SU-33 refueling FBW augmentation/dampening

[DieHard]

Can somebody explain how the augmentation / dampening works on the SU-33 when refueling? I seem to be constantly fighting my own airplane when doing air to air refueling due to the flight controls changing when I extend the refueling probe.

 

Seems like the plane wants to auto level and it fights my inputs when I want to plug in by reversing my input to bring the plane level again when correcting attitude to plug into the tanker.

 

Referring to Message #1 (top of thread) :

 

[Dr_Arrow]

You are completely missing the point. And again; refueling in a turn without autopilot isn't 'idiotic'.

 

Even though the F-18 is not using AP for aerial refueling, in F-16 when you open refueling doors the FLCS changes control gains, so the can have much more precise control and the aircraft is in result much less responsive. The same might go for F-18 or basically any FBW aircraft, which is changing internal control laws (including damping) according to flight situation/conditions (ground, landing, refuel,etc.).

[Fri13]

I think that how difficult it is to master the air refueling even by experienced pilots when in straight and level, that no one would be so idiotic to try that in such conditions that ain't so.

 

@Fri13 but you do realize that pilots do air to air refueling in 'real' planes without FBW since decades...

That should have been "in steady flight" as the tanker will not maneuver from its pattern.

 

Check the standard procedure for flight patterns.

 

The tanker will fly a race track or even a circle depending the airspace conditions.

 

Tanker and receiver both coordinate how turns are made by the tanker navigator that calculates everything and maintains a geographic anchor points.

 

And your video doesn't show a tanker in a dive, in a track turn (25-30 degree roll, ending even a 20km turn radius) or maneuvering so that receiver needs to hunt it.

Instead tanker is flying to keep everything steady.

The procedure perform a aerial refueling is very strict. Where a +-5 degree in pitch and +-10 authority in roll are well in limits.

 

And decades ago before FBW it was even more dangerous to fly and today everyone has FBW systems.

 

And do I need to remind that AP ain't in Su-33 a locked feature where you don't have any authority to maneuver past those?

 

You don't disable FCS for aerial refueling but instead use it there.

A special FBW sensitivity is enabled so it is easier for pilot to fly formation with the tanker.

 

It doesn't mean it is a "handicap mode" for beginners and skilled pilots does AR in dive while pulling cobras all day along around the tanker.

 

There is a reason why +/-10 degree roll in more accurate control is given. And it is more than needed for the fighter to fly formation with a tanker.

 

You are not trying to stay on wing of a acrobatic flight maneuvers. The tanker keeps a steady altitude and it has own anchor points to fly and depending situations limited airspace.

 

It is idiotic to expect that you need to disable FCS for aerial refueling.

 

It is easy with Su-33 to do it because the special mode. And the system as well seems to works as well around trimming point from where mode angles are calculated.

 

So what has a F-18 to do with Su-33?

Where in that video it shows F-18 pilot disabled FCS?

 

OTT

There seems to be a bug in Su-33 when in this special mode. When probe is extended the throttle seems to be as well in special mode for a speed control. Yet you can push throttle for full afterburner that is visually possible confirm and fuel consumption is burning fuel, yet the speed doesn't accelerate or raise at all like without probe extended.

 

In one testing i was behind tanker at 385kmh and dropping, tanker flying at 450kmh and i couldn't retract probe and neither accelerate with full throttle. And burned 1500kg fuel in couple minutes while tanker fly away.

 

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[Fox One]

AFAIK for US armed forces refueling in a turn is not some rare & extraordinary event.

 

In Su-33, I noticed when pressing Lctrl+R in cockpit both the refueling bar switch and FCS refuel mode switch are animated. I don't see any reason why the pilot in real aircraft couldn't leave the FCS refuel mode switch off if he desires so.

 

Refueling in a turn in Su-33 is difficult because you are pretty much fighting the autopilot, at least that was my impression when I tried.

[Fri13]

Even though the F-18 is not using AP for aerial refueling, in F-16 when you open refueling doors the FLCS changes control gains, so the can have much more precise control and the aircraft is in result much less responsive. The same might go for F-18 or basically any FBW aircraft, which is changing internal control laws (including damping) according to flight situation/conditions (ground, landing, refuel,etc.).

think that many are mistaking the soviet Auto-Pilot as something that is "uncontrollable"/"not responding inputs at all" before you disengage it.

 

Instead it is just a authority that uses sensor to do something while still respond inputs but with limits.

 

Like Su-33 allows you to fly barrel rolls when probe extended if so required, but you need more inputs to overcome the dampened limits.

 

Just like in reality Su-27 only needs over 15kg stick force to overcome FCS limiter while we need to press a button for wheel breaks (that is a flip-switch under throttle with guard)

 

Now, not applying inputs and AP place you in level flight, it is there to make things just easier for pilot. With movement inputs dampened it is easy to do small corrections in high stress situation.

