Wing snap at 9,3G ??

[TomCatMucDe]

Hi,

 

I was fighting an F5, I was diving on him from up high, so I could only be fast and the airbrakes dont deploy naturally. Then I pulled 9,3G at 630 knots to chase him and there my wing snapped. why? is this normal? I have pulled higher Gs at faster speeds

attached a screenshot of the Tacview

[shagrat]

Hi,

 

 

 

I was fighting an F5, I was diving on him from up high, so I could only be fast and the airbrakes dont deploy naturally. Then I pulled 9,3G at 630 knots to chase him and there my wing snapped. why? is this normal? I have pulled higher Gs at faster speeds

 

attached a screenshot of the Tacview

Structural limit for the F-14B is some 6.5 G... that does not mean it breaks at 6.6 G,. but you are required to check the airframe for structural damage. Now overstressing the airframe with more than 2 to 3 G for prolonged maneuvers, seems not unreasonable to break something for good...

[FoxTwo]

This is completely normal. This flight controls will not stop you from doing something that will break the aircraft.

 

Normal naval operational limit for the F-14 was 6.5g to extend the life of the airframe. Grumman claimed 9 to -5.5 should be possible. Realistically the airframe was only pushed to about 7.2g during BFM training. I wouldn't pull more than 8 personally.

 

Once you hit 9g, you're exceeding the capability of the airframe. At a 28 degree AoA and pulling 9.3g well, what did you think would happen? At that angle the wings are fully loaded. Also makes a difference if you're full of fuel and how loaded the plane is. 9g on a 55k lb aircraft is a lot different than a 74k lb.

[TomCatMucDe]

Structural limit for the F-14B is some 6.5 G... that does not mean it breaks at 6.6 G,. but you are required to check the airframe for structural damage. Now overstressing the airframe with more than 2 to 3 G for prolonged maneuvers, seems not unreasonable to break something for good...

It was not prolonged pull. It was 2 seconds only.

 

 

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[Airhunter]

Basically don't roll and pull the the same time. That's when I have broken my wings.

[shagrat]

It was not prolonged pull. It was 2 seconds only.

 

 

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...and before the 2 seconds you were below 6.5 G ? You can do a 7 to 8 G pull for a few seconds and only damage the INS, or worse the engines. Either spontaneous pulls beyond 10 G gets you in trouble or more than 7 G for prolonged time, e.g. more than a couple seconds.

The problem is you need to train muscle memory to get the "feeling" for when to unload... as the F-14B has no G-Limiter, or Fly-by-wire, unlike the Mirage or F/A-18C, you need to train the limits and judging by cockpit shake sound and maneuver. Just a matter of some training time.

[BlackLion213]

Hi,

 

I was fighting an F5, I was diving on him from up high, so I could only be fast and the airbrakes dont deploy naturally. Then I pulled 9,3G at 630 knots to chase him and there my wing snapped. why? is this normal? I have pulled higher Gs at faster speeds

attached a screenshot of the Tacview

 

I wouldn't have expected that to happen at 9.3G, but the problem is often the "G transient" and not the figure displayed in tacview. The overall G may be reasonable, but for a split second the G may be way higher - like 12-15 Gs! Instruments like the G meter won't register in time and the blackout effect takes a moment to onset as well. These high transient Gs usually occurs due to very abrupt control movements that would not likely occur in real life due to the force required.

 

The Grumman G rating is actually 7.75 G, but the USN reduced the G rating in the late 1970s as the slow procurement rate made it clear that airframes would need to last a long time. 6.5 G was the "peace time" G limit and 7.5 G was the "war time" G limit.

 

If I remember correctly, the risk of structural failure starts around the high 9s or low 10s, though I thought it was 10+. So either you generated a high transient G or you caught a very small probability of a failure at 9.x G.

 

In either case, the way to avoid such things is slow down the control inputs and smooth things out.

 

-Nick

[TomCatMucDe]

...and before the 2 seconds you were below 6.5 G ? You can do a 7 to 8 G pull for a few seconds and only damage the INS, or worse the engines. Either spontaneous pulls beyond 10 G gets you in trouble or more than 7 G for prolonged time, e.g. more than a couple seconds.

The problem is you need to train muscle memory to get the "feeling" for when to unload... as the F-14B has no G-Limiter, or Fly-by-wire, unlike the Mirage or F/A-18C, you need to train the limits and judging by cockpit shake sound and maneuver. Just a matter of some training time.

I went from 3G to 9.3. The whole thing lasted less than 2 seconds. I will attach later the tacview

 

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[TomCatMucDe]

here is the tacview

Tacview-20190421-143133-DCS-HB Kish Kat Attack.zip.rar

[shagrat]

I went from 3G to 9.3. The whole thing lasted less than 2 seconds. I will attach later the tacview

 

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That should not snap off the wings. I had more than once pulled to a peak of about 8/9 G for a second or two. Ok, that can get the INS to fail, but never lost a wing, yet.

[TomCatMucDe]

That should not snap off the wings. I had more than once pulled to a peak of about 8/9 G for a second or two. Ok, that can get the INS to fail, but never lost a wing, yet.

Me too. I attached the tacview in my last post.

 

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[BlackLion213]

That should not snap off the wings. I had more than once pulled to a peak of about 8/9 G for a second or two. Ok, that can get the INS to fail, but never lost a wing, yet.

 

INS cannot be damaged till G exceeds 11-12+. So also probably related to a very high transient G.

