Problems with trimmer

Hi!

So I'm using the Warthog and Center Trimmer posiiton option

I seems that when i trim the KA50 (say i got it stoped in the position i wanted, stable) when i press trim and recenter the stick, its like i trimmed way more to the side i had the stick when i pressed the button, looks like i have to press the button with way lower stick movement than what i needed to hold the aircraft in whatever attitude i wanted, is this normal or am I doing something wrong?

thanks!

Yeah, it's the way the trimmer works. Someone explained in detail why the slight jump happened, long ago, but I can't remember where.

Hold the trimmer button down, get the copter to where you want (stable), then let the trimmer button go. Let your stick go back to center. Now you get no jump.

Hold the trimmer button down, get the copter to where you want (stable), then let the trimmer button go. Let your stick go back to center. Now you get no jump.

This!

Yeah, it's the way the trimmer works. Someone explained in detail why the slight jump happened, long ago, but I can't remember where.

 

 

Hold the trimmer button down, get the copter to where you want (stable), then let the trimmer button go. Let your stick go back to center. Now you get no jump.

I'll try this and get back to you thanks! It's weird cause the UH1 works flawlessly, Also i Forgot to mention AP channels are usually on, if it's all of I don't get the jump weirdness

...Also i Forgot to mention AP channels are usually on, if it's all of I don't get the jump weirdness

Lol, actually that's a bug. They're actually all OFF. The bug reversed the lights, so now if the light is on, on the AP channel, it's actually off. Someone said they fixed this, but it isn't fixed on my side yet. So, if all your AP channel buttons are lighted, they are actually all off. If they're not lighted, they're on.

At least until the bug is fixed. That's why your not getting any jump when they're "on".

Lol, actually that's a bug. They're actually all OFF. The bug reversed the lights, so now if the light is on, on the AP channel, it's actually off. Someone said they fixed this, but it isn't fixed on my side yet. So, if all your AP channel buttons are lighted, they are actually all off. If they're not lighted, they're on.

 

 

At least until the bug is fixed. That's why your not getting any jump when they're "on".

Oh yeah I'm aware, i mean the AP is actually on ON and i get the jump when i click the trimmer, works fine with ap off

Oh, ok. Yeah, if all your AP channels are off, then your AP is essentially off, so clicking the trimmer isn't going to do anything. There are no AP channels for the trimmer to act on.

Without the AP channels, there is no 20% control by the helicopter on the cyclic and collective ( I assume it's on the collective as well because of altitude AP channel ).

I wish I could find that long explanation someone gave on why there is a jump when you click, but it's essentially the hydraulic controls changing position, or something like that. I guess when you are holding the trimmer down, they are changing as you have the button down, and then click in place when you let up.

"then your AP is essentially off, so clicking the trimmer isn't going to do anything" - That's not correct.

The trimmer button has 2 functions:

- setting the attitude for the AP

- actually trimming the cyclic (rotors)

The latter will still work with the autopilot completely disabled.

Hmm, something to debate. I've looked through the manual trying to find info on this, but there is nothing about what happens when you turn the AP channels off.

What's happening is the autopilot temporarily disengaging when you press the trimmer button.

Let's say you've trimmed the nose down 5° for forward flight and you want to come to a hover. As you pull up the nose to slow down the AP will still try to maintain that -5° pitch and basically negate some of your input (up to 10%). Pressing the trimmer will disable the AP and in turn the 10% nose down input it was applying, causing the nose to jump.

This is what's often reffered to as "fighting the trim/AP" and applies to all AP channels (however altitude hold works with a handle on the collective, not the trimmer on the stick)

To avoid that try getting into the habit of holding the trimmer until you're done maneuvering. That's the way of doing it and you'll find the AP to be much more cooperative.

Ahh, so that's why it jumps when you just click the trimmer. Makes perfect sense. Thanks!

"then your AP is essentially off, so clicking the trimmer isn't going to do anything" - That's not correct.

 

The trimmer button has 2 functions:

- setting the attitude for the AP

- actually trimming the cyclic (rotors)

The latter will still work with the autopilot completely disabled.

Yep.

What's happening is the autopilot temporarily disengaging when you press the trimmer button.

 

Let's say you've trimmed the nose down 5° for forward flight and you want to come to a hover. As you pull up the nose to slow down the AP will still try to maintain that -5° pitch and basically negate some of your input (up to 10%). Pressing the trimmer will disable the AP and in turn the 10% nose down input it was applying, causing the nose to jump.

This is what's often reffered to as "fighting the trim/AP" and applies to all AP channels (however altitude hold works with a handle on the collective, not the trimmer on the stick)

 

To avoid that try getting into the habit of holding the trimmer until you're done maneuvering. That's the way of doing it and you'll find the AP to be much more cooperative.

That's why it jumps yes.

Also... when you "hold the trimmer" you should always press the trimmer just before you start moving the controls. Get the aircraft into a super stable attitude, then release and center.

There are videos onboard real KA-50 where you can clearly hear the pilot "clicking" to trim. It is my humble opinion that the sound is not "Press, release", but it was "release, press". I think they DO hold the trimmer like we do, but they constantly "release" to set the current stick position as trim. Just speculation though...

Real pilots tap the trimmer. Holding it down removes the force trim effect on the stick, which makes it flop around and is undesirable. The clicking sound is not the trim button itself, but the magnetic brake disengaging and engaging.

