Trim for Cyclics without Springs

[nikoel]

Hey Folks not sure if this belongs here or the requested feature page

I am flying with a WinWing SuperLibra with extension and without springs. I have Tightened up the dampers so that the cyclic doesn't move when released but are still fairly non-sticky for small inputs. I still have pedals that have springs in them (the official DCS VKB ones)

I have Cyclic Trimmer Mode set as Joystick w/o Springs
I have Pedal Trimmer Mode set as Central Position Trimmer
FFB is off in the Misc Options Menu

In a hover as an example; I am finding that the trim in the Apache is very hit and miss. Success Rate of around 2/5 times. The Apache goes into the hold modes perfectly but gives up on the hover by starting to rapidly drift without trying to correct

I believe this is due to the fact that when I reach up to the trim-hat and press the trim forwards (for the pedals) and then trim to left to hold attitude, I end up moving the cyclic ever so slightly which might be messing up SAS in it's current flaky state

I believe as an stop gap solution you can give me say a 3% dead-zone when I activate the trim switch that should give enough wiggle room so that the ever so slight movements don't upset the machine

In the meantime I have given up on the trimming altogether, and have been just hand flying her, but it's a bit annoying to do this whilst entering coordinates with your head down. If you have any other advice please let me know

 

trim is so flaky it should have a tinder account.trk

Edited March 14, 2023 by nikoel

[admiki]

Only difference is that my pedals don't have spring.

Attitude hold worked fine until this patch, so I guess ED changed something again (I don't know whether it's on purpose or by accident).

You said it yourself, SAS is WIP.

[nikoel]

2 minutes ago, admiki said:

Only difference is that my pedals don't have spring.

Attitude hold worked fine until this patch, so I guess ED changed something again (I don't know whether it's on purpose or by accident).

You said it yourself, SAS is WIP.

Does this mean that you now get the same broken behavior of the trim functions as I do?

[Trigger]

Had similar problem with TRIM on cyclic. Changed the whole Trim to a 4-way Button on the collective. No longer use of ALT hold. Just TRIM, RESET and ATT hold.

After pressing TRIM, immediately ATT hold and then just a little patience. The bird hovers to 0 at the place where you started the process.

By the way, no springs with pedals. Cyclic, because of the long (25 cm) extension, springs no longer tangible.

Edited March 14, 2023 by Trigger

[admiki]

3 hours ago, nikoel said:

Does this mean that you now get the same broken behavior of the trim functions as I do?

Pretty much yes. It held hover just fine before this patch.

[Floyd1212]

I haven't noticed any change with Attitude Hold since the patch, personally.

Does the Controls Indicator show movement when the drifting occurs?

[admiki]

9 minutes ago, Floyd1212 said:

I haven't noticed any change with Attitude Hold since the patch, personally.

Does the Controls Indicator show movement when the drifting occurs?

No or very, very small amount. Speed hold and pure attitude hold seem to be working fine, it's just hover hold. It does try to compensate, but it's too slow, with increasing amplitude of drift. Altitude hold also doesn't work as it should. I get into hover and engage altitude hold. I gently push forward to ETL and helicopter starts climbing. Collective servo drops down just a tiny bit and you will get "altitude drift" warning before servo gets saturated.

[Floyd1212]

I replayed the track above and it looks like there is a stiff breeze in the mission? Sometimes it seems to hold, but other times it want's to drift off.  Is this an issue of not properly detecting hover hold submode vs velocity hold submode?

Bradmick discussed this in another thread a while back.

In the missions I make for my group to fly I normally have minimal wind, like 3-4 knots, so maybe that is why I am not experiencing this?

