resolved MiG-29 engine fire on touchdown bug

[Faustmacht]

Attached (hopefully) is a track file featuring a MiG-29 landing where it seems that a bug caused one of the engines to fail. This could either be a bug, or it could be that the FOD shields are not properly modelled on the 29 and a bird-strike has occurred (in which case it could also maybe be considered a bug). The game log only had an entry of an engine failure (paraphrasing) and did not specify if the failure was due to a bird strike or not. In this mission aircraft failures were not enabled.

[Rissala]

This bug looks something like this. It always happens right at touchdown.

EDIT:
Is this a birdstrike ED? It seems unlikely since everytime this happens it is right at touchdown and never on takeoff.

EDIT2:
It would help if there was a sound effect for the birdstrike.

 

Edited August 23, 2021 by Rissala

[Flappie]

I cannot reproduce this issue. Please provide a track.

MiG-29S Not so hard_landing-no engine failure.trk MiG-29A Hard landing-no engine failure.trk

[Ironhand]

On 8/23/2021 at 11:08 AM, Rissala said:

This bug looks something like this. It always happens right at touchdown.

EDIT:
Is this a birdstrike ED? It seems unlikely since everytime this happens it is right at touchdown and never on takeoff.

EDIT2:
It would help if there was a sound effect for the birdstrike.

 

 

What is that loud metallic thump as you touch down? Are the cans hitting the runway? I don't get that at all, even when trying to land at the higher speed you landed at.

[XPACT]

In the video engine throttle was kept at idle which is wrong for landing since nozzles can hit the ground, in that configuration they are fully open.

Maybe hitboxes changed? At least I wasn't aware of that, anyways IRL manual states that at landing throttle needs to be at 78-79% minimum if I remember correctly (of course no AB allowed). If engines are kept at proper throttle nozzles are tucked away and won't hit the runway upon touch down especially if it's a harder one, you can see this movement in DCS.

I am doubting that is the case here but still would be nice to have that simulated someday... will probably have to wait for FF MiG-29A

Edited September 2, 2021 by XPACT

[Ironhand]

You might be right about the nozzles hitting the ground. Something certainly is other than the tires. I hadn’t noticed that he was at idle. I’d be helpful to see a TRK of a landing that caused a fire.

 

I made two quick landings today and neither yielded a sound anything like that. Only a faint rumble of tires over pavement…and no engine fire. So I doubt there’s been any change to hit boxes or whatever.

Edited September 2, 2021 by Ironhand

[Flappie]

@RissalaCan you please attach a track showing this? It should contain the answer to our question.

[Rissala]

18 hours ago, Ironhand said:

 

What is that loud metallic thump as you touch down? Are the cans hitting the runway? I don't get that at all, even when trying to land at the higher speed you landed at.

 

Nope, those are just some gear noises. If the engines hit the ground, there is a scraping noise.
 

11 hours ago, XPACT said:

In the video engine throttle was kept at idle which is wrong for landing since nozzles can hit the ground, in that configuration they are fully open.

Maybe hitboxes changed? At least I wasn't aware of that, anyways IRL manual states that at landing throttle needs to be at 78-79% minimum if I remember correctly (of course no AB allowed). If engines are kept at proper throttle nozzles are tucked away and won't hit the runway upon touch down especially if it's a harder one, you can see this movement in DCS.

I am doubting that is the case here but still would be nice to have that simulated someday... will probably have to wait for FF MiG-29A

 

I am aware of the nozzle thing.
2 things disprove this:

The nozzles are still off the ground at 10 degree AoA.
The engine collision model actually ignores the nozzles when they are expanded. The cans clip through the ground until the collision model of the closed position touches the ground and scrapes the engine.

Bonus fact:

There isn't an engine fire when there is a tailstrike. The engine only gets damaged and thrust and RPM is decreased.

Edited September 3, 2021 by Rissala

[Rissala]

10 hours ago, Flappie said:

@RissalaCan you please attach a track showing this? It should contain the answer to our question.

I tested this a while back for 2 hours. Didn't manage to replicate.
Landed 10+ times with a speed of 250-350 and AoA of LESS than the critical 15 degrees. It was mostly about 10 degrees.
This made me think that it could be a birdstrike as the engine covers are not engaged until a slow enough speed. The odd thing is however that other modules (exept SU-25) do not get birdstrikes at all and that the fire happens right at touchdown.
The track of the video was broken since it was a MP mission with Gs exceeding 7 and it was too long. I will also test a dual landing possibility since the bug happened here after the second landing.

18 hours ago, Ironhand said:

 

What is that loud metallic thump as you touch down? Are the cans hitting the runway? I don't get that at all, even when trying to land at the higher speed you landed at.

It could be related to the bug.

[Faustmacht]

I just had a very similar, weird engine failure, though not on touchdown. This time it was mid-flight, without a tree strike (even though trees were close, replay clearly shows that I didnt hit them). Ended up having a right engine fire.

Track file attached

MiG-29 engine failure.trk

[draconus]

1 hour ago, Faustmacht said:

I just had a very similar, weird engine failure, though not on touchdown. This time it was mid-flight, without a tree strike (even though trees were close, replay clearly shows that I didnt hit them). Ended up having a right engine fire.

Have not watched the track but it's a definition of a bird strike when in very low flight without any collision or weapon hit you lose an engine.

Btw, what's your birds setting in DCS? 100 is RL calculated probability. With that setting and over 400 hours flight time I maybe got 2 or 3 bird strikes.

Edited September 7, 2021 by draconus

[Flappie]

Although, the aircraft doesn't visually hit any tree in the track, it could have been a tree hit.

 

However, @draconus is probably right since there are birds in this mission (even though we cannot see them):

 

["birds"] = 140,

 

Edited September 7, 2021 by Flappie

[Rissala]

After 3 months with the birdstrike slider to the "0" position. I can verify that this is a birdstrike thing. I have not seen any more of such incidents.

The thing that is confusing players now is the bad logic with the birdstrikes themselves. There seems to be an issue where the birdstike only happens instantly at touchdown, unlike irl where it can happen at any point during the landing approach and roll.

Edit: Mark this as the solution @BIGNEWY

Edited November 10, 2021 by Rissala