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Message
I agree that with
the pusher, the air is blocked from the center portion of the prop, so the IVO
really doesn't hinder top end speed. It may on the RV.
The IVO Magnum comes
with 2 different ranges on the pitch. I have the high pitch blades which
is what they recommend for my plane. I believe that the pitch range
goes from something like 40-45" on the low end, up to something like 105" on the
high end of the pitch range.
Steve
Hi
Steve,
I called IVO, and of
course they've never heard of such a thing as their props causing drag
at high speeds. Imagine that. Tracy probably just made that up
:-) Anyway, they didn't really inspire me with confidence that they
knew much about props. Mostly, they work from numbers that they have
archived, and give recommendations based on those. Their best
recommendation was for a 3 blade, 68" Magnum, standard pitch prop.
Since I'm planning to run it to 3200+ rpm, they said I don't need the
high pitch
range.
I took a closer look at my
Warp Drive prop (3 blade, 68") today, and find that the hub area should create
far less drag than a typical IVO. Since IVO didn't have any significantly
different recommendation from what I already have, I'll probably continue
working with the Warp to see what I can get. In fact, I took 3 degrees out
of the pitch today, to get the RPM up.
After thinking more about
it, I really can't make any final decisions until I get the wheel pants and gear
fairings on. I may also need to close up the rear of the cowl cheeks,
though that might have to wait until I can do some testing in 90-100 degree
temps to make sure the lower opening is adequate. I will also need to send
the Warp blades back, so they can taper them. Only then will I know how
they work when they're optimized.
Cheers,
Rusty (I need more RPM
Scotty)
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