Structural Failure

[Kurfürst]

On the topic, it seems quite easy to loose wings in Spit. I don't think that the modeling of the wings structural integrity might be the issue but rather the failure is caused by extreamly sensitive elevator.

 

Could be right. My impression that the stick forces are not modelled at all on the Spitfire. Could be violent and sudden control surface deflections imposing sudden load-peaks, even beyond to extent the Spitfire pilot could pull out of his sleeve.

[Krupi]

A note from a spitfire mk 2 is not particularly of use when we are talking about the IX... Mk 2 had fabric controls after all and this caused issue at high speed.

 

We have already confirmed that the skin thickness was increased on the IX, the mk 1 was originally limited to about 350mph in a dive until they tested it to above 450 IIRC.

 

I wil have to get the paragraph from Jeff Quills book where he discusses this.

[Kurfürst]

A note from a spitfire mk 2 is not particularly of use when we are talking about the IX... Mk 2 had fabric controls after all and this caused issue at high speed.

 

Fabric on the ailerons, later changed to metal skinned ailerons, improving their effectiveness. However the issue caused by fabric ailerons was lack of effectiveness at high speeds, even though the manual warns again using too much force on the ailerons in dives because of twisting loads on the wings. Aircraft of the 1940s were typically designed to resist one-axis bending loads well, but not a combination of twisting loads. So if anything, the more effective metal ailerons caused more twisting overloads and had to be used sparingly in dives. Later Spitfire diving procedures explicitly advise caution when using aircraft fitted with metal ailerons.

 

However I doubt these sort of twisting loads are modelled on any WW2 DCS model, so its probably not an issue.

 

We have already confirmed that the skin thickness was increased on the IX, the mk 1 was originally limited to about 350mph in a dive until they tested it to above 450 IIRC.

 

If the Mark I would be indeed limited to 350 mph in dive it would have been a very poor fighter, but it was not. The Mk I was already cleared to 400+ mph dive speeds (430 mpoh IIRC), the later variant's manuals did not change that much, but detailed it a bit more with corresponding Mach number.

 

Confirmed, where, I may have missed that. Skin was mostly very thin on even the Mark IX, since the main load bearing element was the D-shaped leading edge and the main spar.

 

In any case, dive speed limits are not imposed by 'skin thickness' and such, but aerodynamic behaviour, stability in dive. It practically does not matter how marginally thicker the very thin plating on the Spitfire is, if you encounter massive forces when you for example encounter flutter. No matter what plane, it will fall apart when this happens. Dive limit speeds have thus next to nothing to do with permissable g-load.

 

What DOES influence permissible g-load is weight, and permissable g-loads are always referred to and valid for a specific weight, as the g-load linearly changes with more or less weight being present.

 

So if for example the Mk Is when tested at 6200 lbs would fail at about 12 g, at Mk IX weight (7450 lbs, or cc 20% more) it would fail at 20% less load, or at 10 g, and vica versa.

 

Presumably though the airframe was somewhat reinforced during its development to take into account of the weight creep, as was done on other designs. Its very much doubtful however that the later variants g-limits were higher, than the early versions.

[Friedrich-4B]

Anyway, here is the page from the Spitfire II manual addressing this issue

 

 

That page looks to be from a set of Spitfire II training notes, dated June/July 1940 which do indeed mention a 10 G limit.

 

However, as noted in a page posted by Hiromachi, in 1940 wings that had already been damaged didn't fail until 12.3 and 13 G respectively (800 mph @ 6,200 lbs) so the jury's still out on a 10 G limit

 

In addition, the Pilot's Notes General note that the limitations noted often had a safety factor of 2; thus 10G in a set of pilot's training notes could well mean 20 G - see Introductory para (ii) ...

 

 

continuing with section 2 Limiting Speeds (i) Diving

 

 

Nobody has yet posted any reliable figures on the Spitfire L.F. Mk IX's limitations, apart from some speculative comment about the limits being no higher than earlier Spitfire marks. But, as it is, I have no doubts that Yo-Yo has more information about the IX's G limits than all of the rest of us combined.

[Captain Orso]

Hmmm the note in (ii) (c) indicates that the propeller will be driven faster through airspeed in a dive. I don't think I've ever noted this actually happening. Has anybody noticed this affect on the propeller?

[bongodriver]

Hmmm the note in (ii) (c) indicates that the propeller will be driven faster through airspeed in a dive. I don't think I've ever noted this actually happening. Has anybody noticed this affect on the propeller?

 

it also specifies this applies to early types of propeller only.

[firmek]

...

Nobody has yet posted any reliable figures on the Spitfire L.F. Mk IX's limitations, apart from some speculative comment about the limits being no higher than earlier Spitfire marks. But, as it is, I have no doubts that Yo-Yo has more information about the IX's G limits than all of the rest of us combined.

This will be probably the conclusion. I wouldn't expect arriving with extreamly precise historical values. This is due to a number of reasons. During the WW2 most of the airplanes have not been equipped with sensors like G-matters not even mentionning flight parameter recorders. If there are any historical pilot reports of failing wings the description will be rather subjective, without any specific values.

