Think I might finally understand Trim problem!

[doveman]

Doveman,

I was able to duplicate the tap T to make the virtual joystick move without input while on the ground video only after I dropped my deadzone on my joystick to 0. I usually have

Deadzone 5

Sat 100

Sat 100

Curve 20

 

on both x and y

 

Which makes me think the issue is a recentering issue more than need a new trim method ;unless you want the "hold the stick foward to continue to add trim values", at which point I'd say you'd be better off with FFB.

 

I think I've got a Deadzone but let me check.

 

As mentioned, I think I managed to minimise the problem in Central Trimmer mode by making the Recentre zone very small in mods/aircrafts/KA-50/FM/FMOptions.lua like so (the values were 4x this before):

 

----------- for new helicopter trimmer method -----------------------------------------------
----------- (joystick will be disable after trim until it come to neutral zone) -------------
HelicopterTrimmerZonePitch		= 0.05
HelicopterTrimmerZoneRoll		= 0.05	
HelicopterTrimmerZoneRudder	        = 0.1

 

which kinda makes sense as if I'm clicking Trim whilst the stick is already in the Recentre zone, it's going to trim, think it's recentred and therefore "unlock" the stick and register the current position as additional input. However, when I release the stick this additional input should be removed as it's not trimmed in and this doesn't happen so it doesn't really explain it.

[doveman]

Check IRL cockpit videos. They drive it like they've stole it. Jumping all over the place.

 

I don't have the link but there's a video with the pilot landing on a ship deck using a lot of Trim clicks. How could he do that if it was "jumping all over the place"?

[doveman]

Use the old centering method, and re center stick and rudder each time you release trim = win

 

Old method is unusable for me actually. Central Trimmer method I got just about usable I think by tweaking the TrimmerZone.

[doveman]

You fly straight and level with the helicopter compensated, the stick (or spring FFB) is anchored or centered, and coincides with the attitude memorized by the AP. Right.

You enter a small change in attitude, and then you try to compensate, what happens is that the helicopter "jumps" from the attitude memorized by the AP to the position of the stick.

That is the only problem, no matter spring or FFB.

 

I attached another video, a short flight, compensate different attitudes. Note well in 00:45, which induce this effect, there is only a slight variation on the stick, but does not match the stored in the AP, and the helicopter falls nose down.

In the rest of the flight the helicopter remains perfectly stable to compensate.

 

Greetings!

 

Thanks for the video P1KW. It's a good demonstration of the problem.

[karambiatos]

if you trim at any attitude, and then you center you stick leave it centered and keep pressing the trim button and the AP will keep inputting more and more on the previously assigned input, while the virtual stick stays at its assigned trim position.

 

what ive also noticed by lowering the response time of the trimmer is when you press the trim the autopilot assigns a attitude and then the virtual stick starts moving to the assigned attitude, adding onto the autopilot creating unneeded input, ive tried to fix it but at least a little bit and it became a bit better and more managable after putting the HelicopterTrimmerTauInverse to 3 (located in \Eagle Dynamics\DCS World\Mods\aircrafts\Ka-50\FM )

[Ich666]

I don't have the link but there's a video with the pilot landing on a ship deck using a lot of Trim clicks. How could he do that if it was "jumping all over the place"?

 

I know what video you're talking about but couldn't find it. This here is similar, the clicks you can hear is the trimmer. Then again I'm not sure if the Mi-8 even has an autopilot channel system similar to the Ka-50. You might want to look out for Ka-50/52 or similar cockpit footage.

 

EDIT: I think this video here is pretty much our only source in this discussion:

. Is it just me or can we see a similar behaviour like our virtual Ka-50 around the 0:45 mark? To me it looks like he's pitching up a bit on his stick and after he clicks the trim the pitch increases like it is described here. The problem is that the other video, which shows the pilot and his stick too, starts at a later point, so i cant clarify this. Edited February 25, 2013 by Ich666
Saving me a double post.

[Pizzicato]

I don't have the link but there's a video with the pilot landing on a ship deck using a lot of Trim clicks. How could he do that if it was "jumping all over the place"?

 

He couldn't, but that's because a real helicopter's cyclic stick behaves differently to the stick you're using at home. In the real helicopter, hitting the trim button effectively just resets the forces on the stick. That can't work in the sim unless you have a force-feedback stick.

 

If you don't have force-feedback, you're going to suffer the bumps. Central Trimmer mode works much better in my experience (totally smooth), but not everyone has that experience, apparently.

[karambiatos]

To me it looks like he's pitching up a bit on his stick and after he clicks the trim the pitch increases like it is described here. The problem is that the other video, which shows the pilot and his stick too, starts at a later point, so i cant clarify this.

he clicks 0:23 while the chopper is at 15 degrees if you do that in the virtual KA-50 itll end up around 30 or so degrees in a near instant.

[Daniel M]

Back to the very first post (I lost track of the purpose of this thread a while ago :D)

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.

 

Agree for "large" offsets*, as demo'd in P1KW's video, I would be curious what happens if you trim to that hover around 0:45, and when you start transition you don't trim right way, wait until you've "stabalized" to whatever heading etc.(i'll attempt if noone else can tomorrow when i'm back home)

*I will concede that that large offset may be caused by the AP, I can't speak to whether this is a bug or not. I"m also a trim press and holder so YMMV(understand this puts you into a "FD on" type of setting, if even only while holding).

 

 

Sure, when aggressively maneuvering trim isn't really needed (I tend to use the hold-Trim method for that rather than engage FD, mainly because when I need to do so it's because I'm being targeted and I don't have time to fiddle around with my mouse to click on FD. I need to try and remember to toggle it on with my voice control software though). It's more when stopping such maneuvering and wanting to stabilise or just in general flight that the first click of trim might not get it exactly where I want it (particularly with the oversteer problem) and it'd be useful to be able to adjust the Trim without having to recentre the stick in-between.

 

 

Map it!!(or VAC it or whatever :D)

 

The only time i'm on non FD is enroute on a long leg when i'm focused more on setting up Abris or Tgt points in the pvi. When I do get jumped unexpectedly I press and hold trim, yank and bank in non FD until i have enough time to get to FD on.

 

That or get FFB

[StoOopiD]

[karambiatos]

AobTSeYyTNo

the over trim thing isnt there in BS1, it only started with BS2.

 

i attached a track hopefully it works, where you can see the problem perfectly just look hear and look at where the helicopter is every time i trim and what it does after it.

trim.trk

Edited February 26, 2013 by karambiatos

[doveman]

Because I had to delete my Saved Games\DCS folder to get it working, I played a couple of times without realising I had Central Trimmer mode deactivated. It seems some update might have made it even worse and whenever I clicked Trim, even after holding it in steady flight for several seconds, it would rock side to side before settling on an banked Trim position.

 

Hopefully it will be OK again for me when I try with Central Trimmer mode enabled.