[admiki]

5 hours ago, nikoel said:

Hey Folks not sure if this belongs here or the requested feature page

I am flying with a WinWing SuperLibra with extension and without springs. I have Tightened up the dampers so that the cyclic doesn't move when released but are still fairly non-sticky for small inputs. I still have pedals that have springs in them (the official DCS VKB ones)

I have Cyclic Trimmer Mode set as Joystick w/o Springs
I have Pedal Trimmer Mode set as Central Position Trimmer
FFB is off in the Misc Options Menu

In a hover as an example; I am finding that the trim in the Apache is very hit and miss. Success Rate of around 2/5 times. The Apache goes into the hold modes perfectly but gives up on the hover by starting to rapidly drift without trying to correct

I believe this is due to the fact that when I reach up to the trim-hat and press the trim forwards (for the pedals) and then trim to left to hold attitude, I end up moving the cyclic ever so slightly which might be messing up SAS in it's current flaky state

I believe as an stop gap solution you can give me say a 3% dead-zone when I activate the trim switch that should give enough wiggle room so that the ever so slight movements don't upset the machine

In the meantime I have given up on the trimming altogether, and have been just hand flying her, but it's a bit annoying to do this whilst entering coordinates with your head down. If you have any other advice please let me know

 

trim is so flaky it should have a tinder account.trk 3.93 MB · 2 downloads

 

 

45 minutes ago, Floyd1212 said:

I haven't noticed any change with Attitude Hold since the patch, personally.

Does the Controls Indicator show movement when the drifting occurs?

Found a problem. If you engage att hold when red X (or, in other words, not pressing trim) is not where your cyclic is will cause helicopter to go haywire. Get into hover, press trim, engage att hold and it works. @nikoelif you watch your track again with controls indicator enabled, you will see this.

[nikoel]

13 hours ago, admiki said:

 

Found a problem. If you engage att hold when red X (or, in other words, not pressing trim) is not where your cyclic is will cause helicopter to go haywire. Get into hover, press trim, engage att hold and it works. @nikoelif you watch your track again with controls indicator enabled, you will see this.

So Yeah, you've basically confirmed my suspicions in my original post. The ~3-5% Deadzone (or fixing the SAS) when the trim is engaged would do wonders I think

In my case, not moving the stick is not an ideal fix because of these three factors

1) I have no springs but still have it set as close to flying the real helicopters (aka with least amount of stiction possible) thus reaching up to the trim button, pressing it forward and then pressing it left makes the stick move slightly sometimes. - I fixed this with the collective bindings as per a post above

2) I have to trust the system would work and half the time it still won't. The only way to tell is to let the aircraft start drifting and then take over when it doesn't. It's just frustrating. No thanks, I rather just hand fly 

3) To lesser degree I have to have my hand on the stick for when the system doesn't work so I can fix the aircraft or risk having to restart again because it drifted into a nearby tree. This means that its more likely I make those minute inputs

18 hours ago, nikoel said:

I believe this is due to the fact that when I reach up to the trim-hat and press the trim forwards (for the pedals) and then trim to left to hold attitude, I end up moving the cyclic ever so slightly which might be messing up SAS in it's current flaky state

I believe as an stop gap solution you can give me say a 3% dead-zone when I activate the trim switch that should give enough wiggle room so that the ever so slight movements don't upset the machine

 

Edited March 15, 2023 by nikoel

[admiki]

I can't tell how you fly, but that small amount of movement should not influence it.

As Floyd said, there is a lot of wind in that track you posted. How does it work if  you create a mission with no or little wind?

[Floyd1212]

I watched your track again, and took it over to fly it myself. 

When taking over the track, it maintained the "joystick without springs" setting, so it took a second to get it sorted out for my center-sprung setup, but if I press and release FTR, and then carefully hold the stick in place, then set ATT Hold and continue to hold the stick in place, it works fine.  It doesn't really take much to convince it to start drifting, though.

I think with your setup with the dry clutches and no springs, moving the trim off to your collective is the way to go.  Or tighten the clutches up a little bit to reduce the unintended movement?  Unfortunately, the dry clutch sticks don't provide any spring return like the actual aircraft controls do.  Spring-centering sticks are a compromise in one direction, but dry-clutch sticks are a compromise in a different direction.

