a wrote:
On Nov 3, 10:55 am, Ron Wanttaja wrote:
a wrote:
My aerodynamic question had always been why there are fewer pusher
props. In a puller some of the wind energy is used up against the
airplane.
In a pusher, the prop has to operate in turbulent air stirred up by the
structure in front. Depending on the design of the airplane, the prop
also has to be stronger (e.g., heavier) to withstand the cycling loads
if there's a wing or something blocking part of the prop disk from the
slipstream (think Long-EZ).

Ron Wanttaja

Thanks! I seem to remember the pusher in the C310 was less effective
too.

As Steve pointed out, you were thinking of the C336/337 Skymaster. It
*did* have a better rate of climb on the rear engine. One theory I read
was that it was due to the aerodynamics of the rather blunt back end
being better when there was an engine to help suck the air past....

There's no real pat answer; you can find efficient pusher aircraft, just
like you can find efficient tractor planes.

For an example, see:

http://www.ar-5.com/

Years ago, when there was a controversy as to whether paddles or
propellers were most efficient for ships, the British came up with a
simple test: They built two identical ships, with identical engines,
one with paddles and one with a prop. They tied a rope between the
sterns, and had the captains go to full power to see which had more thrust.

Pity you can't do this with a couple of airplanes....

Ron Wanttaja