"Bass, Jerry" wrote:

RV6A  2.85:1 Ross reduction drive which I added a internal thrust

plate.

Pix on previous msg.

Jerry Bass

Thanks again Jerry. Now I know why you are getting 7000 RPM. Ought to

be

fast.

Paul Lamar

Tracy Crook wrote:

Great climb but Fast?  I haven't seen this ratio go fast on anyones
airplane.  It is almost impossible to find a high speed prop that will

work

correctly at the resulting prop rpm.   I have cautioned all who would

listen

that this ratio will result in low top end and high engine rpm.

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

Come on Tracy. Theoretically it is not impossible to find a fixed
pitch prop that will make this airplane go faster. Back in 1933 seaplanes
were going 400 MPH with a fixed pitch wood prop. Now the takeoff distance
is another matter :-) The other issue is the shape of the HP curve.
If the HP peaks at 6000 RPM then yes. Obviously it is not peaked
at 6000 RPM because Jerry is climbing out at 7000 RPM.

Further more Butch, Perry, Vance and Bill are on the job and we will soon
have a low cost variable pitch prop. Hang in there Jerry.

Paul Lamar

The key word in your message is "Theoretically".  I agree that in theory,
the longest, slowest turning prop is the best. We live & fly in the real
world and there, is is very hard to find the prop for Jerry's plane & gear
ratio.  If you know where it can be found, I and others would like to know.

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

I don't off hand but you can always make your own prop. Many people
have. George Graham and Perry Mick come to mind. Also 
if there is enough money involved some of the prop makers would make
you a custom prop I am sure. I know Klause would. If diameter is a problem
due to landing gear limitations you could go to wider blades or a 
three blade prop.

BTW what is intrinsically wrong with cruising at 6000 RPM? We don't 
really know the limits of the rotary engine. For all we know it will 
cruise at 75% power at 6000 RPM for 2000 hours. The four rotor Lemans engine
ran with this RPM schedule for 24 hours with little or no wear.
This engine is still winning races ten years later.

It sure is easy to get a lot more power at 7000 RPM then it is
at 6000 RPM. A lot of the gyro guys running rotaries are running 2.85:1
PSRU ratios with multi blade Warp Drive props. They don't seem to have
any engine problems.

Paul Lamar

 
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