Aileron differential

[Gary Manuel]

Posted by PatMc on 11/05/2019 15:30:06:

Posted by Gary Manuel on 11/05/2019 13:25:47:

Reading with interest. I never realised the complication of coordinated turns.

Slightly off topic but I have a question that has always confused me. On my transmitter (JR DSX9) I have the option of using aileron differential in the main menu. I have a couple of models that require aileron differential; a notable one being a Hobbyking Lancaster. I can't remember the exact figures, but lets say it required 10mm up aileron and 5mm down. Rather than using the aileron differential menu, I simply reduced the travel (end point) of both aileron servos in the downward position. It appears to work OK.

My question is, is there a difference between using the aileron differential menu and simply using the travel adjustment to achieve "aileron differential"?

By using the end point travel restriction you're reducing servo power at the same time making the control coarser.

But surely that's what the aileron differential setting in the menu does too - reduces the amount of travel used in one half of the servos movement. The only way of maintaining the full resolution (and power) of the servo is to set the differential up mechanically using servo arm / control horn geometry with full servo travel in both directions. Any setting used on the transmitter to achieve aileron differential will be at the cost of servo resolution. I just can't see the point of the aileron differential setting in the menu if the same can be achieved by limiting the travel in one direction - or am I missing something?

[PatMc]

I think you're right Gary.
I tend to only use differential on gliders at the same time use spoilerons. My main Tx's are FrSky using OpenTx. I don't use any "menu" differential setting but I increase the available aileron servos movement to max possible, offset the centres & adjust the outputs to my requirements.

[Martin McIntosh]

I have a few models which require quite a lot of differential, namely an o/d 81" Lanc, a HK one, a Precedent Stampe and a Mercury Tiger Moth. The Stampe is done mechanically by offsetting the servo arms as is the 81" Lanc. Servo power on the other two is sufficient to just use the Tx diff. 2:1 on these types of model is about normal. If you wish to roll without the addition of rudder you can always use a mix switch. 30 to 50% rudder mix seems to be about right. Strangely, the Tiggy needs rudder mix but the Stampe does not.

[Birgir]

At last I had the opportunity to test my new aileron differential setup. As suggested, I put in 1:2 differential i.e. twice as much up as down.

This helps a lot and now I must practice using the rudder for coordinated turns.

I also need to practice my landings, nothing serious though.

Thanks again for the advice.