Think I might finally understand Trim problem!

After looking at countless posts about the problem with Trim bump and not being able to use it the proper way, I just stumbled across this post by Brainless which finally explains it in a way that makes sense to me.

http://forums.eagle.ru/showpost.php?p=1351826&postcount=35

So it would seem the only way to use the Trim as intended (i.e. tap after manoeuvring, rather than hold, manoeuvre, release) is to not be using the AP, or in other words have Flight Director engaged.

I guess this must be how the real KA-50 is flown and why we don't see this Trim bump in real video footage.

I hope this post helps any other players who've been struggling with the Trim.

Thanks doveman. Flying the KA-50 is a real pleasure, and it takes time to get used to the helicopter. One small feature is to press "Right-Shift" + "Enter", which will show a small window left below that shows the current trim position. I always fly like you describe above, move the stick to the position required and trim, and recenter the stick. In this way, the helicopter can be flown more smootly, and it allows you to focus on the environment instead of your cockpit and helicopter stability. And i always use the altitude autopilot (Left-Shift+A) to keep my altitude managed while trimming. It helps to avoid crashing the helicopter accidentally.

Sven

I´ve tried flying with Trim-bumping to death. It never worked for me.

Since then i´m flying with said Method (push, manouver, release). Rudders are unchained

from Trim via PeterP´s Mod.

And to hold Altitude you should not forget to pull the Collective Brake. It´s a mighty

Tool for level Flight, e.g in Curves, which often seems to be forgotten. :)

Brainless's explanation is flawed however, since not only the AP gets disabled for a short time, but also your control inputs. In this timespan you have to center your cyclic and rudder (unless you've unchained it from trim) to avoid the phenomenon described in Brainless's post.

 

So it would seem the only way to use the Trim as intended (i.e. tap after manoeuvring, rather than hold, manoeuvre, release) is to not be using the AP, or in other words have Flight Director engaged.

 

I guess this must be how the real KA-50 is flown and why we don't see this Trim bump in real video footage.

Sorry but your guess is wrong.

The problem is still that the real cyclic holds it new position after trim - and your joystick doesn't-

I for instance can use the trim how I like , single press or long - and I will have no "bumping" . because I use a FFB controller that mimics the real one.

As Ich666 already said,

you have this "bump" because you can't coordinate your centering of the stick with the time the stick gets disabled exactly.

Sorry but your guess is wrong.

 

The problem is still that the real cyclic holds it new position after trim - and your joystick doesn't-

 

 

I for instance can use the trim how I like , single press or long - and I will have no "bumping" . because I use a FFB controller that mimics the real one.

 

 

As Ich666 already said,

you have this "bump" because you can't coordinate your centering of the stick with the time the stick gets disabled exactly.

+1

Brainless's explanation is flawed however, since not only the AP gets disabled for a short time, but also your control inputs. In this timespan you have to center your cyclic and rudder (unless you've unchained it from trim) to avoid the phenomenon described in Brainless's post.

It's only further control inputs that are disabled between clicking Trim and re-centering the controls (and then only with the Central Trim option enabled), so I believe Brainless' explanation is correct that at the moment of clicking Trim, the 20% AP in the opposite direction is released and this results in the virtual joystick jerking and the helo oversteering and when Trim is then released the trim (and AP if engaged) is set at this oversteered position.

Sorry but your guess is wrong.

 

The problem is still that the real cyclic holds it new position after trim - and your joystick doesn't-

 

 

I for instance can use the trim how I like , single press or long - and I will have no "bumping" . because I use a FFB controller that mimics the real one.

 

 

As Ich666 already said,

you have this "bump" because you can't coordinate your centering of the stick with the time the stick gets disabled exactly.

I don't think so as I get the bump even using Central Trimmer method, which should lock out the stick at the moment of clicking Trim until it's re-centered. Mind you I just read an old post that says the Unhook Rudder from Trim mod breaks Central Trimmer mode. Is that still the case?

If the 20% opposing AP is disengaging at the moment of clicking Trim, I would expect your FFB stick to jerk further in the direction that you're moving it, as the virtual joystick does. I fail to see how you can have no bumping if the 20% AP is suddenly being cancelled when clicking Trim.

