Hydraulic / Manual Reversion issues

[QuiGon]

So I recently listened to this pocast, where Col. Campbell describes how she survived a missile hit in the A-10 and even brought the aircraft back to base by using the Manual Reversion flight controls after loosing both hydraulic systems. She describes how the aircraft was flying towards the ground after she lost the hydraulics and didn't react to her inputs on the stick. Only after she switched to Manual Reversion, she regained control of the jet.

I've never experienced that in DCS, despite loosing both hydraulic systems quiet a few times, but the flight controls always kept working. Usually when I loose both hydraulic systems, this is because I lost the engines and there is a bug where they produce too much hydraulic pressure while windmilling.

So, after listening to the podcast I now wanted to test specifically how the DCS Warthog behaves when I actually loose the hydraulic systems itself. So I went ahead and created a test mission, where I trigger both hydraulic systems to stop working midflight and what happened is not at all what I expected how the jet would behave:

Upon loosing both hydraulic systems the jet violently pitched up. Trim didn't work anymore, but the flight controls still worked, so I was able to just push the stick forward and regain level flight. This doesn't seem right to me. How can the flight controls still work without hydraulics and without manual reversion?
I was able to fly and maneuver just fine. The only difference was, that there now was somewhat of an input lag, meaning it took the jet a few moments to react to my inputs on the stick.

So that's the first issue I want to report: The flight controls still work without hydraulics and without manual reversion. Also, the stick in the cockpit starts vibrating when hydraulics are gone, which I'm not sure if this is intended behaviour.

Then I turned on manual reversion to see what difference it makes, although there was no need to use them as the jet was still totally controlable without manual reversion. There was a difference though, which unfortunately doesn't seem right either: When I turned on manual reversion, the whole jet started to roll violently left and right on the roll axis when I started maneuvering.

And that's the second issue I want to report: Manual Reversion is not just useless in DCS, it even makes the jet roll violently left and right.

Here's a video of my test (see video description for further info) and a track file:

 

A10 Hydraulic ManualReversion issues.trk

Edited May 23, 2022 by QuiGon

[Akiazusa]

If I understand correctly the hydraulic systems on the A-10 is more like a power steering on your car,so you don't need to exercise ur muscle during every manoeuvring.There are still a lot of cables physically connect the stick and control surfaces,thus in theory you can still control the plane without hydraulic systems but it may need a lot of force. The input lag is ed's way to simulate "need a lot of force so it's hard to control the stick precisely" I guess?

Also on the A-10 if you lost both hyd system,the pitch and roll control will automatically switch to MRFCS,which will bypass the HYD system in both pitch and roll channel. And for roll,you have to manual select MRFCS,and the MRFCS will change cables link from "stick to Aileron" to "stick to Aileron Trim Tab" ,so in roll MRFCS,you are actually control the Aileron Tab and airflow push the trim tab thus move the Aileron surface.

But for battle damage,things may get complex,the cables may brake,and things may get jammed,sensors may get damaged and auto-switch may fail etc etc

Of course,I'm not a pro and it might be wrong.

Edited May 23, 2022 by Akiazusa

[jaylw314]

4 hours ago, Akiazusa said:

If I understand correctly the hydraulic systems on the A-10 is more like a power steering on your car,so you don't need to exercise ur muscle during every manoeuvring.There are still a lot of cables physically connect the stick and control surfaces,thus in theory you can still control the plane without hydraulic systems but it may need a lot of force. The input lag is ed's way to simulate "need a lot of force so it's hard to control the stick precisely" I guess?

Also on the A-10 if you lost both hyd system,the pitch and roll control will automatically switch to MRFCS,which will bypass the HYD system in both pitch and roll channel. And for roll,you have to manual select MRFCS,and the MRFCS will change cables link from "stick to Aileron" to "stick to Aileron Trim Tab" ,so in roll MRFCS,you are actually control the Aileron Tab and airflow push the trim tab thus move the Aileron surface.

But for battle damage,things may get complex,the cables may brake,and things may get jammed,sensors may get damaged and auto-switch may fail etc etc

Of course,I'm not a pro and it might be wrong.

 

Some clarification

• the elevator channel is automatically switched into manual reversion on dual hydraulic loss, so flipping the manual reversion switch does nothing to pitch control, it's already in manual reversion.  The pitch feel changes significantly, but of course you won't notice this in DCS unless you have force feedback
• In DCS, flipping the switch DOES seem to reverse pitch trim control.  Nobody has been able to clarify to me if this is true IRL or not, so not sure if it's a bug.
• The aileron channel is NOT automatically switched into manual reversion.  This is controlled by the cockpit manual reversion switch.  When switched, you're supposed to keep the ailerons neutral for about 4 seconds during the transition, otherwise the ailerons can abruptly release, presumably causing roll transients.  Unfortunately, in DCS this seems to be overmodelled, and almost impossible to prevent if you have outboard stations heavily loaded 
• The aileron trim should be disabled during manual reversion

TL;DR -- the "Manual Reversion" switch actually means AILERON Manual Reversion

Edited May 23, 2022 by jaylw314

[Yurgon]

6 hours ago, QuiGon said:

Manual Reversion is not just useless in DCS, it even makes the jet roll violently left and right.

