correct as is F-15C Structual wing surface failure.

[LT_STARBUCK_107]

Has anyone notice while pulling a high rate turn, the F-15's wings just rips off in flames? Is this realistic?

This should be a strong fighter aircraft much needed in dogfight combat instead of breaking apart like a piece of paper in flames?

Any foreseeable update fix for this unstable condition?

If I'm wrong in this statement please explain to us why this poor flight condition exsist.  I know about G-forces but i think instead of the G-limiter calling out Over-G, over-g, Over-g. Can we implement a g-limiter that does actually something to stop this event from happening.

[Kilo]

Quote

Can we implement a g-limiter that does actually something to stop this event from happening.

The thing is - there is no such thing on the F-15. Actually, the only fighter aircraft we have in game right now (that I know of) that will stop you from tearing it apart is the F-18. All other aircraft will give as much as you ask of them.

How many Gs were you pulling in that turn?

[draconus]

It is strong fighter but there are limits and over-G warning is there for a reason. A fix is in your right hand, pilot.

Flames are wrong, though, in this situation.

[GGTharos]

10 hours ago, LT_STARBUCK_107 said:

Has anyone notice while pulling a high rate turn, the F-15's wings just rips off in flames? Is this realistic?

Haven't noticed it because I don't ham-fist the aircraft, and it pulls 9g throughout most of of its weight range, unless you're running around with full bags.

10 hours ago, LT_STARBUCK_107 said:

This should be a strong fighter aircraft much needed in dogfight combat instead of breaking apart like a piece of paper in flames?

It is a strong fighter ... you're just not a strong pilot

10 hours ago, LT_STARBUCK_107 said:

Any foreseeable update fix for this unstable condition?

There is nothing to fix.

10 hours ago, LT_STARBUCK_107 said:

If I'm wrong in this statement please explain to us why this poor flight condition exsist.  I know about G-forces but i think instead of the G-limiter calling out Over-G, over-g, Over-g. Can we implement a g-limiter that does actually something to stop this event from happening.

It's a poor pilot condition, not a poor flight condition.  Learn how to control g-forces in your aircraft.   And as mentioned, the real eagle has no limiter and therefore neither does the DCS one.  The limiter is you, so get better at understanding how to fly

[=475FG= Dawger]

While I completely agree that the pilot is the G limiter, it is also very unrealistic to be able to create catastrophic wing failure in a brand new F15. The pilot would GLOC long before the wing quit on a new jet.

Could he bend a new jet? Sure. Could he pull enough G to make the aircraft un-repairable after landing? Maybe. Snap a wing off? No way.

[Ironhand]

19 hours ago, LT_STARBUCK_107 said:

…I know about G-forces but i think instead of the G-limiter calling out Over-G, over-g, Over-g. Can we implement a g-limiter that does actually something to stop this event from happening.

Out of curiosity, how many Gs were on the airframe, when the wing came off?

[GGTharos]

4 hours ago, =475FG= Dawger said:

While I completely agree that the pilot is the G limiter, it is also very unrealistic to be able to create catastrophic wing failure in a brand new F15. The pilot would GLOC long before the wing quit on a new jet.

I don't believe this to be the case unless you're flying a very light eagle and even then it's subject to repeated stresses in rapid succession, highly dependent on which flight regime all of this is happening in.

Edited January 23, 2022 by GGTharos

[=475FG= Dawger]

19 hours ago, GGTharos said:

I don't believe this to be the case unless you're flying a very light eagle and even then it's subject to repeated stresses in rapid succession, highly dependent on which flight regime all of this is happening in.

 

You would be wrong.

Real F-15C’s have recorded large G numbers in combat without losing wings and they were not factory fresh.

Catastrophic wing failure from a one time event on a new tactical aircraft just doesn’t happen.

It is a game-ism ED has introduced for game play purposes.

[draconus]

1 hour ago, =475FG= Dawger said:

Real F-15C’s have recorded large G numbers in combat without losing wings and they were not factory fresh.

Catastrophic wing failure from a one time event on a new tactical aircraft just doesn’t happen.

That no pilot was both strong and stupid enough doesn't mean it wouldn't happen. Go fast enough, pull hard enough and no airframe is gonna survive this. I say it may be possible but only science and data would help determine which part would fail first.

Quote

It is a game-ism ED has introduced for game play purposes.

If anything it would be for simulation purposes as the F-15C was one of the last limitless G airframes in DCS.

[=475FG= Dawger]

1 minute ago, draconus said:

That no pilot was both strong and stupid enough doesn't mean it wouldn't happen. Go fast enough, pull hard enough and no airframe is gonna survive this. I say it may be possible but only science and data would help determine which part would fail first.

If anything it would be for simulation purposes as the F-15C was one of the last limitless G airframes in DCS.

As I said earlier, the pilot will GLOC long before the wing will suffer catastrophic failure on a new fighter. We aren’t talking about other parts breaking or getting damaged. We are talking about catastrophic failure of the strongest aircraft structure occurring due to a one time event on a new airplane. 

Its quite obviously not realistic. 
 

 

[GGTharos]

3 hours ago, =475FG= Dawger said:

As I said earlier, the pilot will GLOC long before the wing will suffer catastrophic failure on a new fighter. We aren’t talking about other parts breaking or getting damaged. We are talking about catastrophic failure of the strongest aircraft structure occurring due to a one time event on a new airplane. 

Its quite obviously not realistic. 

I'm familiar with the incidences of over-g in the eagle.  No, saying hat the pilot would GLOC is not necessarily realistic.   Further, these over-g incidences IRL are a single event in the aircraft's 'career' typically, not the high-low pump that happens in DCS in a single flight.  As well, the DCS eagle is capable of developing more G than the real one ever has.

What ED has done seems just fine.  I've never seen it happen to anyone who wasn't running around ham-fisted with full bags.

Edited January 24, 2022 by GGTharos

[=475FG= Dawger]

7 hours ago, GGTharos said:

I'm familiar with the incidences of over-g in the eagle.  No, saying hat the pilot would GLOC is not necessarily realistic.   Further, these over-g incidences IRL are a single event in the aircraft's 'career' typically, not the high-low pump that happens in DCS in a single flight.  As well, the DCS eagle is capable of developing more G than the real one ever has.

What ED has done seems just fine.  I've never seen it happen to anyone who wasn't running around ham-fisted with full bags.

 

Are you not even curious as to why the strongest aircraft structure fails catastrophically before anything else fails? You point out that " I've never seen it happen to anyone who wasn't running around ham-fisted with full bags."

Ever wonder if maybe the pylon, tank or attachment hardware should fail before the wing? Or some other weaker aircraft structure?

Doesn't it seem awfully arcade-like that the wing cracks off before anything else?

It is a pointless waste of engineering and lots of extra unnecessary weight to build an aircraft where every part and accessory exceeds the catastrophic structural failure point of the wing without even suffering damage.

Of course, the F-15C is FC3 so it can be forgiven for being far less than realistic. The problem is that this stuff is being used on other "full-fidelity" DCS modules and seems to be the wave of the future.

Edited January 24, 2022 by =475FG= Dawger

[GGTharos]

3 hours ago, =475FG= Dawger said:

Are you not even curious as to why the strongest aircraft structure fails catastrophically before anything else fails? You point out that " I've never seen it happen to anyone who wasn't running around ham-fisted with full bags."

What, in-game?  No.  There's no structure in game.

3 hours ago, =475FG= Dawger said:

Ever wonder if maybe the pylon, tank or attachment hardware should fail before the wing? Or some other weaker aircraft structure?

I'm not terribly worried about that, no.  This sort of thing, as well as aerodynamic problems caused by warping of the airfame aren't modeled.  The only thing that's modeled is ultimate strength, and it's all ok, it does it's job.

3 hours ago, =475FG= Dawger said:

Doesn't it seem awfully arcade-like that the wing cracks off before anything else?

Given that you need to accumulate plenty of over-g and that the aircraft can pull more G than it can IRL (I wish that could be taken care of, it's not an F-15 issue either, more of a DCS thing), not really - and again, it's modeling ultimate strength, not airframe plasticity or other structural items.

3 hours ago, =475FG= Dawger said:

It is a pointless waste of engineering and lots of extra unnecessary weight to build an aircraft where every part and accessory exceeds the catastrophic structural failure point of the wing without even suffering damage.

Of course, the F-15C is FC3 so it can be forgiven for being far less than realistic. The problem is that this stuff is being used on other "full-fidelity" DCS modules and seems to be the wave of the future.

Right, there's nothing 'FC3' about this.   And of course there's no simulation of the airframe being bent and subsequent aerodynamic issues, etc. etc.

[=475FG= Dawger]

8 hours ago, GGTharos said:

What, in-game?  No.  There's no structure in game.

I'm not terribly worried about that, no.  This sort of thing, as well as aerodynamic problems caused by warping of the airfame aren't modeled.  The only thing that's modeled is ultimate strength, and it's all ok, it does it's job.

Given that you need to accumulate plenty of over-g and that the aircraft can pull more G than it can IRL (I wish that could be taken care of, it's not an F-15 issue either, more of a DCS thing), not really - and again, it's modeling ultimate strength, not airframe plasticity or other structural items.

Right, there's nothing 'FC3' about this.   And of course there's no simulation of the airframe being bent and subsequent aerodynamic issues, etc. etc.

Other modules seem to be able to model a more sophisticated and realistic approach to structural failure. Certain modules suffer from permanent deformation of the structure causing the aircraft to handle poorly. Others model component failures due to high G.

Which is why this is a big issue. Its all very haphazard and trending towards this arcade version of structural damage. 
 

I don’t have any personal investment in the F-15. I fly strictly MP, visual range stuff so the F-15 is never on the menu. However, there are at least three modules suddenly afflicted with this arcade version of structural limits while others retain more sophisticated programming or an apparent absence of limits.

What is the end game? Dumb them all down? Depressing to see DCS go that direction but at least it would be consistent across all modules.

My hope is ED recognizes this as an error and moves to put more sophisticated and realistic structural failure modeling in place instead of this.

 

[BIGNEWY]

Please attach a short as possible track replay showing structural failure, note the aircraft's weight and how many G's you were pulling and I will ask the team about it. 

thanks

[cofcorpse]

23 minutes ago, =475FG= Dawger said:

I don’t have any personal investment in the F-15. I fly strictly MP, visual range stuff so the F-15 is never on the menu. However, there are at least three modules suddenly afflicted with this arcade version of structural limits while others retain more sophisticated programming or an apparent absence of limits.
...
My hope is ED recognizes this as an error and moves to put more sophisticated and realistic structural failure modeling in place instead of this

Could you provide any proof that this implementation is completely wrong? Studies about structural strength of a particular jet?

As long as you don't exceed design limits, nothing bad will happen. 

And as GGTharos wrote, "The only thing that's modeled is ultimate strength, and it's all ok, it does it's job." If you think otherwise, please provide evidence.

[draconus]

26 minutes ago, =475FG= Dawger said:

What is the end game? Dumb them all down? Depressing to see DCS go that direction but at least it would be consistent across all modules.

Simulation can and will go only deeper and get more complex. It is just a matter of will and time. This is the current level of structural over-G damage in this module. I wouldn't expect anything better for a while.

[cofcorpse]

34 minutes ago, =475FG= Dawger said:

My hope is ED recognizes this as an error and moves to put more sophisticated and realistic structural failure modeling in place instead of this.

 

And you are correct. The wing structural failure is the last one to happen. So, if or when some other stuctural will be added, they will happen before wing ripping off. So restrictions will be even stricter.

[=475FG= Dawger]

12 minutes ago, cofcorpse said:

And you are correct. The wing structural failure is the last one to happen. So, if or when some other stuctural will be added, they will happen before wing ripping off. So restrictions will be even stricter.

I am not looking for "less restriction" as you are implying.

Yes, a realistic simulation of structural failure will be much more restrictive than zero effects until catastrophic failure of the wing.

However, a realistic structural failure model would mean it would be exceedingly difficult to actually cause catastrophic failure of the wing on a NEW Airplane (Which is what is simulated AFAIK)

The current method of taking the limit load , multiplying it by 1.5 and setting the wing to come off at that number is silly on its face and easily shown to be false. Reading through the relevant MILSPECS and reports on the structural integrity testing of tactical aircraft quickly reveals that these aircraft are expected to fairly regularly exceed the limit load and approach the design ultimate limit load (1.5 times the limit load) multiple times during the expected airframe lifetime (4000 hours for tactical aircraft) without compromising structural integrity.

There are two types of structural strength to consider. Static Strength and Fatigue Strength, static strength being the ability to withstand a single application of force and fatigue strength being the ability to withstand repeated application of fluctuating load without failure. The force required to reach the static strength limit of metals is MUCH greater than the fatigue strength limit. Fatigue failure requires load cycling to produce structural failure.

An aircraft must be designed to withstand a lifetime of load cycling appropriate to the expected mission. The expected mission parameters for modern fighters requires they be capable of withstanding multiple exceedances of the limit load up to and including the ultimate limit load over the life of aircraft.

The design ultimate limit load is the FATIGUE strength limit load not the static strength of the structure.

Modeling the static failure of the wing at the ultimate limit load is incorrect.

[cofcorpse]

29 minutes ago, =475FG= Dawger said:

I am not looking for "less restriction" as you are implying.

Yes, a realistic simulation of structural failure will be much more restrictive than zero effects until catastrophic failure of the wing.

