--- In Indoor_Construction_at_yahoogroups.com, "barrysholder" <barry@...>
wrote:
>
> Please excuse my lack of terminology but, If I have a sheet prop blade
> cutout and I form it on a 4" dia form and the same on a 6,7, or 8" form
> (same angle) given the same pitch,what difference in performance might
> I see. I'm trying to come up with some Nocal props and these questions
> keep popping into my head. Thanks
>
The short answer is "not a clue"
Now for the long one...
Forming blades on a cylinder at an angle is an easy way to approximate
helical pitch distribution, and adds camber to the blade as well. I
know Fred Rash has done some work on a spreadsheet for cone-shaped
forms, which do even better with the distribution. I would guess that
using a larger diameter form would be detrimental, because the blade
will have a)less camber and more importantly b) severely washed in
tips. Tip-stalls and their related drag are a big efficiency killer.
I say, do a little leg-work and figure out what diameter form and what
angle will give a pitch distribution that is closest to helical.
Or, make a bunch of props. Could be more fun.
Fred, is your excel spreadsheet available online anywhere?
Chris
Building cat II DLG's in Atlanta
Received on Wed Jan 24 2007 - 17:18:31 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET