On Jul 22, 6:11*am, "Bill Daniels" bildan@comcast-dot-net wrote:

I believe the key to the Wright Brothers success with only 12HP was not the
engine, all up flying weight or the wing area but the propellers.

The props were huge and very slow turning giving them astonishing
efficiency. *The total propeller disk area was greater than some WWII
bombers. *100 years on, their propulsive efficiency still exceeds those on
most light aircraft.

I think this is still the key if you want to fly far (if slowly) on a tiny
engine. *Make a big slow prop and attach it to a glider-like airframe.
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There's a bit more to it than that :-) What you are seeing is a very
nice MATCH between the forward velocity of the airplane and the
velocity of the thrust-stream (or slug) being generated by the
propeller(s). It is the MATCH of velocities that results in the high
efficiency.

The 102" dia. props (8.5 feet ! ) were clearly a factor in the success
of the 'Flyer' but their arrangement -- crossing the drive-chains so
as to give contra-rotation, and the careful match of the engine's
output (the 'throttle' was not variable; you had 'running' and 'full
blast') to their guesstimated forward velocity was the stuff of
genius. But those are things outside the area in which I hoped to
make my point: That the elements needed to produce a successful
flying machine are presently available to anyone, anywhere in America,
who has a yen to fly.

-R.S.Hoover