Messerschmitt 109 durability

[Kurfurst]

According to the update notes, currently it is modelled as less durable than two spar designs because... unspecified reasons. 

 

A relevant source from A I R C R A F T E N G I N E E R I N G,  May, 1942, questions the validity of this damage model.

 

A German Report on Effects of Damage*

 

The Me 109 THE aircraft produced by the Messerschmitt company- are well known- for their particular type of construction, the characteristic feature of which is the single wing-spar and stressed skin. The bending forces are, to a great extent, absorbed by the spar and the torsional forces by the covering, which forms a torsion tube. This light and exceptionally rigid construction of the monospar wing was supposed to be inferior to the two-spar wing with regard to resistance to bullets. Experience gained from many operational flights, even under the most intense fire, docs not, however, in any way confirm this view. The first point of interest was the effect of damage to the spar on the strength of the wing. Bullet holes through the sheet-metal spar-web, and even through the web stiffeners, have no

disastrous effect on the strength of the spar, as even when weakened by bullet holes it showed no deformation ; since, with solid members, such perforations cannot interrupt the lines of force, especially when the bullet leaves a flange in the sheet around the hole (Fig. 1). Damage to the flange of the spar is not so serious in effect, because the total bending moment is not absorbed by the spar in the  case of stressed skin construction (Fig. 2). Bullet holes in the upper and lower covering of the wing, even when the bullet hits the  stiffeners, have no effect on the transmission  of the torsional moment, since the entire skin takes part in its absorption in the Messcrschmitt type of construction. The distribution of the longitudinal forces in the fuselage, which are supported by the skin as well as the  longitudinal stringers (profile sections), makes.it possible for the fuselage to suffer considerable damage without endangering the aeroplane (Fig. 3). The repairs to be undertaken are generally simple owing to the straightforward design. In the case of damage to the main components (spar and skin}, the linear design of the wing makes it easier to decide on the type of repair than it is with two-spar wings, since then, in the repair of the damage, it is necessary to take into account the conditions of rigidity governed by the repair method.

[Kurfurst]

French summary report on captured Bf 109E-3, Wing structure. Noted is the considerable thickness of plates, webbing and spar plates used.

 

 

109F flutter analysis by US Material Command, Bf 109F notes "wing torsional rigidity compares favourable with that of a similar AAF Pursuit Plane" (referred to as "Weight Bench Key 26A" in the report - its quite possibly the P-40)

 

 

 

Wing structure further strenghtened in Bf 109G type - "verstaerkter Fluegel - Holm, Rippen, Belplankung" (i.e. reinforced wings - spar, ribs and sheet cover)

 

Edited December 6, 2017 by VO101Kurfurst

[=EXPEND=13SchwarzeHand]

Anyone going to post something to the Devs?

 

If you haven´t I will

[=RvE=Windmills]

Can you make a more complete argument? I feel like I'm putting a puzzle together of various docs that don't necessarily seem to talk about the exact same thing.

[Kurfurst]

Yes, sorry about that. It was getting a bit late.

 

The point is the damage model, as I recall from the dev notes the current model bases the durability of aircraft wings on a preferencial model. IMO it is quite wrong in that it incorrectly assumes weaker wing structure/durability in the 109 models.

 

The posted documents detail the actual structural characteristics of the 109 wing which indeed used a single spar design, but its strenght came from not only the spar but the use of unusually thick aircraft skin and thicker internal stiffeners and longerons, and whole wing forms a single large load bearing torsion box.

 

The current model ignores this and basically punishes types like the 109 (Btw the Spit is somewhat similar as its a single spar design with D-shaped torsion box structure with thicker skin between the leading edge and the spar) for being made of metal and for achieving the same structural strenght with a single spar and advanced light construction techniques.

 

AFAIK the current damage model increases the durability of the wing if they are made of (Stalin)wood (+20% durability), or they have two spars (+20% durability), the durability increases.

 

Frankly this is somewhat of a WW1 view on things as aircraft structures become quite complex in WW2 as the aircraft skin formed an integral part of it and it wasn’t relyiant on Just the number of spars anymore.

 

Simply to put, the current durability model is greatly unfair to the 109.

 

The actual construction factors that materally contribute to the resilence of the wings, namely that self-bearing structures have a lot of alternate load paths, is ignored, and the whole damage model’s sold preference for wood and multiple spars is essentially singles out the 109 to have far less durable wing structure, which is a false assumption imo and is part of the issue why we see so much more wing bucklings on the 109 when a Soviet guns as much as touch them.

 

(the other part of the issue is the appearant preference to AP/kinetic energy in the damage model, but this is the subject of several other threads)

 

While its rear fuselage was certainly not a heavy duty build, the wing certainly was, as indicated by the posted documents and studies.

 

And Btw the first post on the damage test points out why the ‘wood is better from the damage resilence’ standpoint is dubious at best. In these test hits on single metal spars were largely ineffective.

[Barnacles]

Yes, sorry about that. It was getting a bit late.

 

The point is the damage model, as I recall from the dev notes the current model bases the durability of aircraft wings on a preferencial model. IMO it is quite wrong in that it incorrectly assumes weaker wing structure/durability in the 109 models.

 

The posted documents detail the actual structural characteristics of the 109 wing which indeed used a single spar design, but its strenght came from not only the spar but the use of unusually thick aircraft skin and thicker internal stiffeners and longerons, and whole wing forms a single large load bearing torsion box.

 

The current model ignores this and basically punishes types like the 109 (Btw the Spit is somewhat similar as its a single spar design with D-shaped torsion box structure with thicker skin between the leading edge and the spar) for being made of metal and for achieving the same structural strenght with a single spar and advanced light construction techniques.

 

AFAIK the current damage model increases the durability of the wing if they are made of (Stalin)wood (+20% durability), or they have two spars (+20% durability), the durability increases.

 

Frankly this is somewhat of a WW1 view on things as aircraft structures become quite complex in WW2 as the aircraft skin formed an integral part of it and it wasn’t relyiant on Just the number of spars anymore.

 

Simply to put, the current durability model is greatly unfair to the 109.

 

The actual construction factors that materally contribute to the resilence of the wings, namely that self-bearing structures have a lot of alternate load paths, is ignored, and the whole damage model’s sold preference for wood and multiple spars is essentially singles out the 109 to have far less durable wing structure, which is a false assumption imo and is part of the issue why we see so much more wing bucklings on the 109 when a Soviet guns as much as touch them.

 

(the other part of the issue is the appearant preference to AP/kinetic energy in the damage model, but this is the subject of several other threads)

 

While its rear fuselage was certainly not a heavy duty build, the wing certainly was, as indicated by the posted documents and studies.

 

And Btw the first post on the damage test points out why the ‘wood is better from the damage resilence’ standpoint is dubious at best. In these test hits on single metal spars were largely ineffective.

Good work, another point to note if they revisit the more spars=tougher plane equation it might also make the pe2 a bit less 'indestructible'.

[=gRiJ=Roman-]

Great job Kurfurst!    

I also think that the FM from the 109 is not finished yet by the way. Much better with the latest patch but still some research and the following modifications must be done.

[=RvE=Windmills]

(the other part of the issue is the appearant preference to AP/kinetic energy in the damage model, but this is the subject of several other threads)

 

I do feel this is by far the largest factor contributing to this, if AP didn't have the capability of dealing structural damage like it does we'd have a really different DM. Especially considering AP is just more common against 109s than the other way around.

 

 

 

In these test hits on single metal spars were largely ineffective.

 

Though it refers to 'bullet holes', we're usually talking 20mm HE ingame. Does distributing the load across the wing really still matter when the one and only spar gets a big chunk taken out of it, can the rest of the structure take over and allow the wing to continue to take serious G? That is, would your reasonably expect this arrangement to hold up as well as additional spars would?

 

Or again, alternatively, does this suggest that it's more durable than multiple spars or just more durable than a normal single spar construction?

Edited December 7, 2017 by Windmills

[Dakpilot]

"unusually thick aircraft skin and thicker internal stiffeners and longerons,"

 

Perhaps it would be of greater use to compare the unusually thick 1-1.5mm wing aircraft skin to some other contemporary aircraft to give some context.

 

I have vague memories of Mustang being 1.9mm and P-47 being 1.63mm, but don't take these as solid facts

Does anyone have figures for other aircraft? And what alu/dural types were used?

 

Cheers Dakpilot

[Kurfurst]

IIRC its 0,8 mm on the Spitfire for most of the wing, except for the leading edge "D" shaped torsion box where its was either 1,5 or 2 mm thick and served as load bearing element (and as remnant from the original evaporative cooling system originally there). Strictly from memory.

 

Wiki describes the fuselage sheets as varying between 24 - 18 gauge (0,51-1,02 mm).

Edited December 7, 2017 by VO101Kurfurst

[=EXPEND=Tripwire]

Here is a cherry picked example of 109 durability issues. I have lots of cherries to choose from though.

4x 109s destroyed for just 9 ShVAK hits. The 109 that destroyed this plane required to make 27 hits to do the job.

 

[III/JG52_Otto_-I-]

Yes, sorry about that. It was getting a bit late.

 

The point is the damage model, as I recall from the dev notes the current model bases the durability of aircraft wings on a preferencial model. IMO it is quite wrong in that it incorrectly assumes weaker wing structure/durability in the 109 models.

 

The posted documents detail the actual structural characteristics of the 109 wing which indeed used a single spar design, but its strenght came from not only the spar but the use of unusually thick aircraft skin and thicker internal stiffeners and longerons, and whole wing forms a single large load bearing torsion box.

 

The current model ignores this and basically punishes types like the 109 (Btw the Spit is somewhat similar as its a single spar design with D-shaped torsion box structure with thicker skin between the leading edge and the spar) for being made of metal and for achieving the same structural strenght with a single spar and advanced light construction techniques.

 

 

From the monographic magacine about the Bf-109 by Tim Callway  about the wing construction:

 

""The Bf-109 wing spar was a single I-beam spar forming a torsionally rigid

D-box with the ribs and monocoque skin to the leading edge.""

 

You are right Kursfurst,  the D-box works like a wide spar byself..

Edited December 7, 2017 by III/JG52_Otto_-I-

[Barnacles]

Here is a cherry picked example of 109 durability issues. I have lots of cherries to choose from though.

4x 109s destroyed for just 9 ShVAK hits. The 109 that destroyed this plane required to make 27 hits to do the job.

 

Capture5.PNG

 

I would say that this is to be expected as the Dev's have stated that the 109 is programmed to be have more fragile wings to the tune of (1)  20% for having a single spar wing and (2) 20% for not being wooden. I'd say that Kurfurst's OP contradicts the logic of (1) definately and (2) maybe.

[Blutaar]

Heresy.

[Tuesday]

Here is a cherry picked example of 109 durability issues. I have lots of cherries to choose from though.

4x 109s destroyed for just 9 ShVAK hits. The 109 that destroyed this plane required to make 27 hits to do the job.

 

Capture5.PNG

"This block may contain incorrect information, this is due to errors in the game log"

 

I think in-game footage should accompany the website stats if you want to try and use it as proof.  Did he have wingmen?  Did he get insanely lucky and score four pilot kills?  Was he stealing kills?  Doesn't take much to take the credit for an already destroyed plane...

 

Very doubtful that he actually scored 4 kills with only 9 cannon hits unless he had a golden four-leaf clover up his arse.

[=EXPEND=Tripwire]

"This block may contain incorrect information, this is due to errors in the game log"

 

I think in-game footage should accompany the website stats if you want to try and use it as proof.  Did he have wingmen?  Did he get insanely lucky and score four pilot kills?  Was he stealing kills?  Doesn't take much to take the credit for an already destroyed plane...

 

Very doubtful that he actually scored 4 kills with only 9 cannon hits unless he had a golden four-leaf clover up his arse.

 

 

Did he have wingmen?   - yes

Did he get insanely lucky and score four pilot kills?  No pilot kills, all planes destroyed.

Was he stealing kills?  - no

Doesn't take much to take the credit for an already destroyed plane... - none of the 4 planes shot down in that sortie had received any damage prior by other players. Unless as you say the stats page is lying. That reference is more in line of the number of rounds shot when you loose your plane. It doesn't know how many were fired so it counts all as fired.

Stinky four leaf clover almost confirmed...

 

Your right, no video (I rarely remember to record tracks) - but the list of 'you must have some other <insert request for more proof here>' would have continued anyway.

Edited December 10, 2017 by =TBAS=Tripwire

[Tuesday]

Did he have wingmen?   - yes

Did he get insanely lucky and score four pilot kills?  No pilot kills, all planes destroyed.

Was he stealing kills?  - no

Doesn't take much to take the credit for an already destroyed plane... - none of the 4 planes shot down in that sortie had received any damage prior by other players. Unless as you say the stats page is lying. That reference is more in line of the number of rounds shot when you loose your plane. It doesn't know how many were fired so it counts all as fired.

Stinky four leaf clover almost confirmed...

 

Your right, no video (I rarely remember to record tracks) - but the list of 'you must have some other <insert request for more proof here>' would have continued anyway.

 

It's tough to please everyone

[wonders9]

It's tough to please everyone

 

It's not about pleasing anyone. It's about being as realistic and historically accurate as possible. 

[=EXPEND=13SchwarzeHand]

Sorry to ask again, but has anyone filed something to the devs? I think GridIron made a good point.

[SYN_Haashashin]

OP knows very well how to get the info to the devs, other than that...next post out of line and I will lock this.

[=EXPEND=13SchwarzeHand]

OP knows very well how to get the info to the devs, other than that...next post out of line and I will lock this.

Well thanks, but I asked whether he did it or not

[CUJO_1970]

OP knows very well how to get the info to the devs, other than that...next post out of line and I will lock this.

 

This thread is hidden away in FM discussion.

 

Where, exactly, are we supposed to talk about this stuff?

[Dakpilot]

This is the FM section it is not hidden away, there are thousands of posts here discussing lufwaffe aircraft, the above post is exactly why topics get closed.

 

There is no new info in the OP's first two posts, other than, unsubstantiated, somehow suggesting to some mindsets that a 109 should be as strong as a 1 ton heavier P-40, even the claim of 'unusually' thick skin is now edited out.

 

If an unnamed 'engineer' saying bullet holes in spars and ribs don't cause any damage or weakness is cause for reports for dev's to take time and attention then heaven help us. The revelation that a box section is used (just like every other wing) is also not really news

 

Cheers, Dakpilot

[Dakpilot]

If you cannot see the difference in the incorrect L/D ratio debacle and informing the dev's that the Bf-109 has a box section in the wing then I will not accuse you of using (hate the term) a straw man argument.

 

It is not that I am saying there is nothing wrong but the docs posted say nothing of any note.

 

We have the quote of Russian Stalinwood and a general call for a tougher 109 because bullets don't weaken the spars or ribs, and a hinted suggestion that it should be as strong as a P-40

 

Cheers, Dakpilot

[=EXPEND=13SchwarzeHand]

We have the quote of Russian Stalinwood and a general call for a tougher 109 because bullets don't weaken the spars or ribs, and a hinted suggestion that it should be as strong as a P-40

 

Nobody is saying that bullets dont weaken the spars. It is the extend to which wings are torn off a 109 that is far from plausible. I invite you to join MP from time to time to experience it yourself. I think that you are not aware that people do not call for the 109 to be as tough as a p-40, when they criticize the current DM.

Edited December 12, 2017 by II/JG17_SchwarzeDreizehn

[Dakpilot]

Of course people are not calling for that, but the P-40 reference is in this thread, used as evidence to forward the argument/debate.

 

The reference of bullet damage from the unnamed engineer also does nothing to further the argument

 

Cheers, Dakpilot

[Kurfurst]

We have the quote of Russian Stalinwood and a general call for a tougher 109 because bullets don't weaken the spars or ribs, and a hinted suggestion that it should be as strong as a P-40

 

Cheers, Dakpilot

 

Nobody is calling for the wing to be as durable as i.e. the P-40, but the current situation is that you can de-wing the 109 ridiculously easily.

 

In former the patch notes, it appeared to me that as if the Devs are using some sort of universal 'durability meter", where the more spars there is in a wing, the better, or if there is wood used in the wing, its still better for durability. In this reasoning the 109 consistently ends up being in the wrong end of the stick, since it only has one spar - but this does not appear to take into account the peculiarities of the 109 construction, it simply handles it as all things being equal, but this one has only one main spar instead of two, therefore it should be weaker.

 

The intent of this thread is to show that such reasoning is incorrect, by showing with various historical documents how the 109 wing is actually built up - in this design, there is only one main spar because the load bearing element is not only the spar, with only very thin dural sheets as common on other designs, but the designers also used unusually thicker dural plating/sheets that ALSO bear the loads on the wings.

 

You could say that its basically the main spar, housed in another "spar" (or load bearing element) that is the wing sheeting and structure itself. Here again the difference with other designs is the use of thicker plating that can bear loads better.

 

Secondly, the article in the first posts shows that simply going by the number of spars in the wing is not a perfect approach since live trials showed that damage, holes to the main spar effects the wing structure negligibly, at least in the Messerschmitt type wing structure.

[Kurfurst]

A couple of good close ups of 109E wing.

 

 

 

 

[Dakpilot]

What is Messerschmitt type wing structure? It looks pretty conventional to me,

Willi Messerschmitts lightweight construction is well known and documented.

 

Personally if I had a choice I would take two full width spars any day, the thought of a burst of mg/hmg or cannon on the attachment points would scare the hell out of me, I'd rather take an FW.

 

It would be good to see the results of the 'live trials' that show damage to spar does not really effect the structure more than an alternative 'type of wing?'

 

I just remain unconvinced, if in early 30's this 'type' of wing had such good weight to strength capability everyone would have used it

 

Cheers, Dakpilot

[9./JG27MAD-MM]

How can you assume a Wing with to Wings Spars is still intact after it lost one of the Spars or attachment Points do enemy Fire?

Probably the Structure will still collapse because the Wing is not designed  to overcome the Bending and lift Force with one remaining Spar the outcome would be the same...

Making a decision about Spars how many Damage it can take is really arcade style would really like to see DEV mathematical Conclusion about deformation to the breaking Point or different angels of point of Impact ammunition is used so on....

[Holtzauge]

 The notion that the Me-109 should be extra strong due to exceptionally thick wing skin does not seem to be borne out if you look at this report:

 

“In the Me-109, the skin varies between 17 and 22 gauge, and so when judged by our standards is thin” (British gauge 17 Al =1.15 mm and 22 gauge = 0.64 mm)

 

Fw-190 had according to the same source between 14 gauge = 1.63 and 18 gauge =1.02 mm. This was commented in the same report as “is heavy when compared with British practice”

 

Source: The Aeronautical Journal 1944, Structural Features of German Aircraft, D. Leggit PhD and H. Davison Bsc. (Page 174).

 

Note that this report shows that the British did a very thorough job measuring the wing skin thickness since they measured every individual wing plate (See attached Fw-190 figure). Also note that the wing skin thickness figures for the Me-109 given in the report are for the F version not the E version as in post #2.

 

In addition, it should be noted that the Aircraft Engineering quote in the OP is a translation from an article in Flugwher und Technik which in turn based their article on information supplied by Messerschmitt themselves who not surprisingly were of the opinion that their design was good in respect of absorbing battle damage.

