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A10 Hydraulics Question


vulture07

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Hello everyone,

 

yesterday I played one of the Maple Flag IQT Missions, i think it was 7- advanced maneuvers.

 

In the end you have to do a forced landing with both engines off.

 

I assumed that with bothe engines off, the hydraulics should also be gone. So i switched to manual reversion, used the landing gear emergency drop, forgot to fix the wheels, and belly landed that bird losing one wing. I still got a Q- rating :music_whistling:

 

However, afterwards I watched Recon Steward, doing that mission in the youtube channel.

 

He still could use flaps, landing gear and normal flight controls.

 

So, why do these things still work with both engines off? Is there some kind of backup power for the hydraulics.

Do they still work while the engine fans are having some RPM due to the windmill effect?

Or do you not need hydraulics for the flaps and gear?

And when do you realy have to use manual reversion?

 

BR, Florian

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Check the two hydraulic gauges to see the hydraulic pressure. After engine shutdown the pressure remains for a while unless you use it by moving the flaps or speed brake or so. In that case the pressure will drop pretty fast but it's enough to operate those things for some seconds.

But I'm also curious about the flight controls and manual reversion. IIRC the flight controls always work, even if there is absolute no hydraulic pressure left and manual reversion is off. Is that how it should be? I thought the flight controls won't work without hydraulics AND manual reversion off.

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It's a long running bug/incorrect modelling in DCS. The to pressure should bleed off within a few seconds of engine shutdown to well below a usable pressure. Windmilling engines should not be able to supply enough pressure for normal flight controls etc.

 

As it is in DCS now, you never actually need MRFCS or other backup systems. Even with half a wing shot off and/or control surfaces missing you still get full hydraulics operation as well.


Edited by Eddie

 

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It's a long running bug/incorrect modelling in DCS. The to pressure should bleed off within a few seconds of engine shutdown to well below a usable pressure. Windmilling engines should not be able to supply enough pressure for normal flight controls etc.

 

As it is in DCS now, you never actually need MRFCS or other backup systems. Even with half a wing shot off and/or control surfaces missing you still get full hydraulics operation as well.

 

We can still make an "honorary" procedure to go Manual reversion when u r missing a wing:joystick:.

Do you reckon the behaviour of that mode to be somewhat close to the real thing?

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If I remember this correctly from IQT and the mission you're recalling is Respond to Emergencies

In the event of hydraulic failure you're supposed to use the Emergency Retract for the flaps and speed brakes and land immediately. I imagine that you retract these rather than have them deploy uncontrolled.

I made a mnemonic to help remember which side controls what for the training.

Left Hydraulic = fLaps

Right Hydraulic = speed bRakes

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Thanks for the answers. So it's a bug or just modeled wrong, however you wanna call it. When we loose the hydraulics due to engine failure (or other reasons) we should not be able to control the plane anymore without MRFCS, correct? But that's not the case in DCS right now. So if I use MRFCS anyways, even if I don't need to, how is it modeled in DCS? I've never tried it. Does it feel different than normal FCS or just the same? And if it feels different, is it like IRL? From what Snoopy said it sounds like it actually does feel different to fly with MRFCS in DCS, but it's not like it is IRL?

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Thanks for the answers. So it's a bug or just modeled wrong, however you wanna call it. When we loose the hydraulics due to engine failure (or other reasons) we should not be able to control the plane anymore without MRFCS, correct? But that's not the case in DCS right now. So if I use MRFCS anyways, even if I don't need to, how is it modeled in DCS? I've never tried it. Does it feel different than normal FCS or just the same? And if it feels different, is it like IRL? From what Snoopy said it sounds like it actually does feel different to fly with MRFCS in DCS, but it's not like it is IRL?

 

What?

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Ehmmm... yes, I guess (your post is hard to read QuiGon).

When you got no hydraulics pressure (after dual engine loss for example) you lose control over elevators, ailerons, flaps, brakes, speedbrake, NWS, and gear.

 

So you have to switch to MRFCS.

 

What Snoopy said is: In RL when using MRFCS the plane is not as hard to control as in DCSW.

 

EDIT: It is ridiculously hard in DCSW. You fly using your trim controls (which is the way it really works) but it is very hard. You can try it yourself: Climb to a safe altitude, level flight at 300 knots and flick the MRFCS switch. Then use your electrical trim tabs to fly the aircraft. You can land it, but it is pretty hard.

EDIT2: Take a look at the checklists in the manual. They describe what to do. And there is a nice video on YT that explains lots of stuff about it. (I think it is this one, can't watch it here:

)
Edited by Aginor
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Another point that has been overlooked is that you can deploy the undercarriage under the influence of gravity by operation of the emergency undercarriage lever. Just make sure you are lined up, and not far from the threshold.

