Destruction of airframe due to high Gs or even speed

[JazonXD]

So recently as you all know, the 27 had a major update on structure integrity and pulling too many Gs especially repeatedly can cause the wings to break apart. Very good job on that, and it's definitely going towards a more realistic route. That begs the question, does anyone have solid information on the max G limit of the 15? In DCS, I definitely prefer to fly the 15 myself, but I can't help thinking about the massive disadvantage between the aircrafts if puling too hard at low altitude breaks your plane apart...

 

I also remember at some point, somewhere on the forum, there was a documentation of a test pilot in a (I recall it had something to do with NASA) F-15, probably trying to do a maximum speed run and something happened and the vertical stabilizer departed from aircraft, departing the whole plane from flight and the Gs that were on the plane during departure was so great that it ripped the plane to pieces. Pilot died :( I don't remember all the details but I think it went something like this. I also may have exaggerated the ripping apart section.

 

Anyway, will we see be able to see a realistic of effects of G loading on planes soon?

[Dr.Goose]

The current status of the Su-27 is unrealistic (I have seen a break up at 9,4g), but the F-15 is designed to withstand up to 13,5g and has been recorded to pull up to 40g (though only for a very short time). So the next update should fix the Flanker ;)

Edited April 9, 2016 by Dr.Goose

[JazonXD]

The current status of the Su-27 is unrealistic (I have seen a break up at 9,4g), but the F-15 is designed to withstand up to 13,5g and has been recorded to pull up to 40g (though only for a very short time). So the next update should fix the Flanker ;)

 

From what i've seen being discussed on the Su-27 section of the forum, this structural integrity is realistic for the most part. It does say in the flight manual about max Gs being 8g so yeah. Yesterday when I got the update, I tested the whole thing and my conclusion was that it can pull up to 9.8g there about and then anything above 10 is very very risky (10.4) and anything after about 10.4 is definitely break-up.

[Winston60]

I sure hope they don't mess up your beloved F-15C by implementing the new "instant disintegration" feature of the Su-27 as it is now. It's a nice idea to have something like this but totally unrealistic in the way ED has incorporated it into the Su-27.

 

There's no warning, airframe sounds, shaking or any feedback whatsoever before the aircraft just explodes. I've spoken to a few US pilots and they all confirm that modern combat jets will let you know when you have or are exceeding the limits, by the sounds they hear and the way the aircraft acts.

 

In ED's implementation, everything goes well right up to the "BOOM - WINGS OFF!" No noises/sounds, vibration/feedback of any kind and the failure always happens at the exact G vs weight instance. You'd think not all aircraft would explode at the same instant of exceeding a limit. Some would bend or break something but continue to fly in a bent/damaged state, flyable enough to make it home.

 

Overall a nice idea for realism sake, but oh so poorly done here. This new feature needs a lot of rethinking and tweaking.

[pr1malr8ge]

I sure hope they don't mess up your beloved F-15C by implementing the new "instant disintegration" feature of the Su-27 as it is now. It's a nice idea to have something like this but totally unrealistic in the way ED has incorporated it into the Su-27.

 

There's no warning, airframe sounds, shaking or any feedback whatsoever before the aircraft just explodes. I've spoken to a few US pilots and they all confirm that modern combat jets will let you know when you have or are exceeding the limits, by the sounds they hear and the way the aircraft acts.

 

In ED's implementation, everything goes well right up to the "BOOM - WINGS OFF!" No noises/sounds, vibration/feedback of any kind and the failure always happens at the exact G vs weight instance. You'd think not all aircraft would explode at the same instant of exceeding a limit. Some would bend or break something but continue to fly in a bent/damaged state, flyable enough to make it home.

 

Overall a nice idea for realism sake, but oh so poorly done here. This new feature needs a lot of rethinking and tweaking.

 

While I haven't tried the new update nor the su27 in a long time. How ever, with that being said yes you're right in regards that not all air frames will destruct in the same manor but as a game standpoint its hard to have "multiple" destruction linked to one trigger like that.

