Unable to Manually Trim the Aircraft

Just setup my new Warthog HOTAS and tried a Freeflight just to see how the aircraft handles with this stick & throttle. First flight in the F/A-18.

 

I was unable to get the manual trim function to work, even though it was correctly mapped to the trim button on the stick. Also tried the keyboard commands for trim and they had no effect either.

 

I had to maintain a constant forward stick pressure to keep the aircraft from climbing. Flaps were in the Auto position. Actuating the nose-down trim button would do nothing to prevent the aircraft from maintaining a constant climb. Roll trim functions were also inop.

 

Have I missed some switch setting that prevents manual trimming?

Sounds like something is up control-wise. If your flaps are on Auto, you shouldn't be experiencing any significant uncommanded climb. Since you got a new Warthog, are you sure that all of the axes etc are set up correctly and you don't have any inadvertent inputs? About the trim switch, if you go in Controls and press it, are the trim controls automatically highlighted?

You shouldn't have to use pitch trim during normal flight, only during the landing phase to adjust the AOA. I don't think I've ever used it during normal flight. Roll trim should work and have an effect at all times though, which makes me think it's a control issue.

Also, did you start in the air or from a cold start? If you started from the ground, did you perform an FCS reset?

Started in the air as a "Free Flight" Instant Mission.

 

Just ran the same mission again without my HOTAS connected, i.e., just a keyboard connection for controls.

 

When the mission starts, the aircraft is in level flight and immediately begins a slow pitch-up to 10-degrees over a 25 second period. The pitch attitude then slowly drops down to a 4 to 6-degree nose up attitude and slowly oscillates between that 4 to 6 degree range for several minutes, I have not touched the keyboard during this period to invoke any manual flight control commands.

 

After about 10 minutes, the pitch attitude has slowly dropped to about 1-degree nose-up and seems fairly stable at that attitude.

 

Being new to this sim, I have not yet done an in-depth review of the F/A-18 flight control systems. However, I have read on some other threads that the aircraft is programmed to auto-trim to 1-G.

 

During the above described pitch oscillations, I noticed that the aircraft is maintaining 1-G during all oscillations. So, maybe there are some computerized flight control inputs that are controlling the pitch attitude to maintain this programmed 1-G loading.

 

Even with only the keyboard connected, none of the trim commands work. I repeatedly tried to induce some roll by typing RCntrl+, and RCntrl+/. Nothing happened, just stayed wings level. Which seems to indicate to me that must be some type of computerized system over-riding manual trim inputs. But, as noted above, I have not done an in-depth reading of the flight manual. I have flown several USAF fighters and I always had manual control of my trim inputs, so this behaviour puzzles me.

The Hornet doesnt trim in normal FCS law in a clean config. Currently it also does a rather poor job of mintaining that 1G flight, which is unfortunate. It will run away from you in the pitch axis if you let go of the stick in a 5° or 10° climb for example (increase or decrease the pitch angle on its own).

The Hornet doesnt trim in normal FCS law in a clean config.

 

So, does that make the manual trim commands not work? As I stated above, even using the published keyboard trim commands (not HOTAS), I cannot get any trim function at all (pitch or roll).

 

Update: I just tried the P51 and the keyboard trim commands do not work on that plane either. I know my keyboard is working because I am able to control pitch & roll with the arrow keys. Does this suggest some problem with Control menu commands?

Edited February 29, 2020 by Bob1943

Pitch trim in the F-18 when in Flaps auto mode works verrrryyy slowly, however roll trim should be normal.

 

It sounds like you might be in some game flight model or game avionics mode. Go into the options and look in either Gameplay or Misc for anything relating to Game Avionics Mode, or Game Flight Model and make sure they are not ticked.

Well, instead of "Instant Action, Free Flight", I tried an actual "Aerial Re-fueling" mission, and all trim inputs (using the keyboard as my controller) now seem to work normally in that specific mission.

 

So, it may be some limitation in the "Instant Action" mode. Although I don't know why trim would not be operational in that mode.

 

I'll try some of the other "Instant Action" missions and see what happens.

