High engined plan trim question

Hi,
I just came across a video of the Saro "Cutty Sark" twin engined amphibian plane
at and the question occurred to me
what planes with engines as high mounted as this one are like to fly ? ISTM
there must be a huge nose-down with power trim problem. In particular, landing
must have been tricky with the reduced power giving a nose up trim right at the
time you are near the stall and I wondered what the original designers did to
counteract that ?
Reply to
Boo
Loading thread data ...
occurred to me
particular, landing
The engine thrust is offset accordingly. I have a power pod that is used for temporarily converting a 2M sailplane to electric power. (also have a 1/2A glo engine one) Both are set up in a tractor configuration with a positve engine thrust line. I.E., the engine points up in relation to the fuselage center line. Here is a good read on it:
formatting link
Notice he points out that if the engine is placed on, or very nesr, the CG the effect is not as pronounced.
Reply to
Anyolmouse
Both the lateral and verticle CG location enters the question. Granted, the engine can be located on the lateral CG -- it can not be located on the verticle CG. The moment produced by the engine can not be reduced with down thrust to a significant degree. A 10 degree down thrust -- which would be VERY large -- would reduce engine moment by about (sine of 10 degrees) 17 percent. The result is that, during cruise flight the airplane. when trimed for hands off flight must use down trim to counter the engine. When thrust is reduced the moment produced by engine thrust must be replaced by down elevator -- or be retrimed to lower the nose. For a pilot this is a natural thing and not a big deal.
Reply to
Lee B.

Site Timeline

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.