<<  Paul wrote:
 > > BTW this prop design was used in the 30's by the British on a Sword Fish
biplane
 > > and abandoned. IVO's are OK for slow low HP airplanes.
 >
 > Paul,

 Frank and Dorothy wrote:
 >
 > Do your comments above apply to the 'deep pitch' IVO props? I understood
 > that they had been designed to overcome the 170mph limitation of the
 > original IVOProp.
 >
 > Frank.

 They did not change the flat inner part of the blade so these comments still
apply.
 You could probably fix the fixed pitch version with cuffs made from foam and
fiberglass.
 Check the cuffs on a B50 or a Lockheed Electra.

 The variable pitch version is a joke.
 It is a variable twist *prop* and not variable *pitch* prop. There is an
optimum pitch
 and an optimum twist. IVO change the twist in the wrong way to increase the
pitch
 on the outer portions of the blade only while destroying the optimum twist.
 The only reason they get away with this in the market place is because
propellors
 are poorly understood. Check the fast planes. You won't see a IVO on any of
them.

 BTW Chuck Harbert should have been going 220 to 250 MPH with his turbo 3
rotor
 in a standard size Velocity and not just 200 MPH.

 Paul Lamar

On the other hand, the Ivo is cheap, light weight, can be adapted to almost
any engine, is "on the shelf" available and is in flight adjustable.
Lynn E. Hanover

I would hardly call it inflight adjustable. Yes the twist changes in flight.
It also runs into a brick wall at 180 MPH. If your 13B powered airplane is slower 
than that go for it. Dave Atkins has been cruising around with one at less than
180 MPH in his RV6 for years. He made a low pass over Tracy's house with the engine 
screaming but the airplane looked real slow for the sound coming out of the prop and engine. 
Tracy's RV4 airplane with a wood prop looks much much faster in a low pass.
Just an impression. We could  have had some factual numbers on Dave's top speed but
he broke a rudder pedal just before he could run the Sun 100 cross country race
last year.

BTW guys there is $500 waiting for you if you can average more than 200 MPH
in this years Sun 100 at Sun & Fun. Thats $1000 an hour. I will have to remember
to bring the Everett Hatch Memorial Fund check book with me this year.
Fastest rotary powered airplane over 200 MPH wins the $500. Nothing for
second place this year.

Paul Lamar
 
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