 

Update: I just tried the "Instant Action Free Flight" again, and now the trim commands seem to work properly. So, you may be right, i.e., I may have inadvertently selected some kind of setting that was incompatible with manual trim commands. I did play around with the Control menu to make sure I was not in Game mode. Must have done something there to rectify the problem. Although I cannot imagine why manual trim would be rendered inoperable in any mode. Hopefully, the issue is now resolved. I'll try a few more different missions and see what happens.

Edited February 29, 2020 by Bob1943

Ensure that the force feedback option isnt ticked, I have heard of people having this issue when that is selected on non FFB controllers

Well, instead of "Instant Action, Free Flight", I tried an actual "Aerial Re-fueling" mission, and all trim inputs (using the keyboard as my controller) now seem to work normally in that specific mission.

 

So, it may be some limitation in the "Instant Action" mode. Although I don't know why trim would not be operational in that mode.

 

I'll try some of the other "Instant Action" missions and see what happens.

 

Update: I just tried the "Instant Action Free Flight" again, and now the trim commands seem to work properly. So, you may be right, i.e., I may have inadvertently selected some kind of setting that was incompatible with manual trim commands. I did play around with the Control menu to make sure I was not in Game mode. Must have done something there to rectify the problem. Although I cannot imagine why manual trim would be rendered inoperable in any mode. Hopefully, the issue is now resolved. I'll try a few more different missions and see what happens.

 

 

Another thing to look at is the FCS page; as you adjust trim it should show up there. If you're having to use the stick to maintain trim something is not right, and the FCS should be able to tell you what that is.

 

 

I've never had a trim problem in instant action, by the way. So far all the problems I've run into have been PEBSAES (problem exists between stick and Ejection Seat), apart from some minor things that may or may not be bugs. Mostly I just assume it's me.

Ensure that the force feedback option isnt ticked, I have heard of people having this issue when that is selected on non FFB controllers

 

That option was checked when I previously looked on the Control menu. I do remember unchecking it and that is when the trim inputs started working in all the subsequent missions that I tried.

 

That is an interesting discovery. Thanks for pointing that out - I'll keep an eye out for that in the future if I have anymore trim problems.

Another thing to look at is the FCS page; as you adjust trim it should show up there. If you're having to use the stick to maintain trim something is not right, and the FCS should be able to tell you what that is.

 

Where is the FCS page?

Where is the FCS page?

Accessible through either of the three aircraft displays, by going to the Support menu (SUPT) and selecting FCS, it's the lower right option. You can always access the Tactical (TAC) and Support menus by pressing the lower middle button, subsequent presses cycle between the TAC and SUPT menus.

I flew the Hornet for the 1st time in a few weeks and nose up pitch is very pronounced and trim does nothing. It was so bad I dumped my weapons and the plane handled better but still nose up. This is using the full TM Hotas setup.

Come to think of it... I own most of the modules and ALL have been doing strange things. That last update really screwed things up.

I am using the stable release version 2.5.5.

As noted above, the FFB stick option seemed to be the culprit.

Accessible through either of the three aircraft displays, by going to the Support menu (SUPT) and selecting FCS, it's the lower right option.

 

I must be missing something. I don't understand what aircraft displays you are referring to. Are you referring to the main DCS Menu page?

I flew the Hornet for the 1st time in a few weeks and nose up pitch is very pronounced and trim does nothing. It was so bad I dumped my weapons and the plane handled better but still nose up. This is using the full TM Hotas setup.

Come to think of it... I own most of the modules and ALL have been doing strange things. That last update really screwed things up.

This is known to happen if you take off using an incorrect flap setting. It appears to partially break the flight model. Try extending the flaps again in flight, then retracting them. Make sure you're using the correct flap setting for takeoff.

It was an “in air” start with flaps in the Auto position.

As noted above, the problem was the Force Feed-Back option being checked without using an FFB stick.

I must be missing something. I don't understand what aircraft displays you are referring to. Are you referring to the main DCS Menu page?

No, either one of the three displays in the Hornet's cockpit.