 

However, just like Dakpilot pointed out above, there is nothing unconventional about the Me-109 in terms of structural engineering in that the wing skin not only takes torsional loads but also bending loads. This is just sound design practice and all all-metal winged fighters like the Spitfire, Mustang Fw-190 etc did the same so no news there either.

[Kurfurst]

Which report, I cannot see it, unfortunetely. I can see the French report though, which is at odds with your claims.

[Holtzauge]

Fourth line in my post: Source: The Aeronautical Journal 1944, Structural Features of German Aircraft, D. Leggit PhD and H. Davison Bsc. (Page 174).

 

Also note that the French report is for the Me-109E while the figures I posted are for the F version.

[Kurfurst]

Alas, it is such a pity we are not allowed to see for ourselves what it actually says. 

[Holtzauge]

Are you implying something?

[Kurfurst]

I doubt its an implication rather the statement of a fact - i.e. you are unable or unwilling to add to that discussion anything than about half of an unverifiable sentence.

[Holtzauge]

Amiable as always, and true to form, when fact's (in this case that the Me-109 wing skin was not exceptionally thick like you claimed) you can always attack the messengers credibility. In fact what I quoted is perfectly verifiable: I cited a source and even the page number. The report is 35 pages long and if you believe that I misquoted it why don't you buy the report yourself?

[Kurfurst]

Amiable as always, and true to form, when fact's (in this case that the Me-109 wing skin was not exceptionally thick like you claimed) you can always attack the messengers credibility. In fact what I quoted is perfectly verifiable: I cited a source and even the page number. The report is 35 pages long and if you believe that I misquoted it why don't you buy the report yourself?

 

Well, if there would be any credibility to be attacked...

 

Secondly, nobody said it was exceptionally thick. That's a straw man.

 

Thirdly, the French upon inspection certainly thought it worthwhile however to highlight and dedicate a whole paragraph to the 'considerable' thickness of the covering used in the construction, which is BTW clearly visible from up close. In other words, its certainly thicker than some (Spitfire, for example), and perhaps thinner then others. The wing's design quite consciously built on exploiting this considerable thickness of the cover plates to enhance the wings strength. And of course it may vary in depth, and the detachable wingtips may well be just 0.5 mm thick electron. In any case, the French report is quite clear on this so therefore I must conclude that the numbers you have posted are simply incorrect.

 

 

[Edited]

Edited December 13, 2017 by Bearcat

[Holtzauge]

Well, if there would be any credibility to be attacked...

 

Secondly, nobody said it was exceptionally thick. That's a straw man.

 

Thirdly, the French upon inspection certainly thought it worthwhile however to highlight and dedicate a whole paragraph to the 'considerable' thickness of the covering used in the construction, which is BTW clearly visible from up close. In other words, its certainly thicker than some (Spitfire, for example), and perhaps thinner then others. The wing's design quite consciously built on exploiting this considerable thickness of the cover plates to enhance the wings strength. And of course it may vary in depth, and the detachable wingtips may well be just 0.5 mm thick electron. In any case, the French report is quite clear on this so therefore I must conclude that the numbers you have posted are simply incorrect.

 

French_109Wing.jpg

 

[Edited]

 

Well I think the way you compiled your post speaks for itself and says more about you than me actually. What I posted was directed to the other forum members to provide some alternative input and I leave it up to them to decide who is credible or not. I know from experience that arguing with you and Crumpp is pointless so with that I’m pulling the handle on this discussion.

[1_Robert_]

Back to original topic, I have two questions in regards to the 109's fuselage. I've noticed on the rear of the fuselage just before where the vertical stabilizer begins is a comman break point when receiving MG fire. It seems to be right where the "ribbing" of the fuselage ends. Was that a known weak point?

 

Second, I believe I read somewhere that the E and older models had struts on the horizontal stabilizers and the F version got rid of them. Is this modeled in the game?

 

Thanks