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LEBillfish
09-07-2005, 08:56 AM
Hi All;

Posing a question to the developers here, then also customers for their knowledge.....

The Ki-43 was well known to often literally explode into 2 pieces roughly at mid fuselage when hit. U.S. & Australian pilots at first were amazed at the power of the .50cal guns in doing this, yet quickly discovered it was nothing more then hitting the "Oxygen Tanks", them subsequently exploding breaking the plane in 2 roughly mid fuselage.

To the developers was this the intent with most planes I see do this?

To the customers where were the O2 tanks on your favorite rides?

The reason I ask is we see this often with most/all planes. At that point it makes breaking the plane up more then reasonable virtually regardless of the round (even a small caliber "might" be capable of it)...However I would find it difficult to believe if not hitting something like O2 tanks that a plane would halve so easily....Damage to the point the tail folds yet various stringers holding it together when the skin (a big part of structural integrity) is damaged enough absolutely. Yet being blown completely off I'm trying to understand.

Dtools4fools
09-07-2005, 09:23 AM
Indeed the "tail off" graphics has been a point discussed often.

Speculating here but I don't think that its the graphic representation of a hit O2 tank explosion but rather the structural failure. If a representation like you suggest (combined with control loss) would have been chose instead of the entire tail section breaking off there sure would have been much less talk.
I do not know what planes you are talking of when saying that planes halt easily.
However I would like to add that planes do not half that easily. Testing done has shown that; you need to delibarately fire into the tail section and score hits right there, one after another... (of course some planes need less hits some more depending on how strong the plane was).
I once tested "combat shooting" (concetrating in hitting the plane) instead of "tail hitting" (delibarately shooting only at the tail) and voila, tail came off rather seldom... even to planes supposedly prone to "tail off syndrome".

At the end of the day it looks it is just the graphical expression of structural damage of the tail/rear fusealge section.
Maybe its visually wrong represented, myabe someting less spectacular should have used instead.
****

LEBillfish
09-07-2005, 09:50 AM
Well a prime example would be the IL2, as I have with a couple rounds of FF/MG cut an entire mid series tail section clean off...As though exploding yet find it hard to believe (though don't know) that they carried O2.

Now before "explosive MG, or Cannon" ammo is quoted, I'm not saying Mk108 or 103's, 37mm, etc.. I'm speaking of standard 20mm at best and often less such as 12.7mm that when they strike just right and with FEW hits generate the reaction.

Now, I'm no aircraft design expert. However from what I have seen of their construction it becomes quickly clear that the langerons(sp?), stringers, bulkheads and skin all work together. The thin skin actually important much like the shell of an egg....Destroy enough of it and you have failure.

However, how I envision that failure is much different, the tail from the weight of the plane suddenly pushing down folding the tail up on its back the stringers keeping it on. Once falling the twisting and turning could most deffinately twist/break it off......Yet unless an explosion like noted above for the Ki-43, I find it hard to belive it gets "blown off" by a couple well placed rounds.....

So a question, simply wanting to know as we as customers don't have access to damage hit boxes (that I know of) and their end effects.

WOLFMondo
09-07-2005, 09:51 AM
Originally posted by LEBillfish:
The reason I ask is we see this often with most/all planes. At that point it makes breaking the plane up more then reasonable virtually regardless of the round (even a small caliber "might" be capable of it)...However I would find it difficult to believe if not hitting something like O2 tanks that a plane would halve so easily....Damage to the point the tail folds yet various stringers holding it together when the skin (a big part of structural integrity) is damaged enough absolutely. Yet being blown completely off I'm trying to understand.

Anyone ever watched Myth Busters on Discovery channel?

They did an experiment to see if the fate of Jaws could actually happen (putting an oxygen tank in its mouth then shooting it with a rifle) and did experiments firing bullets at oxygen tanks.

They disovered that a round would enter the tank but wouldn't cause it too explode, just let the oxygen out. They had to attach explosives to the tank to actually cause a hole big enough for it to shatter and explode like it did in the film.

LEBillfish
09-07-2005, 09:56 AM
Originally posted by WOLFMondo:
Anyone ever watched Myth Busters on Discovery channel?

They did an experiment to see if the fate of Jaws could actually happen (putting an oxygen tank in its mouth then shooting it with a rifle) and did experiments firing bullets at oxygen tanks.

They disovered that a round would enter the tank but wouldn't cause it too explode, just let the oxygen out. They had to attach explosives to the tank to actually cause a hole big enough for it to shatter and explode like it did in the film.

Perhaps yet this issue with the Ki-43 & .50 cal. rounds was well documented......In kind a divers tank I don't believe is filled with O2, yet compressed air.

