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Stafroty

AP vs HE ammo comparizon/calculations

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Stafroty, you might find the following files interesting:

 

The first one is a US report on the effectiveness of various calibers against P-47s and B-25s. You can get it here: http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA800394

It basically says that 20mm minengeschoss (and 30mm) are most likely to get their rear-attack, near-instant kills on bombers through structural damage, and to get their rear-attack slow kills from either structural or fuel damage. .50 cals, on the other hand were most likely to get their kills through pilot or fuel damage. 

 

The second document is here (sorry, best link I could find): http://www.mediafire.com/download/2qp95d04r5z7azl/german+fighter+damage+from+50+cals.pdf

It is a translation of German testing data. It talks about the effects of .50 cal hits (I believe - I can no longer find the full document, but it is specifically discussing bullet holes rathers rather than cannon shell holes). Regarding hits against the main spar of a Bf 109, it says:

u1GSLPd.png

 

Essentially, the 109 (and I believe many other fighters) have stressed skin construction. This means that the skin of the wing is in tension and is ready and able to take much of the load, should the spar flange be damaged. Furthermore, the spar itself can have large holes in it and suffer no ill effects. I once posted a picture of a 109 prototype wing where the cannon was housed inside the wing. To do this, the main spar had a huge hole cut in it (really, there was barely any height of material left at the widest point of the hole), yet the design still flew fine and did not rip its wings off.

Also, you asked about what the spar was made of - it's duralumin (so are the ribs and the skin). I don't think many WW2 aircraft had steel structures.

 

Really, it seems that AP rounds do most of their damage through causing fuel leaks or fires and killing or wounding the pilot. Structural damage kills are very common with explosives, but much less common for AP rounds, in general. Fighters were designed to be able to take some hits and still fly back. I'm still always shocked when pro-.50 people insist that US .50s must have been able to kill pilots through armor, must have blown off wings after several hits and would have left huge ragged holes in the skin. The reports from both the US and the Germans indicate otherwise for the latter two points. As for the first point, common sense would indicate that rather than increasing the armor of the cockpits if it had no effect, they'd just remove it (save weight; why add more weight if it won't stop the weakest round you regularly face?).

Edited by Jaakariliike
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i agree jaakariliike. And i believe many others agree as well.

 

What is true is that plane cannot fly if it only has its internal stuctrures (skeleton) left. there is no surface which is making the light, but just shapes which resist the airflow.

 

This is true especially true with HE hits from cannon. Of course, every size hole matters, protortionally to their size.

 

it is easy for everyone to test, just put your hand out of car window while its moving on motorway. first keep fingers closed and its a fist.  then open the hand, so its totally flat against the wind. there is much more resistance on it then. fold few fingers and resistance gets smaller. compare the effects with amount of fingers. This very same applies to aircraft and their skin damage.

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p-51_mine.jpg

 

I just love how you scaled up the size of the hits to the bomber, when the P-51D image is smaller scale.

 

Totally a sign of a good poster to make epic mistakes like that.

 

 

 

P51s were quite fragile.

 

P-51s were only fragile because of the inline engine.

 

Their structure was as over-engineered as nearly every other American built plane, so they were actually quite durable.

Edited by Cuteling
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P-51s were only fragile because of the inline engine.

 

Their structure was as over-engineered as nearly every other American built plane, so they were actually quite durable.

 

Eh, the radiator was hilariously vulnerable on the P-51 (probably its most vulnerable part followed by the engine), and the P-51 actually wasn't as structurally over-engineered as "nearly every other American built plane."

 

The P-51 was the first one to get rid of a lot of the over-engineering, but it was still a structurally sound plane compared to most of its competition.  It was still a very heavy, durable, long range plane.  A requirement when you're trying to provide bomber escorts over Berlin when launched from England, while being able to retrieve the plane without losing the pilot for any reason.

 

It was still significantly stronger than a Spitfire, though, and no one can touch the Zero or many other Japanese planes for raw lack of durability, but that's the price Japan paid for ultra-lightweight planes made out of an aluminum alloy that was known for being exceptionally fragile from impact stress (I.E. it tended to fracture when impacted instead of dented or deformed).

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Eh, the radiator was hilariously vulnerable on the P-51 (probably its most vulnerable part followed by the engine), and the P-51 actually wasn't as structurally over-engineered as "nearly every other American built plane."

 

Reputedly, a single 7.92mm to the radiator was frequently enough to down the plane.

 

 

 

The P-51 was the first one to get rid of a lot of the over-engineering, but it was still a structurally sound plane compared to most of its competition.  It was still a very heavy, durable, long range plane.  A requirement when you're trying to provide bomber escorts over Berlin when launched from England, while being able to retrieve the plane without losing the pilot for any reason.

