I stumbled onto this, turns out this is where Vari-prop is doing their UAV
business. Perhaps I mis quoted Larry morgan about the high HP prop.
I wonder how many printer heads we would need to feed a 13b.

http://www.nwuav.com/fuel_injection.html

http://www.nwuav.com/variable_pitch_propellers.html


Paul Lamar

I am very impressed by the Ivoprop electric constant speed prop
http://ivoprop.com/inflightmagnumodel.htm, at EAA chapter 55 we have two
on 13Bs, one has been taxi tested, has anybody had problems with them.
Dave James

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Not recently to my knowledge. They seem to work OK on rotaries. The main
problems occurred when they were mounted on a high torque pulse, direct
drive, large displacement, air cooled aircraft engines, they would fail.

They are somewhat effective but they are really variable twist and not
variable pitch. Variable twist as well as variable pitch is what the V22
Really needs.

See http://www.rotaryeng.net/VTOL.html

Paul Lamar

Does any one know the cause of this failure? Was it an accident?
Dave James

Carter Copter has an interesting technology for variable props.  Seems to
be optimized for higher speeds (RPM).

http://www.cartercopters.com/propeller_system.html

Craig Taylor

Paul, I have read several articles concerning the carter copter. The one
they were flying last year set a forward speed record of some sort for
rotorcraft and had something to do with a speed coefficient "mu" of forward
speed compared with rotor tip speed. Their focus is entirely on their
rotorcraft vehicle and not commercial sales of their components and
propellers. The technology has been flown and  reportably worked as
advertised.The efficiency numbers are impressive, however packaging seems
problamatic. The spinner is huge, probably 2 feet diameter and three feet
long and gives the optical illusion that it is a small diameter prop when it
is actualy 100 inches. We could hide a 20B p-port in the spinner. I noticed
they are using the hollow propshaft and at 380 HP and 1800+ pounds of thrust
with a timing belt reduction on the test  stand rig. Did you notice where
the operator of the test stand rig is stationed.   It looks like the Paul
Lipps prop will be the one to watch as an efficiency improvement.

george grimes