Hoarmurath
09-07-2005, 10:02 AM
position of oxygen tanks on a few aircrafts (shown as a yellow spot):

http://hoarmurath.free.fr/images/oxy109.jpg

http://hoarmurath.free.fr/images/oxyhurry.jpg

http://hoarmurath.free.fr/images/oxyspit.jpg

http://hoarmurath.free.fr/images/oxyp40.jpg

http://hoarmurath.free.fr/images/oxyp47.jpg

http://hoarmurath.free.fr/images/oxyp51.jpg

http://hoarmurath.free.fr/images/oxyp38.jpg

http://hoarmurath.free.fr/images/oxyzero.jpg

http://hoarmurath.free.fr/images/oxyoscar.jpg

http://hoarmurath.free.fr/images/oxysbd.jpg

http://hoarmurath.free.fr/images/oxystuka.jpg

it was only after a quick search...

p1ngu666
09-07-2005, 10:14 AM
oxygen tanks could go up in a big way, remmber theres tracer rounds, and he rounds for cannons.

theres a account of a mossie night fighter which shot down a ju88S, which had GM-1 (basicaly oxygen for the engine, for high alt operation), few hits in the tail and i exploded in a big big way http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

Dtools4fools
09-07-2005, 10:24 AM
Now before "explosive MG, or Cannon" ammo is quoted, I'm not saying Mk108 or 103's, 37mm, etc.. I'm speaking of standard 20mm at best and often less such as 12.7mm that when they strike just right and with FEW hits generate the reaction.

Now, I'm no aircraft design expert. However from what I have seen of their construction it becomes quickly clear that the langerons(sp?), stringers, bulkheads and skin all work together. The thin skin actually important much like the shell of an egg....Destroy enough of it and you have failure.

I do not know about what happens to a hit O2 bottle; I have no idea about the DM of the IL-2 as well.

All that I can speak for is the P-47 DM tail off topic and the testing done there.
Conclusion was that one needs some hits for the tail to come off, it isn't just a "single stray" round occurance.

20mm has HE and does structural damage. Depends what you consider *just a few* hits. If you got 5 2mm hits in rear fuselage alone you are in bad shape...

*****

Abbuzze
09-07-2005, 10:40 AM
Originally posted by p1ngu666:
oxygen tanks could go up in a big way, remmber theres tracer rounds, and he rounds for cannons.

theres a account of a mossie night fighter which shot down a ju88S, which had GM-1 (basicaly oxygen for the engine, for high alt operation), few hits in the tail and i exploded in a big big way http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

I rember in the book of Closterman that he was shocked that he found a bullet that hit his oxygen bottle.

For the GM1, it was laughing gas N2O that is unburnable. But it is oxidizing. So it improves the fuel/air mixture buring and also it cools down to -40?C so it increased the cylinder charging. Nothing more than a NOS-System http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

But I doubt that it would be explode.

Jaws2002
09-07-2005, 10:44 AM
One MK-108 shell detonated inside a spitfire fuselage. British test.

http://img.photobucket.com/albums/v258/<FA>Jaws/pwnspitfire.jpg

Dtools4fools
09-07-2005, 11:02 AM
Couple that damage on that pic that the Germans considered that 4-5 the number of 20mm hits were (compared to 30mm) needed to bring down a heavy bomber, then indeed "few" shots should be needed to down a single engine fighter.
Now additionally those *few* hits are concentrated in the just one relatively small section of the airframe, the rear fuselage.
****

Buzzsaw-
09-07-2005, 11:37 AM
Salute

That picture of 30mm hit on Spitfire is an example of an 'ideal' hit in non-flight conditions. Ie. aircraft is static, round explodes inside the fuselage.

Very different circumstances in flight.

At sharp angles and longer ranges, typical of a maneuvering fighter target, a Mk108 round, due to its very low velocity, is going to deflect off the skin of the aircraft and explode outside the fuselage. In which case, the majority of the force is going to be disappated into the surrounding atmosphere, instead of being confined and the explosive force concentrated inside the fuselage. That will mean a lot less damage inflicted.

High velocity means there is more likelyhood of penetration of the round into the fuselage or wing, and thus increased chance of damage. That was one of the major advantages of the Hispano 20mm. The MG151/20 was better than the Mk108 in this regard, but still had lower velocity and chance of penetration.

LEBillfish
09-07-2005, 11:45 AM
Again, my point is not regarding large rounds or even smaller caliber primarily intended to be very explosive.

I'd say a 30mm Mk108 qualifies as large and explosive.

Kocur_
09-07-2005, 01:48 PM
Now, I'm no aircraft design expert. However from what I have seen of their construction it becomes quickly clear that the langerons(sp?), stringers, bulkheads and skin all work together. The thin skin actually important much like the shell of an egg....Destroy enough of it and you have failure.