 

IIRC, some of the structural lightening done in the P-51F/H was removal of the need for lateral 2G tolerance, and lowering of the landing gear deceleration requirements.

 

The XP-51F ended up some 1600 lbs lighter than the P-51D when empty, but the P-51H apparently put much of that weight back on, as it was only 1100 lbs lighter than the P-51D.

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I just love how you scaled up the size of the hits to the bomber, when the P-51D image is smaller scale.

thx for reply.

Im not following you here totally. If i understand you correctly, you mean that i just compared wings over each others to make that size of hole on P-51 wing?

Well you can see the calculations there made for P51 wing. Sure it is problematic because the picture on it is at angle, not directly from above. So, to make it more accurate against P51, as i use it as an example plane to compare hole area HE ammo makes(not total area damage which included bending stuctures, detaching partially the skin by loosing rivets or fragmentation effect. Just hole it tears on skin, and from that its easy to see, what size of sphere the explosion is with its total destruction diameter. This would not stand exactly with diameter, but is greatly affected if its surface or internal detonation. In surface, half of the sphere is outside the skin, and in internal, much more inside the plane, and that also would mean boost to pressure damage around it.

So, i made picture for you, where i got whole wing span of P51, its 11,28 metres. I divided by 2 to get half of that. Half is 5,56 metres, i again divided that with 2 and its 2,82 metres, again dividing by 2 to get 1,41 metres, dividing again by 2 and 0,705m, again by 2 and its 0.3525m, and again by 2 and its 0,1762m.  One meter is 100cm(centimeters) 1 cm is 10mm.

So the smallest measure there archieved by dividing is 176mm= 17,6cm. and then, making from those smallest measures, its quite easy to fit around 20cm circle in there.

30mm Mine ammo is having weak damage if it only makes 60cm diameter hole. If russians/german guns are able to do  10cm or bigger hole with around 6-10g of HE, and 18g HE is able to do bouble of that with about 2,2 times more explosives. 30mmMG(72-85g) rounds has 4-4,7 times more HE than 20mmMG with 18g, or 7,2-14,1 times more than normal HE ammo on russian/german ammo(6-10g of HE) that would mean that it should then make hole between 72cm-141cm hole (diameter) If its effectiveness scales up. So 60cm diameter hole is at the lowest possible results there can be for that imo. (sure structures inside the plane arent round, but more square in shape inside the wing, so damage would spread more in that shape inside, or on outside skin of the targer, and in structures around the hit zone. that area is just converted to circle.

(Here is anyway pic of P51 with correct size 20cm and 60cm spheres on it, as now the angle isnt affecting the size of hole. (though the hole diameters took from german bomber wing were angled, making them having smaller diameter perhaps than if picture would be taken directly from above.. )

 

 

20-60p51.jpg

 

 

 

p-51_mine.jpg

 

Comparing the areas on the pictures show that you are right with scale change. I believe it doesnt work to calculate width with picture that has target in angle.

 

but, did just calculation with vertical hits:

 

 

To saw P51 totally in two from wing tip to wing tip would take 57 HE ammo which makes 20cm hole, if they hit just perfectly next each other in line.

0.2m x 57 = 11,4m

 

To archieve same result with .50cal ammo, it would take over 868 rounds from it, if they connect next to each other in direct line.

 0,013m x 868 = 11,284m

 

nevermind bout that.

 

Back to AP business vs HE (gotta say, that current calculations i got here at my computer makes AP rounds look good, excellent. Just making or at least trying to make them and HE ammo also, to fit in realistic conditions.  Not just vertical hits etc.

 

consider this as a teaser :  1x .50 cal bullet hole is 1,27 cm²  when striking vertically 

                                       at 45 degree angle, its about 1,5 times bigger

                    near paraller, 10 degree hit, from single .50cal AP makes 64,7cm2 area damage.

                         its JUST about 51 times bigger area than with vertical hit ;) and more better, cannon HE ammo is not able to Do it too well cos they explode and dont travel in the material surface..  to be continued.

Edited by Stafroty
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Heres picture i draw which shows  how AP ammo area damage is affected with hit angle, this only simulates single sheet of target with 2 different thicknes.

 

(Totally paraller hits would not be able to travel thru thin target for whole penetration value against given material, unless the tip of the bullet travels right in middle of target sheet(and stays in that), otherwise round would start slowly to ricochet. How long cut it could  make depends of speed, weight, shape as well of material of jacket  the round has(if any).

 

 

 

10mmangle_of_attack.jpg

Edited by Stafroty
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calculations still going, got some other pic, and gotta say  AP lovers went silent when values of cannon ammo went off "a little"  , bias cos such silence? :)  anyway heres nice picture of spitfire, with all measures and calculations there. will do others as accurate too and that calculation thing too to end with pictures and all that.

