Overspeed causing permanent wing twist?

[Deano87]

Hey all.

I've been flying the Mig-15 a bit recently on the Cold War server and having a great time. But I've noticed a couple of weird things that I just want to check that I'm not imagining things.

I know about the Mig-15s roll instability at high mach numbers and the fact the sim has a randomized wing stiffness calculation per spawn so that you never know which way the aircraft is going to roll once you reach critical mach, that's all good.

What is confusing me is that it seems like the wings are getting permanently twisted when I go even a little too fast and that's effecting the handling of the aircraft for the whole rest of the flight.

For instance, recent flight I got airborne and climbed up to 8000m and the aircraft was handling perfectly, I started a descent and I let the speed get a little fast to the point where the aircraft just started to roll to the right by itself. As soon as i noticed the roll I throttled back and put the brakes out and slowed down to mach 0.75. But from that moment on the aircraft required constant re-trimming in roll, even at much slower speed. Almost like I permanently twisted the wing. When I've grossly exceeded the critical mach I've required almost full aileron to maintain wings level even once slowed down to below 0.7 mach or 800kmh. Externally I see no damage to the wings, but the aircraft definitely feels twisted.

Am I the only one noticing this?  It makes sense if the forces are really that high, but I guess it expected it to be more of a transitory phenomenon than something permanently damaging the aircraft like this.

Cheers

D
 

[Erlkönig]

Hi, I found this to be connected with going too fast with drop tanks attached. For the 400Ls, you must stay below 900 kph indicated, otherwise you get permanent wing twist, which stays in place also when the tanks are jettisoned.

I found nothing wrong with going fast without tanks.

[Deano87]

Ahhhh this is probably my issue as I’m often taking tanks.

Thanks!

[Mordant]

So just don't take tanks? 

From what I understand you either watch your speed very very carefully or you don't take tanks... I personally love not worrying about fuel, so I want to take tanks. Does this wing twisting still happen if you reach critical mach after you've pickled the tanks? Or is this the answer:

On 11/20/2021 at 2:35 AM, Erlkönig said:

"...you get permanent wing twist, which stays in place also when the tanks are jettisoned."

To specify, my understanding of this statement is that the wing twist remains if you've exceeded critical mach with the tanks on, then the tanks are pickled. If the tanks have been dropped and I exceed critical mach, am I ok?

 

Smooth Skies,

Mordant

Edited December 3, 2021 by Mordant
grammar

[lmp]

On 12/2/2021 at 2:14 PM, Mordant said:

If the tanks have been dropped and I exceed critical mach, am I ok?

I did precisely that by accident yesterday. I flew the Persian Gulf dogfight instant action mission, which starts you out with the 400L tanks. I dropped the tanks, dived on the Sabres - got to about Mach .9 - .91 - then I slowed down to safe speeds, killed the Sabres and landed with no controllability issues whatsoever. I didn't do any testing beyond that but it seems to me you're good as long as you drop the tanks first.

[Tiger-II]

900 kph is a TAS limit. This could even equate to approx. Mach 0.7 if you're low enough.

Mach number - you're safe at anything below Mach 0.85 with drop tanks. It's the TAS you've got to watch unless you're very high, but that's hard to do with drop tanks and even harder if they've got any fuel in them.

Edited March 21, 2022 by Tiger-II

[Ravenus]

Read the manual guys. In there you´ll find a very pleasant surprise regarding the high mach uncommanded roll and what to do about it. Cheers