Gimbal roll discussion

[laertesson]

I don’t think this is a bug at this point, so I’d like to discuss when and why the TGP rolls the gimbal. It seems to do it a lot when I am close in to a target with a low dive angle. Anyone have strategies to avoid gimbal roll which makes the target become offset from the cursor?

[Renko]

Yeah, it would be great to know what exactly it is, why and when occurs.

To try to avoid it

There is no description on the manual

[silverdevil]

i an not exactly sure either. though i have done maneuvers different ways while doing an external view to watch the pods optics. it seems to essentially get stuck trying to turn. like us turning our heads to look over our right shoulder then not know we can turn our head the other direction to continue the view arc. without boresight the fix is to set the tgp to stand by and then back to center it.

[Rainmaker]

Yeah, it would be great to know what exactly it is, why and when occurs.

To try to avoid it

There is no description on the manual

 

Has to do with roll limits on the head, before it basically has to unwind itself by reversing roll in the opposite direct.

 

Yes, it is a real thing

[gachatar]

I highly doubt it would be this bad in real life, at this point it messes up nearly half of the attack runs.

[Rainmaker]

I highly doubt it would be this bad in real life, at this point it messes up nearly half of the attack runs.

 

Never counted the actual degrees of allowed roll in game, but reducing the amount or roll has much to do with the person behind the aircraft controls as it does with the pod.

[Eldur]

i an not exactly sure either. though i have done maneuvers different ways while doing an external view to watch the pods optics. it seems to essentially get stuck trying to turn. like us turning our heads to look over our right shoulder then not know we can turn our head the other direction to continue the view arc. without boresight the fix is to set the tgp to stand by and then back to center it.

 

It's literally like looking to the 3/4 o'clock position and up with a VR headset and then having the friggen cable getting struck by the chair's wheel preventing you from turning your head back forward. I really do hate that, and it happens a lot. There's a reason I bought a Quest... but DCS' framerate literally is down the drink with that res on my stone age rig.

 

As for that happening in the A-10C, I usually get that when doing sharp turns at higher bank angles or even the thing which is called an Immelmann (which he never did since the E.III totally was not capable to pull that off, it literally was a hammerhead) after an attack run or a Split S to defeat some SAM. When sticking to 30° AoB orbits, it happens very rarely, but it did happen to me in the past while doing so. In that case I usually just STBY the thing and switch to A-G again and it comes back to life.

 

What I'm really wondering now though is: Why does that never ever happen in the Hornet or Viper or even the Harrier (I guess in that very case, some of you "know" the answer) with the exact same pod?

[Dragon1-1]

Yeah, other aircraft with the same TGP should also suffer from this, the real thing is not capable of unlimited roll. One fun way of dealing with the issue is to do a quick aileron roll to "unwind" the TGP head. :) Of course, you need to have an idea which direction to roll in (or just make a good guess) to avoid making the problem worse. Resetting to boresight also helps, but it's not optimal if you're trying to track something.

 

I also noticed that A-10's TGP loses track during violent maneuvers, particularly if you roll out too fast. The head can't follow the point and ends up off target. It seems that on this particular aircraft, it's far better modeled than on the others.

[Rainmaker]

Yeah, other aircraft with the same TGP should also suffer from this, the real thing is not capable of unlimited roll. One fun way of dealing with the issue is to do a quick aileron roll to "unwind" the TGP head. :) Of course, you need to have an idea which direction to roll in (or just make a good guess) to avoid making the problem worse. Resetting to boresight also helps, but it's not optimal if you're trying to track something.

 

I also noticed that A-10's TGP loses track during violent maneuvers, particularly if you roll out too fast. The head can't follow the point and ends up off target. It seems that on this particular aircraft, it's far better modeled than on the others.

 

Not sure if it’s included in the A-10 software, but GIMB ROLL should be bracketed with <> arrows which denote which way you need to roll in order to clear the advisory. Could be a ‘wish list thing’ but not sure if there is intent to model that or not. Exists in other jets, not sure about this one.

[Nealius]

 

What I'm really wondering now though is: Why does that never ever happen in the Hornet or Viper or even the Harrier (I guess in that very case, some of you "know" the answer) with the exact same pod?

 

It happens to me when doing gun runs in the Hornet with the TPOD on the left cheek station, and I'm fairly certain I've had it happen in the Harrier a couple times too. It doesn't seem as frequent as I remember in the old A-10C, and haven't tried in the A-10C II yet.

[Renko]

What I'm really wondering now though is: Why does that never ever happen in the Hornet or Viper or even the Harrier (I guess in that very case, some of you "know" the answer) with the exact same pod?

 

 

Exactly.

And without a description on the manual we dont know which parameters ED consider to enter gimbal roll

[silverdevil]

Not sure if it’s included in the A-10 software, but GIMB ROLL should be bracketed with <> arrows which denote which way you need to roll in order to clear the advisory. Could be a ‘wish list thing’ but not sure if there is intent to model that or not. Exists in other jets, not sure about this one.