Considering the manufacturers, at best they probably have been able to arrive only with limits based on educated guess - rather than a measured test results. The flight limits provided to pilots would be taking into account some substantial safety margin. Knowing this margin would still not help a lot for already mentioned reasons - not being precise as also pilot not being able to observe actual G values.

Edited January 5, 2017 by firmek

[NightRush]

The simple answer here, there is no known or published data on the full G-Limit of a Spitfire C wing.

 

There is data as someone pointed out earlier where testing was done on damaged wings.

 

I have worked on the restoration of a airworthy Spitfire, as well as the maintenance of a already flying aircraft. One a Mk IX and a Mk XVI.

 

In the certified world of aircraft, in North America atleast, none of our aircraft had a G limit imposed by the airframe, maintenance manual or POH as there is quite simply no data on wing overload G limits.

 

We did however impose company limits, as well. We are not at war anymore.

 

So to put a simple answer, the pilot would and should black out before the aircraft ever thought about over stressing and breaking a wing. DCS should reflect that in my opinion.

[Yo-Yo]

This will be probably the conclusion. I wouldn't expect arriving with extreamly precise historical values. This is due to a number of reasons. During the WW2 most of the airplanes have not been equipped with sensors like G-matters not even mentionning flight parameter recorders. If there are any historical pilot reports of failing wings the description will be rather subjective, without any specific values.

Considering the manufacturers, at best they probably have been able to arrive only with limits based on educated guess - rather than a measured test results. The flight limits provided to pilots would be taking into account some substantial safety margin. Knowing this margin would still not help a lot for already mentioned reasons - not being precise as also pilot not being able to observe actual G values.

 

Negative. The in-flight records during simulated or real combat missions were obtained by English during WWII. And the recorded data has no 10 g attempts...

[rel4y]

The germans measured real G loads as well during combat missions and established a nice tree graph with G-loads vs incidence. A lot of weird things being said in this thread anyway...

 

Comparing static G load trials with real life loads is pretty useless, these were done to compare with factory spec static loads. The most stress will be caused ba asymmetrical loading and torsion of the wings. Also in WWII there were quite some cases where resonance caused an otherwise sound structure to collapse, simply because certain things were not known at the time. I think people proposing 20 G limits cant possibly know what this would mean from an engineering point of view. Thats pretty crazy for a flying structure with non modern alloys nor honeycomb structures..

Edited January 6, 2017 by rel4y

[Friedrich-4B]

The germans measured real G loads as well during combat missions and established a nice tree graph with G-loads vs incidence. A lot of weird things being said in this thread anyway...

 

Comparing static G load trials with real life loads is pretty useless, these were done to compare with factory spec static loads. The most stress will be caused ba asymmetrical loading and torsion of the wings. Also in WWII there were quite some cases where resonance caused an otherwise sound structure to collapse, simply because certain things were not known at the time. I think people proposing 20 G limits cant possibly know what this would mean from an engineering point of view. Thats pretty crazy for a flying structure with non modern alloys nor honeycomb structures..

 

Indeed, there some weird things being said in this thread, which is why, perhaps, you didn't get the joke about 20 G. :music_whistling:

 

My main point was this:

Nobody has yet posted any reliable figures on the Spitfire L.F. Mk IX's limitations....I have no doubts that Yo-Yo has more information about the IX's G limits than all of the rest of us combined.

[HeadHunter52]

Wing Break Trk Attached

 

I went into the SP dogfight and broke a wing, without a whole lot of effort. Track attached.

Spitfire Wing Break.trk

[zxarkov]

I've read that aerodynamic efficiency was optimized on the spitfire by making the wings as thin as possible with the bumps for the hispanos.

 

Versus a plane like the P-51 with a laminar flow wing, the thickest part of the wing is middle and thinner on the edges, hence probably more durable/less drag right?

Edited January 9, 2017 by zxarkov

[Krupi]

Well I experienced it again, sorry no track it was online :(

 

I was in a shallow dive at around 400-450mph and I pulled up only a few degree to level out and BANG goes my left wing, around half way through the roundel it seems to always be the left wing at the same spot?

 

I am sure there is something not right.

[HeadHunter52]

Well I experienced it again, sorry no track it was online :(

 

I was in a shallow dive at around 400-450mph and I pulled up only a few degree to level out and BANG goes my left wing, around half way through the roundel it seems to always be the left wing at the same spot?

 

I am sure there is something not right.

 

I can bear witness to that. I've broken the wings at the roots (both in a couple of instances), about half way out for both, and funny enough, a lot of left wing snaps at root and half way mark.

 

I can do it without ever blacking out or pushing the tunnel vision very far. I think for now, the fix is to screw with the axis saturation.

[Krupi]

Negative. The in-flight records during simulated or real combat missions were obtained by English during WWII. And the recorded data has no 10 g attempts...

 

Hi Yo-Yo I just stumbled upon this scan from "Spitfire: The History, Morgan Eric" and using repaired wings were able to test them up to 12G.

 

 

Unfortunately I don't have this book myself however I know it is very well known.

[NeilWillis]

All we can say for certain is that the wings fail because code was written to make them fail. Unless you reach the loading at which that happens, the wings won't break.

