RCU Forums - View Single Post - Pusher Prop Thrust Line Offset from Datum Line
Old 10-06-2011, 12:22 PM
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rmh
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Default RE: Pusher Prop Thrust Line Offset from Datum Line

ORIGINAL: SeamusG

I'm am totally novice when it comes to aerodynamics so please be kind. [img][/img]

Hypothetically this is a 25 - 30 lb plane. The pusher engine develops maybe 19 lb of thrust. Generally speaking, what is the affect of having the thrust line well above (9'' maybe) above the datum line? Assume that the wing, stab, datum and thrust line have the same incidence.

TIA,

It will drive you nuts- especially on launch-
the salvation is to instantly gain enough speed to get the wing and stab working -otherwise -it noses over fast.
I just junked a similar ,slower setup and went to a setup with the thrustline (pusher ) almost centered on the wing -the design is for camera work.
the problem is that the drag is all lower than the thrust . It is exactly like trying to push a carton across a rug-pushing on the top edge.
Lots of goofball flying boat designs used that same engine up high setup
lousy concept- forces are all working at bad angles.