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Instant trim and Central trim - weakness in both


zero

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Central trim - you must remember to set joystick in center before next trim input. Not intuitive.

Instant trim - the deflection is doubled when trim is activated. Need quick short activations. Going from hover to forward in one large stick push may end up in disaster. Again not intuitive. 

In both cases - finding a nice hover and then activate trim, aircraft is slightly off balance that need to be catch.

I hated Instant trim in the beginning , but learned that this may be the best for now.

I like to see an instant trim set freeze at new position. 

And a trim center reset button. After landing and want to takeoff again, you have to bring up the deflection info panel to reset neutral.

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Zero,

Yes, I am struggling with trim.  I even tried an X-56 that I have with the springs taken out.  I guess I liked the slewable trim in the Huey much better.  At least I could work it off easier, and I did not need the dang controls monitor screen up all the time.

The force trim also effects the rudder (thrust) at the same time so things can really get out of wack in a hurry.

Brunner CLS-E?

Caldera

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2 hours ago, zero said:

Central trim - you must remember to set joystick in center before next trim input. Not intuitive.

That's not how the central trimmer works. You release controls to neutral immediately after pressing the trimmer, and the aircraft's controls maintain their position at the time the trimmer was pressed. There's nothing stopping you from moving the controls or pressing the trimmer again. Coming from the Huey and Hip it's intuitive, and functions the same as the default trim settings on those modules.


Edited by Nealius
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Central trim option works like a charm. Just as with all the other Helos in DCS. Only weird bird is the Hind, that trim still overshoots after trimming, still needs to be fixed by ED. 

For pedals I unhook the spring on my pedals and use the no spring trim option. 


Edited by River
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6 hours ago, Nealius said:

That's not how the central trimmer works. You release controls to neutral immediately after pressing the trimmer, and the aircraft's controls maintain their position at the time the trimmer was pressed. There's nothing stopping you from moving the controls or pressing the trimmer again. Coming from the Huey and Hip it's intuitive, and functions the same as the default trim settings on those modules.

 

Not really - A new center is physically created on stick. Trimming left roll and stop, you can see and feel that the stick is skewed to left in a new center.. This is impossible with most joysticks.

Central trim works fine in most cases in DCS, such as cruise. But , example,  transition from cruise to land, the constant pumping from a new aft trim to center, and then back to more aft trim does not feel right. Now I try to unlearn central trim, and get used to instant trim

I like to see instant trim (as in fixed wing simulated aircraft) without the doubled deflection effect.   

Anyone knows the reason for double deflection trim effect?  

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don't know why the doouble deflection but it makes the transition to hover that much harder, hope they can refine this I just can't get confident in my transition to hover and landing precisley where I want is impossible- and I don't believe you should have to bring up the control window to see your control positions 


Edited by poochies
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56 minutes ago, zero said:

 

Anyone knows the reason for double deflection trim effect?  

 


Yes.

 

Think of it like that: DCS creates a "virtual joystick" for helos. This virtual joystick is what actually controls the movement of the helicopter. You can see the position of the virtual stick when you look down in the Apache cockpit. You can also see its position when you turn on the controls indicator with RCTRL+Return (the white indicators are the position of the virtual stick).

To calculate the position of this virtual stick, DCS adds two inputs together: One of them is the deflection of your physical stick. The other is an offset, which you control by releasing the force trim button. Let's call this offset the "trim position" (this offset is represented as the red crosses in the control indicator).  In the beginning, the trim position is at the center --> red crosses are at coordinate (0,0).  No offset is added to the position of your physical stick --> your physical stick and the virtual stick are in sync. 

Lets say you move your physical stick a bit to the left. The position of you physical stick is now (-10, 0).  The trim position is unchanged, it is still (0,0).  So the virtual stick is now being held in position (-10,0) + (0,0) = (-10,0). Everything looks normal, your physical stick is still in sync with the virtual stick.

Now you press and release the force trim switch (without moving your physical stick). The coordinate of your physical stick remains the same: it's  still  (-10,0). But when you release the trim button, the trim position is updated. It now ALSO becomes (-10, 0). When DCS calculates the new position of the virtual stick it again adds these two coordinates together:   (-10, 0)  + (-10, 0) ->  (-20, 0).  The deflection on the virtual stick has now doubled.


Edited by cow_art
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8 minutes ago, Nevyn said:

This video explains it pretty well.

