Structural Failure

[Krupi]

 

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?

 

Good video, similar to what I am seeing.

 

You definitely weren't pulling particularly severe manoeuvres either.

[bongodriver]

What might be of significance is the fact it was rolling at the time, rolling g limits can be lower, though it does seem a bit too benign to be ripping the wing off. So far I haven't managed to break a wing...yet.

[SoW Reddog]

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.

 

 

That is possibly the most asinine post I've seen here. By that logic, surely we are at full and final release, because ED would never release a beta product nor one that every single facet hasn't had "careful consideration". However the facts speak for themselves.

 

This IS an issue. End of.

[amazingme]

That is possibly the most asinine post I've seen here. By that logic, surely we are at full and final release, because ED would never release a beta product nor one that every single facet hasn't had "careful consideration". However the facts speak for themselves.

 

This IS an issue. End of.

 

If you are so sure about it, can you show us some real life tests with the exact load out as this guy tested? I'm sure Yo-Yo will take them intro consideration if you had them.

[Krupi]

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.

 

 

For starters..

 

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 12, 2017 by Krupi
[QUOTE=Krupi;3013495]You are right in that perhaps it is a case of a sudden jerky input however I was reading about a spit xi

[Krupi]

The thing that really makes me think this is a bug or incorrect is Aileron reversal, we know this was an issue on the spitfire and we know that it was only truly solved with later mark 21 spitfires.

 

If the wings were breaking at 350-400mph then that would have been a much bigger issue than aileron reversal which was experienced at 580mph... It just doesn't make sense

[Kurfürst]

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...

 

IF there is *any* stickforce on the elevator and ailerons in the beta Spit, that is. The rolling agility, which should be severly curtailed by aileron forces at speed suggest there isn't, and basically you would get instant, linear control input. Meaning that you can probably induce very sudden, momentary g-loads (from even a signal spike in the control input for example) that does overload the airframe and induce a wing failure.

 

Considering that the early beta 109 did not have stickforces modelled and the beta Spits breaking behaviour is suspiciously similar to that, I strongly suspect that missing stick forces could be the culprit.

[9.JG27 DavidRed]

i only checked briefly on release day, and afaik stickforces are modeled only partially,...they are modeled for the ailerons, and they are missing for the rudder..elevator im not completely sure.

[Yo-Yo]

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

 

 

Did you ever try to calculate what Mach number it was if 500 mph is ASI, or what IAS it was if the writer converted to TAS to add dramatic notes?

 

Returning to the book... 800 mph - do you think that this fish has to be truncated a bit? :-)

[Anatoli-Kagari9]

IF there is *any* stickforce on the elevator and ailerons in the beta Spit, that is. The rolling agility, which should be severly curtailed by aileron forces at speed suggest there isn't, and basically you would get instant, linear control input. Meaning that you can probably induce very sudden, momentary g-loads (from even a signal spike in the control input for example) that does overload the airframe and induce a wing failure.

 

Considering that the early beta 109 did not have stickforces modelled and the beta Spits breaking behaviour is suspiciously similar to that, I strongly suspect that missing stick forces could be the culprit.

 

That! And the - Star Wars-like - pitch / turn rates I can achieve when pulling my stick during a dogfight to turn into a foe that just passed in the opposite direction... All of a sudden I am flying 180º away from my initial direction, and behind him as if there was no gravity, control force, ...

 

It's the early-beta effect I believe :-)

Edited January 14, 2017 by jcomm

[Krupi]

That! And the - Star Wars-like - pitch / turn rates I can achieve when pulling my stick during a dogfight to turn into a foe that just passed in the opposite direction... All of a sudden I am flying 180º away from my initial direction, and behind him as if there was no gravity, control force, ...

 

It's the early-beta effect I believe :-)

 

I would like to hear confirmation on any truth to this.

 

We know that the stick forces on the spitfire were very light, at least on the elevator, so perhaps it is already modelled.

[Solty]

That! And the - Star Wars-like - pitch / turn rates I can achieve when pulling my stick during a dogfight to turn into a foe that just passed in the opposite direction... All of a sudden I am flying 180º away from my initial direction, and behind him as if there was no gravity, control force, ...

 

It's the early-beta effect I believe :-)

 

109 does that all the time. One second you are behind her, then suddenly she's flying perpendicular and you can't pull lead.

Edited January 16, 2017 by Solty

[amazingme]

109 does that all the time. One second you are behind her, then suddenly she's flying perpendicular and you can't pull lead.

Not really..