 

Re the real thing, and how the reversion system actually works - I can't help you there.

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Yeah, in fact there are lots of workarounds.

- elevators and ailerons can be used (kind of) electrically via MRFCS

- you can still retract the speedbrake by using an emergency retract switch

- you can still lower the gear manually

- there is an emergency brake (which does not work well btw.)

- flaps also have an emergency retract (which does not work perfectly in all situations but that's explained by the way it works)

 

The only thing you really lose completely AFAIK is NWS.

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Yeah, in fact there are lots of workarounds.

 

- there is an emergency brake (which does not work well btw.)

 

The emergency brake only switches from the right to the left hydraulic system if I recall correctly. So if you don't have either hyd sys available, the emergency brake is useless as well.

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- elevators and ailerons can be used (kind of) electrically via MRFCS

 

That is incorrect, they are controlled by manual inputs through cable/pulleys

 

So if you don't have either hyd sys available, the emergency brake is useless as well.

 

Also incorrect. The A-10 has an emergency brake accumulator that even if both systems are gone is good for three "pumps" on the brakes.


Edited by Snoopy
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That is incorrect, they are controlled by manual inputs through cable/pulleys

 

 

 

Also incorrect. The A-10 has an emergency brake accumulator that even if both systems are gone is good for three "pumps" on the brakes.

 

 

Wait, what? There are cables/pulleys attached directly from the cockpit to the trim tabs?

I always thought the pilot uses the trim hat on the stick for steering, which works electrically.

Does the MRFCS disconnect the stick from the hydraulic system and the pilot controls the plane by cables attached to it (which I then assume are connected to the stick all the time)?

 

As for the brakes: Thanks for the confirm, Snoopy. That's what I meant by "the brake does not work well." That brake accumulator is a small hydraulic fluid tank like the one for inverted flight, right?

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A10 Hydraulics Question

 

Wait, what? There are cables/pulleys attached directly from the cockpit to the trim tabs?

I always thought the pilot uses the trim hat on the stick for steering, which works electrically.

 

Cables go directly to the actuators. When's switching to manual reversion the system is more complicated than simply being connected straight to trim tabs. If I get time today I'll post a more detailed description.


Edited by Snoopy
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Snoopy, is there only an accumulator for the brake system, or is there also a larger accumulator to give some level of sustained hydraulic pressure after the pumps are no longer powered, like some other birds? Someone stated earlier that the hydraulic pressure would drop 0 as soon as the engines shut down.

It's a good thing that this is Early Access and we've all volunteered to help test and enhance this work in progress... despite the frustrations inherent in the task with even the simplest of software... otherwise people might not understand that this incredibly complex unfinished module is unfinished. /light-hearted sarcasm

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Snoopy, is there only an accumulator for the brake system, or is there also a larger accumulator to give some level of sustained hydraulic pressure after the pumps are no longer powered, like some other birds? Someone stated earlier that the hydraulic pressure would drop 0 as soon as the engines shut down.

 

Two different things. Both the left and right systems would drop to zero but the emergency accumulators would be charged to 3000 psi until used then drain to zero.

 

But yes, with the engines shut down hyd pressure for the left and right system should be zero, even if the engines are windmill spinning.


Edited by Snoopy
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Hey guys,

thank you all for your input and answers.

 

 

 

If I remember this correctly from IQT and the mission you're recalling is Respond to Emergencies

 

Actually I was talking about the mission "BFT06 Advanced Handling" not "BFT08 Emergencies".

 

In BFT06 you are supposed to shut down your engines and simulate a forced landing. Even with engines out, you have enoug hydraulics to use flaps, gears, speedbrakes, brakes, and normal flight control.

 

In BFT08 you geht a scripted dual hydraulics failure, that forces you to go to MRFC. You still have your engines on that landing :)

 

So as a conclusion, I understand that in DCS A10 the hydraulics work quite a while with both engines off. They would not work in RL.

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  • 2 months later...

I know it's a much larger aircraft... but on the KC135s we used to bleed the hydro pressure after the engines were off by cycling the rudder pedals... now it's been a few years but I remember that taking 5 or so cycles.

 

I would assume in the A10 you would have a little bit of hydro pressure left.


Edited by StandingCow

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I know it's a much larger aircraft... but on the KC135s we used to bleed the hydro pressure after the engines were off by cycling the rudder pedals... now it's been a few years but I remember that taking 5 or so cycles.

 

I would assume in the A10 you would have a little bit of hydro pressure left.

 

You assume incorrectly.

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