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Severe Flight Modeling Glitch. Post Stall behaviour.


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I managed to stall the viper in a Dogfight and went full Afterburner to save her. I then got the plane in a hovering state, with thrust cancelling out gravity. However the plane was relatively unresponsive to inputs while it was slowly rocking from side to side, while still maintaining altitude like a helicopter. Full stick forward did nothing, rudder had effect, but could not bring her out of her limbo. The akward thing was, that while i was hovering in position, my thrust vector was not downwards but slightly off, or in other words my nose was not pointing directly upwards. Yet i was still hovering in position and gently rocking from left to right as if grabbed by some pre-baked stall-animation.

Only when the fuel was nearly empty, did i somehow manage to exit this hover-stall-state. I don't know how exactly.

 

I've saved the track file, however on my pc it did not play correctly. Maybe because i used some time acceleration during replay (it happened +20min in the mission)?!

Also it's too big to upload here, even when zipped (7mb).

 

If this problem with weird post stall afterburner glitch hovering is not yet documented, i can maybe upload the track elsewhere and provide a link.

 

My personal wishlist after 2 years with dcs: https://forums.eagle.ru/showthread.php?t=216873

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At what altitude did you stall? And are you saying it didn't lose any altitude while hanging there?

The F-16 should in extreme cases get stuck in a nose high "falling leaf" deep stall which requires use of the MPO (Manual Pitch Override) switch to be able to get out of. If you were nose high, but you were actaully losing altitude, then this is what you were in, if you were literally hovering in the sky, then no idea.


Edited by Deano87

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31 minutes ago, Deano87 said:

At what altitude did you stall? And are you saying it didn't lose any altitude while hanging there?

The F-16 should in extreme cases get stuck in a nose high "falling leaf" deep stall which requires use of the MPO (Manual Pitch Override) switch to be able to get out of. If you were nose high, but you were actaully losing altitude, then this is what you were in, if you were literally hovering in the sky, then no idea.

 

 

i think i lost quite a lot of altitude in the beginning, but when i got into the hover i was only few thousand feets high. i would guess 3000, but did not check. and yes, at that moment i was completely stable, not loosing altitude. only rocking a bit from side to side and maybe slowly moving a sideways.
i did not know about the f-16 deep stall you mention. it seems to me, that i was indeed in such a state, only that after a time my altitude stabilized and i was in that weird hover. the aircraft was very light at that point: no ordnance left, no gun ammo left, no ext tanks, no tgp and full afterburner does empty the internal tanks quite efficiently.

 

maybe this stall characteristic is indeed hardcoded (lut-based) and the programmer did not calculate correctly for a plane so light, so that the aircraft wanted to gain altitude (by thrust alone) but could not, because it was "captured" in that hard-coded stall behaviour.

when i was nearly completely empty on fuel i somehow managed to "roll out" of the stall (i think by pitching with the rocking movement), the aircraft tipped over and i managed to get it back to stable flight only some meters above the water surface. the "rolling out" also felt natural to me. it went from that weird nose up stall to a more typical stall behaviour which was easy to safe with the high thrust that aircraft produces.

 

so the big "glitch" was maybe only me hovering with constant altitude (for quite a long time by the way - an enemy f-5 had time to do several gun passes on me, but could not hit).

the weird nose up stall and the final roll out would seem plausible to me now, if it wouldn't have been for the minute of hovering with 80° nose up attitude in between...

 

My personal wishlist after 2 years with dcs: https://forums.eagle.ru/showthread.php?t=216873

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I don't think the deep stall behavoir is hardcoded, every time I've got into it, its been very dynamic and unpredictable and different. I just think perhapse you managed to settle into some weird balance point. Have you treid re-creating it?

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28 minutes ago, Deano87 said:

I don't think the deep stall behavoir is hardcoded, every time I've got into it, its been very dynamic and unpredictable and different. I just think perhapse you managed to settle into some weird balance point. Have you treid re-creating it?

 

i was hovering for so long that i could check the outside camera and it was clear to me, that this was not physically correct. for a balance thrust would need to go roughly downwards but i was hanging there slanted. maybe 80° nose up, maybe 70°. also i did not significantly alter altitude while burning through most of my fuel. i played enough KSP to know for sure that that was not rocket science.

 

i can't recreate it unfortunately, because i had the viper from the free trial and on steam the trial ended yesterday. if someone else wants to try to recreate: i had expanded all my mubnitions, missiles and gun and was at roughly 50% percent internal fuel.

i entered the stall on full military power and went full AB when realizing the severity of the stall (high nose stall, like deano87 mentioned in his reply). i did only minor control inputs because i was assuming the f-16s high thrust/weight ratio and fcs would save me anyway. the afterburner then slowed my descend to a stop which left me in this weird slanted hover.

My personal wishlist after 2 years with dcs: https://forums.eagle.ru/showthread.php?t=216873

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I'll have a go... obviously you had everything like game flight model etc disabled in the options?

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My Fathers Aviation Memoirs: 50 Years of Flying Fun - From Hunter to Spitfire and back again.

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@moderators: i see, i got the "cannot reproduce" batch. would it help, if i provide a link to my trackfile? you'd have to sit through 20min of me just cruising around testing radar modes and aim-9 HOBs before the stall happens. i cannot open the trackfile myself (i guess) because i have no access to the module any more. otherwise i could have tried to capture a video.

My personal wishlist after 2 years with dcs: https://forums.eagle.ru/showthread.php?t=216873

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Yes if you have a track, although long tracks may not playback correctly it is worth a try. Please link and we will take a look.

 

If you are bale to reproduce on a airstart mission it would be best

 

thanks

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