SNIP<

Things are not as bad as Vance makes out. Yes the

high pitch prop may

be stalled but it is still generating thrust and

that is a function

of the HP going in. If the prop static RPM is 6000

instead of 5000 RPM

the engine is putting more power into the prop.

The classic example is the high bypass ducted fan

air liner. Yes the duct
is horribly

inefficient at low speeds but the engine has a

zillion HP.

Tracy Crook wrote:

Klause's Varieze is another example. His fixed pitch

prop is optimized

for 250 MPH and yes his airplane does not take off

as well as a Varieze

with a prop optimized for 200 MPH. He still gets out

of SZP with

a 2000 foot runway with room to spare. Not only that

he runs his prop

up to 3100 RPM or so so the diameter is not large.

Paul Lamar

If Klause made that prop work at 2100 rpm (like we
would turn at 6000 engine
rpm with a 2.85 - 1 drive) you would have a point.  I
just haven't seen it
done, regardless of blade width, number of blades,
ducted, etc, etc.  Lets
see a valid example of high speed AND low prop rpm.

Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

Osprey V22!

What you meant to say was "see a valid example of high speed, same diameter 
AND low prop rpm". I'll check with Don.

Paul Lamar
 
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