engine thrust angle in extra
 

Hello all
I shifted my Extra 60 engine recently from o.s 61fx to a Webra 1.20
I have good power now but i am struggling with vertical maneuvers like 4 point roll in vertical downline or any similar maneuver, the plane trends to pitch up (like if I were applying up elevator) at minimum throttle.
For the landing it's pretty much the same thing, when a cut off throttle the plane pitches up and does not penetrate I mean, I had to program an elevator-down mix so I could be able to land the plane.
At mid or full throttle the plane flies straight
I am almost sure this is due to vertical engine thrust angle, but I don't know whether should I add up or down angle?
Any hint will be highly appreciated
Regards
Omar

RE: engine thrust angle in extra
 

Omar,
I am in NO way a trim expert but if I may throw something out to think about until the experts give you their opinion...
If we are talking about power off downlinethen engine thrust would not have anything to do with it unless the up or down thrust is so gross you are having to put substantial elevator trim in for straight and level.
I believe pitiching up in the downline (power off) could be caused by wing incidence.
Have you checked it?
If you can adjust it try increasing the angle of attack of the wing slightly.
This will cause you to carry a little down trim on the elevator from where you are now. This in turn will decrease the pitch up, throttle off in the downline.
Make small changes!
Good luck!
JLK

RE: engine thrust angle in extra
 

Ooops!
The above was assuming your CG is the same from the OS to the Webra.
Is it?
JLK

RE: engine thrust angle in extra
 

Yeah, I would suspect the CG moved forward with the heavier engine. This would require up trim for level flight, and could cause the nose up on downlines. But, he says it also pitches up at low throttle on landing approaches as well, a nose-heavy plane would not do that.

I seriously doubt the thrust angle would cause any problems on down lines, the thrust angle affects the up lines more.

The Extras have a pretty high thrust line, and that (I think) can cause a pitch up on down lines, from the braking action of the prop. I think the down-mix at low throttle is probably the best fix.