combat trim Pros and Cons

[Flyboy]

can someone explain me how does combat trim work in the game?
it doesn't keep my plane straight and level, there is still a roll effect from the prop.
is there any cons on using it?

tried using the search option but its not very good..

[FLS]

Combat Trim is convenient. It sets the trim according to your speed and assumes no flaps. It is not an auto pilot.

I generally don't use it. I mostly stay manually trimmed for cruising speed and use auto pilot modes.

When you are very slow you might find CT has trimmed you nose up more than you really want to be. You may want to turn it off for stall fighting.

[TequilaChaser]

Is great to see you back posting on the message boards, Flyboy!

Are you back in the game as well?  I hope you are....

Are you still in the IAF and if so what are you flying these days?

~S~ 

TC /  Johnny

p.s. - There will be 2 KOTH events the last Saturday this month of March, come join in on the fun!

[Oldman731]

can someone explain me how does combat trim work in the game?
it doesn't keep my plane straight and level, there is still a roll effect from the prop.
is there any cons on using it?

Combat trim is supposed to trim you level (the yellow light) or at close-to-best climb speed (the red light) (which you can also use in descent, by retarding the throttle).  If your plane is still rolling around, it might be you need to calibrate your controllers.

Because combat trim is always trying to keep you at best level-flight trim, it may take longer to pull out of a dive in some planes.  I use combat trim all the time, except in P-38s and Franks, where the recovery-from-dive response is noticeable.  Not that my use should be persuasive, but Shane also used combat trim all the time, and his success should be persuasive.  If you rely on manual trim, you may well be skidding or slipping all the time without noticing it, thereby losing speed.  Nevertheless, there is a determined segment of the AH population which believes that you can get better performance using manual trim.  I don't buy it, but the debate has been continuous since combat trim was first implemented lo, these many years ago.

- oldman

[Flyboy]

Thanks for the help.

Oldman maybe i dont undetstand you but ithink you might mixed up combat trim and the differnt autotrimms available (level. Speed. Angel- the different color lights)?

To my understanding (and i am probably wrong) the combat trimm supose to keep your plane at sync. No roll pitch or yaw inputs unless the pilot move the stick. No matter what is the air speed, engine setting or the nose position of the plane.

A short offline test shows the CT isnt perfect in canceling those effects.

Im trying to determine if i loose something when using it instead of manual trimm.
I now understand that its along time dispute. Iallso understand that using or not using it is not a big mistake.

Would like to see more information on how the CT works if anyone can point me to it...

Good to see you too TC i sent you a PM

[Oldman731]

Thanks for the help.

Oldman maybe i dont undetstand you but ithink you might mixed up combat trim and the differnt autotrimms available (level. Speed. Angel- the different color lights)?

You're right.  Please ignore my description of the red and yellow lights (although the description is accurate as to auto trim).  So far as I know, however, combat trim otherwise is supposed to work as outlined - keeping you in trim for your current speed.

- oldman

[Wiley]

Simply put, CT works off a table based on airspeed.  If memory serves it adjusts about every 5mph IAS or so.  So at 200mph, it puts all 3 trim tabs at a certain location.  At 205, it adjusts them slightly, and so on.

It is not perfect.  It is not designed to be.  It puts you reasonably close to in trim most of the time so you don't have to worry about it as you are flying around and fighting, changing airspeed as you go.  It is based on a clean airframe at full throttle more or less, with no flaps.  Putting flaps out or carrying ord or adjusting your throttle will change things so it will not be in perfect trim.  Some planes just won't trim straight at certain speeds, the Typhoon or Tempest below 200mph for example.

Generally speaking I just leave it on.  If I'm flying something like an F4U or a 109 that uses a lot of flaps, I will blip it off around 200mph if I am entering a stallfight, as I tend to use manual trim at that point on my elevator with flaps out.

Wiley.

[FLS]

Combat Trim is not precise, it just sets the trim to approximately center your stick, it's not meant to replace the auto pilot.

If you understand how speed changes affect trim then you can leave CT off or just turn it off when you need to.