You also need to consider though that the Russian way of design is to make it only capable of what they intend to do. I.e. if the original design called for a max of 8g then they would have build it to withstand probably 15-20% more which would be in the 9.5g realm. after that it will just fail in spectacular fashion. Also keep in mind that the Russians do not use the absolute best but rather just use what is cheapest and will get the job done. This is vs what the Americans do where we tend to go 200% and use high end materials that cost a fortune. Like say the f15 where it is benched to 13g with an operational cert of 9g and has been proven over 15g where it did bend the air frame and "totaled" the aircraft but did safely return the pilot. On a side note also where Americans also tend to use extremely DIFFICULT and expensive manufacturing techniques. Case in point is when the SU27 was being designed they were trying to replicate the F15 wing but could not do it. Hense the reason the SU27 has LEX to get it's turning ability to be comparable to the the f15 and that is only in low speed. Had the SU27 been designed before the f15 we would have basically an f15 with a f22 wing and it would absolutely demolish the su27 in all aspects of flight.

 

anyways look at this vid at the of the Ruskies stress testing watch around the 31minute marker

 

Edited April 10, 2016 by pr1malr8ge

[Kuky]

^^^

Good point. I saw that stress testing procedure and what they said was that if the testing part can withstand more force then required its considered to have room for improvement meaning reduction in weight. Same thing applies for the airframe. If its too strong it means its too heavy and should be redesigned to reduce weight.

 

I am not sure if you would hear cracking while airfrsme is bending (considering you have other external noises and you wear helmet) but the pilot would not wait to hear such noises in the first place. Pilot should know what not to do do that he doesn't overstress the aircraft. Why somilator pilots shouldn't be doing the same?

[SinusoidDelta]

^^^

Good point. I saw that stress testing procedure and what they said was that if the testing part can withstand more force then required its considered to have room for improvement meaning reduction in weight. Same thing applies for the airframe. If its too strong it means its too heavy and should be redesigned to reduce weight.

 

That's engineering in a nutshell. The glass isn't half full, it's twice as large as it needs to be :lol:

 

Regarding the video, we don't know what is 100% load is. 100% involves a safety margin. This is also whats called a quasi-static strength test. Static strength of an assembly does not correlate directly to dynamic strength in which loads are applied in less than 1 second and intertia comes into the equation. So when it comes to instantaneous G, it's anyone's guess what damage will happen to the airframe. Overload information in the manual gives you a ball park. FEA gives some direction but accuracy costs a lot of money. Beyond that, we don't have real life Su-27's at our disposal to validate the FEA so accuracy could never be confirmed. Empirical data could be sourced from accidents involving airframe failures but I don't know what has occurred or if that information would be public.

Edited April 10, 2016 by SinusoidDelta

[Winston60]

Very good video. A fascinating watch. I suggest ED interview some real life fighter pilots, current or retired, as to what feedback they encountered when stressing aircraft.

 

My few queries to a few US pilots found that they did hear or perhaps felt airframe stress.

 

By the looks of that static stress test, in a simulator environment how could you miss seeing the wing deform that much?

[Bond 42]

The problem I have with over-g'ing and ripping apart a plane in a sim, is the fact that we can't feel the G forces... In any real plane you'll feel the forces and adjust accordingly... You won't be tearing off wings ha. It's hard to "simulate" that in a desktop sim.. without constantly monitoring your G meter, and that's no fun.

[probad]

we do get cues like the breathing, and as a somewhat ironic twist the f-15's lack of g-suit becomes as boon as the onset of blackout prevents you from overstressing the airframe.

 

the energy bleed that some people dislike so much similarly has a positive side here as it generally tends to avoid catastrophic energy retention.

Edited April 10, 2016 by probad

[Bond 42]

we do get cues like the breathing, and as a somewhat ironic twist the f-15's lack of g-suit becomes as boon as the onset of blackout prevents you from overstressing the airframe.

 

the energy bleed that some people dislike so much also turns out to have a positive side here as it tends to generally avoid catastrophic energy retention.

 

 

 

Exactly..