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[Fri13]

AFAIK for US armed forces refueling in a turn is not some rare & extraordinary event.

 

In Su-33, I noticed when pressing Lctrl+R in cockpit both the refueling bar switch and FCS refuel mode switch are animated. I don't see any reason why the pilot in real aircraft couldn't leave the FCS refuel mode switch off if he desires so.

 

Refueling in a turn in Su-33 is difficult because you are pretty much fighting the autopilot, at least that was my impression when I tried.

The turn is standard practice depending receiver and situations.

The tanker ain't maneuvering while in turn or level flight. It stays in steady flight all the time so receiver doesn't need to chase it.

 

Lots of things has made approach and finding a tanker easier, but still there are standards for doing it.

 

And the dampened inputs in Su-33 seems to be for trimmed attitude.

 

Before yesterday i had never performed or tried air refueling. Not my interest. I only know the standard procedure for it.

 

So i took Su-33 for a straight and level and level turning aerial refueling in a standard weather and performed a two refueling for both tankers successfully. It was super easy by all the assistance the systems gave.

Now i didn't start in straight and middle of fueling start turn, but went to turning pattern (needed to use EOS to find the turning tanker).

 

I do use the center trimming button in Su-33, realistic or not. But didn't notice any difference between both once I trimmmed for the angle.

 

So no need to fight against AP at all.

 

 

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[Fri13]

Well, in that case my whole response wouldn't be appropriate, but it's certainly not my fault if you are using wrong terms.

No it ain't your fault, as you can't know what I mean unless I say what I mean. That is sole reason why "you know what I mean?" is stupid as others don't know so.

 

The point is, AR dampening aint required to be disabled regardless the tanker attitude. It just dampens the stick from a trimmed position so it is easy to do small corrections.

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[horus-DCS]

So, is there a way to turn this AP mode off? I just don't need AP for AAR. Why should I use a system which is making control more difficult?

 

 

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[Ironhand]

So, is there a way to turn this AP mode off? I just don't need AP for AAR. Why should I use a system which is making control more difficult?

 

 

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Aparently not. At least none of the usual commands affect it.

[Fri13]

So, is there a way to turn this AP mode off? I just don't need AP for AAR. Why should I use a system which is making control more difficult?

 

 

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And how it does it more difficult?

How you need over +/-5 pitch and +/-10 roll from an trimmed position in a normal stick movements?

 

Why the Soviets implemented a system that makes it more difficult to do air refueling instead easier?

 

 

 

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[ricktoberfest]

I don’t think it’s more difficult than other aircraft, but you have to fight the autopilot while turning which can be hard with cheaper joysticks (holding a slight pressure without over compensating). Also when you add in the excess movement of the AI tanker it becomes that much harder. In turns the tanker doesn’t really keep speed and altitude as well as it should. I have no problems with a little movement, but 20 meters up and down is quite a bit in a close formation like that.

 

 

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[Fri13]

I don’t think it’s more difficult than other aircraft, but you have to fight the autopilot while turning which can be hard with cheaper joysticks (holding a slight pressure without over compensating). Also when you add in the excess movement of the AI tanker it becomes that much harder. In turns the tanker doesn’t really keep speed and altitude as well as it should. I have no problems with a little movement, but 20 meters up and down is quite a bit in a close formation like that.

 

 

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Trim.... Don't fight.

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[horus-DCS]

And how it does it more difficult?

How you need over +/-5 pitch and +/-10 roll from an trimmed position in a normal stick movements?

 

Why the Soviets implemented a system that makes it more difficult to do air refueling instead easier?

 

 

I don't care how you think about the system, why Russians implement it, whatever.

 

I'm just curious about HOW TO TURN THAT OFF.

[FSKRipper]

I don't care how you think about the system, why Russians implement it, whatever.

 

I'm just curious about HOW TO TURN THAT OFF.

 

NOT AT ALL! if you see capital letters better as it was already said before.

[ricktoberfest]

Trim.... Don't fight.

 

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Last time I checked (I could be wrong) you can’t trim in that mode

 

 

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[Ironhand]

Trim.... Don't fight.

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

 

You have mentioned trimming several times now, I believe, but you can't trim in that mode. Yes, you can input the trim but the system ignores it. There is no change to ailerons, etc induced by the input.

 

As an experiment, trim for a full-on left roll and, then, extend the probe. Watch what happens.

[Fri13]

You have mentioned trimming several times now, I believe, but you can't trim in that mode. Yes, you can input the trim but the system ignores it. There is no change to ailerons, etc induced by the input.

 

As an experiment, trim for a full-on left roll and, then, extend the probe. Watch what happens.

I trim all the time.

The stick centers to trimmed position and it keeps it in level and the roll/pitch axis in special mode is centered to it.

