Finer Trim Control -- Su-25T

I've had DCS for some time but being on the poor side, I still only fly the Frog. Lately I've been trying formation flying, flying with a pair of AI Frogs. What I find is I can't trim the pitch to maintain their altitude. I see myself descending and give it one click of up trim and then 10 seconds later I have to give it one click of down trim. I can't get it bang on.

This is not new. I also use FSX. Same problem. I know from experience that left alone the aircraft will find its own altitude where it will fly dead level but the difference between one click and the next is at least 200 feet. Not good enough for formation. As an addendum, aileron and rudder trim are even worse. When I have an unbalanced load I cannot come even reasonably close to trimmed when I trim manually. The autopilot though, has no problem. I suspect it is continually making corrections, but who knows?

The question is, is this fixable or is it purely a hardware problem. Saitek Pro Flight Yoke. Yeah, not ideal, but it's what I have.

I've had DCS for some time but being on the poor side, I still only fly the Frog. Lately I've been trying formation flying, flying with a pair of AI Frogs. What I find is I can't trim the pitch to maintain their altitude. I see myself descending and give it one click of up trim and then 10 seconds later I have to give it one click of down trim. I can't get it bang on.

 

 

This is not new. I also use FSX. Same problem. I know from experience that left alone the aircraft will find its own altitude where it will fly dead level but the difference between one click and the next is at least 200 feet. Not good enough for formation. As an addendum, aileron and rudder trim are even worse. When I have an unbalanced load I cannot come even reasonably close to trimmed when I trim manually. The autopilot though, has no problem. I suspect it is continually making corrections, but who knows?

 

 

The question is, is this fixable or is it purely a hardware problem. Saitek Pro Flight Yoke. Yeah, not ideal, but it's what I have.

I think that it is fixable by using axis curves, because they also apply to trim. I can trim Su-25T just fine. The other possibility is to use alt stabilization autopilot, but do not set the altimeter base pressure to other value than 760 mHg.

I've had DCS for some time but being on the poor side, I still only fly the Frog. Lately I've been trying formation flying, flying with a pair of AI Frogs. What I find is I can't trim the pitch to maintain their altitude. I see myself descending and give it one click of up trim and then 10 seconds later I have to give it one click of down trim. I can't get it bang on.

Neither aircraft are designed to hold perfect attitude/speed nor the trim is designed to hold it perfectly. For long cruises use the autopilot or just the regular stick and trim corrections.

Formation flying OTOH demands constant focus and small inputs on both stick and throttle.

Different modules have different trim sensitivity but it's usually as you described it.

The "transition to level flight" autopilot mode will trim the aircraft for you. If your speed remains constant and you don't fly into any weather it should be more or less hands off. The aircraft will retain the trim settings from the autopilot after you disable it.

Thanks guys. Since I've never seen a "fix" for this, I'm not surprised with the negative responses.

I am aware of and use the autopilot and axis curves, as well as the need for 760 on the baro. They do help but not enough. I don't expect perfection from the trims but they do seem too coarse. As draconus points out, formation requires enough concentration. I don't need to fight the trim too.

feefifofum, autopilot Baro altitude should do the same thing. I may use that to establish the proper altitude, then turn it off, but it feels like cheating.

There's no fix because there's no bug. Trim sensitivity could be lower and that's it - question to SMEs.

Also it's not cheating when it's IRL aircraft feature.

There is only one kind of ''hands free'' flight in any aircraft, autopilot. Watch any video of aircraft in close formation, and they each bob up and down, surge forward and backwards. If they're really elite, like Blue Angels or something, the movements are very small, but they are still there.

There is no such thing as 'trim and never touch the stick'. It does not exist unless you are using augmented flight systems. Atmospheric turbulence and tiny imperfections in your movements and controls WILL cause deviation. Small changes in airspeed WILL cause deviation. It's not a question of 'if' it's a question of how much. Additionally, combat aircraft are not airliners. Airliners are built for maximum stability and efficiency, combat aircraft are built for maximum performance and are typically UNstable BY DESIGN.

There are exactly two conditions in any game where you won't encounter this :

#1 The game doesn't model it or you've got it turned off

#2 The aircraft you're flying has stability augmentation. The deviations are still there, but the flight systems are compensating FOR you

DCS models it unless you turn it off and set weather to 0 across the board.

The 25T is not augmented, manual controls only.

Conclusion : use the autopilot or 'fly' the aircraft

The autopilot is as sensitive and good as is the trimming accuracy. If you can't trim well, then autopilot can't do it any better than you.

It can be seen on any airliner how the automatic trimming works, constantly wheels rolling up and down, but that is not because trim is not accurate, but because there are so much external forces.

In DCS the trimming is not accurate enough, a quick click of trim button and aircrafts goes from +3 meter attitude to -2 meter attitude, try to refine it and you are suddenly +5, then again +2 or -4 etc.

With trim you are suppose to perform very fine control inputs, not to fight against trim that constantly is trying to kill you to go totally opposite direction you want.

But there is a HUGE difference what controllers/methods you are using for the trimming.

Example with the AV-8B Harrier and CH Fighterstick I couldn't get it trimmed at all to stable flight, instead few seconds later it was either pulling hard up or diving on the ground. It took very careful button presses to get them as short as possible to get it fine tuned. Something that you wouldn't do in reality.

But with VKB MCG the thing is totally different, with a 8-way hat (not the trim mode) I can without effort just tap couple times the direction I want and it goes almost to ballpark, need to readjust trim just now and then.

And now it is similar with a Su-25A, far more easier to trim than trying to push any button on the keyboard or CH stick / throttle.

With keyboard and other controllers I can almost use trim as good to fly aircrafts than a actual stick, because it has such speed and effect. But with VKB MCG I can't as it is very smooth, accurate and gentle way to control aircraft.

And when it comes to example flying in formation or performing air refueling, VKB MCG made it super easy as you fly the aircraft then with the trim. You just trim, trim and trim.

And it really is like flying with blue angels with VKB MCG, you can trim so easily and well that you don't even notice that you are already doing the corrections, something that was impossible with any other as you literally go all over the directions with each push and press.

And it really is like flying with blue angels with VKB MCG, you can trim so easily and well that you don't even notice that you are already doing the corrections, something that was impossible with any other as you literally go all over the directions with each push and press.

Maybe you're on to something that may as well be a DCS bug or just how the controller processes the input/output operations (timing and signal resolution). We usually have 8-way hat-switch for the trim. Are you using any curves in pitch/roll? This can also explain the difference users are having in trimming Su-27/33 and Mig-29.

I will try to do some tests with my controller (TM HOTAS X).

edit: Apparently you can't use the trim as axis or by analog hat, can you?