 

 

I watched this last night.  This is a brilliant explanation of the trim options and why there really is nothing else they can do about trimming cyclic on spring-back joysticks. 


Edited by Buschwick

[sIGPIC][/sIGPIC]

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6 minutes ago, Sobakopes said:

Default trim mode on mi8 and mi24 is the way to go. Surprisingly it's not available on the Apache. It's a blunder. 

Instant Trim (FFB friendly) is the same as default on the older choppers.

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"Muß ich denn jedes Mal, wenn ich sauge oder saugblase den Schlauchstecker in die Schlauchnut schieben?"

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One thing they could do, is to simply add a timeout to the central trimmer mode: After trim release is pressed the physical stick is disabled until

a.) the stick is returned to center

or

b.) a certain amount of time has passed (0.5 seconds or some configurable amount )

That way you get the smooth operation of central trimmer mode, but avoid being completely locked out of your controls when you fail to return the stick _precisely_ to the center for whatever reason.


Edited by cow_art
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4 минуты назад, cow_art сказал:

One thing they could do, is to simply add a timeout to the central trimmer mode: After trim release is pressed the physical stick is disabled until

a.) the stick is returned to center

or

b.) a certain amount of time has passed (0.5 seconds or some configurable amount )

That way you get the smooth operation of central trimmer mode, but avoid being completely locked out of your controls when you fail to return the stick _precisely_ to the center for whatever reason.

 

Exactly like that works default mode on other modules. 

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Just now, Sobakopes said:

Exactly like that works default mode on other modules. 

Ah great, thanks! I wasn't sure if that's the case (I have gotten used to instant trim, I have not tried the central mode in any of my helo modules in a very long time).

All the more reason for ED to update central trim mode then!  🙂

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6 minutes ago, cow_art said:

One thing they could do, is to simply add a timeout to the central trimmer mode: After trim release is pressed the physical stick is disabled until

a.) the stick is returned to center

or

b.) a certain amount of time has passed (0.5 seconds or some configurable amount )

That way you get the smooth operation of central trimmer mode, but avoid being completely locked out of your controls when you fail to return the stick _precisely_ to the center for whatever reason.

 

This means basically:

a) central trimmer mode as it is now

b)revert to instant trim after half a second, which is really quite quick, this would basically render central position obsolete. Any longer delays would be pointless because it would still revert to instant trim, after the user being locked out because they didn't return the stick to center.

In reality both methods require returning the stick to centre, as with instant trim you get the jump which you have to counter. Central position gives you a bit of space to do that. As I have a short spring loaded stick I find the central mode pretty good and clean. I would think with a long extended stick the instant trim would be better. It is all about timing.  

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28 minutes ago, Hoirtel said:

This means basically:

a) central trimmer mode as it is now

b)revert to instant trim after half a second, which is really quite quick, this would basically render central position obsolete. Any longer delays would be pointless because it would still revert to instant trim, after the user being locked out because they didn't return the stick to center.

In reality both methods require returning the stick to centre, as with instant trim you get the jump which you have to counter. Central position gives you a bit of space to do that. As I have a short spring loaded stick I find the central mode pretty good and clean. I would think with a long extended stick the instant trim would be better. It is all about timing.  

No sorry it seems I didn't express this clearly enough.

Both conditions a.) and b.)  are checked simultaneously and both can cancel the control lockout (whichever happens first cancels the lockout). The assumption is that you normally want to return the stick to center after trimming (because you want to avoid the jump you mentioned).  At least I do in 95% of the cases. And I need only a fraction of a second to center the stick (exact amount of time could be configurable of course). In all these cases the central trimmer mode works perfectly fine and you get NO jump.

The problem with central trimmer mode is, that if you fail to return the stick precisely to the center you are locked out of your controls (that tends to happen when things are hectic). To remedy that problem, condition b.) exists. It releases the lock after a certain amount of time, even if you didn't manage to return your controls precisely to the center. In this case you probably will get a jump, yes. But b.) is a contingency and a small jump definitely beats crashing because your controls don't react anymore.

(Edit: if you manage to always return your controls to the center perfectly, you'll probably never notice condition b.) is there at all. But if you don't you'll be thankful for it 🙂 )


Edited by cow_art
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I think most folks would be happy with the central trim if a "reset" command was added to set the controls back to center.

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