How to get out of this stall condition?

[OnNom]

If you nose the Su-33 down kinda hard, it flips on its back and then engines and hydraulics go out.

 

Here is a short video demonstration:

 

How do you get out of this stall? I have been doing my best to avoid nosing the aircraft down, but I get into this situation more than I would like.

The engines flaming out, in particular, makes it very difficult to recover from.

 

Thank you!

Edited July 27, 2020 by OnNom

[Airhunter]

It's a bug, can't and shouldn't ever happen in the real jet.

[TaxDollarsAtWork]

With regard to this 'Deep stall' as I don't know what else to term it.

 

 

The best way to recover is by inducing as much violent up and down nose rocking, by putting the stick full roll right full & rudder right and alternating full roll left & full rudder, when you reach the highest point the the nose will go on either side.

 

 

Eventually the rocking builds up and at about 60 degrees you are able to roll out of the maneuver into controlled flight.

By which point the engines will also recover from their compressor stalls automatically.

 

 

 

It is important to start the recovery process as quickly as possible as it will take time to build up again the momentum to carry the nose to that sweet spot again.

 

 

 

I've attached a track showcasing this.

Su-27 Deep Stall recovery.trk

Edited July 27, 2020 by TaxDollarsAtWork

[Yo-Yo]

It's a bug, can't and shouldn't ever happen in the real jet.

 

It did happen. At least one Su-27 was lost after improper tailslip maneuver. It was unrecoverable negative stall.

 

And the best way to recover is not to push the stick forward without any fear.

[Airhunter]

It did happen. At least one Su-27 was lost after improper tailslip maneuver. It was unrecoverable negative stall.

 

And the best way to recover is not to push the stick forward without any fear.

 

Source? I know the FCS is literally programmed to prevent this. If that was the case the famous cobra maneuver or a tailslide wouldn't be possible (safely anyway).

[OnNom]

Source? I know the FCS is literally programmed to prevent this. If that was the case the famous cobra maneuver or a tailslide wouldn't be possible (safely anyway).

 

In a cobra, you pull back hard to get an extremely large positive angle of attack, then push the stick back down to return to a neutral angle of attack.

 

A cobra doesn't involve large negative angles of attack; which are required to get into the stall condition in my first post.

 

With regard to this 'Deep stall' as I don't know what else to term it.

 

 

The best way to recover is by inducing as much violent up and down nose rocking, by putting the stick full roll right full & rudder right and alternating full roll left & full rudder, when you reach the highest point the the nose will go on either side.

 

 

Eventually the rocking builds up and at about 60 degrees you are able to roll out of the maneuver into controlled flight.

By which point the engines will also recover from their compressor stalls automatically.

 

 

 

It is important to start the recovery process as quickly as possible as it will take time to build up again the momentum to carry the nose to that sweet spot again.

 

 

 

I've attached a track showcasing this.

 

Thanks, I'll check this out and practice it.

[Yo-Yo]

Source? I know the FCS is literally programmed to prevent this. If that was the case the famous cobra maneuver or a tailslide wouldn't be possible (safely anyway).

 

Su-27 FCS does not operate with negative g area. So, the pilot is in charge not to overcome negative g restriction. Tailslide is possible and safe only if the pitch is kept is in very close range. The incident with Su-27 I wrote was just due to improper tailslide technics.

 

Thiis is well known incident as the plane was crashed by a general in 2012 near Besovets airfield.

Edited July 27, 2020 by Yo-Yo

[AeriaGloria]

And IIRC correctly, there are Su-27SK manuals that specifically warn against this and mention it as a very dangerous area of the flight envelope

 

In addition if you are in Su-27 you can use the parachute to recover. Better get good at rocking if you find yourself in one while flying Su-33

[TaxDollarsAtWork]

And IIRC correctly, there are Su-27SK manuals that specifically warn against this and mention it as a very dangerous area of the flight envelope

 

In addition if you are in Su-27 you can use the parachute to recover. Better get good at rocking if you find yourself in one while flying Su-33

Where did you find the full version?