[Krupi]

Did you ever try to calculate what Mach number it was if 500 mph is ASI, or what IAS it was if the writer converted to TAS to add dramatic notes?

 

Returning to the book... 800 mph - do you think that this fish has to be truncated a bit? :-)

 

HI Yo-Yo,

 

I forgot to respond to your post, apologies.

 

I completely agree that any pilots account is up for debates given the potential difference in TAS and IAS, this document shows that the spitfire was supposedly able to go to ~600mph in a dive.

 

http://www.spitfireperformance.com/sd2011.jpg

 

Yet in DCS if we get anywhere above 350-400 and try to use the ailerons, even slightly, our wings rip off! No one has yet confirmed if this is how it should act or not?

 

Truncated yes, but that means they were still attached to the aircraft. ;)

Edited January 16, 2017 by Krupi

[Tomsk]

Considering that the early beta 109 did not have stickforces modelled and the beta Spits breaking behaviour is suspiciously similar to that, I strongly suspect that missing stick forces could be the culprit.

 

Yeah, I've thought that ... it seems quite similar to the beta 109 without stick forces. Which is to say you maybe wouldn't be able to break the wings in real life because you wouldn't be able to pull hard enough to do it ... but perhaps in the DCS version you currently can. It's a good theory. Does anyone know if stick forces are supposed to be modeled for the Spit already?

[Hiromachi]

I actually have recorded 4 videos in game, in quickflight alone just trying to repeat what someone posted ~2 pages before when he dove on 109 and broke his wings at speed around 320-340 mph. I have slight curve on my stick but nothing great, also some of the videos are in slow-motion which allowed me easier to keep an eye on G's (even at speed decreased its still extremely rapid G increase with stick deflection at given speed).

 

 

 

At this attempt I did not break my wings but managed to black out:

 

 

Take a notice of speed, G load and AoA.

 

I'd do more tests but dont have time right now (RL, work, that kind of stuff you all know :) ) so might come back to it later. For the moment I think that acceleration not to exceed is set around 10 G, at some points one can reach 10.9 G or so but in general flying close to that load is extremely dangerous. But the problem is there is no way to track that in actual game at all, there is no gauge in cockpit to help us with that and its damn easy to pull those 10 G's even at relatively moderate speeds (and as you can see it happens faster than even pilot feels or notices it as no blackness was experienced until very late !). Little stick movement at wrong speed and bam, our wings go off even without thinking its that easy.

Personally I think I am going to reduce sensitivity further, it will affect maneuverability but should improve my precision with that aircraft and reduce chances of disassembling aircraft midair.

 

I should try to dive at much greater speed and yank that elevator as hard as I can and see if I can hit 20 G. I bet above 20 G pilot transfers via osmosis through cockpit floor :helpsmilie: :megalol:

[rel4y]

It sustained 10.8 Gs on the 3rd video. That sounds pretty good for dynamic loads. I guess you really have to be careful with that elevator... Good tests! Thank you very much! +1

[Hiromachi]

It sustained around 10 G's, it was jumping up and down around that number as I was trying to keep the load delicately moving stick. Yes, that is pretty ok. I dont know ultimate G load designed for this airframe but would expect it in 10-13 G ballpark.

However I sustained that in two times deacceleration (pressed twice button combo to reduce game speed) for a brief time, in normal speed that would be split seconds. It's pretty damn hard to do that in normal speed since its so easy to reach that load to separate wings from fuselage.

 

I really wonder if that was the case in reality, so one could so easily break his wings - thousands of pilots flew those warbirds and I cant recall any unusual numbers of wing failures or airframe overstressing. Hell, I even know folks who flew Spitfire in Vintage Wings of Canada and never heard anything of extremely delicate elevator handling. If that was the case in reality than I will consider from now on Spitfire as an aircraft dangerous to its own pilot :)

 

Now I do consider that we use short sticks with different deflection range which cannot so easily reflect the movement of actual thing - hence why some of us use cheaper way by adjusting curvature and sensitivity, while others spend money on extensions. But still, Spitfire must be flown with great care.

[Krupi]

Awesome Hiromachi, thanks for taking the time to share your videos.

 

I agree I have never read anything on structural failure as it is modelled in DCS, I have read about the low elevator forces and how this led to overstressing of the aircraft and damage to the skin I have never read anything on the wings falling off bar one well known incident that was found to be fatigue damage presumably because the aircraft had been overstressed.

 

There were some issues with MkV that turned out to be systems being installed incorrectly and drastically shifting the COG leading to catastrophic failure however this was addressed.

