The following is information I am repeating, but have no first hand
experience with. I subscribe to several forums and lists that have
discussed this from time to time in the context of Canard aircraft and
auto conversion engines.

One person who was running a Mazda rotary/wankel conversion in an RV 4
had a speed penalty incurred by using the product. He had a benefit at
low speed with regards to performance, but broke even with a fixed pitch
cruise prop around 140-150mph (that was installed later) and he had a
signigicant penalty on the high end with the IVO top speed being about
187 mph and with the cruise prop getting him about 210-215 mph. Some of
this is from his website (www.rotaryaviation.com) and some of this is
from telephone conversations with him.

I have given the IVO serious consideration for use on a Velocity with a
Mazda engine conversion, and the IVO magnum used was the higher pitch
variety. Apparently, since the prop adjusts by "blade warping", only the
outer portion of the prop blade changes pitch and the inner portion does
not.

There have been reports of one flavor of lycoming causing problems with
the torque pulses.. but I want to say this was the 360 CID variety of
lycoming. A website forum with a thread on it is www.canardzone.com in
the "Flying and Performance - Prop" subforum. The thread is labeled,
simply enough "Ivo". Also have seen some incidental discussion of the
IVO but not much substantive at "canardaviationforum.dmt.net", another
Canard based forum.

If used, you need to pay attention to detail with regarding prop bolt
torque... the blades are essentially sandwiched between two flanges to
hold them in position. There was a fatal accident caused by a field
repair that was done under questionable circumstances by the pilot (who
didnt have a torque wrench) that caused a slung blade and loss of
aircraft and 4 people. This was more the pilots fault than the props..
the instructions are supposed to be pretty clear about the procedure.

The consensus I have arrived at is that this prop does have utility, but
it is not well suited to high speed applications. Perhaps a bush
plane/cub copy would be able to take advantage of the adjustable pitch
function without having to worry about a penalty at high airspeeds.

Dave



canflyboy wrote:
Has anyone have anything to say, good or bad, about the Ivo Prop propeller
for the Lycoming engines? The adjustment feature is quite unique and
interesting, but I'd like to heard from users in the field for their opinion

Thanks

Canflyboy