Things that go "BOOM"

[HagarTheHorrible]

Do you think that hitting an oxygen bottle will cause any secondary damage ?  Are they modelled in the sim as part of the DM, do they go "BOOM" when hit or do they puncture and leak out so that hypoxia might set in above a certain altitude ?

 

What happens when an oxygen bottle is hit by enemy fire, is it armoured, if it explodes how much damage would it do ?

[Finkeren]

What would happen when an oxygen tank ruptures on a plane?

 

A lot of things I imagine, and not all of them easily predictable.

 

First it's important to note, that most oxygen tanks aren't easy to puncture. They are generally heavily built and able to withstand a lot of abuse and have a shape that easily deflects projectiles.

 

Should an AP round or an explosive shell manage to puncture the container or destroy the valve the oxygen would quickly leak out and fill the compartment. I think it is very unlikely that it would "explode" in any sense of the word, but depending on the pressure of the container and the size and shape of the hole(s) the outflowing gas could be quite forceful. It might even dislodge the container from its mount and send it crashing through the fuselage wrecking all kinds of havoc.

 

The oxygen would quickly fill the compartment it leaked into, causing any fire that might be ignited to spread wildly. If it spread in the pilot compartment it might raise oxygen levels to a dangerous level, but in a non pressurized cockpit it would quickly dissipate and could easily be countered by simply opening the canopy. Toxicity would not be accute because of the low pressure, though it might still cause dizziness.

 

All things considered, I think the effects of a punctured oxygen tank are quite difficult to model in a simulation. Simply having it explode is not a very realistic representation of what might happen. The most dramatic effects would propably be the relatively sudden loss of oxygen supply for the pilot and the boosting of any fire that might be in the area.

[HagarTheHorrible]

That was pretty good. What if the bullet was incendiary ?

 

From what I understand, while oxygen was available in WW1, if with a crude delivery system, it was generally disregarded as it was considered just one more thing that would explode, catch fire and kill the pilot.

[DD_bongodriver]

You realise this completely ruins the movie 'jaws'

[Sternjaeger]

I think it's fairly appropriate to say that the damage caused by a ruptured oxygen tank (or any other high pressure tank) would be pretty catastrophic.

[Rodolphe]

...

 

http://en.wikipedia.org/wiki/Qantas_Flight_30

 

 

 

 

Check the last 2 pages for the probable oxygen cylinder trajectory.

 

http://www.atsb.gov.au/publications/investigation_reports/2008/AAIR/pdf/AO2008053_Prelim.pdf

 

...

Edited January 26, 2014 by Rodolphe

[Wandalen]

You realise this completely ruins the movie 'jaws'

Not at all :-) http://www.scubabomb.freeservers.com/Scubadag.htm

[Finkeren]

I think it's fairly appropriate to say that the damage caused by a ruptured oxygen tank (or any other high pressure tank) would be pretty catastrophic.

I think it's important to distinguish between a "punctured" tank and a "ruptured" one. Any AP round fired from a reasonable distance might puncture the tank and release a powerful jet of gas, which might cause the tank to dislodge and posibly cause some damage. However, it would take a powerful HE shell detonating directly inside the tank to blow it open and more or less release its pressure at once, which might be enough to blow part of the plane apart.

 

The first scenario is relatively likely, the other is not IMHO.

You realise this completely ruins the movie 'jaws'

Along with about a hundred other movies.

 

Hollywood physics yay!

[DD_bongodriver]

even in a non pressurised fuselage a high volume of pressurised gas quickly venting into the cabin could cause a rupture in the structure, maybe just pop off the canopy, but if in a high g turn and part of the structure gets a sudden deformation it could compound and cause catastrophic failure.

[Mastermariner]

_{http://www.youtube.com/watch?v=0ZJ3W1dmEng}

 

Master

[Sternjaeger]

I think it's important to distinguish between a "punctured" tank and a "ruptured" one. Any AP round fired from a reasonable distance might puncture the tank and release a powerful jet of gas, which might cause the tank to dislodge and posibly cause some damage. However, it would take a powerful HE shell detonating directly inside the tank to blow it open and more or less release its pressure at once, which might be enough to blow part of the plane apart.

 

The first scenario is relatively likely, the other is not IMHO.

 

Along with about a hundred other movies.

 

Hollywood physics yay!

 

rupture is the consequence of a puncture. The real determining factor here is what sort of pressure these tanks have.

[DD_bongodriver]

modern aircraft can be up to 1500 p.s.i, but I guess it will vary.

Edited January 26, 2014 by DD_bongodriver

[Mastermariner]

I Think you all are confusing compressed air with compresed oxygen.

Master

[Rodolphe]

...

 

On board Flıght crew oxygen system pressure (e.g. : B737) can be as high as 1850 psi.

 

...

Edited January 26, 2014 by Rodolphe

[DD_bongodriver]

I Think you all are confusing compressed air with compresed oxygen.

