known Trimming problems

Eagles787 · March 22, 2022

I know there is a long thread in the Apache general section regarding Force trim and people having difficulties in trimming the aircraft. I just wanted to report the problem here under bugs as well so it can be looked at.

Since nearly all of us use a centering spring input device for the cyclic due to the lack of FFB devices on the market, we have the choice in special options for trimming to select either Instant Trim or Center Trimmer mode. Currently both modes have some difficulties in it's operation.

Instant Trim: When your cyclic is out of center and you press and release the trim button, your current cyclic stick position is stored as it's new center point and now on top your current stick position is added so that your total control input is basically doubled. It is difficult to return your cyclic to it's center position instantly and so it causes a jump in your aircraft's attitude. A small delay (eg. 0.5s or maybe a variable option) could be helpful here so you have a little time to return your cyclic to it's center position. This used to be the Default mode of trimming in the older modules like the Huey I think.

Center Trimmer mode: When your cyclic is out of center and you press and release the trim button, your current cyclic stick position is stored as it's new centerpoint, however your control input is now frozen until you return your cyclic to it's center position. This is a good concept, but it is now possible to have difficulty in finding the exact center position to unfreeze your control axis. Many users have a long stick extension and loose springs for flying helicopters and this doesn't help in finding the center position. This can cause not having control of the aircraft for several seconds or even until a crash. In this case also a small time out delay could be helpful. If a control axis is not sensed to be centered after a certain time delay (eg. 1.0s or maybe a variable option) then the control input gets unfrozen and giving control back to the pilot. So with this option your controls unfreeze by either sensing center position, or the time out delay, whatever comes first.

I think adding these timing options to the trimmer modes could make the operation of trimming more reliable, predictable and easier to use. We are stuck with spring centered input devices, and should have a user friendly trim system to accommodate for this limitation.