[Mars Exulte]

@OP

First, you shouldn't be ''pushing down on the nose kinda hard''. Flankers have a negative G limit of -1 to -1.5. The way you ''avoid that'' #1 is to NOT do that in the first place. Secondly, RTFM regarding structural and aerodynamic limits. Every aircraft has them, and 99% chance you're exceeding them.

 

@airhunter

Forbidden negative G maneuvers, and high angle of attack maneuvers, have exactly zero relevence to each other. Cobras are a post stall, low velocity, low bordering on zero-G maneuver with relatively low stress on the airframe.

 

Negative G maneuvers exceeding declared limits can be expected to have some sort of unpleasant result, from aerodynamic instability to structural failure. They are there for a reason, not because an engineer got bored and decided to doodle numbers on the page.

[Airhunter]

*slaps table* gotta love all these experts here who have never flown any aircraft or taken any aerodynamics class in their life.

 

 

Here's a link for the cockpit view of said cobra maneuver inputs. :joystick: It has nothing to do with pushing excessive negative G's (would love to see someone do that in real life for more than a few seconds). In the DCS thing you can still maintain full aft stick and the nose will keep dropping forward and flipping the aircraft over. If any of you guys stating that this "prohibited" regime is mentioned in the manual, please do let me know by showing me the exact paragraph either via PM or here. The pitch axis FBW protections disallow certain high AOA scenarios by cancelling out / filtering the pilot's inputs. Why should this principle be abandoned in the negative AOA regime? You do realize that in inverted flight the wing does in fact operate in the negative AOA regime, right?

[OnNom]

The best way to recover is by inducing as much violent up and down nose rocking, by putting the stick full roll right full & rudder right and alternating full roll left & full rudder, when you reach the highest point the the nose will go on either side.

 

 

Eventually the rocking builds up and at about 60 degrees you are able to roll out of the maneuver into controlled flight.

By which point the engines will also recover from their compressor stalls automatically.

 

 

 

It is important to start the recovery process as quickly as possible as it will take time to build up again the momentum to carry the nose to that sweet spot again.

 

 

 

I've attached a track showcasing this.

 

Was practicing last night. Your comment here was super helpful.

 

Found if I fixed the issue in the first 5s or so, I am able to get out of it nearly 100% of the time. The plane noses down, pitches up, then flips on its back. Before fully flipping over, one still has a fair amount of control authority even if the plane is being disagreeable.

 

Once it fully flips over, I was able to get out of it about 2/3rds of the time. Both of these are a massive improvement to my 'whelp, I'm dead' experience previously.

[TaxDollarsAtWork]

Snip.

 

 

 

 

I'm certainly glad this has helped.

 

 

There are other things you can try that might help like putting the flaps down or enabling/disabling the FCS at certain points in the recovery.

 

 

 

I just haven't tested them enough to see if they're truly impactful in the manoeuvre.

[Ironhand]

...In the DCS thing you can still maintain full aft stick and the nose will keep dropping forward and flipping the aircraft over.

Only if you assume that you can perform the maneuver with any parameters you want. Within certain parameters, however, you never go a$$ over teakettle:

 

 

 

If any of you guys stating that this "prohibited" regime is mentioned in the manual, please do let me know by showing me the exact paragraph either via PM or here.

They’re referring to the Operating Restrictions section of the manual, pg 10, I believe. Only one actually addresses how the aircraft flies: At speeds less than or equal to 300 km/hr, you are restricted to -0.5 G to avoid entering a spin. The -1.0 and -2.0 restrictions are there to limit structural fatigue.

 

You do realize that in inverted flight the wing does in fact operate in the negative AOA regime, right?

