BobR wrote:
On Aug 28, 2:36 pm, cavelamb wrote:
Jerry Wass wrote:
Dan wrote:
BobR wrote:
On Aug 28, 3:13 am, Oliver Arend wrote:
Regardless of what is fact and what is fiction, most of what has been
said about composite canard pushers vs. metal classic tractors is
comparing apples to oranges (IIRC, in Germany we usually compare
apples to pears). Advantages and disadvantes have been pointed out,
but do not relate to the original pusher-vs.-tractor question. The
Cessna Skymaster example in the original text suits it much better.
Apart from the problem of aft CG and hence the difficulty to make a
single-engine pusher in a classical wing layout, there are two
opposing factors:
1. The tractor engine works more efficiently since the prop is in an
undisturbed air stream. The slipstream may be able to increase maximum
lift on parts of the wing, but can induce a rolling moment. The
turbulence created creates more drag, especially on the fuselage.
Also, putting the engine up front makes it less likely to have an
aerodynamically optimized fuselage.
2. The pusher engine works less efficiently since the prop sits in an
airstream that has already passed fuselage and wing. OTOH, the
fuselage can be shape-optimized more easily and sees an undisturbed,
laminar airflow. Maximum lift is likely to be a little lower.
Now, which of these effects is the dominant one? Also, if you have a
twin engine airplane, the fuselage is out of the equation, so the
final result may be different!?
Oliver
So let me sum it up thusly.... 6 of one, 1/2 dozen of the other.
On the other hand..... there are more fingers.
Dan, U.S. Air Force, retired
Are we speaking of 6 fingered hands??--that would broaden the subject
sumwhot
starting from ten on this hand we have - 10, 9, 8, 7, and 6.
Plus five on the other hand would be = eleven?- Hide quoted text -


There you go again using that educated government math.

It could be worse, he could be using algebra. That's when you stop
counting on your fingers and start using your toes.

Higher level math usually requires illegal substances.

Dan, U.S. Air Force, retired