aloha Paul
I would like some advise about the props  used on RX8 engines,
Warp Drive or Ivoprop would be OK?
JC Castro

Depends on the airplane you are building. A 3 or four blade
carbon Warp Drive might be OK for a slow airplane like a bush plane
or sea plane. Both props are twisted for slow airplanes.

People have had trouble with fiberglass Ivo props hitting a drag
wall around 180 to 190 MPH due to the flat hub area.
They are also very flexible torsionally speaking which
is not good as they tend to untwist. Don't believe the IVO
claims of using carbon fiber as there is only a tiny amount
of carbon in the crashed IVO props I have seen.

An efficient prop is very thin near the tips so the
material needs to be stiff and strong. Back in WW II
the best props were made with hollow steel blades.

You need a stiff prop twisted and pitched for either top
speed or cruise. Your choice. Aluminum props are stiffer
and stronger than wood. They are stiffer than fiberglass.
So far they are almost universally used at Reno air races.

Carbon fiber is very stiff and strong and light weight but it
has not lived up to its potential so far.

Never the less wood works pretty good.

Cato has a good rep.
http://www.cattoprops.com/

Tracy is running a 74 inch wood Performance Propeller but I am
not sure that is best for top speed. It is good for climb
and low speed thrust.

Also the power your engine
is tuned for and the drag of the airplane are also factors.


Talk to the prop maker. Tell him how fast you want to go,
your HP and the type or drag of your airplane and he should
be able to design a prop twisted and pitched for that
configuration.


Paul Lamar ...No rotor no motor.

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