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Post by maddog on Sept 29, 2011 18:15:54 GMT -5
Our club has just gotten the airworthiness certificate for our mascot of the EAA Chapter 1156. www.1156.eaachapter.org/But the reason I am posting here is to ask the opinion of running a different propeller than the one that we have. We are currently using a 59x28 Tennessee wooden propeller on a EA81 direct drive. Using different web sources I think that we should be using a 54x24... Thanks n advance! mb
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Post by maddog on Oct 2, 2011 18:37:45 GMT -5
Maybe a little more information will help. Static we are getting 2800 rpm and 3000 WOT/SL.
We would like to be getting around 3600 rpm WOT/SL.
Vne for the Pietenpol is ~85mph, and normal cruise is ~65 mph.
mb
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Post by schrome on Oct 2, 2011 20:03:20 GMT -5
mb, this may not be the best group for your question because of the differences between a Sonerai and a Pietenpol. Is there a group for Piets or Soobies?
Ed
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Post by maddog on Oct 2, 2011 23:03:31 GMT -5
Thanks for the response schrome and yes the the difference between a Piete and a Sonerai are night and day hence the placement in off topic category. I guess that I was hunting for more info on the fact that the engine displacement was close to the same. Both are direct drive and therefore volumetric efficiency should be close. Just wanting to pick the brains of my peers to see if they had any incite to the workings of propellers in different situations. The direct drive subie can have one third more power for one third less weight than the model "A" engines that were placed on the original design.
Just something to talk about in off topic besides politics...
mb
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Post by raceair on Oct 4, 2011 13:05:12 GMT -5
maddog...Your prop numbers seem to be way off for the Soob, but I have never experimented with a soob... Example, ....my 28 h.p. rotax 277, on my Skylite ultralight, has a 2.58/1 reduction, the engine turns 6,250 rpm, and I run a 60" dia. x 28" pitch.....this gives me about 190 pounds of thrust at a propeller speed of about 2400 rpm. ....With the rpm numbers you provided, I would think your 59/28 prop would be tip stalling, and the 54/24 would produce very little thrust..... A small disc area prop on a large, draggy airframe like the Piet is not a good combination.....What does the Engine builder say?....Ed
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Post by juergen on Oct 6, 2011 2:45:40 GMT -5
Hi Maddog, when you tell me your email, I will send you a prop calculation sheet, so you can see, what prop is the right for this plane. The calculator is based for Sterba props and it work very exact for this props. with best regards Juergen
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Post by richardmw on Oct 18, 2011 19:29:55 GMT -5
I flew a Piet for 4 years. Hurricane Charley brought an abrupt end to my air camper in 2004 . I have flown nine different types of aircraft in the past 34 years . The Piet was the most FUN !!!!
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