|
Actually, Scotty, I do have a fixed-pitch prop. But
my prop has very little drag; I have to use a lot of braking to bring it to a
stop (on the ground, of course!). And this with an idle rpm of 680! I'm sure
you, with all your knowledge of things aerodynamic, have a copy of "Aerodynamics
For Naval Aviators". Look on page 149 where it compares wind-milling vs
stopped drag vs pitch. It turns out that a prop with 23 deg. to 60
deg. pitch has less drag wind-milling than stopped. My effective pitch,
from VMPH X 1056 / rpm, usually computes to
76". That works out to 27 deg at the 75% radius of a 63" diameter prop. That,
along with the minimal area of my prop beyond 12" radius, is the reason it has
so little drag. 'True, even though my 235 has a best L/D of 15:1 at 110 mph
IAS, it probably won't get that with the engine off. One of these days I'll have
to shut off the engine, at altitude, and see if the prop will even
wind-mill, and what kind of glide I do get!
Paul
|