However, how I envision that failure is much different, the tail from the weight of the plane suddenly pushing down folding the tail up on its back the stringers keeping it on. Once falling the twisting and turning could most deffinately twist/break it off......Yet unless an explosion like noted above for the Ki-43, I find it hard to belive it gets "blown off" by a couple well placed rounds.....

Very well said! In case of semi-monocoque design most of stresses are carried by skin. Longerons add some part of longitudinal strenght of the fuselage, but their, and frames too, primary role is not to let thin aluminium skin bend and collapse and to provide shape.
The more structural strenght of a fuselage is lost, the larger area of holes in fuselage perimeter is. That is the reason for using cannons with explosive shells. Solid mg or hmg projectiles are very less likely to cause such a failure, simply because they pass skin leaving holes not much larger than their caliber.
So IMHO fact that semi-monocoque fuselages are cut in game by hmg or even mg fire must be only graphical representation of any possible damage, perhaps including explosions of O2 tanks, but surely not representing that directly.

Kocur_
09-07-2005, 01:52 PM
At sharp angles and longer ranges, typical of a maneuvering fighter target, a Mk108 round, due to its very low velocity, is going to deflect off the skin of the aircraft and explode outside the fuselage. In which case, the majority of the force is going to be disappated into the surrounding atmosphere, instead of being confined and the explosive force concentrated inside the fuselage. That will mean a lot less damage inflicted.

And my GUESSING would be, they realised that, so used very sensitive, inertial fuse to ensure shell would go off on impact.

Kocur_
09-07-2005, 02:02 PM
Anyone ever watched Myth Busters on Discovery channel?

They did an experiment to see if the fate of Jaws could actually happen (putting an oxygen tank in its mouth then shooting it with a rifle) and did experiments firing bullets at oxygen tanks.

They disovered that a round would enter the tank but wouldn't cause it too explode, just let the oxygen out. They had to attach explosives to the tank to actually cause a hole big enough for it to shatter and explode like it did in the film.

There are differnt kinds of O2, or any other pressure tanks. Modern ones indeed dont explode, but rather crack letting pressure go off. I dont think those guys were able to get any old O2 tank.

Some number of US aircraft losses over VIetnam was due to O2 tanks explosions, causing further damage, ususally to hydraulics. Modern military planes have on-board oxygen generators, generating O2 from atmosphere, to avoid explosion of O2 tanks.

WWMaxGunz
09-07-2005, 06:15 PM
Possibly it is fuel tank or leaked fuel mixed with air in the rear fuselage exploding?
Or maybe just mach stem effects destroying enough to cause a peel and break due to air
drag at over 100 mph? Bombers would take more due to more actual redundant structure
and bigger internal spaces needing bigger shells to get mach stem distances and still
have the power for such wide destructive effect.

p1ngu666
09-07-2005, 07:29 PM
well, it would be pressured, to how much? dunno, but uve got a sudden expansion of oxygen, more of a explosion really, so that could severly damage the structure, plus uve got very hot stuff to ignight anything flamable, and planes are FULL of flameable stuff, paint burns for example...

rockets are basicaly fuel, and a oxygen being pumped together arent they?

Kocur_
09-08-2005, 12:08 AM
Hmm http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif Aluminium burns too and very nice. Of course it takes high temperature to ignite it. Aluminium powder is a major component of modern solid rocket fuels (Minuteman was AFAIK the first).

Dtools4fools
09-08-2005, 09:09 AM
At sharp angles and longer ranges, typical of a maneuvering fighter target, a Mk108 round, due to its very low velocity, is going to deflect off the skin of the aircraft and explode outside the fuselage. In which case, the majority of the force is going to be disappated into the surrounding atmosphere, instead of being confined and the explosive force concentrated inside the fuselage. That will mean a lot less damage inflicted.

High velocity means there is more likelyhood of penetration of the round into the fuselage or wing, and thus increased chance of damage. That was one of the major advantages of the Hispano 20mm. The MG151/20 was better than the Mk108 in this regard, but still had lower velocity and chance of penetration.


Where you got that from?

I have seen a picture of a 30mm shell hitting a B-24 tail section. Was US test firing. Done in an "typical angle" a 30mm would hit the tail like if shot from a 262.

And it did get inside and exploded inside...
And it severad "most if not all" controls. And the testers thougth that if B-24 might have been in flight the entire tail section might have come off.

Even if penetration of 30mm Minengeschoss is not high due to relatively low muzzle velocity and type of shell it still will be enough to go through the skin of an aircraft at a few hundred meters of range!

The French 37mm L/21 Antitank gun for example has for its HE shot a penetration of 7mm (of ARMOR plate) at 500m range at impact angle of 60 degrees. Muzzle velocity is 367m/s.

So the 30mm is smaller gun, Mienengeschoss is even weaker in construction (thinner walls) but still it will be able to pass through the NON ARMORED skin of an aircraft.


