"Yes. Warp drive makes a flexible prop with a steel rod in the middle that
twists the tips with an electric motor, to change profiles for climb to
cruise. That is one feature that had better not be copied."

Sorry Morgan, but it is Ivo that makes them prop. Warpdrive are rather
rigid.

J.P.
"Morgans" wrote in message
news

"LCT Paintball" wrote in message

With the butt kissing done, I hope you'll excuse my ignorance.

That is some first class "butt kissing." g

I don't have many answers, but I'll answer what I think I know, since no
one
else has answered.

I was interested in the discussion concerning the weight of different
prop
materials. Has anybody tried to make a hollow aluminum prop?

They are a standard in larger props.

What about titanium?

Don't know. I think the answer here, is that it is too brittle to stand
up
to the vibration, torque, and twisting.

Carbon fiber?

Yes. Some have been made with carbon fiber or fiberglass over wood or
foam
cores.

What kind of testing needs to be done on a home built prop?

Much has been written, and there are even programs to predict performance.

Are there prop styles that can be copied without patent infringements?

As long as you don't copy too closely. There are some special features of
some props that are copyrighted.

Has anybody tried making a flexible prop?

Yes. Warp drive makes a flexible prop with a steel rod in the middle that
twists the tips with an electric motor, to change profiles for climb to
cruise. That is one feature that had better not be copied.

My thinking is that it might be possible to create a prop with a low
angle
of attack for high power take offs, then have it flex to a higher angle
of
attack as the load
decreases.

This has been done with a extremely swept back shape, called "scimitar",
that as it unloads at high speed, the tips twist back to higher angles of
attack. I am unaware if this is currently being produced. The trick is
to
select materials and thickness, to get the twist just right, to work as
desired.

Could something like that give the performance of a constant speed prop
without the complexity and added weight?

There will always be tradeoffs of complexity and weight for this.

If I were to play around with different prop designs, is there somebody
around here with the knowledge and time that might be willing to test
them
for me?

Hmm. My suggestion is learn, and do it yourself. g

I am sure there are more, here, that will correct some of what I have
said,
and add more, given time.
--
Jim in NC