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Stabilizer Trim Speed

Posted: Thu Dec 21, 2023 3:03 pm
by Alpin-Flier
Hi Roar and all

I tried to optimise my stabiliser trim wheel in my PMDG 737-800. Up to now, I controlled the wheel in the virtual cockpit (VC) by the switches on the steering wheel, sending NUM1 and NUM7 keys to MSFS. The SW position was then copied to my HW wheel. The problem: I could not operate the HW trim wheel manually, because the SW had control for deviations. So I looked for a solution, where the HW trim wheel itself controls the position, when not in Autoflight mode.

First, I used Var 2353 with values 8192 and 16384 as soon as the HW wheel became different from the wheel in the VC. That worked over the whole range 0 to 15°, but was extremely slow. E.g. I operated the up- or down-switch for two seconds, but the VC wheel needed 10 and more seconds to follow the new HW position. Quite inacceptable.

Then I changed the script, not using Var 2353 anymore, but again the key commands NUM1 and NUM7. These make the VC wheel turn much faster, but the problem is now the range. Below about 4.0° the VC wheel does not turn any more. This is normal for the operation by switches on the yoke (following the real plane), but going manually below 4° is not possible this way.

Any idea, how this problem can be solved? I would need a variable controlling the whole stabiliser range with a reasonable speed for up and down, or even better, a direct axys control (unfortunately not supported by PMDG). Thanks for any ideas.

Best regards
Urs

Re: Stabilizer Trim Speed

Posted: Fri Dec 22, 2023 1:52 pm
by Alpin-Flier
Hi all

After some further investigation I have found a solution. First, I had to notice: Trim wheel speed and range are dependent from flaps. With flaps up the range is restricted to ~ 3.95° - 14.5°, the rotation speed is quite low. With flaps extended, the speed is rather fast and the range from 0° to ~ 17°. To allow the synch from my HW wheel to the SW wheel I must program the following:

with flaps up
- limit the electric switch controllable range of my HW wheel: 4° to 14.5°
- lower the motor speed, so that the SW wheel can follow immediately the HW

with flaps extended
- full range with electric switches or manual trimming
- motor speed as high as possible, but so that the SW wheel can follow the HW without delay.

This is then near the real. Exception: when flaps are up, the SW wheel can be turned with the mouse below 4°. Just turning the HW wheel below 4° will not do anything. But IMHO this case is not really needed.

Comments or questions are most welcome, of course.

BR Urs