CSM 720 setup help

[PsiLo]

Maidened the 6hv yesterday and tail was not holding well even with the gain up near 100. Today I changed the ball from 13mm on the bls 251 to 17mm, setup the gyro again and holding better.

Problem now is that right rudder has a massive delay to stop. I.e. I move nose 45 degrees and release, but the nose carries on another 45 degrees before stopping! Only happening on right rudder so what do I need to change in the software to stop this??

[p4ddy]

I had the same issue ages ago & i can't remember why it done it?? The csm has to hold BANG ON in rate mode before it works & it has it's way of telling it's not set quite good enough.

[p4ddy]

I've just remembered it was because it wasn't quite holding bang on in rate & i'd used quick trim to eliminate the remaining drift




Oh it's piro stop to adjust delay

[Tim Procter]

If you have the USB dongle and the software for your computer there is an option to set all defaults.

Do that and start again.

[rapidgaz]

hello Gerd, i have had 2 of these now and have been on 5 diff models, and have all been great out of the box, so no change from default

[PsiLo]

If you have the USB dongle and the software for your computer there is an option to set all defaults.

Do that and start again.

hello Gerd, i have had 2 of these now and have been on 5 diff models, and have all been great out of the box, so no change from default

Maybe I should have been clearer in my opening post, but when I setup the 720 I went in via the software and reset to defaults. I then changed the frame rate and servo centre pulse (760/333 for my BLS 251) and changed the servo speed to match the BLS251 (0.059/60deg).

Having done all this I went through the quick setup routine and set reversing, limits etc.

Then I went to test fly and it was here that I discover that on right rudder input the tail overshoots terribly. So, out the box on my setup this is not working at all well and I need to try and tweak it to get it working. Beginning to wonder why I didn't just stick with the Quark now as this has been rock solid out the box on the other helis

As it is only the right stops that are overshooting, I guess I need to adjust the right stop gain, I assume I will need to increase this can anyone confirm?

[Tom Burgess]

Yes, increase right stop gain Gerd

[moyesboy]

If the stops aren't even left and right then perhaps your servo arm isn't 90 degree to the pushrod when the heli is in the hover?

you can get different mechanical stop gain by offsetting the servo arm deliberately. However on a .50 size this isn't usually critical. Much more to be gained by optimising things mechanically on a 450 where the tail performance is more marginal.

Do take a look at your tail mechanics for anything sloppy or coming apart on the pitch slider, and dodgy tail grip bearings that might stick.
I flew a raptor for someone which had a very strange assymetric tail response, and it turned out the pitch slider was in two parts, only working one way, only capable of right rudder.

All my 720s are on default settings, except for the servo stuff for the BLS251.

[PsiLo]

Thanks guys, just reading through the manual again and realised I didn't do the quick trim in Mode 0 (rate mode). I am fairly certain the tail linkage is slop free and not binding so will go and test in rate mode and do the quick trim and then see what happens

The left and right hand stops are not equal. Stops from right hand turns are slow but clean while left hand stops are bouncy.
The mechanical tail trim needs setting correctly. Carry out the procedure in the Quick-trim section of this manual and reassess. If the problem exists after
the trim has been set correctly use the PC interface to adjust the left and right stop gains to get the stop quality you want. If you still have problems, try
reducing one servo travel as follows: - if bouncy when stopping left turns, reduce the right pitch travel limit and vice versa.

[Grant_beltcp]

I was just going to say that if everything seems OK mechanically do the quick trim feature and I would expect that to sort it out. if not - go back to rate and set it mechanicaly for no drift, then do the quick trim and see how it is then.

[PsiLo]

Guess i have just gotten lazy using the Spartans! Set tail for about 6 degrees and slap it on, never bother setting in rate it just works

[Grant_beltcp]

It may be that your just used to align heli's rather than spartans. I havnt had a problem with either of my CSM's like you do, but I set all the bell cranks and servo horns at 90 degrees rather than by the pitch. I find it easier, and it's what my Align's and Synergy have said to go by rather than pitch. Apart from having to hook the CSM up to the PC to change the servo perametres I have only done the normal TX set up aswell without the auto trim. Let me know how you get on - Might be able to talk you through a few other options tonight on MSN.

[p4ddy]

As i said, you cannot get away with a slighly bad mechanical set up with a csm. Do not use quick trim until there is NO drift at all or it will still be slightly off.