If your virtual joystick isn't jerking when clicking Trim then perhaps you are flying with different settings/AP to me.

Anyway, I'm going to try it with FD and hopefully it's usable like that.

If the 20% opposing AP is disengaging at the moment of clicking Trim, I would expect your FFB stick to jerk further in the direction that you're moving it, as the virtual joystick does. I fail to see how you can have no bumping if the 20% AP is suddenly being cancelled when clicking Trim.

Do you know what a FFB Stick is ?

and do you know that the Ka-50 uses a Force-Trim System that can be simulated by a FFB Stick ?

I guess this must be how the real KA-50 is flown.....

Most definitely not.

Serious:

Do you know what a FFB Stick is ?

and do you know that the Ka-50 uses a Force-Trim System that can be simulated by a FFB Stick ?

My point is if the FFB stick tracks the virtual stick (unlike a non-FFB stick that obviously can't) and the virtual stick is jerking then surely the FFB stick should as well.

Most definitely not.

Well if you're saying the real helo is flown without FD on and the AP on, yet it doesn't jerk/oversteer when clicking Trim (which it clearly doesn't), I can only assume there's a major bug in DCSW that's causing this then.

My point is if the FFB stick tracks the virtual stick (unlike a non-FFB stick that obviously can't) and the virtual stick is jerking then surely the FFB stick should as well.

No it doesn't .

Using a FFB controller is the most natural thing you can think off - no overreacting or things you have to care about.

You just trim - that's it.

, I can only assume there's a major bug in DCSW that's causing this then.

Center/time sensitive trimmer method is only a crude workaround for the missing Force-Trim at your controller. And it has its flaws.

I can only assume there's a major bug in DCSW that's causing this then.

There is a bug, but it's yours alone - it's your lack of Force Feedback Controller :)

You cannot even begin to compare trim In-SIM with the real Helo if not doing so with a FFB controller. It is modelled to work as if taking for granted that the SIM is ran with a FFB controller.

Edit: Norrised........

Have a look how the "perfect" controller behaves for a Force-trim system :

 

http://www.sukhoi.ru/forum/showthread.php?t=73514&page=4&p=1913338&viewfull=1#post1913338

 

 

 

 

This controller is only for Helicopters.

Here is my build that is also working for a Fixed-wing aircraft:

...now compare this with a normal spring-loaded stick design,

and you will understand why the center/time sensitive trim implementation you use is only a "crude workaround".

I have always been a fan of Flight Director but I fly with AP only now for a couple of months. I hold down the trimmer if I want to do something special. Engaging targets in FF is so much easier!

I have the central trimmer mode option disabled and I use a non FFB joystick. No problems and never had problems. I just let the stick center the moment I release the trimmer. I do not experience any bumps on releasing the trimmer and I'm not even letting the stick go.

Even without an FFB joystick I don't understand why there are so many complaints about the trim system and the infamous 'bump'. I must be doing something right... :)

I just let the stick center the moment I release the trimmer. I do not experience any bumps on releasing the trimmer and I'm not even letting the stick go.

 

Even without an FFB joystick I don't understand why there are so many complaints about the trim system and the infamous 'bump'. I must be doing something right... :)

Yes , you do.

It's your timing.

:)

Buy a used MS FFB2 and you will, instead of understanding the trim problem, understand the trim :) That's what I did. I will never fly the Ka-50 without FFB again unless my joystick stops functioning.

Have a look how the "perfect" controller behaves for a Force-trim system :

Yeah I know that a FFB stick holds it's position.

The actual stick I'm using is irrelevant though as it's the virtual stick that's jumping when I click Trim. It seems it was the Detact Rudder from Trim mod that was the main problem though as after uninstalling that, using Central Trimmer mode it no longer seems to do that.

I haven't fully tested to confirm (was trying to video it but it kept going wrong!) but it seems that with Central Trimmer mode disabled it still jumps when clicking Trim (not releasing it) however. I'm sure you're going to tell me it's my timing but there's no way I could centre the stick in time as it literally jumps as soon as I click Trim so I'd have to be trying to flick the stick back to centre at the same moment I click Trim and I can't see that twitchy, hyperactive movements like that can leave the pilot calm and in control of the bird, so I very much doubt that's what pilots in the real helo have to do (unless someone has a video showing that they do).

