In article , "PAW" wrote:
This is a BS question, but I'm curious.

Not a BS question at all. You definitely could do this. Unfortunately, the
hydraulic route will come at a price of reduced efficiency. You will probably
loose 15-25 percent of your horse power. With this in mind, though, you can
easily pick the proper size pump and motors to get the rpm of the propellers
anywhere you want, with the engine running at what ever rpm it likes. Why
heck, you could even put small motors on the main wheels and use them for
brakes and to run the airplane backwards for parking. That would turn some
heads.

best luck,
tom pettit



I was looking at some hydraulic motors the other day and was wondering if
a pump and motor could be used to drive a prop. A crazy example; two
hydraulic motors and a couple pumps (powered with a mazda 13b maybe ??) to
power something like a Cessna 337 in-line thrust type aircraft.
Understanding weight would be an issue, I'm wondering how it would, or could
,work. I was looking at an Eaton motor that was rated at (up to) 3200 RPM @
about 120 ft. lb of torque. Weight was 20 lbs. They have a pump (48 lbs)
that moves 42 gpm @ 4000 psi.

Is it possible? Single place would be fine.