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P-51 wing failure - a potential issue.


Hiromachi

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A few days ago during online mission I had an unexpected event, as during pullout both of my wings failed and this was accompanied by sort of an explosion animation (??) as both of my wing roots started burning and smoke was coming out of wing root while I was rolling and going straight to the ground.

At first I thought that I was hit by friendly AA but that turned out not to be the case and as it appears both of my wings failed during pullout which is peculiar in that it happened not at the peak load but at a time when my speed was decreasing and I was slowly relaxing the stick.

 

I did not record that live as my FPS in game does not leave good enough margin to keep recording all my flights and also because it was totally unexpected, but thanks to Tacview I managed to get flight situation in detail and capture it.

Here is the video:

 

As you can see during dive I was flying near the dive limit (505 mph - 813 km/h indicated) but eventually when trying to obtain firing solution and pull out of dive (for obvious reasons) I reached 6.8 G's, which was significant so I started relaxing the stick and trying to let her come out of the dive gently. Then, about 2 - 2.5 seconds later when speed dropped by 15 km/h and acceleration was only 4.1 G's both of my wings sort of ... "exploded". I presume this was a peculiar wing failure but cannot understand why it happened at that moment, not when I was at the peak of acceleration but when I was already in process of gentle pullout.

I have maneuvered mildly during previous combat, though two to three times I've reached 7.1 - 7.3 Gs and once in diving roll I've reached 8.2 Gs for about a quarter of a second. Weight during this event was very low as I've expended 502 rounds of ammunition (27 %) before and fuel state was aprox. 43 gallons (15 on left tank, 28 on the right). So I guess my weight was around 8600-8650 lbs during this event. Not sure if its important, but my aircraft was equipped with underwing racks as before entering combat we've used external fuel tanks.

 

In any case, I felt its worth investigating and checking for a potential bug, since I couldn't explain it myself.

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When you overstress the airframe several times you need less G's for destroying the wings.

 

So It seems you passed the airframe G limit and in the next hard pull, even with less G's you broke the plane.

" You must think in russian.."

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I dont buy that, I have exceeded manual limit of 8 Gs once for a very brief moment and it was a minimal excess of 0.2 G, where 8 G limit has to be taken into consideration with 1.5 safety factor. Any other time I stayed below 8 G limit so I stayed in manual limits.

 

Besides, read what I've posted. There was no next hard pull failure, the failure occurred during the moment I was relaxing the stick and G's were decreasing. I thought that perhaps deceleration was too fast, but dont think 3 G deacceleration in 2 - 2.5 sec is rapid.

AMD Ryzen 5900X @ 4.95 Ghz / Asus Crosshair VII X470 / 32 GB DDR4 3600 Mhz Cl16 / Radeon 6800XT / Samsung 960 EVO M.2 SSD / Creative SoundBlaster AE-9 / HP Reverb G2 / VIRPIL T-50CM /
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Its only a guess.

 

I know ED had introduced overstress on the airframes, ( Su-27 is the one i´ve used more ) and the damage is a function of repeated over G making the airframe more likely to be damaged at lower G´s every time you pull.

 

In your case i really dont know, maybe with wing tanks racks the G limit is lower, or maybe the breaking point is something like ON-OFF taking in count the previous overstress.

 

I´m only trying to figure out what could happened to you.

 

If that is not an overstress failure and not AAA damage then im running out of ideas.

" You must think in russian.."

[sIGPIC][/sIGPIC]

 

Windows 7 Home Premium-Intel 2500K OC 4.6-SSD Samsung EVO 860- MSI GTX 1080 - 16G RAM - 1920x1080 27´

 

Hotas Rhino X-55-MFG Crosswind Rudder Pedals -Track IR 4

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No worries, I did not wish to sound harsh mate. If I did, please accept my apologies.

All I know is that I've been flying P-51 for four years now and broke my wings number of times, but in most of events I knew why it happened and that it was clearly my mistake.

 

This is a rare instance where I did not understand why it happened (particularly in game it surprised me as it looked like something hit me as both wings exploded). It is possible that racks affect G tolerance, but then I wish this was indicated in manual and how far they do. But I also was flying at some very low weight, a few hundred pounds more than empty weight so there is that.

 

It just always surprises me that wing fails in P-51 often at moderate G's. Especially seeing Galloping Ghost accident, where aircraft in a split second reached a vertical acceleration of 17.3 G and a moment later only a section of the left elevator trim tab separated. Wings remained attached until crash. But then again, it also had 8 feet shorter wingspan which would surely affect the maximum load tolerance, even though it was still a ww2 air-frame to some degree.

AMD Ryzen 5900X @ 4.95 Ghz / Asus Crosshair VII X470 / 32 GB DDR4 3600 Mhz Cl16 / Radeon 6800XT / Samsung 960 EVO M.2 SSD / Creative SoundBlaster AE-9 / HP Reverb G2 / VIRPIL T-50CM /
Thrustmaster TPR Pendular Rudder Pedals / Audio Technica ATH-MSR7

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Another thing im considering is online issues.

 

Maybe your individual flight parameters like speed and G are synchronized perfectly ALMOST, all the time, but lag could introduce very brief desync just in very hard maneouvers, and even when you are not registering a G peak, the online lag and the Game is doing It, causing a unintentional overstress.

 

Only a guess.

 

Maybe you can try yo reproduce It in SP and if with same parameters you dont break anything It could be an online issues under lag.

" You must think in russian.."

[sIGPIC][/sIGPIC]

 

Windows 7 Home Premium-Intel 2500K OC 4.6-SSD Samsung EVO 860- MSI GTX 1080 - 16G RAM - 1920x1080 27´

 

Hotas Rhino X-55-MFG Crosswind Rudder Pedals -Track IR 4

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If they broke off together it most likely was load related (fire or not is irrelevant with current damage modelling, as the fire and smoke still don't indicate anything apart from some general "damage").

 

However, seems like the lowering-limit-load calculation in the code went bonkers for some unexplained reason and activated when it wasn't supposed to? There might be a new bug, but further testing would be necessary, preferably in both SP and MP, as MP in this sim introduces some bonus shenanigans indeed.

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Burning Skies. As far as I'm aware there is no wind on that one.

AMD Ryzen 5900X @ 4.95 Ghz / Asus Crosshair VII X470 / 32 GB DDR4 3600 Mhz Cl16 / Radeon 6800XT / Samsung 960 EVO M.2 SSD / Creative SoundBlaster AE-9 / HP Reverb G2 / VIRPIL T-50CM /
Thrustmaster TPR Pendular Rudder Pedals / Audio Technica ATH-MSR7

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ok. then it wasn't turbulence.

i can't think of any reason why that would have happened, but i must say even tough i haven't broke my wings in that kind of situation, i've gotten sudden and unexpected g-lock in similar situation (easing off the stick). maybe the g effects sometimes come with small delay?? my experiences were also in mp enviroment. never offline.

 

or maybe it's the way the cumulative stress (either to plane or pilot) is modelled. luckily this is not something that happens often, so at least im able to "forgive" it to the sim ;)


Edited by voodooman
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This is just a personal opinion of course but I would like it if planes would be more g resistant in dcs.In real life you can feel g differently than you can in a game.Maybe add a sound of metal failing.It was done like that in il2 1946 and it helped.

 

There is an example of a mig 25 that pulled 12 g and it seriously weakened the structure and probably deformed it seriously but it didn't brake.And the g limit on that mig is ridiculous, like no more than 2.2 g with fuel tanks and 4.5 g as absolute limit.


Edited by otto
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  • ED Team
This is just a personal opinion of course but I would like it if planes would be more g resistant in dcs.In real life you can feel g differently than you can in a game.Maybe add a sound of metal failing.It was done like that in il2 1946 and it helped.

 

There is an example of a mig 25 that pulled 12 g and it seriously weakened the structure and probably deformed it seriously but it didn't brake.And the g limit on that mig is ridiculous, like no more than 2.2 g with fuel tanks and 4.5 g as absolute limit.

 

If this plane has sooo much g tolerance limit it is not worth to exist because of excessive weight of the structure. Possibly you mixed it with MiG-29... Generally, the breaking load is about 1.5 from the service limit.

 

Planes ARE resistant in DCS. One has a possibility to overstress the plane but once or twice during a mission, but if somebody wants to abuse the plane too much - it's a bad idea.

 

In all cases where the plane was beyond the service limit, it was ONLY ONCE, by the way.

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Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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If this plane has sooo much g tolerance limit it is not worth to exist because of excessive weight of the structure. Possibly you mixed it with MiG-29... Generally, the breaking load is about 1.5 from the service limit.

.

 

 

I've read about a mig 25 pulling 12 g in an old magazine and I found an article on global aircraft website that lists some basic info about the mig 25 of Viktor Belenko that landed in Japan.

One of these pieces of info is that a mig 25 pulled 11.5 g during dogfight training but after that the plane was in extremely bad shape.

I can only presume Belenko told this story himself.

But it might be just an exaggeration heard from another pilot.

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