You might also look at using something like Joystick Gremlin to interrupt the axis output from your stick from ever reaching DCS unless you have the FTR button pressed.  (Not sure if you fly with FTR held, or if you just tap it when needed.)  Or assign another button to toggle the axis between "enabled" and "disabled" so that the game won't see any slight drifting unless you have the axis enabled.  

Or maybe there is a way to create that dead-zone you are looking for with Joystick Gremlin (or similar) where the axis is disabled until it detects a movement threshold, then it re-enables it automatically.

[nikoel]

7 hours ago, Floyd1212 said:

I watched your track again, and took it over to fly it myself. 

When taking over the track, it maintained the "joystick without springs" setting, so it took a second to get it sorted out for my center-sprung setup, but if I press and release FTR, and then carefully hold the stick in place, then set ATT Hold and continue to hold the stick in place, it works fine.  It doesn't really take much to convince it to start drifting, though.

I think with your setup with the dry clutches and no springs, moving the trim off to your collective is the way to go.  Or tighten the clutches up a little bit to reduce the unintended movement?  Unfortunately, the dry clutch sticks don't provide any spring return like the actual aircraft controls do.  Spring-centering sticks are a compromise in one direction, but dry-clutch sticks are a compromise in a different direction.

You might also look at using something like Joystick Gremlin to interrupt the axis output from your stick from ever reaching DCS unless you have the FTR button pressed.  (Not sure if you fly with FTR held, or if you just tap it when needed.)  Or assign another button to toggle the axis between "enabled" and "disabled" so that the game won't see any slight drifting unless you have the axis enabled.  

Or maybe there is a way to create that dead-zone you are looking for with Joystick Gremlin (or similar) where the axis is disabled until it detects a movement threshold, then it re-enables it automatically.

Thanks for the additional advice on how to overcome the issue. I am just sticking to hand flying for now - I much prefer the realistic feel of the cyclic than having the clutches tightened. Hopefully the SAS keeps improving

In your second paragraph you may have incorrect understanding of how the real trim function works. It may have been just the way you worded it, but in case you’d like to know as a thanks for looking at my track here is a quick explanation. Now take it with a grain of salt as my real life experience is not in the Apache but other civilian built helicopters, however they all work pretty much the same

The real aircraft often has a “centring point” created artificially either via mechanical servos or motors etc… which work similar to springs to apply force against your inputs back to that specific point

When force trim is pressed those forces are cancelled. The pilot then can move the cyclic in whichever direction he desires without forces acting against his inputs. Upon releasing the force trim button, the forces re-activate. But that centre point has now moved to where the cyclic is now. The cyclic does not move back to center. It is then held in place by those electronic motors. The pilot can still move the cyclic by overpowering those forces. The motors will gently work against the pilot until force trim is either triggered again or the cyclic is returned back to the same point.

Edited March 16, 2023 by nikoel

[admiki]

1 hour ago, nikoel said:

Thanks for the additional advice on how to overcome the issue. I am just sticking to hand flying for now - I much prefer the realistic feel of the cyclic than having the clutches tightened. Hopefully the SAS keeps improving

In your second paragraph you may have incorrect understanding of how the real trim function works. It may have been just the way you worded it, but in case you’d like to know as a thanks for looking at my track here is a quick explanation. Now take it with a grain of salt as my real life experience is not in the Apache but other civilian built helicopters, however they all work pretty much the same

The real aircraft often has a “centring point” created artificially either via mechanical servos or motors etc… which work similar to springs to apply force against your inputs back to that specific point

When force trim is pressed those forces are cancelled. The pilot then can move the cyclic in whichever direction he desires without forces acting against his inputs. Upon releasing the force trim button, the forces re-activate. But that centre point has now moved to where the cyclic is now. The cyclic does not move back to center. It is then held in place by those electronic motors. The pilot can still move the cyclic by overpowering those forces. The motors will gently work against the pilot until force trim is either triggered again or the cyclic is returned back to the same point.

