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Seems like 6 of one, 1/2 dozen of another?
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 |
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