Master

 

Not really, compressed gas is compressed gas, it's all about the pressure inside a cylinder and what happens when that cylinder fails.

[Mastermariner]

Simplified, Oxygen will burn if ignited air will not.

 

Master

[Rodolphe]

...

 

 

http://en.wikipedia.org/wiki/Fire_square

 

...

Edited January 26, 2014 by Rodolphe

[DD_bongodriver]

Simplified, Oxygen will burn if ignited air will not.

 

Master

 

What gas is irrelevant, it is about a pressurised cylinder failing, any pressurised container is a potential bomb, doesn't matter if it's full of farts or unicorn breath.

[Rama]

Oxygen is not flammable.

Yes, oxygen isn't a fuel, it's an oxydant, which is the other constituant of a combustion. Without oxydant, no combustion (and so no fire). The more available oxydant, and the more you feed the combustion of any fuel. Since the oxygen is the only oxydant contained in air, if you replace air by pure oxygen, the combustion will be optimal (and the fire give maximum heat).

[Finkeren]

Oxygen will burn if ignited air will not.

 

Master

Wow, that is just amazingly inaccurate.

 

What we refer to as "burning" is a rapid oxydation of some sort of fuel vapor (solids and liquids don't burn). Oxygen is ofc one part of that chemical reaction, but by its very definition it is not the oxygen that's "burning" but the fuel vapor.

[Sternjaeger]

yes, it's the mixture of fuel and air (or oxygen) that is inflammable, the two taken separately will not burn.

[76SQN-FatherTed]

A sudden increase in the amount of oxygen present in the cockpit would make flammable things burn better if ignited, but, as Bongo keeps trying to point out, it's the bursting of the pressurized cylinder that would be the most destructive aspect. I think that is what happens in Jaws, isn't it?

[Finkeren]

rupture is the consequence of a puncture. The real determining factor here is what sort of pressure these tanks have.

I can't speak as to the quality of Soviet oxygen tanks of the period, but in general pressurized tanks are made to be very resillient against rupture. Take a look at the many videos online where gun nuts shoot at pressure tanks. Very seldom, if ever does one rupture violently, but they are quite often punctured and thrown around by the jet of leaking gas.

 

This isn't a balloon, where the whole thing is ripped apart by the pressure once you poke a little hole in it. Pressure tanks are built specifically not to rupture.

[DD_bongodriver]

a 20mm projectile will make a nice big hole, pressurised gas will escape very rapidly through a big hole, rapid enough to qualify as explosive in the same way a pressurised aircraft can have explosive decompression.

[II/JG17_HerrMurf]

I don't know why but I was under the impression some or all fighter aircraft used LOX but I was wrong. Probably carried over from a misimpression from childhood that was never addressed. An also, those incredibly small tanks in all of my 1/48 Monogram models back in the day.

 

It may be slightly OT but here is an interesting article on the development of closed circuit oxygen systems.

 

http://www.ww2f.com/topic/20227-oxygen-tanks/

Edited January 26, 2014 by HerrMurf

[HagarTheHorrible]

I would imagine aircraft oxygen bottles are more economically built than others, in order to save weight, aluminium seems to have been common, so maybe less robust.

 

I expect then that the real problem with oxygen would have been if there was a fire, elsewhere, close by, as it would act as an accelerant and if somewhat confined would cause significant structural damage as it ignited and the gases rapidly expanded as they burnt.

 

I can't quite make out from some of the earlier answers what the conclusion is, if a tank was pierced by a bullet would a following incendiary round ignite the gas in the tank or fuselage or would it pass through the gas without further effect ?

[Finkeren]

I can't quite make out from some of the earlier answers what the conclusion is, if a tank was pierced by a bullet would a following incendiary round ignite the gas in the tank or fuselage or would it pass through the gas without further effect ?

If the gas in the tank is oxygen, then no it will never ignite no matter what. Fire is a rapid oxidation process and therefore, by definition, pure oxygen cannot burn.

[Finkeren]

a 20mm projectile will make a nice big hole, pressurised gas will escape very rapidly through a big hole, rapid enough to qualify as explosive in the same way a pressurised aircraft can have explosive decompression.

Sure enough, that can happen, as I also acknowledged before. My point is, that it would be rare. A 20mm AP round would likely punch right through the tank leaving two holes marginally larger than the bore diameter of the cannon. An HE shell would often detonate before reaching the tank.

Edited January 26, 2014 by Finkeren

[71st_AH_Mastiff]

Simplified, Oxygen will burn if ignited air will not.

 

Master

wow I'm going to blow up with all this Oxygen I'm breathing...lol

[FuriousMeow]

He meant pure concentrated O2, not the myriad of elements in the atmosphere you inhale with each breath.

[DD_bongodriver]

He meant pure concentrated O2, not the myriad of elements in the atmosphere you inhale with each breath.

 

Yes, and he was still wrong, O2 is not flammable.

[FuriousMeow]

I know, I was responding to the post above mine.