 

OK, so you already know that real life helicopters don't have cyclics that can be moved just from moving your grip on it. Tighten those clutches some more.

[Raptor9]

There seems to still be some confusion as to how the force trim interacts with the flight computer and the logic of the hold modes themselves. The force trim mechanism in the AH-64D is indeed like other helicopters from a mechanical standpoint, but the force trim is also intertwined with the Flight Management Computer in conveying pilot intentions to the FMC. In addition, it is important to understand that just because a hold mode is enabled, it does not mean it is engaged with the flight control servo-actuators.

You can enable Attitude Hold using the Force Trim/Hold Mode switch at any time, even on the ground. But the hold mode will not engage with the flight controls to provide inputs unless certain criteria are met. One of these factors is the position of the cyclic in relation to the force trim reference point, which corresponds with the position of the cyclic when the force trim was no longer being depressed. The Controls Indicator represents the cyclic's force trim reference location with the red X. If the cyclic is not within roughly 2% of this position, you can toggle Attitude Hold all day and display the box around the TAS readout, but it will have no effect on the flight controls.

Once the cyclic is returned to the force trim reference position (assuming the force trim is not being depressed), Attitude Hold will attempt to capture the hold values that exist at that precise moment, depending on what sub-mode it is in and other engagement factors being met, and it will engage with the flight controls to attempt to hold this value. However, if the cyclic is moved away from the force trim reference position, you are once again exceeding the hold mode "breakout" value for the cyclic, and the hold mode will disengage from the flight controls (it won't deactivate altogether, which is why the hold mode box remains around the TAS readout).

Alternatively, if the force trim is depressed, this will also cause the hold mode to disengage; and when the force trim is released it will establish a new reference point for the hold mode to use, since the reference point now coincides with the current cyclic position (assuming you stopped moving the cyclic when you stopped depressing the force trim).

However, it needs to be stressed that the hold modes are not a full authority autopilot. The pilot needs to place the helicopter into a stable, trimmed state prior to engaging the hold modes. You can enable Attitude Hold at any time, but the force trim should only be released when you have reached the position, velocity, or attitude you want to be held.

For example, if the force trim reference position is 1 inch forward of your current cyclic position, and you are holding a hover without the force trim depressed, and you activate Attitude Hold by pressing the Force Trim/Hold Mode switch to the left, the only thing that will happen is the box will appear around the TAS readout. Attitude Hold won't engage in Position Hold sub-mode to maintain the hover because the cyclic is beyond the breakout value. If you then let the cyclic spring forward or quickly moved it forward that 1 inch to the reference position, you have now incurred two factors to make the hold mode's job that much more difficult:
1) You have input a forward pitching motion that the hold mode now needs to arrest.
2) You have now biased the SAS sleeve in the pitch servo up against it's aft authority, limiting it's ability to not only stop the initial pitch motion, but also to regain the original reference position, which is now receding aft away from the helicopter because the aircraft has started to move forward from the forward pitching motion that you have incurred.

In addition, simply tapping the force trim to update the force trim reference position does not guarantee the hold modes will have their full authority to use. It takes 3 to 5 seconds for the SAS sleeve in each flight control servo to center within it's authority, but it can only accomplish this while the force trim is being depressed. Simply tapping the force trim updates the reference position but does not allocate enough time for the SAS to center, in order to regain it's full authority in both directions that it may need to command the swashplate to move.

To summarize, although the flight model and SCAS behaviors are still WIP, a good number of these "buggy" behaviors are being incurred by players refusing to use the force trim or expecting the hold modes to be able to perform the job of a full authority autopilot. I'm not saying anyone in this thread is guilty of not using the force trim, but I do see quite a number of posts of players stating they just don't use the force trim. While that is certainly an option, it is needlessly making things harder on themselves, and it directly interferes with the proper use of the various hold sub-modes in pitch, roll and yaw.

