[EVALUATING] 1.2.10.32275 (openbeta) FFB + Trim

[Eldur]

Just had a look at the most recent openbeta version to see the FFB.

I think it has some nice touches, like gaining pressure on the elevator by increasing speed which will need a lot of readjustment in how I fly this thing as I've been using SimFFB (which just works if you fire it up or let it reinit after the sim has been started).

 

But well, I came across a little problem which I don't think (and hope) is intended. Trimming the elevator makes two things where it should really just do one.

It does and should do this: Move the spring force center of the stick

It does and should NOT do this: Change the elevator deflection at the same time

 

At least that's what I think... basically I expect the trim to do absolutely nothing if I don't touch my FFB2, but how it's modelled in this version, it's like doing the trim twice, which reduces its accuracy by half :)

Edited March 12, 2015 by Cobra847

[Flagrum]

If it moves the stick, why should the stick not move the elevators?

[Eldur]

It moves the elevator even if I let loose the stick so it doesn't move at all.

[Flagrum]

It moves the elevator even if I let loose the stick so it doesn't move at all.

But that is because of the dead-man sensor of the joystick, right? As soon as you grab the stick again, it should recenter at the last trimmed position (which corresponds to the actual elevator setting).

 

Try covering the sensor with tape - like many (all?) others do it as well.

[Eldur]

That's absolutely not the problem I have, maybe it's hard to describe.

 

But well, the other modules all just shift the FFB stick center while trimming as soon as FFB is available, no matter if the light barrier is obstructed or not. But they don't move the plane's control surface anymore which is how it is if no FFB is available.

The FW-190D-9 is different BTW. The FFB stick center stays at the same spot and the whole horizontal stabilizers twist up or down as it has no trim tabs and doesn't shift the forces if I understand it correctly.

Now the MiG-21 trim behaves like both of the above mentioned at the same time. But it should either be one of them. I don't know the technical details, but it seems that the trim system is rather comparable the the FW-190 one, as the whole stabilizer is the whole control surface with no elevator or even trim tabs on it.

[Flagrum]

That's absolutely not the problem I have, maybe it's hard to describe.

 

But well, the other modules all just shift the FFB stick center while trimming as soon as FFB is available, no matter if the light barrier is obstructed or not. But they don't move the plane's control surface anymore which is how it is if no FFB is available.

The FW-190D-9 is different BTW. The FFB stick center stays at the same spot and the whole horizontal stabilizers twist up or down as it has no trim tabs and doesn't shift the forces if I understand it correctly.

Now the MiG-21 trim behaves like both of the above mentioned at the same time. But it should either be one of them. I don't know the technical details, but it seems that the trim system is rather comparable the the FW-190 one, as the whole stabilizer is the whole control surface with no elevator or even trim tabs on it.

Hrm ... I don't get it. :o)

 

If I trim the 21, my G940 moves accordingly - i.e. the center shifts forward or backward repectively. And therefore I expect that the control surfaces are also moving - as if I had deflected the stick by myself. And that is what they do ...? But should not!? Why not? :dunno:

 

I trim forward. The aircraft should go nose down. And the stick reflects this attitude. To go level again, I would have to pull the stick (or trim in the opposite direction).

 

:confused:

[Eldur]

Try to keep your stick at the same position while trimming, regardless of the force that kicks in and see how the MiG puts her nose up/down while doing so. Then repeat it with the A-10C, F-15C or Su-25(T). In these and all other planes except the FW-190 the nose stays where it is unless you actually move your stick with the force shift.

 

Another test that can be done, AFAIK the G940 also has such a light barrier sensor but as opposed to the FFB2 going limp it centers at it's actual center then like a non FFB stick:

 

While sitting on the ground, don't touch your stick, check your elevators in F2 view and trim up or down completely. Your stick shall stay centered, if not, hold it centered. You'll see the elevators will deflect as you trim. Stop trimming as you reach either max up or down and then grab your stick, it will move to it's new FFB spring center and see how your elevators move up or down further. Again, do the same check in other planes - nothing happens until you'll grab your stick.

