On Apr 15, 3:11*pm, wrote:
On Apr 13, 8:20 pm, WingFlaps wrote:

Does anyone have any idea of the ratio between thrust power and churn
power?

Less than 80%. Look in Wiki for discussion of losses.

* * * Wiki isn't so accurate. The figure for max efficiency is in the
range of 85 to 87%, depending on AOA and a bunch of other stuff. The
Wright Brother's propeller on their Flyer had an efficiency of 83%
because they understood that it was a rotating airfoil rather than
some sort of paddlewheel.

83%? BS. Even if it had reached optimal speed it would have struggled
to get 70% (note the CFD calcs do not include surface roughness
losses):

http://www.fluent.com/about/news/new...i2_fall/a2.htm

It was lucky that Orville knew from tests a bit about about props (he
estimated 66% efficiency) or it might not have flown at all. That of
course was not such great insight on his part as the theory of
propellor design was well known from naval architecture.

Cheers