 

+1 this... but i too do not know if it is IRL. better to be closest to IRL.

[skypickle]

I click stdby and then AG. Resets to boresight as well.

[QuiGon]

In the old DCS A-10C you can just press China Hat Aft Short to boresight the TGP if it is gimbaled. This makes the TGP to unwind itself. Now with the new A-10C we don't have the boresight command anymore and have to cycle to STDBY and back to AG or use some other workaround. Hopefully we will get the boresight OSB button that apparently exists in current real life A-10Cs.

[gachatar]

If it really bothers you, you can make some autohotkey script that quickly presses OSB keybindings for TGP standby and AG and put that on your hotas.

[Deezle]

This started to get worse in the A-10C a couple years ago.

 

 

Now in the II, I often get a gimbal roll notifications as I'm turning towards the target, but when I roll out for the attack, it usually goes away and all is well.

[javelina1]

I click stdby and then AG. Resets to boresight as well.

I've done this as well...

[Fri13]

If one doesn't perform any barrel rolls, then the TPOD shouldn't get any cables tangled inside as it should basically be always using very limited scale from its whole gimbal limit.

 

The low angle attack of course is similar thing, if aiming TPOD boresight below the target, then it can easily roll around its Z axis like one would be flying a aileron roll or barrel roll.

 

So the guideline should be, avoid as much you can flying toward target with TPOD boresight below target.

 

Another way to think about is that if your target will never get above your aircraft horizontal plane, then TPOD shouldn't be at all gimbal limited.

[jaylw314]

Not sure if it’s included in the A-10 software, but GIMB ROLL should be bracketed with <> arrows which denote which way you need to roll in order to clear the advisory. Could be a ‘wish list thing’ but not sure if there is intent to model that or not. Exists in other jets, not sure about this one.

 

IIRC, there is an arrow next to the GIMB ROLL warning. However, when I tried rolling in that direction, I don't recall it fixing the problem.

[Deezle]

IIRC, there is an arrow next to the GIMB ROLL warning. However, when I tried rolling in that direction, I don't recall it fixing the problem.

Roll in the opposite direction of the arrow. I've had limited success with this. I usually just standby the TGP and deploy it again.

[Eldur]

It happens to me when doing gun runs in the Hornet with the TPOD on the left cheek station, and I'm fairly certain I've had it happen in the Harrier a couple times too. It doesn't seem as frequent as I remember in the old A-10C, and haven't tried in the A-10C II yet.

 

Thanks, wasn't aware of this. I'm a centerline guy. I can imagine, especially with gun runs that it happens when you have the thing on the left side, do a gun pass, where the TGP is aligned slightly to the right, then pull up steep enough that it begins ro roll up on the right sight until it hits the limit. Now if you happen to do a left hand turn, it will be locked up there trying to get to the other side.

 

So basically, a GIMBAL ROLL> message means, you've got to turn right, not just roll. You need to get the target into the right hemisphere of your airframe so the TGP head can unwind there. And yes, the arrow is definately there, I've seen it after the beginning of this discussion.

[Rainmaker]

Roll in the opposite direction of the arrow. I've had limited success with this. I usually just standby the TGP and deploy it again.

 

That would be the opposite of what you should do if it’s modeled correctly.

[Deezle]

That would be the opposite of what you should do if it’s modeled correctly.

I don't know what's correct, I just know what works.

[Meyomyx]

The answer to the OP is in the way the camera is mounted and articulates. The head of the pod can rotate and the camera can essentially ONLY slew down. Tracking involves the head rotating and then the camera tilting down. You can demonstrate this with your arm outstretched and a pointing finger ... but you can only move your finger DOWN or rotate your arm. You can track pretty much anything in this way.

 

Now, in the aircraft, the problem comes when you are pointing AT or BELOW the thing you're trying to target. If you're slightly off to one side, the camera can't look slightly left - it has to rotate to 90 degrees and look "down" . Allowing the aircraft to point slightly to the other side will require the pod to rotate 180 degrees to track it. Worse, if the target is now above your direction of travel, it will need to rotate "upside down" and "look down" to maintain the lock. Of course, it can only rotate so far so it will bang up against the stops.

 

To see what I mean, track a target a point straight at it or slightly below it. Now look out the window at your pod and see how hard the seeker is rotating trying to keep the lock ...

 

SO, if you are relying on a TGP target lock, you must try to KEEP THE POD TARGET POINT BELOW the FPV as you roll in and perform the attack - so that the pod ONLY has to rotate relatively small amounts to track the target. If you roll in aiming below the target point, the pod will end up trying to "look up" ... and rotate through crazy angles ... until it can't, at which point you'll get the GIMBAL ROLL message.

[QuiGon]

We also have the boresight function back now (although as an OSB on the MFD), which helps a lot to deal with this issue.