 

-Nick

[Wizard_03]

Transient G is more dangerous then sustained G IRL, if we’re talking damage to the airframe. It’s the difference between an elephant slowly sitting on you, and an elephant falling on you.

 

Those quick high G spikes are what break things, not the slow onset of G.

[shagrat]

INS cannot be damaged till G exceeds 11-12+. So also probably related to a very high transient G.

 

 

 

-Nick

Likely. From the TacView I noticed he was at 1.05 Mach when entering the dive and never slowed below 1 Mach while pulling from 0.1 to 9.3 G in just 2.5 seconds. It looks like the G TacView shows are only related to the Pilot, as over the last second the G is a flat line and indicating a black out(?) while in the Sim you may have pulled further (extrapolating the curve over another second would get to 10 to 11 G plus...

[TomCatMucDe]

Likely. From the TacView I noticed he was at 1.05 Mach when entering the dive and never slowed below 1 Mach while pulling from 0.1 to 9.3 G in just 2.5 seconds. It looks like the G TacView shows are only related to the Pilot, as over the last second the G is a flat line and indicating a black out(?) while in the Sim you may have pulled further (extrapolating the curve over another second would get to 10 to 11 G plus...

There was no blackout, in fact there was no black out effect at all... That's what I find strange, there is no way to judge if I am.oukking too much on the airframe if the pilots doesn't feel anything at all. I mean there is no way that you can reach the G meter in the cockpit while fighting.

 

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[Hummingbird]

Again, the Tomcat's airframe was tested to 13 G's by Grumman, so no breakage should occur until you approach this loading symmetrically. With asymmetric loads things start breaking sooner however, so keep that in mind.

 

In real life service some cats went as high at 12 G's without damage, just FYI.

[TomCatMucDe]

Again, the Tomcat's airframe was tested to 13 G's by Grumman, so no breakage should occur until you approach this loading symmetrically. With asymmetric loads things start breaking sooner however, so keep that in mind.

 

In real life service some cats went as high at 12 G's without damage, just FYI.

I was Winchester. Expended all my missiles and was going after the F5 with guns only.

 

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[Hunter Joker]

Basically don't roll and pull the the same time. That's when I have broken my wings.

Exactly! I could pull 13.5 G without break anything, but I fly the cross, if I pull no stick roll, only rudder, if I need also to roll, ease the pull...

 

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[TomCatMucDe]

Thanks for the hint guys. Is this how it is supposed to be ? I mean that the wings break if there is a pull and roll at the same time?

 

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[F900EX]

I have broken my wings in swept mode around 400kts in a tight bank...

 

FM needs some work IMO

[probad]

Thanks for the hint guys. Is this how it is supposed to be ? I mean that the wings break if there is a pull and roll at the same time?

remember when flanker players were in disbelief and denial as well?

[shagrat]

I have broken my wings in swept mode around 400kts in a tight bank...

 

FM needs some work IMO

I find it interesting, that whenever some guys break their planes and they get told it is because they fly too aggressive "there must be something wrong with the FM"... I have not even once(!) snapped a wing in the Tomcat. Never ever. I tested today a bit with pulling more than 9 to 10 G and still my wings never came off. Since the Tomcat is available I had my wings shot off, I damaged my INS multiple times, I got in a handful of flatspins as a result of bad flying and could recover twice before crashing into the ground... apart from that, I learned to fly the Tomcat deliberate and with smooth, yet quick, measured inputs. I am sure I can squeeze a bit more performance with some more training, but I don't break my plane when following the brilliant advise of SMEs like Victory205. So I am quite sure, the FM is pretty spot on when it comes to structural limits.

[Voyager]

I'll have to run it down again, but I recall a NACA paper on aileron loading under maneuvers that concluded that, under rolling high G turns the wing tips would see considerably higher G forces than the core of the aircraft. Think of it as cracking a whip: your hand is moving fast, but the tip of the whip is moving far faster.

 

So, if you a rolling in a 9.3 G (core) turn, the wing tips are likely seeing a complex of the core G force and additional Gs due to the effect of the rapid roll. Do we have a quick calculation of the centripital force the wing tips would likely see during a max rate roll under 1G? I'd expect it's non-trivial.

[Hummingbird]

I was Winchester. Expended all my missiles and was going after the F5 with guns only.

 

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You misunderstood, I mean if you're rolling and turning at the same time, by doing that you're loading up the airframe asymmetrically which means one side is taking a higher percentage of the total load factor. This will lead to breakage at lower G loads than when you're doing straight symmetrically loaded turns.

[TomCatMucDe]

I find it interesting, that whenever some guys break their planes and they get told it is because they fly too aggressive "there must be something wrong with the FM"... I have not even once(!) snapped a wing in the Tomcat. Never ever. I tested today a bit with pulling more than 9 to 10 G and still my wings never came off. Since the Tomcat is available I had my wings shot off, I damaged my INS multiple times, I got in a handful of flatspins as a result of bad flying and could recover twice before crashing into the ground... apart from that, I learned to fly the Tomcat deliberate and with smooth, yet quick, measured inputs. I am sure I can squeeze a bit more performance with some more training, but I don't break my plane when following the brilliant advise of SMEs like Victory205. So I am quite sure, the FM is pretty spot on when it comes to structural limits.

Per the tacview I was not flying Bert aggressively. I don't think I was banking hard either.

I have never flown a real Tomcat, I can't judge the FM but it does look strange that the plane breaks under 9G with a bit of bank.

 

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