[Drano]

Wiley and FLS have it right. FWIW, I hardly use CT in the 38 for a couple of reasons. First, as there's no torque affect or p factor to deal with, there's nothing messing with rudders or aileron trim--unless I lose an engine. This does happen to me a lot tho! That and I have trims mapped to my stick and am always adjusting especially elevator trim as speed rises and falls. I've found I can just as easily put the stick where I want it that way. This is especially important in dives or on flaps turning at slow speed. At the extreme ends of the speed range CT doesn't guess so well and without manually adjusting elevator trim you'll find yourself either lawn darting or fighting to push yourself around a turn rather than pulling thru. At "normal" speeds its just fine tho. I'll kick it on when in simple transit from here to there.

Sent from my Moto Z (2) using Tapatalk

[Drano]

I'd add that the stick I'm using, the VKB MCG-PRO, has a special hat switch on it unlike any other hat currently out there and it's perfect for this. All of the hats on this stick-there are 5--are 4 way with a center button also. One of those is an 8 way with a center button press. This one is dual purpose. You can use it like an 8way pov hat. But here's the special feature! Long press the center and it becomes another axis controller! I have it set up to control pitch and roll trim in this mode. Short press centers it. Another long press can take you back to pov mode. Very handy!

Sent from my Moto Z (2) using Tapatalk

[FBKampfer]

It's always been my understanding that CT keeps the aircraft trimmed for level flight at your current airspeed only in the absence of control input, and any stick or rudder input overrides any trim settings by the fact that trimming only adjusts the point at which the surfaces come to rest at "neutral", so to speak. It doesn't alter the range of motion available for flight control.

Practically speaking there shouldn't be much of an effect for combat per se, save that your aircraft will tend to level in the absence of stick input. So if you're just letting your sights drift onto a target, you may notice it, but beyond that, any effect should be limited to the time it takes for the control surfaces to deflect the additional distance during stick input opposite of the trim setting (that is, the elevators will have to move slightly further when you nose down, if you have your elevators trimmed up).


I have always pretty much left combat trim on, save for specific instances, such as when I'm lining up a shot in an aircraft where the nose can bounce around a bit (Ta-152 comes to mind), in which case I simply trim in the direction I need my sights to move.

Also landing in the Ar 234 where trim keeps pulling your nose up quite severely.

Effectively I treat trim as windage and elevation adjustments on rifle sights. Most of the time, your battle sights (or just leaving it alone and using hold over in the case of a scope, that is to say, just leaving CT on and moving the stick) works just fine. But every once in a while, you'll adjust your windage or elevation.


But as I'm given to understand, you will never be fighting your trim settings for maneuvering.

[Drano]

Don't confuse combat trim with auto pilot or auto level. Auto level will keep you straight and level regardless of your trim as long as there's no control input. Any stick or rudder movement breaks it and will have to be reset to continue straight and level.

Trim is different. Different speeds, alts and engine settings (torque and p factor) affect how the wind travels over the surface of the plane. These changing forces can induce yaw or pitch or roll or all of the above. Planes have little trim tabs on their control surfaces that are adjustable in the cockpit (our planes in AH don't have the tabs - - the whole surface moves). That way the pilot can tune those forces out and be able to fly with the stick comfortably centered rather than be at some odd angle while flying straight and level. That's all trim really does. Just because the stick is centered doesn't mean you're gonna be flying straight and level if your plane is out of trim. Think of combat trim as auto trim. It just adjusts automatically so that you don't HAVE to do it yourself. Just be advised that when going very fast or very slow it likely won't be right. And if changing speeds quickly either fast to slow or slow to fast, it's gonna lag adjusting to where it's supposed to be. That's where manual trim just works better. It's not to say you can't maneuver while out of trim--you can! It's just not very intuitive.

Sent from my Moto Z (2) using Tapatalk

[Flyboy]

Simply put, CT works off a table based on airspeed.  If memory serves it adjusts about every 5mph IAS or so.  So at 200mph, it puts all 3 trim tabs at a certain location.  At 205, it adjusts them slightly, and so on.

It is not perfect.  It is not designed to be.  It puts you reasonably close to in trim most of the time so you don't have to worry about it as you are flying around and fighting, changing airspeed as you go.  It is based on a clean airframe at full throttle more or less, with no flaps.  Putting flaps out or carrying ord or adjusting your throttle will change things so it will not be in perfect trim.  Some planes just won't trim straight at certain speeds, the Typhoon or Tempest below 200mph for example.

Thanks for the support guys.
What wiley wrote make sense. That fit the feeling i got when i tried to figure out the plane behavior with ct.

To sum things up for me.
there is no advantage in using ct over manual trim besides comfort and in some flight envelopes ct can actually get in the way instead of helping.