 

I hope you can follow me now :)

 

PS: Nothing changed in the actual release of this version, so it's not just an open beta thing.

 

BTW I just found out that the elevator stick force depends on the ARU-3VM translation. If set to manual, the stick forces stay the same at whatever speed the system is set to. Low speed = almost limp, high speed = stiff.

 

Actually I'd like to have the minimum stick force in this regard to be a tad stronger.

[Flagrum]

Try to keep your stick at the same position while trimming, regardless of the force that kicks in and see how the MiG puts her nose up/down while doing so. Then repeat it with the A-10C, F-15C or Su-25(T). In these and all other planes except the FW-190 the nose stays where it is unless you actually move your stick with the force shift.

 

Another test that can be done, AFAIK the G940 also has such a light barrier sensor but as opposed to the FFB2 going limp it centers at it's actual center then like a non FFB stick:

 

While sitting on the ground, don't touch your stick, check your elevators in F2 view and trim up or down completely. Your stick shall stay centered, if not, hold it centered. You'll see the elevators will deflect as you trim. Stop trimming as you reach either max up or down and then grab your stick, it will move to it's new FFB spring center and see how your elevators move up or down further. Again, do the same check in other planes - nothing happens until you'll grab your stick.

 

I hope you can follow me now :)

 

PS: Nothing changed in the actual release of this version, so it's not just an open beta thing.

 

BTW I just found out that the elevator stick force depends on the ARU-3VM translation. If set to manual, the stick forces stay the same at whatever speed the system is set to. Low speed = almost limp, high speed = stiff.

 

Actually I'd like to have the minimum stick force in this regard to be a tad stronger.

Now I got it! And now I also understand why it is difficult to explain ... I try to make a mental picture of it .. .and fail. lol.

 

Maybe!? It is intentional? The trim is, at a closer look, really a bit weired - even if we leave FFB out of the equation.

 

If you trim all the way forward, the control surfaces are all the way deflected. But the remaining stick travel distance is 50% - you can pull it back only to the center, but not into your lap. The control surfaces therefore go from fully deflected to neutral, but not into the opposite direction.

 

Maybe the strange FFB implementation is because the physical stick can be outside the virtual stick deflection range. Example: pull stick into lap (-50% deflection), trimm all the way forward - virtual stick deflection range is now +50% - 0, but the physical stick is held at -50%. Therefore the actual input from the physical stick is transformed to the range of the virtual stick.

 

Watch the controls indicator when trying my example: the current input (the small circle) moves upward although you still hold the joytick fully deflected. Because in the real aircraft, you could simply not hold the stick as we can when trimming.

 

... does that make some sense? :cry:

[Eldur]

That's something I noticed in other planes here as well. Full trim + Stick fully in opposite direction = controls centered. Not sure if that's correct :)

[Flagrum]

That's something I noticed in other planes here as well. Full trim + Stick fully in opposite direction = controls centered. Not sure if that's correct :)

I believe now, it is correct.

 

In RL the max. deflection is limited by the amount the contol surface can move. Push stick fully forward, control surface deflection is at maximum. More is not possible. Now trim completely to the opposite direction but keep the pressure on the stick. The trim mechanism will force your stick to the center, because otherwise you would input even more forward deflection but which the control surfaces can not handle - they are already at max. deflection.

 

And the FFB implementation replicates that as good as possible. It just can't apply so much force that the stick will move if you hold it too tightly in place. Therefore the algorithm just adds a subsequently growing "deadzone" (and thus only the virtual stick position is actually forced to move).

Edited September 25, 2014 by Flagrum

[Eldur]

I noticed one more thing that also shows my initially described problem.

 

Fly level at not so high speed, kick in the SAU recovery AP, it will level out the plane by trimming, then go 100% mil, accelerate for a while and then deactivate the SAU AP. With FFB, the nose now will kick up violently, without FFB it will keep going straight. This is due to the dual trim issue.

 

Definately something that needs more work.

