
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Old 03-31-2012, 05:43 PM
  #2
resourcecapital
 
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Default RE: Webra Speed 40 Pylon

what condition is the engine in? this will tell you what you can use as a prop.
what rpm does the engine spin at lets say a standard sport 9x6 if over 17k the try pylon 8.8x8 8.8x9w props. this will tel you what the engine will do.
next it is test, test, test
tyr about a dozen props in this range you will find that the best engine prop may not be the best flying prop. engine going like a raped ape airplane not gooing anywhere. the prop must have enough thrust to overide airframe drag. only testing will do.

a clasic example is an ugly stick will fly well on a 10x6 prop but whatch what it does on an 11x5 or 12x4. the engine rmps are about the same but thrust is so much more and it really puls the airplane through the air.
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Old 03-31-2012, 06:08 PM
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dbacque
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Default RE: Webra Speed 40 Pylon

The engine is broken in but lightly used. I did expect to be trying lots of different props but needed to find a start point so thanks for the info. What kind of RPM range should I consider redline on this engine?

Thanks,
Dave
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Old 04-05-2012, 09:19 AM
  #4
jaka
 
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Default RE: Webra Speed 40 Pylon

Hi!
9x6, 9x6,5 or 9x7 APC!
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