 

Perhaps stick forces are not fully modelled or the blackouts not working correctly, whatever the reason something feels very off.

 

I have an extended stick, nothing like the length of the actual one however I am very interested to see what this will perform like once it is finished :D

 

Edited January 17, 2017 by Krupi

[Krupi]

Interesting information in this book...

 

https://books.google.co.uk/books?id=b1g7AwAAQBAJ&pg=PT345&lpg=PT345&dq=spitfire+structural+failure&source=bl&ots=DeWbyANCw6&sig=h-wTRuzMYZfg9_wx6ZDqzwfoofk&hl=en&sa=X&ved=0ahUKEwiSweSY3cjRAhXE6CwKHScaCKIQ6AEIJjAC#v=onepage&q=spitfire%20structural%20failure&f=false

[Hiromachi]

That stick you build up there puts my new joystick into shame. Damn Krupi. I hope when you make it you will record a video with review and experiences, wonder if it will be worth it to pursue such thing myself.

 

In regard to that book ... if thats exactly the case, 10 G ultimate (although as quoted before on that picture, Farnborough established that wings did not break even at loads close to 13 G) then I wonder why people call Zero flimsy when it had sturdier wings than Spitfire :)

Excuse for absence of accelerometer is truly amusing. One would argue that same rule could be applied to armor or fuel tank protection.

 

Also, does anyone have the following book ?? : https://www.amazon.co.uk/Secrets-Spitfire-Shenstone-Perfected-Elliptical/dp/184884896X

I wonder if this one could contain any interesting data for us.

[Krupi]

I brought the spade grip some time ago but was just using it as a normal grip on top of my Warthog along with my tarmac aces KG13 grip, however given the difference in the forces and the unique design of the British control columns

I decided to make a 1:1 replica.

 

I am hoping I can get it all plugged in for a quick test by the end of the month, however it will only be using testing dampers I will have to wait a few weeks for the proper dampers to be delivered.

 

Nice find can't say I have heard of that book! Might be worth a purchase.

 

Regarding the 13g testing l would like to see some more details on how they tested it.

[MAD-MM]

You can open the Input Window in Flight, still the Rudder have no Stick Force at all able to move in full deflection at any Speed, the Aileron produce stick forces.

Elevator you can pull full deflection at any Speed.

Remember 109 Thread where rolling in a dive also add Force to the Wings with elevator Pressure, probably Stickforce help with this issue but could also something wrong.

[Yo-Yo]

I brought the spade grip some time ago but was just using it as a normal grip on top of my Warthog along with my tarmac aces KG13 grip, however given the difference in the forces and the unique design of the British control columns

I decided to make a 1:1 replica.

 

I am hoping I can get it all plugged in for a quick test by the end of the month, however it will only be using testing dampers I will have to wait a few weeks for the proper dampers to be delivered.

 

Nice find can't say I have heard of that book! Might be worth a purchase.

 

Regarding the 13g testing l would like to see some more details on how they tested it.

 

 

It was a static test on the special test machine - the wing was loaded with a complicated system of links that simulated lift distribution. The structural damages were examined after the test.

 

The test was conducted for a GW of 6200 lb

The proof load for this mass is 9/1.2 =7.5

9 g and then 10 g were applied without permanent measured deformation.

The failure began at 11.5 and leaded to full structural failre at 12.3 - 13 g depending on load distribution.

So, the ultimate destructive load is not more than 13 g for 6200 lb.

Then, let's calculate the limits for 7400 lb. that is 19% higher than 6200

Proof load = 6.3

Elastic load 10/1.19 = 8.4

Start of failures 11.5/1.19 = 9.6

Destructive 13/1.19 = 10.9

 

 

Be careful...

 

And do not forget - any your trip to the dangerous zone lowers the ultimate g value...

 

 

By the way, your statement about the ailerons leading to wing failure is wrong - see the screenshot, the wings are ok...

Probably, you add unwanted pitch input.

Edited January 17, 2017 by Yo-Yo

[Krupi]

Interesting, thanks for taking the time to provide a detailed response Yo-Yo always good to peak behind the curtains to see how you make decisions.

 

Fascinating to see that the static testing is still done in a similar manner today, I was expecting the test to have been a bit more archaic. I suppose if we are honest we are still essentially using the engineering principles developed by these chaps in the 40's, 50's & 60's...

 

I would expect to see and feel a bit more from the pilot and aircraft before I got to 10G, are the effects still being worked on & are the stick force's fully implemented yet?

 

You could be right about the elevator input, my stick is currently not screwed down.