Yeah, that looks quite familiar; reported here. Back then, it looked to me as if it mostly happens to a clean jet, but doesn't develop when the jet is loaded with a few external stores.

[jaylw314]

3 hours ago, Yurgon said:

Yeah, that looks quite familiar; reported here. Back then, it looked to me as if it mostly happens to a clean jet, but doesn't develop when the jet is loaded with a few external stores.

LOL, I think you're right, I might have had that backwards in my head.  Either way, I suspect it's an excessively modelled aileron "float-up", but that's just speculation on my part.

[Dragon1-1]

3 hours ago, jaylw314 said:

TL;DR -- the "Manual Reversion" switch actually means AILERON Manual Reversion

Not really. It does toggle manual reversion for pitch, but only if you haven't lost your hydraulics. Handy for practicing this mode of control. In fact, Iron Flag features a mission just for that. 

[jaylw314]

1 minute ago, Dragon1-1 said:

Not really. It does toggle manual reversion for pitch, but only if you haven't lost your hydraulics. Handy for practicing this mode of control. In fact, Iron Flag features a mission just for that. 

Ha!  You're absolutely correct, of course!  I'm just so used to getting blown up on a regularly basis that I forgot that people need to practice it! 

[Dragon1-1]

It's good to practice it, too, since the jet flies like a very ill-tempered hog when in it, particularly if you want to trim it in pitch. It is possible to get it under control, but by no means easy.

[QuiGon]

4 hours ago, jaylw314 said:

Some clarification

• the elevator channel is automatically switched into manual reversion on dual hydraulic loss, so flipping the manual reversion switch does nothing to pitch control, it's already in manual reversion.  The pitch feel changes significantly, but of course you won't notice this in DCS unless you have force feedback
• In DCS, flipping the switch DOES seem to reverse pitch trim control.  Nobody has been able to clarify to me if this is true IRL or not, so not sure if it's a bug.
• The aileron channel is NOT automatically switched into manual reversion.  This is controlled by the cockpit manual reversion switch.  When switched, you're supposed to keep the ailerons neutral for about 4 seconds during the transition, otherwise the ailerons can abruptly release, presumably causing roll transients.  Unfortunately, in DCS this seems to be overmodelled, and almost impossible to prevent if you have outboard stations heavily loaded 
• The aileron trim should be disabled during manual reversion

TL;DR -- the "Manual Reversion" switch actually means AILERON Manual Reversion

 

Interesting, I learned quite a few things there! Thanks!
So in other words, there is nothing particularly wrong there in DCS, just the simulation of the flight controls and how they should behave doesn't translate very well through a non-FFB stick?
 

4 hours ago, Yurgon said:

Yeah, that looks quite familiar; reported here. Back then, it looked to me as if it mostly happens to a clean jet, but doesn't develop when the jet is loaded with a few external stores.

Oh, there's the old A-10C bug forum! I was looking through bug reports before I made mine but didn't see the legacy A-10C sub forum

Edited May 23, 2022 by QuiGon

[Frederf]

Man Rev has changed through the history of DCS:A-10C. Originally it worked on a muscle-limited standard control scheme then it changed to a relative axis scheme. The first one was almost indistinguishable from PFCS because the pilot kept the stick in the commanded pitch position with up to 50lbs or more of force exactly until this force was exceeded. Despite it being difficult and cumbersome to fly in reality, this "perfect match up to max pilot muscle" masked the quality of man rev flying, that it was difficult and required maximum attention and minimum maneuvering. Then it was changed to be relative controls so that X% forward stick would slowly increase pitch stick forever. This made it hard and cumbersome to use but was entirely unrealistic from a mechanical point of view.

 

[jaylw314]

2 hours ago, QuiGon said:

Interesting, I learned quite a few things there! Thanks!
So in other words, there is nothing particularly wrong there in DCS, just the simulation of the flight controls and how they should behave doesn't translate very well through a non-FFB stick?

I should qualify my statement that it would work with a FFB stick, since I don't have one   I'm not sure exactly how the implementation in FFB works, but @Frederf's description above sounds pretty believable

Edited May 23, 2022 by jaylw314