 

No amount of debate will alter the fact that the designers want them to fail at a given point, and they chose that point after - we hope - careful consideration.

 

We could debate all the factors that affect real wings, whether it be shock loading, sustained or gradual loading, flutter, or anything else. The fact remains that wings can and do fail, and Yo-Yo has decided to make them fail in the module at the point it does for a reason, and unless we have a convincing, and coherent reason to ask for that to change, and can back it up with anything but anecdotal evidence, then his decisions will stand.

 

I'd sooner see them fail than allow absurdly excessive manoeuvres to occur in combat. We just have to find the limits, and stay within them - just as real world pilots have to stay within flight envelopes.

 

It's a question of balance - as we often see people demanding in other threads regarding BFM performances.

[Krupi]

Do you recall the initial release of the 109? It had a very similar issue in that during turns the wings tips would simply rip off, that was fixed and it is no longer a problem.

 

If you want to ignore the issue go ahead, however I refuse to. Until they resolve the issue of the wings failing under relatively benign manoeuvres I will not stop digging up evidence of the contrary.

 

Balance? What on earth does balance have to do with anything this is DCS

Edited January 11, 2017 by Krupi

[NeilWillis]

By all means continue to dig up evidence, as long as it isn't just anecdotal, it will of course be relevant. No, I don't want to ignore it, but who are we to say what is right or wrong unless we have something to back it up with, that's all. I followed the debate over the 109 too. However, the same guy that designed the code for the 109 was probably behind the Spitfire, so lessons learned will of course already have been applied.

 

It is also quite conceivable that there is currently a place holder set of code that may well be getting updated. We have only seen the Beta version so far.

 

There may be a lot we don't know.

[rel4y]

Hey Krupi! Can you check at how many Gs the wings break off? You probably know this already, but its Ctrl + Z twice for me and you can read out the real TAS and Gs of the plane from the bottom bar. Maybe if you have some spare time, could you check the exact Gs the wings fall off? That would be really helpful. I cant buy the Spit until its out of Beta, its not on Steam yet.

[Krupi]

Sure, when I get some time I plan on doing some thorough test and save the tracks.

 

currently I have experienced the issues only online

[firmek]

All we can say for certain is that the wings fail because code was written to make them fail. Unless you reach the loading at which that happens, the wings won't break.

 

No amount of debate will alter the fact that the designers want them to fail at a given point, and they chose that point after - we hope - careful consideration.

 

We could debate all the factors that affect real wings, whether it be shock loading, sustained or gradual loading, flutter, or anything else. The fact remains that wings can and do fail, and Yo-Yo has decided to make them fail in the module at the point it does for a reason, and unless we have a convincing, and coherent reason to ask for that to change, and can back it up with anything but anecdotal evidence, then his decisions will stand.

 

I'd sooner see them fail than allow absurdly excessive manoeuvres to occur in combat. We just have to find the limits, and stay within them - just as real world pilots have to stay within flight envelopes.

 

It's a question of balance - as we often see people demanding in other threads regarding BFM performances.

I fully agree with your point, there may be however other things which could be happening.

1. There is simply a bug in the implementation which causes the wings to fail in situations and/or under stress values that ED didn't plan them to fail.

2. Everything works correctly as ED intended while some assumptions/values might need fine-tuning

3. Everything works as intended and reassembles the historical references as close as possible while we just need to learn handling the Spitfire during structural stress conditions.

Frankly speaking, it'll be probably difficult to arrive into constructive and precise conclusions without input from ED.

[9.JG27 DavidRed]

well,...the spit is very early beta, and as krupi pointed out, the 109 had a similar issue.so its definitely possible that there is an issue.i myself only managed to brake a wing once in the spit, and there it was because i really over-reacted.(jumping between 109 and spit online is quite a challenge in regards of correct inputs)

 

one thing we have to keep in mind are the very very low stick forces on the elevator. in the spit you are able to pull way quicker and way harder on the stick compared to all other ww2 modules. so the same deflection on your home joystick doesnt resemble the same deflection in-cockpit between the modules.and the spit is a special case where it is probably multible times the deflection of the 109 for example. so while its impossible for our 109 pilot to pull enough on the stick to get a certain amount of Gs, its easy for our spit pilot...

 

 

so while i myself didnt have the same problem i had back then with the 109, i already observed a couple of spits online, where it indeed loocked a bit overdone.where they pulled relatively gentle and lost a wing. might be that they pulled hard earlier already, so that there was already some damage done to the wing, but still i wouldnt be surprised if there is indeed a problem.

Edited January 11, 2017 by 9./JG27 DavidRed

[Krupi]

You are right in that perhaps it is a case of a sudden jerky input however I was reading about a spit xi pilot diving to evade me163 and doing a (in his own words) violent 90 degree turn at 500mph, if you tried that in our spit you would turn into a manned propeller powered javelin

 

Here is the article

 

Edited January 11, 2017 by Krupi

[No.54 FatBen KL-F]

 

This video shows the wings beaking at maybe a little over 360mph. A little drastic as higher wing loading should be expected from the 109?