Edited January 26, 2014 by FuriousMeow

[=RvE=Windmills]

I don't think there has been much of any info on what the DM is supposed to look like in the end, or is there?

[Jaws2002]

Everything in that silly 109 goes boom when hit by that mean 23mm gun.

 

Love that thing.

[AbortedMan]

Yes, and he was still wrong, O2 is not flammable.

I dunno man...I watched a guy in my shop foolishly dust himself off with an air compressor that was hooked up to and pumping pure O2 then about 45 seconds later he went to the smoke pit and lit up a cigarette...his BDU and coveralls caught fire from the inside and ignited a fire in his pants part of the coveralls...hilarious to watch, but a real dangerous situation. So, effectively for this discussion and effect, oxygen is indeed flammable...the mainstay of the question/discussion is: it's going to make a very volatile situation in terms of flammability in a cockpit/fuselage that is under fire from any caliber of incendiary ordnance.

 

Also, I'm not sure if they used liquid O2 back in WW2, but I serviced F-16s/A-10s with LOX carts and I was under the assumption liquid oxygen was the go-to form of oxygen containment for fighter aircraft/altitude purposes (doesn't compressed air tanks, especially under very high pressure, have a tolerance of altitude and pressure differences in regards to reaching low pressure altitudes?).

 

Liquid O2 is flammable as all hell. It'll combust/bubble as soon as it hits asphalt if it's still liquid by the time it hits the ground. Can anyone confirm whether or not compressed O2 or LOX was being used in these aircraft we're talking about?

Edited January 27, 2014 by AbortedMan

[=IRFC=SmokinHole]

This is a pretty educational discussion. But of the dozens accounts I have read of air combat (I'm not a big WW2 reader mind you) I've never come across a mention of an O2 bottle causing any problem other than running out. Think of the thousands of bomber sorties, each carrying lots of bottles and often getting shot at. You'd think that if exploding bottles was a regular occurrence it would get mentioned more often than it does in wartime folklore. So maybe the idea isn't one we should expect included in BoS. But ARMA3! How fun it would be to take out an enemy diver this way! (Yes I know that water greatly dampens the effect. But who needs real physics in a tactical FPS?). Someone needs to move this discussion over to the BI thread.

[Skoshi_Tiger]

The cylinders or spheres used in WWII would be of significantly different construction. I believe the Spitfire tanks were created from overlapping metal bands. So who knows what they would do when punctured? I doubt the effects would be the same as those shown in the videos.

 

It was interesting to note that in the video neither cylinder ruptured. Also in an aircraft if would be securely fastened to the structure of the aircraft (Nobody in their right mind would want 20KG of mass bouncing around inside their plane) so I doubt punctured tank like those shown would cause too much damage to the aircraft. Though it would be extremely distracting and disconcerting to the pilot. A couple of years ago one of my scuba tanks vented through the valve on a very hot day. It took a minute or so to empty and it sounded like a jet plane was spooling up in the shed.

 

One thing to note, with the reduction of pressure anything in line of the stream of gas would suffer from extremely cold temperatures. (in my case above the top of the cylinder was covered in hoarfrost) I wouldn't want to be in it's path.

Edited January 27, 2014 by Skoshi_Tiger

[Finkeren]

Liquid O2 is flammable as all hell. It'll combust/bubble as soon as it hits asphalt if it's still liquid by the time it hits the ground. Can anyone confirm whether or not compressed O2 or LOX was being used in these aircraft we're talking about?

Sorry mate. But you're looking at it the wrong way. In the examples you posted, the O2 isn't burning, but the high concentrations of it helps some flammable material catch fire. The combusting asphalt is a good example. It's an oil product which is combustible under the right circumstances such as having very large concentrations of oxygen in the surrounding air.

 

Again, oxygen cannot burn for the simple reason that fire is an oxidation process. Oxygen is one part of the chemical (and photoelectrical) phenomenon that we call "fire", but by definition it's not the oxygen that's burning but whatever fuel molecules is binding with the oxygen.

[Mastermariner]

Oh dear! We are playing with words and trying to be more clever then our next.

We all remember the lessons I school, it takes three things to make a fire: Oxygen, combustible material and heat! Remove one and it will extinguish the fire.  

Now if you fill the cockpit with oxygen, the paint, rubber and pilot will burn just add some heat and it will be inferno.

And yes we are burning it in our bodies! We inhale air that have 21% oxygen and exhale the same air now 18% oxygen, that 3% keeps us alive and keeps, among many other things, our  temperature at 37C.

 

And that concludes this for me.

 

Master

[DD_Squawk]

A bit of a tangent, but I know of one airframe mechanic with a nasty burn scar on her neck and shoulder obtained from refilling the O2 on an aircraft.

 

It seems that 'some brain dead monkey' decided it would be a good idea to lubricate the valve because it was sticky and squeeked.

 

High pressure flow (friction) + fuel (grease) + compressed O2 = FWOOSH!