[SDsc0rch]

what i feel should be simulated (to SOME extent) is the fact that the "S-switch" isn't on the HOTAS - yet it is employed in the sim like its on the HOTAS (ie.. quick on and off)

 

people are "gaming" the sim in ways that you can't "game" the real world jet

 

the way it should be modeled in the sim, is to only permit engagement/disengagement of the S-switch if the a/c is experiencing less than a specified G-loading threshold ----- say maybe 2Gs or 3 or 4 (get some feedback from aircrew)

 

have you ever tried to move your hands around the cockpit during a hard turn? it is very difficult...

 

 

 

now, for balance, i am hearing the complaints about the SU breaking up in unusual circumstances - probably straining credibility

 

okay, maybe we need to look at that

 

 

 

but in the interest of REALISM, we should only permit S-switch operation during conditions where a real-world SU pilot would be able to engage or disengage that switch

 

we want realistic aircraft in the sim, right?

[probad]

i am hearing the complaints about the SU breaking up in unusual circumstances - probably straining credibility

 

i disagree with this, it's the people who are experiencing these troubles that lack credibility. credible documents state the flanker isn't rated at the weight that many of these pilots are used to flying at.

 

some people are not aware that everything is a double edged sword. the flanker has a g-suit and retains energy fantastically but what we are witnessing are both those features backfiring on people not aware of what they really mean. it's equivalent to a person who doesn't have pain receptors.

[SinusoidDelta]

Translated straight from the real flight manual for reference.

 

Note the limitations through the transonic region (0.85 < M ≤1.25)

 

Maximum operational overload at design

gross weight of 21,400 kg :

- Pu max = 8.0 at M≤0,85

- Pu max = 6.5 at 0.85 < M≤1,25

- Pu max = 7.0 for M > 1.25

For instruments that are different from the calculated gross weight ,

Overload is set at the rate of :

- M • Pu max = Const = 171,000 kg at M < 0.85 , but not

more than 9.0 =pu

- M • Pu max = Const = 139,000 kg at 0.85 < M≤1,25 but

not more than =7.0 pu

- M • Pu max = Const = 150,000 kg at M > 1.25 , but not

more than =7.5 pu

 

Edited April 10, 2016 by SinusoidDelta

[Mike5560]

we do get cues like the breathing, and as a somewhat ironic twist the f-15's lack of g-suit becomes as boon as the onset of blackout prevents you from overstressing the airframe.

 

AFAIK, F-15 pilots wear G-suits. Unless you're suggesting the G-LOC onset is like not wearing one.

[Kuky]

I don't see any valid reasons to complain about this realistic feature. You should not be disabling the FLSC in situations where you are fast as it can make the aircraft pull more G's then what it is rated (designed) for. If you want to be a good VR pilot, then learn not to do things real pilot would not do (not a good one anyway).

 

Why you see this as "not fun" is beyond me... is it all about winning in MP here even if it means doing things you would never even be able to in real life?

 

I fly the flanker and never have the need to disable the G limiter. The Flanker flies just fine with it on... it is very manoeuvrable airframe but if very heavy then don't fly it as it if were light and empty of fuel and weapons and you won't over-G the airframe and won't break it. If you are against another Flanker that is lighter, and the guy flies it good, well that's just tough luck. You can't win every time.

[GGTharos]

IMHO the G-loc onset is at least 3x if not 6x too early in terms of time.

 

AFAIK, F-15 pilots wear G-suits. Unless you're suggesting the G-LOC onset is like not wearing one.

[doodenkoff]

Why you see this as "not fun" is beyond me... is it all about winning in MP here even if it means doing things you would never even be able to in real life?

 

 

Uh, that's pretty much the strongest motivation of most multiplayer servers. It's why aimbots, wallhacks, and other cheats rule so many FSPs. It isn't about having some fun, it's all about the WINNING and having the largest epeen. Many, many players will find any possible cheat or exploit and use it without guilt.

 

It's also why I don't participate in them for the most part.

[JazonXD]

I don't see any valid reasons to complain about this realistic feature. You should not be disabling the FLSC in situations where you are fast as it can make the aircraft pull more G's then what it is rated (designed) for. If you want to be a good VR pilot, then learn not to do things real pilot would not do (not a good one anyway).

 

Why you see this as "not fun" is beyond me... is it all about winning in MP here even if it means doing things you would never even be able to in real life?