High velocity guns with AP rounds are NOT made to go into the structure simply. Thsoe are meant to go through the entire structure and damage something in there - penetrate pilot armor, penetrate fuel tanks, penetrate engine block.
HE rounds were designed to explode on impact and do structural damage this way.
Mienengeschoss was desigend to explode INSIDE the structure and do even MORE structural damage this way.

Just beceause 500m/s is slower than 800m/s it does not mean that this bullet is going on a late afternoon walk. It still is faster than the speed of sound!!!
****

LEBillfish
09-08-2005, 10:18 AM
Amazing......we have the the largest collection of A.D.D. pilots on the planet....Aluminum burning?...30mm Mk108's bouncing?, 37mm antitank rounds? Paint burning?

Hard news all, by the time paint and aluminum is burning (itself the fuel) the dance has been long over......and what part of,

"Again, my point is not regarding large rounds or even smaller caliber primarily intended to be very explosive. I'd say a 30mm Mk108 qualifies as large and explosive."

was missed?........Ah well.... http://forums.ubi.com/images/smilies/51.gif

Dtools4fools
09-08-2005, 11:20 AM
LEBillfish,

so talking about solid shot only.
At the beginning it seemed that you included 20mm as well which does have HE shot - an entirely different story.
So 20mm should be different than guns with no HE.
20mm belongs in the "cannon and big gun" category.

For 0.50 cal or other MG's and HMG's there would be some testing to be done...
Only numbers that I have are those of test done by Fritzgryphon in P-47 DM topic. 109 neded about 11 0.50cal hits average, P-47 over 30 until "tail comes off".
20mm was about 4 (Me)-6 (p-47) hits for comparison.
So that's 3 to 6 times as many hits needed for 0.50cal.
Dunno if that is too little or too many...

Might be all right especially if one considers that the bullet entry hole is a small one, but that the exit hole will be quite a bit bigger. Again there would the sample pic of the 20mm hit in the P-47 topic - at one side a clean hole, at the other side a significantly bigger hole. Same goes for fifity albeit in smaller scale of course. So the "structural damage" would be kind of 10 small holes and another 10 bigger ones on the other side (for 109) - at least the way the tests were done. I think its OK that a tail comes of then, but that's just my GUESSING now...

And about the HE shot of tank gun, I just got that one to show that HE has penetration as well (even way less than solid AP shot) and aircraft skin certainly can not deflect shells. Skin is not armor.
But that is off topic indeed http://forums.ubi.com/images/smilies/16x16_smiley-tongue.gif

****

Abbuzze
09-08-2005, 04:38 PM
Originally posted by Buzzsaw-:
Salute


At sharp angles and longer ranges, typical of a maneuvering fighter target, a Mk108 round, due to its very low velocity, is going to deflect off the skin of the aircraft and explode outside the fuselage. In which case, the majority of the force is going to be disappated into the surrounding atmosphere, instead of being confined and the explosive force concentrated inside the fuselage. That will mean a lot less damage inflicted.

High velocity means there is more likelyhood of penetration of the round into the fuselage or wing, and thus increased chance of damage. That was one of the major advantages of the Hispano 20mm. The MG151/20 was better than the Mk108 in this regard, but still had lower velocity and chance of penetration.

The MK108 shell was slow... compared to other shells from other MG´s and cannons, BUT we are talking about a supersonic bullet! Sometimes it seems that people believe that you can catch such a MK108 shell with our teeth http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif
All unarmoured parts of a plane can be penetrated by bullets very easy. Mineshells had ******ed fuses to let it blow up in the structure of the plane...

Dtools4fools
09-09-2005, 10:44 AM
Started a few short tests; For early war Zero it took an average of 12 hits too "take the tail off". 0.50 cal hits that is. 7 hits and 14 hits was the most common number needed. One exeption where only 2 hits were needed.

A quick run up with P-47: there were 79/70/55/71/61 hits needed for tail off...

Those were all at rear fuselage aimed.

Will do more testing with more standarized procedure...

Any planes you are intersted in particular?
****

OldMan____
09-09-2005, 12:09 PM
Alluminium does burn.. and bur harder that anything else that is not an explosive. Incendiary ammo was mae exactly to put fire on alluminium. Not that hard to happen.



Oxigen does NOT explode alone. Oxigen is only conburent, you need comburent + fuel + heat to make fire and explosion. In an airplane you have lots of fuel.. and quite easy to puncture both O2 and fuel tank since most times they are not far away. That is only way that O2 will explode.


If you have a bottle with 100% of O2 inside it.. you may try light a falme inside it and it will not BURN!! No Fuel. O2 is not a fuel

Kocur_
09-09-2005, 02:16 PM
Cant say for others, I meant explosive-depressurisation, which in case of old bottles would cause it to produce fragments and some blast, kinda like a shell.