Really? By that logic, a level horizontal turn, being half inverted, should have no AoA because the positive and negative cancel each other out? :)

[Airhunter]

Only if you assume that you can perform the maneuver with any parameters you want. Within certain parameters, however, you never go a$$ over teakettle:

 

 

 

 

They’re referring to the Operating Restrictions section of the manual, pg 10, I believe. Only one actually addresses how the aircraft flies: At speeds less than or equal to 300 km/hr, you are restricted to -0.5 G to avoid entering a spin. The -1.0 and -2.0 restrictions are there to limit structural fatigue.

 

 

Really? By that logic, a level horizontal turn, being half inverted, should have no AoA because the positive and negative cancel each other out? :)

 

Again, send me said statement in your manual. Every aircarft has operating limitations, however the original S/P Flanker has built in protections in the pitch axis. This is like saying I can exceed the envelope in my Airbus or 777 just by yanking the stick/yoke in an unexpected manner.

 

To your second point, nice try. AOA is the angle between the relative wind the the chord line of the wing. i.e. what the wing perceives, regardless of aircraft attitude, in a level, inverted, 1G, 0VSI flight the airfoil perceives a negative AOA, thus creating lift along the netagive z-axis. This gets more complicated when you bring airfoils into play but let's just assume a symmetrical airfoil for this case.

 

You guys act like a 15$, arcady and simplified video game plane is the real thing and performs exactly like the real deal, within the ever so flawed video game that is DCS. Why is it then so hard to admit you are wrong and accept the fact your video game doesn't really represent reality in any way shape or form and has "bugs" and flaws like many other areas of said video game - you get great visuals and the visual perception of being there and flying something that resembles a Flanker but reality is you are sitting at your desk at home. And unless anyone knows how to simulate post-stall mechanics, where there is literally no performance data available for and any estimations without precise fluid dynamics and inertia models are useless.

Edited July 28, 2020 by Airhunter

[dundun92]

For the Su-27 manual, heres the quote. Its the #3:

[AeriaGloria]

In addition Airhunter, just becuase it’s FBW and has protections doesn’t mean it will always save you. The protections must be bypassed to even perform a cobra by pushing past the breakthrough on the stick. The reason you need to do it at slow speeds is becuase the inertia/aerodynamic forces at high speeds and high alpha causes the pitch down to be too fast to be recoverable, that’s probably why you experience not being able to stop the nose. Some of the cobras you see on YouTube are done much slower then they might seem, as slow as 180kmh or so, once you perform a cobra at that speed there just isn’t the forces to move the nose down fast enough to be unrecoverable if you’re proactive on the stick back,, that slow is the safest way to perform it. It is nothing like the FBW of an Airbus or other advanced planes in game

 

 

You want us to admit we are wrong, but it is a real characteristic of the aircraft, as Yo-Yo mentions even caused a crash. The FBW barely protects you from anything in the first place, it has basic G and AOA limiting designed for one particular weight. The real plane as well as the simulation, even though they may have significant differences, will certainly kill you if you move the stick the wrong way

 

Plane has a lot of inertia, and no matter how much computer is behind the controls, they can’t stop a motion above a certain inertia unless their airspeed is high enough, so if you’re slow enough to have the authority to do a cobra and develop the inertia, but not fast enough to have the stability or control authority to stop it within the time you’re in AOA of good Control, then no FBW will save you

 

I have experienced this many times but never at high speed, such as the .85 Mach mentioned that correspond to -2G limit. It makes more sense when you read about Soviet pilots were taught to never do negative G, to ALWAYS roll over. You see this reflected in design with low inverted G limits of structure and engine fuel feed. Why design out a bad characteristic that pilots may not even encounter, just tell the pilots it’s dangerous, if they fly the way they are taught it should rarely be a problem anyways

 

If you fly it with very limited negative G, you’ll be fine. If you do Cobras slow enough and are proactive in stopping huge swings of the nose, you’ll be fine

Edited July 28, 2020 by AeriaGloria

[Mars Exulte]

@airhunter

I dunno if there's a communication issue here, or perhaps you're that category of pilot that is such a blowhard you rush to blow the horn of your 1337 skillz no matter how it makes you look.