 

I fly the flanker and never have the need to disable the G limiter. The Flanker flies just fine with it on... it is very manoeuvrable airframe but if very heavy then don't fly it as it if were light and empty of fuel and weapons and you won't over-G the airframe and won't break it. If you are against another Flanker that is lighter, and the guy flies it good, well that's just tough luck. You can't win every time.

 

I don't fly the flanker that often, so out of curiosity, what's the G limiter disable and what does it do? Is it the same thing as the direct control? Thanks

[pr1malr8ge]

I don't fly the flanker that often, so out of curiosity, what's the G limiter disable and what does it do? Is it the same thing as the direct control? Thanks

They are one and of the same. it allows full deflection of the control surfaces at any flight envelope.

[Bond 42]

I don't see any valid reasons to complain about this realistic feature. You should not be disabling the FLSC in situations where you are fast as it can make the aircraft pull more G's then what it is rated (designed) for. If you want to be a good VR pilot, then learn not to do things real pilot would not do (not a good one anyway).

 

Why you see this as "not fun" is beyond me... is it all about winning in MP here even if it means doing things you would never even be able to in real life?

 

I fly the flanker and never have the need to disable the G limiter. The Flanker flies just fine with it on... it is very manoeuvrable airframe but if very heavy then don't fly it as it if were light and empty of fuel and weapons and you won't over-G the airframe and won't break it. If you are against another Flanker that is lighter, and the guy flies it good, well that's just tough luck. You can't win every time.

 

 

 

When I said "no fun", I'm not meaning that I don't want it to be real life... It's a sim, with certain limitations. I want/expect it to be as real as possible. But the only way to do that is to simulate G forces with black/red outs and breathing. That's the only way we can in a desktop sim... Without actually feeling the Gs yourself, it makes it difficult to manage at certain flight envelopes.

That being said, I wasn't meaning if you shut the override switch (if that's what it's called, I don't fly it) that you should be able to do anything. I agree, if it's off there should be repercussions with overspeeding or excess Gs.

[JazonXD]

They are one and of the same. it allows full deflection of the control surfaces at any flight envelope.

 

ahh okay i see. it also disables and pitch assistance at certain speeds correct? once you enable ASC, the elevators deflect down quite a bit compared to when the g limiter is still on. everything also becomes super sensitive.

 

Is this also equivalent to disabling CAS channels on the F-15? I believe that the 15 does not allow you full deflection at all envelopes.

[GGTharos]

The CAS schedules the deflection so that force of pull = consistent g.

 

You can probably still get max deflection, as limited by the hydraulic power available to move the horizontal stabs. In some cases physics will simply not permit full deflection, never mind the CAS :)

 

Is this also equivalent to disabling CAS channels on the F-15? I believe that the 15 does not allow you full deflection at all envelopes.

[Frostie]

I don't see any valid reasons to complain about this realistic feature. You should not be disabling the FLSC in situations where you are fast as it can make the aircraft pull more G's then what it is rated (designed) for. If you want to be a good VR pilot, then learn not to do things real pilot would not do (not a good one anyway).

 

The fun thing is you don't need to press the S button to break the wings.

 

Mastering the DCS Flanker FM has got to be one of the toughest FM challenges in simming. From low speed negative Gs putting you on your back as you plummet to your death, high speed defensive breaks snapping your wings off, auto pilot nut case the burden grows and with it still in beta there is plenty room for more, bring it on I say much more enjoyable than the humdrum F-15 FM. :D

Edited April 11, 2016 by Frostie

[SinusoidDelta]

The CAS schedules the deflection so that force of pull = consistent g.

 

You can probably still get max deflection, as limited by the hydraulic power available to move the horizontal stabs. In some cases physics will simply not permit full deflection, never mind the CAS :)

 

CAS only commands < 20 degrees aoa. Beyond that it only dampens pitch. Without the dampening I suppose pitch could be commanded somewhat instantaneously. I assume a big factor why the eagle can't rip its wings off is due to its favorable static stability characteristics, unlike the flanker.

Edited April 11, 2016 by SinusoidDelta