CSM system, hard nose up after loop?

[cmassa]

I have Trex600 with CSM flybarless system. No matter what I do I cannot get this to stop. When doing big loops it will suddenly give a hard up elevator when coming out of the loop at the bottom, sometimes the nose ends up almost pointing straight up. It is also seems to do this in fast turns, the nose suddenly pitches up. I have played with the gains a lot which hasn't seemed to help much. Flips are just fine. No problems on the aileron side of things. Any ideas. I'm just about to put the flybar back in. I know someone wants to say it but please don't tell me to get a Vbar or other system because that is not going to happen (no more cash right now). I just can't get comfortable with it because it is too unpredictable. A flying buddy has an almost identical helicopter which has none of these problems. I put in his settings and it was just as bad.

Chris

[Skookum]

I don't know the system, but it sounds like it's running out of cyclic pitch range in elevator. Try increasing the cyclic pitch range available to the gyros, maybe increase the servo travels. Just a suggestion.

[cmassa]

Thanks but I'm not sure I see how that could be the cause. Could you give me a little more information? This is usually when I am near neutral pitch and only a little elevator input when leveling out in the loop. It suddenly noses up sharply. My servos can tilt the swash all the way to binding on the shaft if needed.

[Skookum]

In fast forward flight, the heli has a natural nose-up tendency. This increases if you add collective. A cyclic gyro for flybarless will silently trim this out, but if for some reason it runs out of ability to trim it out, it will "let go" and suddenly nose up. It's sort of like if you don't have enough pitch range on your tail, and the tail kicks over at a moment of high torque load. If the elevator gyro has an adjustable "integrator limit" increasing that would be similar to increasing the cylic pitch range.

[cmassa]

Thanks for the info. I get it now. I checked and the gyro has the full travel of the swash available to it. Unfortunately my problem does not appear be a problem with settings in the gyro. I switched the aileron and elevator gyros yesterday afternoon, reprogrammed them and the elevator problem went away and it started doing some odd things with aileron so I think I have a bad gyro. It's a lot harder to tell on aileron. A friend has a spare gyro that I'll try and see if it fixes everything.

[cmassa]

OK, that's not it either. I took it out for some more testing this morning and it still does the hard nose up at the end of a loop with the gyros switched. I have throws maxed out. I have made many different adjustments in the settings for the gyros but it still does it. I guess I'll put the flybar back and see what happens?

[arky]

thats the reason i sold my csm system in the end i couldn't stop this, fully but if you give it as much cyclic travel as you can get withot bindin it will improve it a lot.

[cmassa]

I finally just put the flybar back on and it is flying fine now, except for some radio glitching now. Maybe I'll just sell the other two gyros. I'm still using the cyclock to improve the mixing problems with CCPM in my Futaba 9C radio.

[Bjorn]

Have you tried sending a mail to Colin Mill at csm?
The were eager to help when I had some issues with my 720 gyro..
Nice support from csm for me at least .