 

Again high AoA post stall maneuvers, i.e. Cobras, do not involve strong negative G moves like ''shoving the stick forward while traveling at high speed'', which I assume is what OP is doing.

 

The accuracy of the flight model is irrelevant, though I will say the FC3 planes have the SAME FM as the other modules. The SYSTEMS are simplified, NOT the FM. Regardless, still beside the point. The Flanker prohibits negative G maneuvers. That's a fact, your 1337ness has no bearing on that, nor your inability to RTFM. We can discuss whether the result is accurate, but those limits are there for a reason.

 

If you're actually an airline pilot, I can only shake my head in pity for your coworkers.

[GGTharos]

You guys act like a 15$, arcady and simplified video game plane is the real thing and performs exactly like the real deal, within the ever so flawed video game that is DCS.

 

Where is your source? You stated that it is a bug and the real FBW would not allow this. Do you have the FBW logic diagram that would prove you right, for this particular model of the aircraft?

[Ironhand]

Airhunter said:

Again, send me said statement in your manual...

No need. Someone already has.

 

Quote

...To your second point, nice try. AOA is the angle between the relative wind the the chord line of the wing. i.e. what the wing perceives, regardless of aircraft attitude, in a level, inverted, 1G, 0VSI flight the airfoil perceives a negative AOA, thus creating lift along the netagive z-axis...

Only if the wing orientation remains equivalent when inverted. If you adjust the wing orientation to maintain level flight inverted, it’s not negative. But whatever. I really don’t care as long as what I can do in the sim fairly represents what the real deal can do.

 

On that note, thank you for the video. Watching it closely, I realized one of my errors. Here’s the cobra with that error corrected:

 

 

Edited December 3, 2020 by Ironhand

[BBCRF]

Su-27 FCS does not operate with negative g area. So, the pilot is in charge not to overcome negative g restriction. Tailslide is possible and safe only if the pitch is kept is in very close range. The incident with Su-27 I wrote was just due to improper tailslide technics.

 

Thiis is well known incident as the plane was crashed by a general in 2012 near Besovets airfield.

Это утверждение полностью не верно,я уже писал ранее по поводу этого, открываем рукодоство к самолету Т-10К и читаем "Расходный отсек с учетом эволюции самолета и наклона нижних поверхностей бака №2 действует как ловушка топлива, обеспечивающая тем самым бесперебойную подачу его на двигатели насосами подкачки.

В качестве насосов подкачки в расходном отсеке установлены два гидротурбонасоса. При действии нулевых перегрузок, в случае отлива топлива от насосов подкачки, в работу вступает бачок-аккумулятор." Только в случае отлива топлива от насосов может произойти такое.Только в случае отлива топлива от насосов и опустошение бачка-аккумулятора перестанут работать двигатели,Но конструкция Бака №2 выполнена так что у ГТН всегда есть топливо как бы самолет не маневрировал

Edited July 30, 2020 by BBCRF

[BBCRF]

МСА запрака 7000кг.

Эффект наблюдается когда с МГ увеличиваешь обороты двигателя и он глохнет при этом не возможно выйти из этого положения.Хотя на испытаниях Су-33 такой эффект был только с вращением при этом двигатели работали

[LanceLynxx]

according to the su27sk manual, the recovery procedure is to apply power to get airspeed and roll out of it. font punch the throttle to AB and your feeder tank wont go out immediately.

[BBCRF]

according to the su27sk manual, the recovery procedure is to apply power to get airspeed and roll out of it. font punch the throttle to AB and your feeder tank wont go out immediately.

Топливная система данного самолета в игре настроена не правильно

[TaxDollarsAtWork]

Топливная система данного самолета в игре настроена не правильно

 

I don't doubt this but can you link the page from the manual so we can make a bug report and bring proper attention to this and other Su-27/33 bugs