[RESOLVED] Stall and Spin FM issue

[chn6]

I love DCS MiG-21Bis very much, he is better than all known flight simulation software is more outstanding, so I hope to perfect.

 

In testing the stall and spin, I found MiG-21 in the stall after entering the spin, can be supersonic and finally explosion.

 

I provide the attached Tacview file acmi.

 

MiG-21Bis_FMbug.txt.rar

本帖最后于2015年3月12日，由Cobra847编辑

[Art-J]

Noticed the same a couple of times, when testing airplane handling in spins. It seems that MiG's flight model doesn't like flat spins, it sometimes goes crazy and accelerates the plane to supersonic speeds much faster than emergency afterburner :D. Next, before you know it, BOOOM happens.

 

Not a big deal for me, because you usually don't spin the MiG in normal combat anyway, but this peculiar behaviour might need to be looked into somewhere in the future.

[MTFDarkEagle]

... it sometimes goes crazy and accelerates the plane to supersonic speeds much faster than emergency afterburner :D. Next, before you know it, BOOOM happens.

 

Ah!! I'm not the only one encountering this!! :P

[Dolphin887]

Noted. Will check.

 

However, consider:

- object in a free fall from e.g. 6000m will reach ~340 m/s terminal velocity (we are ignoring the impact of drag in this case).

 

So the terminal velocity in case of 21 spin will inevitably be very high, but i will check that drag is calculated correctly.

[MTFDarkEagle]

Noted. Will check.

 

However, consider:

- object in a free fall from e.g. 6000m will reach ~340 m/s terminal velocity (we are ignoring the impact of drag in this case).

 

So the terminal velocity in case of 21 spin will inevitably be very high, but i will check that drag is calculated correctly.

 

Ta.

I have a track file where it happened what I quoted above, from an older version (1.2.10 if I recall correctly). If you want I can upload it.

 

It's basically when pulling a lot of AOA, it goes out of limits, and if you keep the stick back the aircraft will dramatically accelerate up to and through mach 1 (followed by the aircraft blowing up).

[eekz]

I also want to mention that MiGs stall behavior is odd. See attached track.

mig21_aoa.trk

本帖最后于2014年11月17日，由eekz编辑

[iFoxRomeo]

I had one happening with 1.2.10 one month ago.

 

 

Fox

[chn6]

THX all, thank you Dolphin887!

 

DCS MiG-21Bis is the best one for not only DCS, and all other simulator, All chinese pilots will love it.

[eekz]

Taken in version 1.2.12 and track played on v. 1.2.14

Plane behaviour in stall is 'spiky' and looks unnatural

track

[Golo]

Taken in version 1.2.12 and track played on v. 1.2.14

Plane behaviour in stall is 'spiky' and looks unnatural

 

The fact that it looks unnatural to you is not prove that it is wrong.

 

Go read manual sections on stalls and spins an you will find out about unsteady oscilations around all 3 axes.

[eekz]

The fact that it looks unnatural to you is not prove that it is wrong.

Of course it does not prove anything. Just my opinion you know. It's up to developers whether to check it or not, and whether to fix it or not. Or to tell that its correct.

 

Go read manual sections on stalls and spins an you will find out about unsteady oscilations around all 3 axes.

 

I did it. I do not argue with the fact that there should be those oscilations. I doubt that they should occur in such "spiky" manner when plane inertia cant be felt.

 

But once again, my opinion does not prove anything. If it can be explained that it is currently correct it the sim such an explanation would be much appreciated.

[Golo]

OK, then its a question of a magnitude and frequency of those oscilation.

 

To be honest I was wondering about them too and also of inecial rotation effect that sometimes accompanies stalls/spins. But since I have no data on them

im not questioning them because of unnatural feel.