Pitch trim sensitivity

[captain_kaoss]

Is the pitch trim in the F-4E broken? I have a winwing F-16EX stick with pitch trim mapped to the pitch hat switch. Even a momentary press of pitch up or down causes significant change of either nose up or down attitude. It's very difficult to trim for level flight, the pitch changes are dramatic

[Zabuzard]

Is the pitch trim in the F-4E broken? I have a winwing F-16EX stick with pitch trim mapped to the pitch hat switch. Even a momentary press of pitch up or down causes significant change of either nose up or down attitude. It's very difficult to trim for level flight, the pitch changes are dramatic

This is expected and correct behavior due to the bellows vs bobweights system (as explained in depth in some similar threads already).

(Make sure you have the force feedback checkbox in the DCS settings disabled though)

There is also a Special Setting in the F4 settings to help users who have trouble with this (correct) behavior, I think it was called stick smoothing period or something like that.

The core difference to some other aircraft is that trimming in the F4 doesnt trim the stick, it "trims the bellows". The bellows apply their force dynamically based on airspeed measured at the tail (bellows intake). They pull the stick aft the faster you are. They are the opposing force to the bobweights which push the stick forward the more G-load you have. Trimming essentially scales the force the bellows decide to apply. The outcome is a highly dynamic play of forces that changes constantly and it leads to the Phantom naturally wanting to fly in large oscillations.

Test pilots also noted this as a bit annoying but ultimately decided, after a bit of tweaking on the system by the engineers, that its not a problem in practice if you "just fly the aircraft", i.e. not going hands off stick. And there is also the autopilot after all.

Also, trimming is done in micro clicks, dont hold it :)

[captain_kaoss]

I've definitely been doing micro clicks but the trim input is still dramatic. I also tried the smoothing setting and increasing the seconds but that didn't seems to change anything. Maybe its an F-4 quirk but its so difficult to trim

[Zabuzard]

If you got a video or something that would help to figure out whether what you are experiencing is normal or abnormal.

Make sure that "Use Force Feedback" checkbox in the DCS settings is unchecked, it causes super weird stick and trim behavior if you do not actually have FFB and somehow DCS has it enabled by default.

For some users their stick also sends inputs to the game longer than its actually held IRL. This would cause microclicks to actually be longer clicks. Some sticks have software where this minimal signal duration can be set and lowered (you can then also confirm it in Windows built-in Joystick input tester thing).

[LeCuvier]

On 10/11/2025 at 6:18 PM, Zabuzard said:

...The core difference to some other aircraft is that trimming in the F4 doesnt trim the stick, it "trims the bellows". The bellows apply their force dynamically based on airspeed measured at the tail (bellows intake). They pull the stick aft the faster you are. They are the opposing force to the bobweights which push the stick forward the more G-load you have. Trimming essentially scales the force the bellows decide to apply. The outcome is a highly dynamic play of forces that changes constantly and it leads to the Phantom naturally wanting to fly in large oscillations...
 

Interesting reading!
I struggle with the pitch control not only for the trim, but also for the response to stick movements which, to me, appear very "nervous". These "large oscillations" don't help when I try to aim at something. So I added "slow" pitch trim commands to my "default.lua" with pitch trim response values reduced from 1.0 to 0.3. Will see how that works for me.

[LeCuvier]

I found that Heatblur provides 3 different setting speeds ("normal", Fast and Slow) for a number of commands (e.g. "Weapon Slew". I do not believe that the real Phantom has those options, but it helps the sim users. A good reason in my opinion to do the same for the pitch trim command.

[Zabuzard]

I found that Heatblur provides 3 different setting speeds ("normal", Fast and Slow) for a number of commands (e.g. "Weapon Slew". I do not believe that the real Phantom has those options, but it helps the sim users. A good reason in my opinion to do the same for the pitch trim command.

We have a Special Options that tackles the problem properly (Stick Pitch Smoothing Period).

Approaching it officially from the inputs isnt a good idea and anyone who did it might in the future run into it not working anymore. gr0ver provided some detailed explanation in some threads somewhere here on the forum.

[LeCuvier]

11 hours ago, Zabuzard said:

We have a Special Options that tackles the problem properly (Stick Pitch Smoothing Period).

Approaching it officially from the inputs isnt a good idea and anyone who did it might in the future run into it not working anymore. gr0ver provided some detailed explanation in some threads somewhere here on the forum.

My understanding is that the stick smoothing option helps to make stick input less "nervous".
I wouldn't think that it helps to "slow" the pitch trim, which is the main subject of this thread.
Please correct me if I'm mistaken!

My method for providing a slower pitch trim is to add these lines to the "default.lua under "Saved Games" (I use the command injector by @Quaggles):

{pressed = iCommandPlaneTrimPitch, up = iCommandPlaneTrimPitch, value_pressed = 0.3, value_up = 0,	name = _('Trim - Nose Up Slow(Hat Aft)'), category = {categories.flight_controls, categories.stick}},
{pressed = iCommandPlaneTrimPitch, up = iCommandPlaneTrimPitch, value_pressed = -0.3, value_up = 0,	name = _('Trim - Nose Down Slow (Hat Forward)'), category = {categories.flight_controls, categories.stick}},

This methodis very robust.

[Zabuzard]

It was made specifically for trim and everything tied to that. I.e. bobweights and bellows.

I know how you did it with the binds but its likely that there will be a point where this method will stop working.

Give the Special Option a try, see if thats better for you :)