Vince Orton wrote:

There are several issues that would need to be worked out.  Here's a few
thoughts on the matter:
1) Can this "generator" generate enough current to drive a prop pitch
adjustment motor?
        a) how much force/torque is required to adjust and hold the

props?

        b) how much current is required for this control motor?
        c) can this be generated at ~1000-2800 RPM prop speeds?
        d) without a heavy, bulky coil and/or magnet setup?

A lot of the necessary inputs to calculate this are already known.  The
existing LAEV hub already has a DC motor with known torque, current, voltage
requirements.  But I don't know what they are.  Paul?  Butch?

As for weight, that is what calculators are for.  First, let's find out what
is going to be required for coil size, winding density, etc.

2) Can the motor be geared such that the prop shaft torque cannot
"reverse drive" the motor?  This would mean that a) loss of electrical
power results in a fixed pitch prop (it's last setting), and b) that no
current would be required to maintain a given pitch setting.

This has already been accounted for in the design of the lead screws.  Fine
thread, low pitch.  Isn't going to back-drive.

3) For efficiency reasons, the two coils (or coil/magnet) would have to
be very close - the closer the better.  We may even adopt an irregular
or protruding shape for the back of the spinner (under the cowl) to
maximize the interaction between the spinner's generating coil and the
stationary magnetic fields.

This is essential.  We need to know what kind of runnout is expected between
the mounting point (PSRU housing?) and the spinner back plate.  Also,
whether the coil can be mounted on the aft side of the spinner rear
bulkhead, or whether it must go inside.  Electrically not an issue (aluminum
is non-magnetic), but it will make a difference in the spacing and therefore
the necessary winding density.

4) The prop cannot be adjusted without the engine running (I think this
is a non-issue).
5) The more current that can be generated, the faster the prop pitch can
change.
6) What does all this weigh - it's way out there at the prop, remember.
7) Generator coils/magnets need to be out at the radial edge of the
spinner to maximize linear speed, and increase generator efficiency.
8) The horsepower required to run this generator-come-prop-govenor would
be negligible.
9) The control system to determine prop pitch could be just about
anything
        a) Manual switch, pilot controlled (+ off -)
        b) Electrical circuit, constant speed (set RPM)
        c) Computer controlled, whatever-you-want

Yup to all of the above.  If I can get the motor requirements and physical
envelope (spinner back plate dims, spacing) I believe I can pencil-whip a
proposal.  Then we can sanity-check it to see what such a device might
weigh.  If it's 20 pounds, forget it.  If it's 5, that may work.  Remember,
the LAEV is a *lightweight* prop.  Also, all this stuff would have very
little gyroscopic effect since it's mass is concentrated at the center of
the prop disk.

Tom Kendall

We are not sure yet. Torque and current depend on the pitching moment
of the blade and that changes with a lot of aerodynmamic variables.
My guess it is on the order of ten amps plus or minus five.

Paul Lamar

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