Vance Jaqua wrote:

I also share most of your misgivings about the Ivo
prop  but I agree that you have overstated the
limitations. Varying the twist does vary the pitch in
the most significant outer parts of the prop -
remember that more than half the disc area is outside
the 70 percent point, and well over half the mass
flow. 

However, the inner area which cannot be
discounted is terrible. 

I also have nervous thoughts
about structure - Mark - the previous owner of your
cruiser, fitted an Ivo to his 235 powered 2 place, and
lost some top speed even tho he was able to turn
higher (more HP) compared to his fixed pitch prop. He
also reported that all four indicator tapes broke with
only a few hours of operation. He has returned the
prop (it was a demonstrater loaner). I think the Ivo
can be of significant benifit on slower, draggier
aircraft with
smooth engines (six or more cylinders, two or more
rotors) with high static thrust requirements - Vance

Wait till you read the next message showing the aoa's and C sub L's 
at max pitch and 200 MPH :-)

Of course it works on ultra lights with six cylinder engines :-)

It is well known that a little wing tip washout is helpful in reducing the 
induced drag of any rectangular wing. This results in a more elliptical 
lift distribution on the  wing resulting in lower induced drag.
Check your local Cessna. 

That is not the case with the IVO prop blade. If 
anything the tip has more angle of attack than inner portions due to the silly 
twisting the blade idea. This results in the inner portions of the blade having 
less aoa than the outer portions increasing the tip vortices, consequently the 
induced drag and decreasing overall prop efficiency. 

A bad idea all the way around.

Paul Lamar
 
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