 

That is what makes it so super easy to fly in turns as you stay there with it.

 

I can either trim before the probe or after extension.

 

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I usually post from my phone so please excuse any typos, inappropriate punctuation and capitalization, missing words and general lack of cohesion and sense in my posts.....

[Ironhand]

I trim all the time.

The stick centers to trimmed position and it keeps it in level and the roll/pitch axis in special mode is centered to it....

Is this a FF stick we're talking about? Because that's certainly not what happens with a vanilla stick. I extend the fuel rod and bank. I can then add trim to the max allowable in the direction of the bank and the aircraft will immediately return to straight and level flight, when I let go of the stick.

 

If prior to extending the fuel rod, I engage max allowable airelon trim (which will induce a roll) and, then, extend the rod, the ailerons are brought back to neutral and I end up in straight and level flight. This is what these folks are experiencing with their vanilla sticks.

 

EDIT::: Just read this this morning: Now possible to trim with new update.

Today's update added trimming to "Refueling Mode"

Edited October 20, 2017 by Ironhand

[ricktoberfest]

Looks like the trimming in RF mode was a bug that’s been fixed in beta now. Should be able to trim in refueling mode now.

 

 

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[horus-DCS]

EDIT::: Just read this this morning: Now possible to trim with new update.

Today's update added trimming to "Refueling Mode"

 

 

I've read the news too. It means the system wasn't complete...

 

It is a good news but the AAR AP system is still annoying feature for me. If it doesn't fight pilot's input like that, I don't even need the trimmer in the first place. I(and most of the pilots also) usually do AAR in A-10C, F-15C, M-2K smoothly, without any trimming.

[Fri13]

I've read the news too. It means the system wasn't complete...

 

It is a good news but the AAR AP system is still annoying feature for me. If it doesn't fight pilot's input like that, I don't even need the trimmer in the first place. I(and most of the pilots also) usually do AAR in A-10C, F-15C, M-2K smoothly, without any trimming.

So you are holding stick in the needed angle all the time?

 

I can do that hands off, in turn or straight.

 

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[Esac_mirmidon]

Every pilot of the world uses Trim ALWAYS.

[Ironhand]

I've read the news too. It means the system wasn't complete...

 

It is a good news but the AAR AP system is still annoying feature for me. If it doesn't fight pilot's input like that, I don't even need the trimmer in the first place. I(and most of the pilots also) usually do AAR in A-10C, F-15C, M-2K smoothly, without any trimming.

The Russian airframes behave a bit different than the F-15 at least. I don't own the M-2K and it's been so long since I've been in the A-10 that I've forgotten how much trimming it requires.

 

The F-15's FBW is a trajectory control system. Both the Su-33 & -27 FBW is as well but behave as if they aren't because of additional programming. So they are much more influenced by the slightest speed changes. The refueling mode should be dampening that overriding programming making refueling easier because there is less responsiveness to changes in airspeed. Basically it's allowing the underlying FBW trajectory system to have more influence over the controls. Or that's my take on it at least. I reserve the right to be completely off base.

[horus-DCS]

Every pilot of the world uses Trim ALWAYS.

 

Don't get me wrong, I didn't tell trimming is not to be used at all.

Of course pilots do trim whenever they want to.

 

I'm just saying those other planes don't fight the pilot's input so much @ AAR mode like Su-33(at least in the latest stable version).

 

 

The Russian airframes behave a bit different than the F-15 at least. I don't own the M-2K and it's been so long since I've been in the A-10 that I've forgotten how much trimming it requires.

 

The F-15's FBW is a trajectory control system. Both the Su-33 & -27 FBW is as well but behave as if they aren't because of additional programming. So they are much more influenced by the slightest speed changes. The refueling mode should be dampening that overriding programming making refueling easier because there is less responsiveness to changes in airspeed. Basically it's allowing the underlying FBW trajectory system to have more influence over the controls. Or that's my take on it at least. I reserve the right to be completely off base.

 

Thanks for the explanation.

Now I consider it's a Russian style :music_whistling:

[Esac_mirmidon]

Thats correct.

 

Trim is for helping pilots, not mandatory of course, but in my experience ( i have several virtual squad mates that are real pilots, they always use the trim )

 

On another hand i dont have an idea how is working the Trim-AFCS-dampening system in the real Su-33 in refuelling mode but taking in count today ED updated 1.5.7 allowing trim in refuelling mode makes me wonder that is because its possible in real life.

 

Also think about the AFCS combined mode ( that the way russians call this mode ) where you can use an autopilot mode ( like refueliing mode ) and just push a button on the stick, keepingit pushed, change attitude, and release the button and the AFCS will keep the new attitude by itself.

 

The well known Attitute Hold AFCS mode.

 

This is not working right now in DCS for the Su-33 and if ED implement it its gonna be very easy to make changes while refueling even without trimming.