However, a realistic structural failure model would mean it would be exceedingly difficult to actually cause catastrophic failure of the wing on a NEW Airplane (Which is what is simulated AFAIK)

The current method of taking the limit load , multiplying it by 1.5 and setting the wing to come off at that number is silly on its face and easily shown to be false. Reading through the relevant MILSPECS and reports on the structural integrity testing of tactical aircraft quickly reveals that these aircraft are expected to fairly regularly exceed the limit load and approach the design ultimate limit load (1.5 times the limit load) multiple times during the expected airframe lifetime (4000 hours for tactical aircraft) without compromising structural integrity.

There are two types of structural strength to consider. Static Strength and Fatigue Strength, static strength being the ability to withstand a single application of force and fatigue strength being the ability to withstand repeated application of fluctuating load without failure. The force required to reach the static strength limit of metals is MUCH greater than the fatigue strength limit. Fatigue failure requires load cycling to produce structural failure.

An aircraft must be designed to withstand a lifetime of load cycling appropriate to the expected mission. The expected mission parameters for modern fighters requires they be capable of withstanding multiple exceedances of the limit load up to and including the ultimate limit load over the life of aircraft.

The design ultimate limit load is the FATIGUE strength limit load not the static strength of the structure.

Modeling the static failure of the wing at the ultimate limit load is incorrect.

A lot of words and no exact information. I'm sorry, we can't do anything without information. 

"approach the design ultimate limit load (1.5 times the limit load)" - you can approach 1.5x design limit many times, but you can't exceed it in current implementation. 

"he force required to reach the static strength limit of metals is MUCH greater than the fatigue strength limit." - How much greater? Again, no information.

"The design ultimate limit load is the FATIGUE strength limit load not the static strength of the structure." - Could you proof that? 

"Modeling the static failure of the wing at the ultimate limit load is incorrect." -Why?

[stefasaki]

1 hour ago, cofcorpse said:

A lot of words and no exact information. I'm sorry, we can't do anything without information. 

"approach the design ultimate limit load (1.5 times the limit load)" - you can approach 1.5x design limit many times, but you can't exceed it in current implementation. 

"he force required to reach the static strength limit of metals is MUCH greater than the fatigue strength limit." - How much greater? Again, no information.

"The design ultimate limit load is the FATIGUE strength limit load not the static strength of the structure." - Could you proof that? 

"Modeling the static failure of the wing at the ultimate limit load is incorrect." -Why?

The fatigue limit is always lower than the static limit. For aluminum it is halved after around 10^5 cycles, which is typical for an airframe life. This means that if an aircraft breaks up at 9 g's after 10^5 cycles then it is should be able to withstand 18 g's when it's new. This is an over-simplification of the problem but it should give you an insight.

Edited January 25, 2022 by stefasaki

[cofcorpse]

23 minutes ago, stefasaki said:

The fatigue limit is always lower than the static limit. For aluminum it is halved after around 10^5 cycles, which is typical for an airframe life. This means that if an aircraft breaks up at 9 g's after 10^5 cycles then it is should be able to withstand 18 g's when it's new. This is an over-simplification of the problem but it should give you an insight.

 

Completely unusable. How did you get this value, 18G?

[jackmckay]

Sorry for interruption. Thing is that prior mechanical failure in non brittle materials there is always obvious visual deformation on any structural geometry exceeding yield linear stress and entering nonlinear zone. That means plastic deformation. Fatigue is strength degrading factor and is expressed in allowable stress cycling thus limiting geometry strength over time. Not an issue in most cases as most stress concentrated zones do appear visually by surface texture change and can be detected and observed. Most airframes do have skin as primary structural element and all stress is accumulated there. In combination with fatigue and set stress limit or factor of safety airframe manufacturers do predict airframe lifespan in years. Catastrophic failure is not first option but rather second as first goes plastic deformation, aerodynamics degradation and then ultimate failure.

[cofcorpse]

Please define what you are talking about. The already made mechanism does not work correctly, which is indicated in the title of the topic, or the failures are not sufficiently developed, which will be offtopic in this thread.

[Spurts]

I think they are trying to say both.  FWIW, structural test of a brand new aircraft involves finding the critical load condition and simulating the forces and moments to 150% to see if it snaps.  The goal is to be close to 150%, not over 200%.  Design load limit can be exceeded, but it is not supposed to be exceeded, and it is certainly not the planned exceedance.  No fighter jet makes it to 10^5 hours, more like 10^4 (unless you are trying to imply 10 cycles per hour, which sounds very aggressive, IIRC 1.2-1.3 was used for the F-16) and it needs structural reinforcement through SLEP programs to get there.