In article b4726e68-6571-4f76-8a3a-
, says...
On May 6, 2:00*pm, wrote:
Jim Logajan wrote:
wrote:
True that propeller research went away around WWII, but wind turbine
research is currently a hot topic and that's what the propeller
becomes when the engine stops.

True, but if the propeller airfoil has asymmetrical camber then when the
engine stops, the relative wind is inverted (coming from the wrong side -
similar to inverted flight.) So it wouldn't be terribly efficient and
attributes like prop stall angle differ from engine on versus engine off.

When the engine stops producing power, it becomes a frictional load to
the prop, which becomes a wind turbine.

There is nothing about the prop being attached to an airplane that
invalidates analysis as a wind turbine under that condition.

Whether it is an efficient wind turbine or not is irrelevant, it is
still a wind turbine when the engine is not producing power and air
is flowing past it.

--
Jim Pennino

Remove .spam.sux to reply.

Yeah,, but. If the prop is not efficient enough to even rotate with
the wind passing over it it never really becomes a wind turbine....
Those need to spin to be called that. A non rotating prop is called ..
DRAG . A rotating prop not under power is called more DRAG.. IMHO

Well if you can provide some evidence, that would be good.

Q. why is the prop windmilling in the first place?

Q2. I have a prop and I drag it through grease - as I do so it turns to
"allow" it it's passage through the grease. Now if I was to hold the
shaft so the prop does *not* rotate - surely that would be harder to
pull through the grease now. ?

--
Duncan