Hmm, but I wonder if it causes a jump for them, just like in the sim.

Hmm, but I wonder if it causes a jump for them, just like in the sim.

"Real pilots tap the trimmer."

But they're also running FFB :).

Hmm, but I wonder if it causes a jump for them, just like in the sim.

I don't recall there being this issue in the early days of the shark. I think the problem appeared when ED introduced the central trimmer mode.

Hears a great video to watch for those who haven't seen it as you can hear the trim solenoid clicking.

It doesn't have to do with central trimming mode, all that does is make it so that whenever you press trim, your joystick movements will be ignored until you return the joystick to the center position. The reason why it jumps is because people are using non-FFB joysticks where they hold down the trimmer instead of tapping it. The same jumping effect can be observed if you've trimmed the helicopter, then turn on Flight Director without touching the joystick. Flight Director does the same thing as holding down the trim button, except it doesn't disengage force trim effect.

It doesn't have to do with central trimming mode, all that does is make it so that whenever you press trim, your joystick movements will be ignored until you return the joystick to the center position. The reason why it jumps is because people are using non-FFB joysticks where they hold down the trimmer instead of tapping it. The same jumping effect can be observed if you've trimmed the helicopter, then turn on Flight Director without touching the joystick. Flight Director does the same thing as holding down the trim button, except it doesn't disengage force trim effect.

I understand. To clarify my previous post, i'm not saying it's an issue with central trimming mode. I know what it does. I'm just saying I don't recall this "jump" trimming issue in BS1. Possibly when BS2 was introduced there was some changes in the behavior.

Might have to dig up the vanilla BS1 CD, install and compare the behavior.

Edit: Well installing BS1 didn't work. lol

Re-read your post Ranma13. Now i'm confused. My only issue with the trim is when for example. You are in a hover , pitch down 20deg, tap trim & center stick, then the shark will dip the nose double that to 40deg. Holding trim while performing the pitch forward to 20deg then releasing trim causes no issue.

"The reason why it jumps is because people are using non-FFB joysticks where they hold down the trimmer instead of tapping it."

No.

Very compelling argument. How can someone argue with "no"? Oh wait, I know:

Yes.

:)

It jumps when you didn't settle the aircraft properly before releasing the trimmer.

For an extreme example...

Say you're flying along, trimmed well and at high speed, and you want to slow down...

You press trim, pull the stick back some random distance that you think is about right, release the trimmer button and then just hope...

What happens is that if you pulled the stick a small amount this may be OK, and the airframe will achieve equilibrium somewhere within the 20% AP control authority of the trimmed position.

In the case where you've pulled it back too far though... The attitude of the aircraft will pitch back and settle, but it will be up against the 20% control authority of the AP channel. When you press trim it will move the control surfaces to the trimmed position immediately and "jump".

You can test this by moving the stick a small amount and then click trim repeatedly... and it WILL jump every time you press trim. So on the surface this seems to support your claim... but it does not. When you think further into the problem you understand that what's going on is that if the airframe was not in equilibrium when you released trim, then when you press trim again the AP channels will release (mostly... they still damp of course) and allow the control surfaces to move to the location where the trim button was last released at.

So... to prove my point...

Go fly the Shark... get to a stable turn while holding trim. Be sure to let the aircraft settle into equilibrium. THEN release trim. Now... When you press trim it won't jump.

So... the problem isn't with FFB users who hold trim. It's with forcing the AP channels to use some of their 20% control authority to maintain current attitude when you release the trim when you don't have the stick very close to the right place for that equilibrium to occur. I suspect this doesn't happen with FFB because because the stick moves to where the AP channel wants it to be to maintain equilibrium at that attitude. With nonFFB the stick locks at the trim spot and doesn't physically move when the AP asks it to. This is also possible with no FFB... you just have to be mindful about it. The point is though... It has nothing to do with holding trim. It has to do with stick position relative to equilibrium just before you release trim.

The "solution" would be to allow the AP channel to offset the center position of the axis when the trim is not pressed. In effect allowing the ball to move around under the stick, commanded by the AP channels.

Right now, when trim is released and AP channels want to move the stick...

With FFB the stick moves. Easy Peazy.

With no FFB the AP channels move the control surfaces, but can't move the stick. so when you press the trim there's a difference in where the AP channels would have moved the stick and where the stick actually is (it's at the trimmed spot).

If they disconnected the stick and the ball... logically via programming... and allow the ball to move around commanded by the AP channels then the "center" position would be correct when you press trim.

Hmmm...

I need to talk to ED about this.

M1Combat, you should stop basing your arguments off incorrect guesses. The AP does not move the stick on FFB devices. I think you should pick one up (MS FFB2 is only ~$50 on eBay), which will resolve your misunderstanding of how the FFB works.

Re-read your post Ranma13. Now i'm confused.

Sorry, I misspoke. To better clarify OP's issue, imagine that there's a rubber band around the front of the helicopter's nose, and every movement away from the rubber band will cause it to stretch and try to pull the nose back to the original position. When you trim, you're resetting the rubber band's position to wherever the nose is pointed at the time the trimmer is pressed:

When you hold down the trimmer, this reset is happening constantly until you release the trimmer:

OP's issue is that he's moving the nose to a position that he wants, but some of the movement he's applying is to counter-act the AP pulling the nose back to the original position. He gets it stable, but when he taps the trim, the rubber band effect suddenly disappears and the helicopter jumps more than he intended: