Frontflip out of nowhere?

[Matic_Prime]

Hi,

 

just got the SU33, and this plane rocks!

 

For me it is way more fun than the F15.

 

However ive got one issue: In the last mission when I decrease altitude and push the stick down to shoot some trucks :pilotfly: my SU-33 did a frontflip without a warning.

 

Screen turned black, pilot dead, mission failed :cry:.

 

I never touched the famous S button or the trim...

 

So: Is there a reason for this behavior and how to avoid it :huh:?

 

Many thanks in advance.

[Matic_Prime]

Hase nobody ever experienced this issued with the SU-33?

 

Maybelline its a bug, bitte the screen turns black and i cant control the aircraft. When i press f2 i can see the Su33 dropping out the sky upside down until i smash into the ground...

 

Anyone ever experienced that behavior?

[bolek]

Whether it is correctly simulated or not, this is apparently caused by large negative g's (instant lost of consciousness or pilot death). Su-27 has been behaving like this for a long time. So, to avoid it, roll inverted, pull back on the stick and roll back.

[Matic_Prime]

Whether it is correctly simulated or not, this is apparently caused by large negative g's (instant lost of consciousness or pilot death). Su-27 has been behaving like this for a long time. So, to avoid it, roll inverted, pull back on the stick and roll back.

 

Thank you sir.

 

Will do in the future. Maybe Eagle Dynamics will have a look in this behavior in Modern Air Combat.

 

KR.

[Ironhand]

Hase nobody ever experienced this issued with the SU-33?

 

Maybelline its a bug, bitte the screen turns black and i cant control the aircraft. When i press f2 i can see the Su33 dropping out the sky upside down until i smash into the ground...

 

Anyone ever experienced that behavior?

 

Red-out followed by blackout due to negative Gs, yes. An actual front flip while under full FBW control, no. Would love to know how you managed to induce it. I tried what you described but never ended up on my back.

[Auditor]

I actually experience this once in a blue moon. Basically I will be flying along like normal and then suddenly, and I think it's because of an overcorrection that induces negative Gs, it will nose down and start tumbling. All control is lost and unless I'm >10,000 AGL it's basically a death.

 

I don't know if it's a FBW bug or a network code bug, either ways it's frustrating when it happens. Fortunately, it doesn't seem to happen all that much. I've had this happen while completely unloaded and when fully loaded, so I can't say that it's a loading thing. It just appears to be a negative G thing.

[Auditor]

Also, one other thing I will add that I'm not sure is intended behavior: If you nose down and enter negative G's anywhere near the trans-sonic region while your nose is high; you will continue to nose down until you are in an inverted spin, no inputs after the initial nose-down seem to correct or change anything and you can only escape this by entering the spin, waiting, and then exiting it.

This does not affect the SU-33 as much as it does the default flanker (I encounter this far more with the SU-27 and J-11A than I do in the SU-33), however; it can still happen.

 

It requires almost intentional input to do that in the SU-33 as it is heavier, but it can happen in the SU-27 from mere accidental correction. I think this has been a problem reported in the SU-27 PFM models in the past, but I don't think anything was ever done about it. The two issues you're referring to may be related.

 

First picture is -0.1 G at .6Mach, and exactly the point where I lost control of the aircraft. No inputs past that would affect the aircraft in any significant way as it started to pitch over. Second picture is -3.5G at .5 Mach, and is the highest G experienced and the only point where I came close to redding out (However, my pilot remained conscious through this exercise.), and finally the point where I went inverted and my inputs would function once more; allowing me to regain control of the aircraft.

 

Again, this is the J-11A, but I think the SU-33 suffers similar problems. If anyone has any hints as to what happened, let me know.

EDIT: this was NOT with the FBW turned off. FBW was enabled through the entirety of the next few images. The S button was never touched, and is in fact wasn't on my HOTAS when this tacview was made.

Edited October 6, 2018 by Auditor

[rrohde]

I never touched the famous S button or the trim...

 

... and you're sure the 'S' button isn't somehow assigned to your HOTAS and thus ends up in the "On" position?

 

That happened to me until I realised I had it on a toggle switch that I sometimes use in another module, and depending on the toggle switch position on my throttle, I start any 27/33 mission with the S button in "On" modus without realizing it (until I nose down like you while airborne). Needless to say, I ended up making sure that S is not mapped anywhere. :)

[AeriaGloria]

There’s a lot of old flanker threads about this pre dating the PFM. It is maybe exaggerated but reportedly it’s in the SK manual, Russian flying doctrine doesn’t like pulling negative G’s

 

https://forums.eagle.ru/showthread.php?t=134851

[VC]

I've never had this happen to me, but I have had sudden no-warning black-out when pitching down.

 

 

This raises an interesting question, since this topic came up in various Mig-29 PFM threads with regards to that plane having almost no downward pitch authority at speed. Russian doctrine regarding negative Gs was brought up, and it seems the behaviour is correct.

 

 

So then, shouldn't the Su-33 also be a bit more limited in its ability to pitch down suddenly at speed, if neither the airframe nor the pilot can take it?

[McShetty]

This is normal and expected. It's because of being tail-heavy. Push too much neg G and end up in an inverted stall you can't recover from (it is recoverable but very difficult). Being tail heavy is the same feature that enables the Su-27/33 to be very maneuverable, and when removing the limitations by pressing the S key, to do the cobra.

 

 

AFAIK this is modeled (mostly) correctly and real pilots are almost never pushing neg or flying inverted in combat. That's air-show stuff.

 

 

 

When you roll-in on targets you are not suppose to push negative. Rollover inverted to whatever it takes, pull +Gs and then roll-out with your nose on the target. The Su-27/33 certainly can roll fast enough for this.

[rrohde]

This raises an interesting question, since this topic came up in various Mig-29 PFM threads with regards to that plane having almost no downward pitch authority at speed.

 

That's where the trimmer comes in - you trim for downward pitch to overcome that; I even trim when I want to descent at a 10deg dive angle. :)