 

spit_2_blueprintvsphoto.jpg

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0A6e0J2l.png

 

I went and measured those holes; the 30mm hit is 167mm x 226mm in size, and the 20mm hit is 118mm x 64mm in size.

 

 

 

 

Heres picture i draw which shows  how AP ammo area damage is affected with hit angle, this only simulates single sheet of target with 2 different thicknes.

 

(Totally paraller hits would not be able to travel thru thin target for whole penetration value against given material, unless the tip of the bullet travels right in middle of target sheet(and stays in that), otherwise round would start slowly to ricochet. How long cut it could  make depends of speed, weight, shape as well of material of jacket  the round has(if any).

 

High explosive shells are significantly affected by impact inclination too; too high an angle, and they either fail to fuse correctly or ricochet off.

 

 

 

 

calculations still going, got some other pic, and gotta say  AP lovers went silent when values of cannon ammo went off "a little"  , bias cos such silence? :)

 

argument-pyramid.jpg

 

If your response is in the lower portion of that pyramid, don't post it.

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Wellington-bomber-fire-damage.jpg

 

Look at all that 'damage' Wellie must have been hit by a million calibre shell or something, I mean look at that 'hole' it goes around the plane!

 

Yet.... somehow... it flew home, funny that.

 

Perhaps damage to the skin of a plane doesn't have a significant impact upon the underlying structure and instead causes a lot more superficial but scary looking damage along the surface, outside of the wings and control surfaces damaging the skin of the plane won't have any guaranteed impact on their ability to continue flying beyond increasing drag.

 

Your damage isn't the hole you make in the skin, your damage is your ability to compromise the structure or critical components and in that respect AP shells certainly aren't behind by 26k times. While some shells did fragment not all had enough casing around the explosives to produce significant fragments, mineshells in particular were known for this as they explicitly thinned the walls of the shell to pack in more explosives.

 

Consider this analysis.

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Wellington-bomber-fire-damage.jpg

 

Look at all that 'damage' Wellie must have been hit by a million calibre shell or something, I mean look at that 'hole' it goes around the plane!

 

Yet.... somehow... it flew home, funny that.

 

you know, plane uses its wing surface to stay in air?  you might have seen WW1 era planes which looked bit like plane above.

 

let me show you  FE2d.jpg

 

 

 

Perhaps damage to the skin of a plane doesn't have a significant impact upon the underlying structure and instead causes a lot more superficial but scary looking damage along the surface, outside of the wings and control surfaces damaging the skin of the plane won't have any guaranteed impact on their ability to continue flying beyond increasing drag.

 

emotions doesnt belong here, even scary ones. Like you mentioned, DRAG. it causes that and lots. How fast was plane capable of flying or how hard maneuvers could it still make wihtout breaking?  That plane has its wings OK. It stays in air with wings, and with controls, ailerons, rudder, elevator. 

If other wing of that plane would have looked like that, would it still have returned to base? :)

 

And sure, Area damage on skin does affect quite alot on speed. Really minor details did affect speed of a plane, like rivets. they were small ones. Also gaps between cowling did cause drag. or landing gear gap.

 

OF course it causes some kind of problems to plane. IF fighter loses its tail surface on fuselage, its kinda underdog after that. it certainly will affect more than just speed.

 

Your damage isn't the hole you make in the skin, your damage is your ability to compromise the structure or critical components and in that respect AP shells certainly aren't behind by 26k times. While some shells did fragment not all had enough casing around the explosives to produce significant fragments, mineshells in particular were known for this as they explicitly thinned the walls of the shell to pack in more explosives.

 

like i said, im still doing that calculation thing, and i havent claimed it to be ready :) ive said that surface area damage does affect  plane flying behavior. and cannons should excel on that as well with local damage they do with HE hits. And AP ammo would be different thing.

 

Consider this analysis.

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Wellington-bomber-fire-damage.jpg

 

Look at all that 'damage' Wellie must have been hit by a million calibre shell or something, I mean look at that 'hole' it goes around the plane!

 

Yet.... somehow... it flew home, funny that.

 

you know, plane uses its wing surface to stay in air?  you might have seen WW1 era planes which looked bit like plane above.

 

let me show you  FE2d.jpg

 

 

 

Perhaps damage to the skin of a plane doesn't have a significant impact upon the underlying structure and instead causes a lot more superficial but scary looking damage along the surface, outside of the wings and control surfaces damaging the skin of the plane won't have any guaranteed impact on their ability to continue flying beyond increasing drag.