[Flagrum]

I noticed one more thing that also shows my initially described problem.

 

Fly level at not so high speed, kick in the SAU recovery AP, it will level out the plane by trimming, then go 100% mil, accelerate for a while and then deactivate the SAU AP. With FFB, the nose now will kick up violently, without FFB it will keep going straight. This is due to the dual trim issue.

 

Definately something that needs more work.

Post a track, please.

[silverofx441]

The FFB works with the G940 now??? No more buzzing?

[Eldur]

1.2.11 beta: still nothing happened around FFB double trim, what a bummer :(

 

Do I have to start posting kitten pictures to get this fixed? :D

[iFoxRomeo]

...

Do I have to start posting kitten pictures to get this fixed? :D

 

:megalol: give it a try....

 

 

Interestingly the Sabre and the Fishbed suffer both from double trim. But the "new" Flanker does not(1.2.11 ob). There the trim works perfectly.

 

 

Fox

[Dolphin887]

Noted.

[Eldur]

Thx for picking this up :)

[Eldur]

As it's not listed in the 1.2.12 openbeta changelog, I presume it isn't fixed in there. Also did a short test, track is attached.

 

Shortly after ~12:16 sim time, right after my first pass over the trucks on the "X site" and egressing northish and then to the west and later southwards, I conduct the first test:

 

Plane is trimmed for the speed I hold, then I keep my hand on my stick, but not giving any input. The light barrier is triggered, FFB active. I just trim up and down several times. Not applying any force to the stick, it wanders back and forward as I trim. This is what it should in most cases.

 

Then I turn around northish again and repeat the test, with a single difference: I don't touch the stick, FFB motors are off and it stays centered where I leave it. Again, I trim jinking up and down. The plane still reacts. But it shouldn't when the FFB center moving like in case 1 is in as this basically results in the trim being doubled.

 

Just as a side note, after all that I came in a bit high on the landing approach, touched down a bit too hard on my right main wheel, but any landing you can walk away from is a good landing, isn't it? :music_whistling:

[Eldur]

1.2.15 and still nothing happened... :(

[Cobra847]

1.2.15 and still nothing happened... :(

 

We are evaluating what the correct behaviour is.

[iFoxRomeo]

As the double trim problem still persists I made a video to show what seems to be a bug. For comparison the Su-27 trim function is shown at the end.

 

 

 

Fox

[Eldur]

Thanks for doing that video and posting it here. It perfectly showcases the issue. And it's not related to the FFB2, but to FFB per se as you're using the G940.

By the way, both the F-86 and MiG-15 of Belsimtek suffer from the very same problem, I'm just not sure if it's been reported already, but I think I at least mentioned it over there at least once in some beta release threads, but I never did a comprehensive report, just a link to this very thread plus a "here, too" notice.

 

And I'd like to know, if you've made the same experience I did with the Su-27 PFM: http://forums.eagle.ru/showthread.php?t=135349

This plane is unflyable for me with FFB... such a bummer!

[Eldur]

Haven't seen anything regarding this issue in the 1.5. OB patch notes... still hoping to see this addressed until the 1.5 release version's out :)

 

Thanks in advance :thumbup:

[Eldur]

Whatever might be correct (I still think it's not), we FFB users have a 100% disadvantage in trim precision compared to the ones that don't have or use FFB. And we still can't enable or disable it on the fly in 1.5, otherwise I'd just untick FFB while flying the MiG-21 (and all Belsimtek planes which have the same issue ATM as well as the Su-27 with it's half-hearted trim range) and use that shiny little simFFB tool instead. But I'd prefer to rely on the devs. Not to mention other projects as the Tomcat, Corsair or even Viggen coming along in the future - i don't want these issues again and again.

[Lascaille]

The Mig-21 has neither trim tabs or a fully moveable tailplane. Therefore trim is effected by changing the neutral position of the elevators themselves. Yes in real life this reduces control authority (adding back trim has the same effect on the control surfaces as pulling the stick back. As the position of the stick directly reflects the position of the control surfaces the stick will move as you trim.