Su29 50cc KnifeEgde issue
 

Hello,I own the Sebart SU29


Everything seems ok but when i try to do Knife edge - the more i push the rudder, the more i get pitch down on the elevator. its very strange to me.

Anyone familiar with that kind of an issue?

CG is too far aft.

So you say i should add weight in the front ?!
This is the issue for sure?

It's better to move equipment forward to shift CG. What is happening is that because down trim is being used to compensate for the aft CG that trim becomes more effective while in knife edge. I'm betting that on the maiden flight it wanted to climb?

I dont recall the maiden, but i can say that during landing the nose wants to go up.
I know its a bit tail heavy, and most of the gear is already in front. I will move the main batt forward and see what happens.

I always try balance close the mfg's recommended center point. Then I roll inverted and let go of elev - it should divert very little. I use elev to make tiny correction in flight if necessary. I'm just a sport aerobat so you may want to be more precise.

The classic CG test is to roll inverted in a 45 degree upline and release the controls. A slightly forward CG that will give you a smooth flying plane will pull slightly to the canopy. When I was setting up my Extra, a pretty experienced IMAC pilot told me to look for a 4-6 count before the plane was heading downwards. I followed that advice and got a very smooth flying plane. I could get better snaps and spins with a more rearward setup, but the plane does well enough. I do need a fair amount of mix for knife edge flight, but that's a small price to pay for a plane that doesn't get tossed around in the wind and is very predictable through all maneuvers.