 

emotions doesnt belong here, even scary ones. Like you mentioned, DRAG. it causes that and lots. How fast was plane capable of flying or how hard maneuvers could it still make wihtout breaking?  That plane has its wings OK. It stays in air with wings, and with controls, ailerons, rudder, elevator. 

If other wing of that plane would have looked like that, would it still have returned to base? :)

 

And sure, Area damage on skin does affect quite alot on speed. Really minor details did affect speed of a plane, like rivets. they were small ones. Also gaps between cowling did cause drag. or landing gear gap.

 

OF course it causes some kind of problems to plane. IF fighter loses its tail surface on fuselage, its kinda underdog after that. it certainly will affect more than just speed.

 

Your damage isn't the hole you make in the skin, your damage is your ability to compromise the structure or critical components and in that respect AP shells certainly aren't behind by 26k times. While some shells did fragment not all had enough casing around the explosives to produce significant fragments, mineshells in particular were known for this as they explicitly thinned the walls of the shell to pack in more explosives.

 

like i said, im still doing that calculation thing, and i havent claimed it to be ready :) ive said that surface area damage does affect  plane flying behavior. and cannons should excel on that as well with local damage they do with HE hits. And AP ammo would be different thing.

 

Consider this analysis.

 

 

You're sorta making my point here, skin damage means catastrophic lost of lift or control when applied to your airfoil or control surfaces but only mean a significant but not life-threatening increase of drag when you're hitting the fuselage. The conclusion is clear, skin damage isn't a consistent measurement for it's ability to take down an airplane and trying to measure based on that is very likely to bring you to the wrong results.

 

The cartridge energy approach may not take into account the differing impact kinetic or explosive energy may have on different parts of the aircraft but at least it doesn't depend on that to get it's starting figure for the power of the round.

 

If anything all this analysis should be directed towards adjusting damage models to reflect what should happen to them from those sorts of shells, the CE or KE of the shells in the first place should all be drawn from the ammo description because it'll be more accurate and consistent and will be more available for all the weapons out there. For example, does anyone have a clue what sort of damage a 6-pounder AP shell would do to a bomber? Nobody tested it and there's few to no comparable tests, yet we can get the KE and CE from the shell description while hoping that all these damage reports give a reasonable description for the damage model.

 

As an example, given what we've seen from the wellington in that image you could conclude that the fuselage should go pink/red very quickly with a large drag increase but the structure shouldn't fail until a much higher damage threshold is reached as the structure is well designed to shrug off explosions and simply be missed a lot by AP, beyond what we could expect the collision models to ever represent.

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Wellington-bomber-fire-damage.jpg

 

Look at all that 'damage' Wellie must have been hit by a million calibre shell or something, I mean look at that 'hole' it goes around the plane!

 

Yet.... somehow... it flew home, funny that.

 

That's because of the geodesic frame it was built with which is structurally very durable, but because of the amount of work required that construction technique wasn't widely used so most planes are in fact less durable than that.

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Just a novice question here: could it be fire the cause of the damage we can see in the Wellington? That could give analysis of the picture a different angle.

 

 

 

 

Edit: Gaijin replaced my nub with the word ace :P

Edited by Richardsen
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Just a novice question here: could it be fire the cause of the damage we can see in the Wellington? That could give analysis of the picture a different angle.

 

Yes it was fire damage: https://www.flickr.com/photos/16118167@N04/6181273173/in/set-72157627369682951. I had a better source yesterday, but can't find it right now. Essentially, it was hit with some form of AA or AAA and was set on fire. Its fuselage cover was cloth, which is why it was so easily set alight.

Edited by Jaakariliike
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Yes it was fire damage: https://www.flickr.com/photos/16118167@N04/6181273173/in/set-72157627369682951. I had a better source yesterday, but can't find it right now. Essentially, it was hit with some form of AA or AAA and was set on fire. Its fuselage cover was cloth, which is why it was so easily set alight.

 

Thanks for clearing it up for me :) I will continue following the debate. It makes me wonder if the standard german HE shell had enough punch to twist or break elements of the frame. Because the way we can see it here, hits in that area are not going to down the aircraft, since it is not as critical as other surfaces in maintaining the Wellington in the air; although I can imagine some drag issues.

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For example, does anyone have a clue what sort of damage a 6-pounder AP shell would do to a bomber? Nobody tested it and there's few to no comparable tests, yet we can get the KE and CE from the shell description while hoping that all these damage reports give a reasonable description for the damage model.

 

Clearly it would inflict inferior damage to a 20mm HE hit, as the 57mm AP shell would only make a 57mm diameter hole, versus the 200mm diameter hole for the 20mm HE shell.

 

/sarcasm

 

 

Which clearly demonstrates the severe flaws with the approach the OP is using; even a 200mm AP shell would rate as comparable to a 20mm HE shell, as according to the OP, they would both produce 200mm diameter holes in the target.

 

So, does anyone think a heavy cruiser's 203mm guns should have equivalent per-hit firepower to a 20mm HE shell?

Edited by Cuteling
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So, does anyone think a heavy cruiser's 203mm guns should have equivalent per-hit firepower to a 20mm HE shell?

 

If an 8 inch shell hit a plane, the stress of the shell hitting the airframe is liable to tear the entire plane apart unless it hit on a high deflection shot directly into the wing at a part that is not near the landing gear/spar.

 

But then again, the OP still thinks removing 200mm of skin is somehow over 10 times superior to putting ~4 times as many holes into the plane all the way through any unarmored section that isn't the engine.

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You're sorta making my point here, skin damage means catastrophic lost of lift or control when applied to your airfoil or control surfaces but only mean a significant but not life-threatening increase of drag when you're hitting the fuselage. The conclusion is clear, skin damage isn't a consistent measurement for it's ability to take down an airplane and trying to measure based on that is very likely to bring you to the wrong results.

 

It seems that the wellington got only 1  hit behind its right wing. there the parts of structure is missing. And from that point also the covering fabrics are torn off because of the airflow. Id say its quite an damage for 1 hit.

 

I dont myself believe that if ONLY the skin of fuselage behind pilot is torn out, it would drop plane. of course if they are aluminium sheets and got stuck on rudde/elevators would affect its capability to maneuver. 

What im trying here to do is to be real not biased with this. But sure u and i agree that the wellington  missing fabric cover of tail sure got serious hit on its speed which means it affected it flying behavior.(FM in game)

Also the damage is quite balanced on both sides of the fuselage, which does mean that the drag is even in both sides. same with sop side and bottom.  It would most certainly affect differently if only other side of the fuselage is missing its skin.

 

 

The cartridge energy approach may not take into account the differing impact kinetic or explosive energy may have on different parts of the aircraft but at least it doesn't depend on that to get it's starting figure for the power of the round. 

 

This has been discussed already ealier. Cannons and AP rounds Do different kind of damage.  Also AP rounds are more likely to penetrate whole plane without losing its all kinetic energy(both cannon and machinegun AP ammo)  which means energy calculations are wrong. Maybe add in calculations the angle of attack, to make it simplifier,  when shooting from rear, Areal damage/Kinetic for AP rounds is at its maxium, as there ist biggest amount of stuff on their trajectory path. But shooting like 20 degrees from side or over/under to target gives less material to be hit as well reduces the impact angle areal damage in both skin and inside structures. You can look at plane blueprints which shows inside structure, just put trajectory paths on it from different angles and it gives idea what they might be able to hit and at which angle, how big cut there would be in different parts, like skin, inside parts and again skin when exiting if KE left.  Also when shooting at side to plane, 90 degrees, wings offers a great target for this kind of shooting. 

Dont know how hard it would be to put "sphere" around plane with sectors on it from which damage is calculated. It would check the angle of the incoming AP ammo.

 

If anything all this analysis should be directed towards adjusting damage models to reflect what should happen to them from those sorts of shells, the CE or KE of the shells in the first place should all be drawn from the ammo description because it'll be more accurate and consistent and will be more available for all the weapons out there. For example, does anyone have a clue what sort of damage a 6-pounder AP shell would do to a bomber? Nobody tested it and there's few to no comparable tests, yet we can get the KE and CE from the shell description while hoping that all these damage reports give a reasonable description for the damage model.

 

That damage would be affected alot againt from direction it hits and where. Areal damage alone is quite big with it on direct hit as is penetration ability with KE.

If shot at rear and hitting side of fuselage in such manner that it cuts all the skin as well internal parts its effects would be pretty nice :)  or, it just entering the plane again from rear, and doing almost anything, perhaps breaking radioset etc, and hitting then pilot in the head though seat armor. or go next to his head and smash windscreen.  against engines would be nice too.

 

Why i am doing this is to get somekind of hope to have difference between AP hits and HE hits. HE hits should affect much more on flight modelling, behavior of plane after hit, cause higher drag made by higher areal damage. (yes internal area isnt here added) 

 

Example, on wing:  if burst of cannon rounds eats up 1 square meter area off from surface, would same lenght burst from machineguns eat up only 0,1 square meters.  They both could do comparable internal damage to planes wing, but outer surface isnt comparable. and HE rounds then should affect Many times more on its flying behavior, because that area is causing such alot drag and lack of lift.

 

 

As an example, given what we've seen from the wellington in that image you could conclude that the fuselage should go pink/red very quickly with a large drag increase but the structure shouldn't fail until a much higher damage threshold is reached as the structure is well designed to shrug off explosions and simply be missed a lot by AP, beyond what we could expect the collision models to ever represent.

 

i dont know if it could take any further damage than that due airflow. i bet all that could be torn of is already torn. You can see that there is stripes of fabric torn above and under the elevator wings, but not around them, cos they were duralumilium sheets on it and around rudder base as well. They might need much higher speeds to make them rip off, high angle dive for example cos i dont believe that the bomber could archieve any high speeds after its tail is already naked :)  I dont quite understand what you mean with that "shrug off explosions and simply bs missed a lot by AP" ... Isnt every plane quite the same from inside? internal stucture is quite simple in them, and on that wellie it seems to be more complicated, made from wood, and fastened by aluminium bands.  that one hit on that was able to cut at least 2 of those wooden strips per direction, totalling at least 4 of them (angled beams), thats with 1 hit.

How many more cut beams it would still withstand?   All the photos we are able to see are those who were lucky and did withstand them, but we dont see pictures of those which didnt. 

like for example, i havent seen photo of fighter plane after hit by 30mm (ww2) in main wing or fuselage.  All i know is that single P-47 was able to take some 20 rounds from 20mm on it and lots of 7,72machinegun hits.

It wasnt common thing to happen, and i believe that it was only time when that did happen. Others with less hits did go down. It was quite an miracle to that to be happen, and thats perhaps the reason why that story is up there in the first place :)

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Just a novice question here: could it be fire the cause of the damage we can see in the Wellington? That could give analysis of the picture a different angle.

 

 

 

i dont think its been in fire. Wooden structure would be black? also tail part would be black. But it is known that the fabrics cover was quite easy to burn.

 

(hmm, jaakariliike says its been in fire ) does that fabric cover burn so fast then?

(also it says it wall all metal, while other source said it was wooden made (earlier models?)

Edited by Stafroty
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Clearly it would inflict inferior damage to a 20mm HE hit, as the 57mm AP shell would only make a 57mm diameter hole, versus the 200mm diameter hole for the 20mm HE shell.

 

/sarcasm

 

 

Which clearly demonstrates the severe flaws with the approach the OP is using; even a 200mm AP shell would rate as comparable to a 20mm HE shell, as according to the OP, they would both produce 200mm diameter holes in the target.

 

well if that 200mm AP happens to hit target wing from under it, hitting it vertically (90degree angle) it certainly would make hole size of its caliber, on both surfaces (+ of course internal damage)  But at higher angle it would have more stuff on its path. You might have not understood whats been said in here.

 

So, does anyone think a heavy cruiser's 203mm guns should have equivalent per-hit firepower to a 20mm HE shell?

 

Who thinks that 203mm AP round would make bigger hole than its caliber? if it hits sheet of aluminium vertically, would the hole be quite the diameter of its caliber, same applies to 20mm AP ammo, as well .50 AP ammo as well 7,62mm ammo.  And if 20mm HE is able to blast 10-20 times its own  caliber hole on that target doesnt mean that 203mm AP wont have penetration capability. I dont follow your logic here. its quite hard.

 

Perhaps you are trying to say, that  IF aluminium sheet, lets say its 100cm x 100cm on size and its 0,5mm thick, would then 203mm  destroy it totally? with just steel slug going thru it?  is that it?
 

 

Perhaps you should start your own thread about AP rounds againt HE rounds, and put it show results opposite way to fit it to your liking and needs. 

 

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If an 8 inch shell hit a plane, the stress of the shell hitting the airframe is liable to tear the entire plane apart unless it hit on a high deflection shot directly into the wing at a part that is not near the landing gear/spar.

 

 

lets see. stress of hit? like if it hits engine? or what would cause that stress? Do you count it so duraluminium skin/internal parts would suck all its kinetic energy, that the 203mm AP round would stop on that target?  I believe only engine hit would be able to transfer its KE on target, at least MANY times more than with fuselage/wing hit, which would just let it go thru them like knife in butter(as someone here put it) Sure i understand if it travels trhough entire plane , it leaves behind it a trail of 20cm tube without nothing left on it and would be totally free to do so. Its still totally up to what it hits on its path. If just outer surface and not at many structure bars, not much would happen.

 

 

But of course, what taranok didnt take in account is that how big turbulense there is made from such big round, that alone would shake the plane. That also shows how inaccurate taranok claim is ;) /sarcasm.

 

 

 

But then again, the OP still thinks removing 200mm of skin is somehow over 10 times superior to putting ~4 times as many holes into the plane all the way through any unarmored section that isn't the engine.

 

Im thinking? no, i calculated.   1+1 = 2     You can think its 4 or 9.  and again, like its been said. that what is now made here is only true against sheet of aluminium, single sheet. at at direct hit, 90degrees. 

 

no its not me who is thinking like that, its just that i suggest that from damaged surface area, that how it would affect on flight modeling. My calculations dont take account the internal structure, at least here yet. 

 

Have you tried to figure it out with measures/calculations etc how many rounds it takes and from which directions?  im sure you havent.   Well, try it. put some math in it. bring it up also with graphics etc to show it.

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Example, on wing:  if burst of cannon rounds eats up 1 square meter area off from surface, would same lenght burst from machineguns eat up only 0,1 square meters.  They both could do comparable internal damage to planes wing, but outer surface isnt comparable. and HE rounds then should affect Many times more on its flying behavior, because that area is causing such alot drag and lack of lift.

 

I disagree with a lot of what you're saying here but I'm going to focus on this statement. You're saying that HE rounds would do more damage to the skin then AP where the AP rounds will do comparable internal damage... if it's a machinegun. Putting aside the fact that you're mixing calibers in your comparison you've tacitly admitted that your own methodology is flawed as, just like you said, internal damage may be similar but the skin damage would be dissimilar. This implicitly states that the internal structure of the plane will react differently then the skin will ( which was the point of the Wellington post ) and that the methodology of measuring damage based on the damage done to the skin will be of no help for determining the damage done to the internals.

 

What's more this means you're emphasizing a type of damage that fairly rarely took down planes, part of the reason we have pictures of planes with battle damage of this type is the fact that those who had their structure seriously compromised or critical systems destroyed simply didn't make it back.

 

Starting the analysis from the energy going into the shell when it's fired will always yield more consistent and better results.

 

As an example for the problematic nature of what your analysis is suggesting take for example the ammo loadout of the early spitfire, which certainly seemed to shoot down planes historically, and compare that potential firepower you're estimating it to be, less then a high-end estimate from an HE round. Knowing that even 20mm rounds usually required more then a single hit to down an aircraft it seems impossible for a spitfire or an 8 gun hurricane to ever shoot anything down when it requires their entire 2560 round loadout to hit the target to get the effect of a single 20mm round. Given the accuracy rates of pilots in WWII and the nature of an 8 gun wing-mounted torrent of bullets I doubt it's even plausible for the lowest suggested power difference between 20mm and 7.62, 392:1.

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I dont follow your logic here. its quite hard.

 

 

It's quite simple: you are trying to compare HE versus AP damage in terms of being able to kill aircraft, and your results haven't produced anything even remotely resembling reality.

 

You own method of calculations say a 20mm HE shell would inflict similar levels of damage to an aircraft as a 203mm AP shell, which is frankly completely absurd.

 

This has happened because your method for comparing AP vs HE is inherently FLAWED.

 

 
 

lets see. stress of hit? like if it hits engine? or what would cause that stress? Do you count it so duraluminium skin/internal parts would suck all its kinetic energy, that the 203mm AP round would stop on that target?  I believe only engine hit would be able to transfer its KE on target, at least MANY times more than with fuselage/wing hit, which would just let it go thru them like knife in butter(as someone here put it)

 

Compare the energy levels of a 20mm Mine shell to a 203mm AP shell.

 

20mm Mine shell: 92 gram weight, 20.24 grams of HE (PETN), 750 m/s muzzle velocity

Kinetic Energy = 25.88 kj 

Chemical Energy = 117.59 kj (and I'm overestimating that by assuming all of it is PETN, which it wasn't; only about 90% was).

Total energy = 143.47 kj

 

203mm AP shell fired by a 8"/55 naval artillery: 152 kg, 760 m/s muzzle velocity

Kinetic Energy = 43,897.60 kj

Chemical Energy = not gonna bother finding out the HE filler charge size, or work out its energy.

 

Now, compare the 203mm AP shell has 306 times as much energy as the 20mm Mine shell; even if the 203mm AP shell only transfers a grand total of 1% of its kinetic energy into the aircraft it impacts, it is still delivering more energy than the 20mm HE shell.

 

Frankly, even 10% is a very low amount of energy to transfer, and with over 4 megajoules of energy delivered, the 203mm is going to tear the target aircraft to shreds even if it passes through one side and goes out the other.

 

 

 

Sure i understand if it travels trhough entire plane , it leaves behind it a trail of 20cm tube without nothing left on it and would be totally free to do so. Its still totally up to what it hits on its path. If just outer surface and not at many structure bars, not much would happen.

 

Sure, lets do a 3-dimensional volume comparison.

 

20mm HE shell with a 20cm diameter sphere = 4,188.79 cm^3

200mm AP shell, passing 1 meter through target (20cm diameter x 100cm length circular cylinder) = 31,415.90 cm^3

200mm AP shell, passing 0.5 meters (20cm diameter x 50 cm length circular cylinder) = 15,708.00 cm^3

200mm AP shell, passing 0.2 meters (20cm diameter x 20 cm length circular cylinder) = 6,283.19 cm^3

200mm AP shell, passing 0.134 meters (20cm diameter x 14 cm length circular cylinder) = 4,209.73 cm^3

 

So provided the 200mm AP shell passes at least 130mm through the target, the volume it effectively destroys is greater than the 20mm HE shell.

 

And most aircraft had wings considerably thicker than that; take the P-47, it had 307mm thick wings at the root.

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It's quite simple: you are trying to compare HE versus AP damage in terms of being able to kill aircraft, and your results haven't produced anything even remotely resembling reality.

 

You own method of calculations say a 20mm HE shell would inflict similar levels of damage to an aircraft as a 203mm AP shell, which is frankly completely absurd.

 

This has happened because your method for comparing AP vs HE is inherently FLAWED.

 

I thought he pretty clearly stated that he was just trying to show that HE round hits should have a much more significant impact on the flight characteristics/handling of the damaged fighter than AP hits. It seems to just be you two who are putting words in his mouth and saying that he's saying a single 20mm hit is more likely to get a kill than thousands of MG hits.

 

Compare the energy levels of a 20mm Mine shell to a 203mm AP shell.

 

20mm Mine shell: 92 gram weight, 20.24 grams of HE (PETN), 750 m/s muzzle velocity

Kinetic Energy = 25.88 kj 

Chemical Energy = 117.59 kj (and I'm overestimating that by assuming all of it is PETN, which it wasn't; only about 90% was).

Total energy = 143.47 kj

 

203mm AP shell fired by a 8"/55 naval artillery: 152 kg, 760 m/s muzzle velocity

Kinetic Energy = 43,897.60 kj

Chemical Energy = not gonna bother finding out the HE filler charge size, or work out its energy.

 

Now, compare the 203mm AP shell has 306 times as much energy as the 20mm Mine shell; even if the 203mm AP shell only transfers a grand total of 1% of its kinetic energy into the aircraft it impacts, it is still delivering more energy than the 20mm HE shell.

 

Frankly, even 10% is a very low amount of energy to transfer, and with over 4 megajoules of energy delivered, the 203mm is going to tear the target aircraft to shreds even if it passes through one side and goes out the other.

 

Why do you think "even 10% is very low"? It entirely depends on what you're hitting and with what. If you fire a .50 BMG at 1mm thick sheet metal, you're going to trasnfer maybe 1% or less of its energy. If you fire a .50 AE (same diameter as the .50 BMG, obviously, but less than 10% of its energy) at an engine block, you're going to absorb all of its energy.

 

Likewise, if a 203 AP shell hits a fighter in the nose or tail, it's going to rip it to pieces. If it flies up vertically through the wing, it will barely transfer any of its energy - in this case, the 20mm HE would have been as (or more) effective.

 

Sure, lets do a 3-dimensional volume comparison.

 

20mm HE shell with a 20cm diameter sphere = 4,188.79 cm^3

200mm AP shell, passing 1 meter through target (20cm diameter x 100cm length circular cylinder) = 31,415.90 cm^3

200mm AP shell, passing 0.5 meters (20cm diameter x 50 cm length circular cylinder) = 15,708.00 cm^3

200mm AP shell, passing 0.2 meters (20cm diameter x 20 cm length circular cylinder) = 6,283.19 cm^3

200mm AP shell, passing 0.134 meters (20cm diameter x 14 cm length circular cylinder) = 4,209.73 cm^3

 

So provided the 200mm AP shell passes at least 130mm through the target, the volume it effectively destroys is greater than the 20mm HE shell.

 

Wow, what fighter has 130 mm thick material in it?? The only thing I could think of is the engine block or a shot the whole way from nose to tail (or vice versa).

 

And most aircraft had wings considerably thicker than that; take the P-47, it had 307mm thick wings at the root.

 

Oh, the P-47 had 307mm thick solid metal wings, did it? 

 

Or have your "3D volume" (is there a 2D volume??) comparisons been comparing how much volume of air the two rounds are pushing around? Is that really a big issue for planes; having the air in their wings pushed around? And you've been assuming that the hole in the wing is the widest point of the 20 mm HE "sphere", despite the fuzes of German HE rounds having a slight to moderate delay (depending on the fuze), meaning the explosion would be occurring partially inside the wing.

 

The 203mm AP round is more likely to do more damage, because a fuselage hit would rip the fuselage with its huge amount of energy. But if we're comparing wing hits that are perpendicular to the wing face, the 203mm is only going to do considerably more damage if it hits a spar.

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