Have you checked your endpoints are the same for left and right

Any sub-trims in there limiting throw?

make sure the servo horns are level at midstick (50% throttle stick)

Different rates on each half of the stick movement?

Start a new virgin model in your transmitter with all fresh settings and see if it still does it.

Make sure you're not using too much sub trim to square up the servos (you should be aiming for less than 10 points on each servo).

If it still does it, then you've got some mechanical problems somewhere.

Come to think of it I did have to use quite a bit of sub trim. I have +24 points on my pitch channel. How are you guys leveling your servo arms? Are you just eyeing it or are you using some sort of tool? Just to note these are ds610s with the single armed servo arm that comes with the servos.

My end points are different left and right. For my aileron I have 60% with the throttle down and 110% with the throttle up. I take it this is bad? To fix this do I need to use less sub trim?

I'm not using any rates and they are all 100% and equal.

Sorry for all the questions but thanks for all the suggestions and help.

Thanks,
David.

Endpoints should be the same left and right, the throttle shouldn't make any difference to the aileron, unless you're not mode 2 on your tx. Either way it needs to be the same both sides. Not sure how the single arms line up but 24 on the subtrim is quite a bit but shouldn't give you what you have. You could try and swop the arms to different servos and see if you get a better result, the less you use subtrim the better.

Note: I am assuming the OP is using a FB heli. I am still on flybars and dont know how things would change for a FBL setup. If this is for FBL and this is all wrong then sorry in advance .

This is not entirely true Dave. Remember endpoint adjustment is on a per servo basis and is applied before any ccpm mixing is applied. The fact its aileron end point in this instance just means its controlling the servo plugged into the aileron port of the rx.

Adjusting endpoints at full positive and negative pitch (or high and low throttle) is used by many (myself included) to level the swash at its maximum and minimum points and its really just compensating for the small differences between the 3 cyclic servos. Furthermore its not uncommon to have different endpoint values for the swash at high and low positions. In an ideal world we would not require any end point adjustment and our servos would be perfectly matched but this is not always the case .

However having said this an end point value of 60 sounds way off to me and I would not be surprised if this is the cause of the uneven pitch that has been seen (I would not expect to have to use any more than say +- 10 points of adjustment using end points). Either the OP has done something wrong during setup or his cyclic servos are badly matched.


Also a subtrim value of 24 will be fine. There is nothing wrong with subtrim, all it does is move the centre point of the pulse slightly so instead of being at say 1520us it may be 1500 or 1540us. I have read that the idea of "subtrim is bad" may come from the fact some older radios got their knickers in a twist when running high subtrim values but this was a programing issue in the tx and should not be the case any more.

If you have massive subtrim values then it could possibly cause a problem because you would simply run out of servo travel. However if you always mount the servo on the spline that is closest to 90 you will never have to use more than half a splines worth of subtrim which is hardly any movement when compared to the servos full travel

Of course you are correct but it was this statement that confuses things, there is something odd here with aileron being mixed with throttle. No more than a few % should be needed to correct any ECCPM mix errors, 60% to 110% is way too much not to cause problems. As said I think start again, use one of the many setup videos on HeliFreak to help.

Yeah sorry I have not explained it very well but what bolders said was what I meant. By the way I forgot to mention it is a FB helicopter.

Yes I think the best thing for me to do is just start fresh and closely follow the setup videos availible.

Thanks,
David.

Hi David,
Just before you start all over again - have you set it up in the first place with the TX trim tabs (next to your sticks) not centred? Check their positions on the monitor if your TX has one.
Good luck, Marty

Hi Marty,

Yes I set it up in the first place with the trims centered.

Thanks,
David.

Is the problem at the bottom end or top end of the head? By this I mean the swashplate (bottom) or the levers and rods that convert the swash position to a rotation of the main blades. If you are having problems with different movements of the swashplate with left,right and up, down then that is a tx or servo or servo horn position problem. If the movement of the swash is correct but is not being correctly translated into main blade rotation, then that is head geometry. Either an incorrectly assembled head or incorrect rod lengths. They do need to be set very accurately to about 0.1mm.

I think I found the problem.

I reset the model and the problem was fixed. The problem started when I used more than roughly 12 points of sub trim. To try and fix the porblem I have ordered some more servo arms to try and see if I can use less sub trim as my current values are around 30 on the closest to central spline.

I will report back when I make progress.

Thanks,
David.