Anyway, I'll try and get that video done.

There is a bug, but it's yours alone - it's your lack of Force Feedback Controller :)

 

You cannot even begin to compare trim In-SIM with the real Helo if not doing so with a FFB controller. It is modelled to work as if taking for granted that the SIM is ran with a FFB controller.

 

Edit: Norrised........

Well if it's impossible to fly with a non-FFB stick without using the Central Trimmer mode, then I'll just use that but it would be nice if this was made clear by ED (perhaps the Enabled/Disable FFB option should also toggle Central Trimmer mode).

As I've said though, I think the stick is irrelevant as the virtual stick is jumping as soon as I click (not release) Trim, so I can't see how a FFB stick would fix that, as if it's working it's going to mirror the virtual stick and jump as well.

[...]

 

... I click Trim and I can't see that twitchy, hyperactive movements like that can leave the pilot calm and in control of the bird, so I very much doubt that's what pilots in the real helo have to do (unless someone has a video showing that they do).

 

Anyway, I'll try and get that video done.

I try to explain it again for the last time:

Real Helicopter pilots have not to do what you are doing and all others that fly DCS with a normal spring-loaded stick.

They simply position the stick how they need and trim and/or move the stick while holding trim. (..and they also don't have to move their feet like crazy with each new trim...)

Than they release the trimmer - and the Stick is spring-centerd at the new position.

You can only replicate this behaviour with a FFB Stick,

or with a mechanism like in this following video.

And its the same in a real helicopter with a force-trim system:

Edit:

-Trimming the Ka-50 Black Shark

-Part 1 - Autopilot

-Part 2 - Autopilot

and when you are confident about your cyclic-trim,

you wan to read about your rotor-pitch trim:

Is it even possible to maintain speed and/or altitude?

I sure would like to make one of those. Any links to instructions?

First of all, I don't understand why having a FFB stick or not is even relevant to the discussion. The forces your hand applies to the stick(the input) should be exactly the same in all cases - whether you have a FFB joystick, a spring stick or a force-sensing stick like the X65f. Of course a FFB stick is going to more accurately represent the motion of the real Ka-50's cyclic, but that's beside the point. Apart from that fraction of a second it takes for a spring stick to return to centre after trimming, the inputs are identical.

Now to what we should be discussing: the OP provided a link to a post by Brainless, in which he said that trimming resets the autopilot to hold your current orientation, and this is what causes the 'overreaction' when you hit the trim button.

So you're fighting the autopilot, holding the aircraft at an angle, and then when you trim the autopilot is neutralized, resulting in you overshooting your desired orientation. It equates to something like this:

Want to pitch down 20 degrees? Pitch down 10 degrees and trim.

Want to turn 30 degrees to the right? Turn 15 degrees to the right and trim.

There's a constant exaggeration in the controls, and from the sounds of things, this is caused by the way the autopilot is reset by the trimmer.

I didn't discover the Flight Director override button until I'd been playing for almost a year, but when I did, the first thing I thought was "now this is how trimming SHOULD work!".

With a FF stick like G940 (with a piece of tape covering the optical grip sensor) you don't get the bump because the stick will physically remain in the trimmed position instead of going back to center vertical position even if you let go of the stick after trimming....as in the real KA50.

However, there is still a bump for rudder trimming even for FF users because there is a bug where central trimming mode doesn't work for the rudder when FF is enabled for the joystick (central trimming mode gets disabled even for rudder when FF is enabled for joystick). For rudder, as soon as trim button is released, it adds the amount of physical rudder displacement instantaneously to the trimmed amount causing the bump. I reported this to ED many years ago but it was ignored most likely because they didn't understand what I was trying to say.

At any rate, all of this is moot for G940 users right now with latest version of DCS currently due to another unrelated trim axes bug where the work around is to disable FF....

Trim bump is not an issue.

The issue is the autopilot over-correcting during trim, illustrated in the following 8-second clip:

See how the 'trim bump' is barely noticeable even on the input graph.

Meanwhile the autopilot exaggerates the trim by a full ten degrees.