Front Electric Sustainer

On Sun, 01 Nov 2009 09:51:45 -0800, kirk.stant wrote:

This looks like a natural for a single blade prop, folding flush into a
contoured recess in the bottom of the nose.

That would be nice to see from a propeller efficiency point of view too,
because the prop could be bigger while absorbing the same power. The
bigger the prop the more efficient it is. Propeller ground clearance
would be irrelevant for a sustainer system.

I remember seeing an Antares 20E and an ASW-22ble launch within 10
minutes of each other, so the ground and air conditions were very
similar. The ASW-22 has 49hp (36 kW) and (I think) a 0.9m diameter prop
while the Antares swings a 2m prop with a 47 kW motor. The Antares was
off the ground in about 1/3 the run the '22 needed and climbed out at
least twice as fast. I don't know how the takeoff weights would compare,
but if they're not too different the additional 30% power output in the
Antares wouldn't account for the takeoff and climb out difference I saw,
but the different props could easily do it. A two blade prop is rather
more efficient than a 5 or 6 blade unit and the almost 5:1 difference in
swept area would make a big difference to drive efficiency, especially at
low speeds.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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