Another bad tracking in climbs

[stuartaw]

I've just been flying a plane with a new motor, which will now climb vertically for much longer than before... but I'm needing a lot of right rudder to hold it straight while climbing vertically or near vertically.

The plane appears to be trimmed OK over a wide speed range when horizontal, and is OK inverted (it needs elevator, but that's expected from airfoil and CofG). It's a low winger with quite a bit of dihedral, so there is significant yaw-roll interaction.

Does anyone know what the rudder in climb means about the trim/balance of the plane? Is it inadequate side-thrust? Bad rudder/aileron trimming?

TIA

Stuart

[flyfalcons]

Bigger engine = more p-factor and more spiraling slipstream hitting the left side of the tail, requiring more right rudder. Putting more right-thrust in will make the plane behave differently when inverted. I trim my aircraft so when I pull vertical I won't have to touch the rudder for 2-3 seconds. After that almost every plane will need rudder correction, especially ones with large engines.

[CurtD]

This is the classic indicator of inadequate engine right thrust. If possible add shims behind the mount or in some way shift it so that the engine points more to the right. Make small changes (about a degree at a time) until it will track straight in vertical climbs. You shouldn't notice any difference in normal, level flight (except better tracking at the top of loops) when adding right thrust.

[stuartaw]

Thanks folks. I'll try a little more right-thrust and see if that helps.