EDIT: And just to clarify as to what did change in the recent Open Beta update, it was the criteria for when Attitude Hold could be enabled. Prior to the update, there was an inaccuracy in the logic that required the cyclic to be within the breakout value to enable the Attitude Hold. This was fixed to how it should be in this recent update so that you can enable it at any time, even on the ground, even if the criteria for it to engage doesn't exist at that moment.

Edited March 16, 2023 by Raptor9

[Floyd1212]

7 hours ago, nikoel said:

In your second paragraph you may have incorrect understanding of how the real trim function works. It may have been just the way you worded it

It was just the way I worded it. 

After the 32 page Force Trim thread, Raptor9's thoughtful explanations throughout this forum, and all the other research I have done, I have a good understanding of how it works in the real thing.

I really wish Virpil or WinWing would make the hardware we need to get the most out of these helos.  I realize we are a small niche within an already small niche market, but it would be glorious to have hardware that behaves the way it should, and is not a compromise.

[admiki]

2 hours ago, Floyd1212 said:

It was just the way I worded it. 

After the 32 page Force Trim thread, Raptor9's thoughtful explanations throughout this forum, and all the other research I have done, I have a good understanding of how it works in the real thing.

I really wish Virpil or WinWing would make the hardware we need to get the most out of these helos.  I realize we are a small niche within an already small niche market, but it would be glorious to have hardware that behaves the way it should, and is not a compromise.

VPforce

[Cyborg71]

Just a final clarification in relation to force trim (excluding hold modes) please. 

When using force trim to achieve the intial trimmed position, should the force trim button be -

1. Held in the "on" position whilst cyclic adjustment is made and then when happy, the button is released?

2. Cyclic adjustments are made and when happy a quick 'click and  release' of the force trim button to establish the new trimmed cyclic centre?

For context, I'm using an unsprung clutched cyclic. Recent chsnges to open beta have improved a previously sketchy hover hold for me. In flight attitude and altitude modes not so much.

Edited March 18, 2023 by Cyborg71

[Floyd1212]

From what I understand, in the real world, you would do #1.

In DCS, you can either do #1, but you can also do #2 and get a way with it.  Holding the FTR tells the SCAS to stop "working against you" while you are intending to maneuver the aircraft.

I find it difficult to hold the button I have mapped to FTR on my Warthog stick for extended periods of time.  I'm actually surprised the stick on the real Apache has this mapped to a "hat up" function, as I would think this would be hard to keep pressure on the button for extended periods.  In the Blackhawk, the FTR button is under the thumb in a resting position on the grip, which would seem to be easier to maintain downward pressure.

[admiki]

You should do #1. Reason for that is that servo sleeves need up to 5 seconds to reset to your new position. And that will give best authority to servos.

 

[Cyborg71]

Thank you for your replies. 

I have been using the method (2) up to this point, but will now try the ftr held as suggested.

Again, contextually, I'm using Komodos Apache cyclic, so the buttons are roughly in the right places. To echo Floyd1212's comments, it's pretty awkward to persistently hold that button up whilst finessing the cyclic. I accept (of course) that the sizing, feel,  feedback and operation of what I use is not the irl version.

[markturner1960]

Hi, I have a Virpil CM3 dry clutch base, that I have adjusted so it stays in whatever position I place it. I almost never use the force trim as a result. Should I be? And if so, why? 

[corbu1]

You should use the FTR button. Otherwise your FMC will not know your new center position. Which FMC should know. You will get problems when using the hold modes.

I have a cyclic that stays in place as well and use it with the trimmer no springs option in the DCS special menu.

[markturner1960]

Thanks, FTR being force trim release? IE Push the switch up( I have my 4 hat switch bound up, down (back), ATT hold and Alt hold ( left and right) Press is FMC release.

So, get aircraft stable depress the switch? Or push the switch up ? 

Edited May 19, 2023 by markturner1960

[admiki]

If you binded FTR to up, then push it up