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Raven Morpheus
May-26-2015, 12:13
Hey all

I'm trying to see if I can get a decent calibration on my trim wheel box. I've got 10 turn pots on each axis but I find I'm turning them a lot before I even get any sort of noticeable reaction in-game from the plane, I can see the in-game trim wheels moving though, it's just that the input seems to be far too fine.

I am thus wondering if I should calibrate my trim wheels so that they match the rotation of the in-game cockpit trim wheels?

Problem is I don't know the rotation of the trim wheels on the various planes.

I've just had a quick look in the Hurricane Mk1 Rotol 100 Octane and for the rudder trim wheel it appears to rotate so that the text on it is completely upside down whether I go left or right. Now I'm thinking that means it's got a rotation of 360 degrees (180 left, and 180 right)?

The elevator trim wheel I can't work out though, because there's not much of a reference point to use, I think it moves 270 degrees when from it's default position I trim nose down, and I think it moves the same when I trim nose up, so that's be 540 degrees rotation, right?

Can anyone help me out here and shed some light on this (and possibly provide similar details for the Spitfire)?

TIA

DoubleStandards
May-26-2015, 12:18
Sorry I can't help you out, but someone in the know should be along to help. I will follow this thread as I also am setting up a more functional cockpit, including trim wheels.

Artist
May-26-2015, 14:58
I am using 10-turn potentiometers, too (see this post (http://theairtacticalassaultgroup.com/forum/showthread.php?t=16244&p=188520&viewfull=1#post188520) and following), and while I have to admit to seldom use more then two turns both sides (from center position) I really appreciate the precision this gives me especially on rudder trim in the Spitfires: I often adjust by much less then 12° (30th of a turn, a 300th of the full range).

1lokos
May-26-2015, 15:27
Multiturn potentiometer with less turns (3, 5) is available:

http://www.bourns.com/data/global/pdfs/3543.pdf

Raven Morpheus
May-29-2015, 10:16
OK well I don't know the exact degrees of rotation for the elevator but 270 seems to work ok as I've calibrated in windows control panel my 10 turn pot for elevation trim to 270 and I'm getting a whole lot better response in the game from the plane with regards to trimming.

Raven Morpheus
Jun-03-2015, 16:29
At the weekend I decided to drop the BBMF an email asking about degrees of rotation on the trim wheels in a Spitfire, Hurricane, and some other planes (I know the BBMF has had a P-51D on loan or fly with them), not really expecting a reply, but someone from the BBMF has very kindly replied with some very useful information, at least for the Spitfire so far, he's asking the engineers about the Hurricane.

On the Spitfire there are two turns up and two turns down on the wheel for elevator trim, and one turn up and one turn down on the wheel for rudder trim.

Now, I wonder if that matches what the wheels in the cockpit do in-game? Either way I'll be setting my trim wheels to that when flying Spitfires.

I also sent the exact same email to the Imperial War Museaum at Duxford (hence why I asked about more than just the Spitfire and Hurricane, as the IWM has loads of planes relevant to both IL2 CoD and IL2 1946) but only received an autoreply which indicates I probably won't get a reply from them, which is fair enough, they must get thousands of emails a week.

farley
Jun-03-2015, 18:50
Raven,

Have you watched the elevator trim gauge on the control panel in the Spitfire when turning your trim wheel?
That would give a good indication of how much the trim is moving when you are moving your wheel.

I have the Saitek Pro Flight Cessna Trim Wheel, and using that, it takes about 30 movements (not full revolutions) to go from one trim extreme to another.
I would imagine that each turn is about 1/4 a trim wheel revolution.

I find it does very well in enabling fine trim adjustments. but i sure have to work it hard if i lose my elevator controls and have to use the trim to help me land!

17502


I know this information is like comparing apples and oranges for you, but i'm just mentioning it to you so you'll have some sort of idea of what is out there.
Hope it helps a little bit?

1lokos
Jun-03-2015, 19:27
This will depend of potentiometer, for example I set elevator trim in joystick throttle axis that turn around 60 degrees, then the in game trim move full up or full down with this 60 degress movement.

If you use a 10 turn potentiometer - 3600 degress - and calibrate the for use full course in Windows control pane, you need turn then 10 times to get in game trim full up or full down.

Test this, calibrate the 10 turn pot in Windows control panel turn then only 720 degrees (2 turn, like real Spitfire) for each side and test in game if the response is adequate, as you are turn the pot partially you are not varying the voltage from 0 to 5v and so not using the USB controller full resolution.

Example if the USB controller is 12 bits - 4096 points possible per axis you are using ~1638 points (40%), what is probable most than sufficient for trim.

As comparison, CH Products resolution is 8 bits - 512 points per axis, Saitek X-52 PRo is 10 bits - 1.024 points.

Raven Morpheus
Jun-04-2015, 13:08
I find it does very well in enabling fine trim adjustments. but i sure have to work it hard if i lose my elevator controls and have to use the trim to help me land!


That is precisely what I'm saying, that I was working hard just to trim my plane. Recently with calibrating my elevator trim wheel (10 turn pot) to only use 270 degrees I've found it much easier to trim, because I don't have to move the knob on the pot too far to get a reaction from the plane. It seemed with the 10 turn pots (Bourns pots btw) set to their full 10 turns I had to turn them a long way (a good number of full turns) before the plane even reacted (and yes the dials, wheels, gauges etc. in the cockpit do move to correspond with my input).

What might be better is if I could somehow set up 2 pots in series, one lets say of 2 or 3 turns for coarsely trimming to a point, and a 10 turn pot for further fine trimming (not that I've needed such fine control recently, 270 degrees seemed fine enough in the Hurricane), but I wouldn't know exactly how to wire up 2 pots in series, if that would even work with them attached to a Bodnar BU0836 board...

Plus it'd be a bit unrealistic as you only have 1 wheel per trim axis in the cockpit anyway.

So, for the Spitfire (seeing as I'm now flying one in the campaign) I'll be using the data given to me by the BBMF, and calibrating my pots accordingly - it will at least be realistic and should hopefully work as well as 270 degrees did for me on the Hurricane.