One of the few good (maybe the only) upside to Chuck's crash
is; we now have a broken IVO prop blade to dissect.

This is a cross section drawing about one foot out from the hub.
Looks like a Clark Y more or less. The pitch angle at this point is only
20 degrees or so which is way far short of what it should be. Most props in
this region of the blade are 45 to 60 degrees. Consequently it would
take about a three foot diameter spinner to turn this prop into something
useful and then it would have trouble absorbing 200 HP. You could,
on the other hand, fabricate enormous foam and fiberglass cuffs to 
fix the totally inadequate pitch angles near the hub.

If you use this prop on a high speed airplane as is you will run into a
brick wall somewhere around 180 to 190 MPH. Inner portions of the
blades will go into a negative angle of attack absorbing all your
horsepower and canceling what little thrust is being generated
by the outer portions of the blades.

Note this is a variable TWIST prop and not a variable PITCH prop.
Twisting the blades on this prop does little or no good. Only the 
outer portions of the blades are twisted and that is not what is
needed. The inner portions of the blades must be drastically 
increased in pitch to make this an effective prop!


Paul Lamar
 
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