Things that go "BOOM"

[Finkeren]

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

It might be that we're mincing words, but it kinda matters in the context of an oxygen tank taking a bullet, whether there should be instant fire, a "chemical" explosion (i.e. combustion) or whether it should just be the force of the high pressure being released causing damage.

[Allons]

This thread reminds me that many ppl are not really beyond mediaeval alchemistry. Greetz, Allons!

[LLv34_Flanker]

S!

 

 

 Grease + O2 is not a very good combo, at all. Sure goes boom if any pressure. We were told in the Air Force that NEVER blow your clothes with O2 or you could risk being a torch the next moment.

[DD_bongodriver]

No it doesn't

[II/JG17_HerrMurf]

One of my favorite Python sketches.

A man walks into an office:

 

Man: (Michael Palin) Ah. I'd like to have an argument, please.

Receptionist: Certainly sir. Have you been here before?

Man: No, this is my first time.

Receptionist: I see. Well, do you want to have the full argument, or were you thinking of taking a course?

Man: Well, what would be the cost?

Receptionist: Well, It's one pound for a five minute argument, but only eight pounds for a course of ten.

Man: Well, I think it's probably best if I start with the one and then see how it goes from there, okay?

 

etc, etc, etc

Edited January 28, 2014 by A1FltTrn_HerrMurf

[DD_bongodriver]

text just doesn't do it justice..

 

http://www.youtube.com/watch?v=kQFKtI6gn9Y

[BigPickle]

You realise this completely ruins the movie 'jaws'

 

"Smile you sanava bitch!"

[79_vRAF_Friendly_flyer]

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.

 

I'm not sure if a rupturing oxygen tank will cause fire that easily. The decompression itself will lower the temperature, so even if the two other components oxygen and combustible stuff (plane, pilot) is there, the temperature will actually drop.

 

The question is if the drop in temperature will be enough to offset the lowered flashpoint temperature caused by the increased amount of oxygen available. I guess it depends on how much room the oxygen has to dissipate into, and whether there's an available heat source (an already existing fire for instance) present.

[III/JG11_Tiger]

text just doesn't do it justice..

 

http://www.youtube.com/watch?v=kQFKtI6gn9Y

Classic Python comedy, they had a few duds but the good sketches are very good.

[Georgio]

The two things that spring to mind about the whole O2 bottle scenario is that the combination of 300mph slipstream, ruptured O2 bottle, fire and lots of aluminium doesn't bear thinking about.

Also I don't know for sure but I'd imagine that if an enemy is getting hits on you, especially cannon hits, then a ruptured O2 bottle is the least of your worries...

Regarding Python, I was extremely pissed to find that both the internet and phone lines were constantly busy the instant that the Python show tickets went on sale.

Finally got through after 40 minutes to be told that all tickets had gone. Surprise surprise, an hour later tickets were on EBay, tickets sites for ten times their face value, what a scam....

[=69.GIAP=C0NAN]

Some things said here bothered me slightly so I did a little research. From experience I know that up until the advent of the F-22 and F-35, modern fighters use liquid oxygen systems. You can carry more oxygen in a smaller space seems to be the reasoning.  The F-22 and F-35 use Onboard Oxygen Generation Systems (OBOGS) which literrally use compressed air from the engine (pre-combustion) run through a system which seperates the oxygen from the air and sends it to the pilot. At least one fatality has occurred when at 50,000 feet a pilot pulling the throttles to idle will essentially remove his own life support... I believe they have this fixed.

 

Anywaaayys, LOX seems to have been first used on the British Electric Lightning in the late 50s. Prior to that, a combination of low pressure (USAF) and high pressure (USN, Luftwaffe) systems were used. What is germane to this discussion is that these systems were always a liability for explosions in combat. Any projectile striking the tanks and causing a leak or rupture was highly likely to cause an explosion or severe fire. Bullets, releasing their energy in a stike, may with sufficient energy create a "pyrophoric" effect or "sparklies" (my pet name). With the flash that is sometimes actually a plasma as a heat source and in the presence of nearly pure oxygen, both steel and aluminum will burn somewhat efficiently as anyone with oxy-acetylene cutting torch experience could guess (see HMS Sheffield in the Falklands) and any dust, grease or other combustibles present will create an explosive environment if contained. I believe what you would normally see is a smll explosion that may or may not threaten the integrity of the aircraft. The devs will likely have some sort of reaction in the DM.

 

If you are actually interested in this topic, http://webs.lanset.com/aeolusaero/Articles/A_Brief_History_of_US_Military_Aviation_Oxygen_Breathing_Systems.pdf , offers a fairly short and interesting read. Note that at high altitude, 100% oxygen is not enough. Even breathing pure oxygen above 35-40,000 feet will not prevent hypoxia unles the "partial pressure" is sufficiently high to actually saturate the aveoli of the lungs. It has to be forced in. I can share more about modern combat breathing systems like the USAF "Combat Edge" system if anyone is interested.

Edited February 8, 2014 by =69.GIAP=C0NAN

[DD_bongodriver]

I thought the main feature of 'combat edge' was the occipital bladder in the back of the helmet and an upper torso pressure garment mainly for increasing g tolerance, pressure breathing has been around for much longer, so is the upper torso garment for enhancing pressure breathing?

[LLv34_Flanker]

S!

 

 Finnish Air Force F/A-18C/D uses OBOGS, since we aqcuired them in the 1990's. Last model of F/A-18 using LOX was AFAIK the A and B models. OBOGS should get enough air from the compressor as long as the engine is running thus providing enough oxygen to the pilot. The fatalities Conan described could be of faulty OBOGS unit, they tend to have some quirks. Just some thoughts..

[=69.GIAP=C0NAN]

Right you are Bongo! Pressure breathing with Combat Edge is at a far higher pressure than used in aircraft without it. The torso garment doesn't squeeze like speed jeans but restricts chest cavity expansion. Just as a SCUBA diver must never hold his breath - especially during an ascent - without the vest, the higher pressures presented to the mask would risk embolisms and/or actual tearing of the lung tissue as the lungs were forced to over-expand. The nape-strap bladder you mention forces the mask to the face to try to contain the pressure. It isn't as much about partial pressure of oxygen as it is about making it easier to breath (still VERY hard) at 7+ Gs.

 

Flanker, I only have a rudimentary knowledge of the pressure requirements for the OBOGS. Does it come of a high pressure bleed or low? Dunno. My speculation was that at idle at ridiculous altitudes (50k+) the system simply didn't provide enough oxygen to the pilot - dunno why it didn't. Will research. It is an insidious onset and he was likely unable to do anything. Sadly, he may have woke up going straight down above the mach with too little altitude to do more than realize he was toast. Interesting about the F/A18s. I know of some tactical design elements of the F-22 and F-35 that have migrated to earlier aircraft, but am unaware OBOGS had done so. Perhaps of interest, my trusty 737, on the newer aircraft, has a similar system that isolates the nitrogen to use to flood the fuel tanks with that inert gas to mitigate against fuel tank fires.

[=69.GIAP=C0NAN]

OK. Read this and similar articles. USAF doesn't know what the problem is either. REALLY?!?!

http://defensetech.org/2012/08/01/air-force-places-f-22-blame-on-valve/

 

The article also casts doubt on how my vest had been rigged when I flew with it. I had mine set up so at G onset, the vest would blow up to match my current chest size - not constrict further. Maybe we were doing it wrong? Evidently, the system is no longer thought to help? (It sucks being retired!) Also, the F-22 boys may be using it up high where partial pressures of oxygen would matter? Dunno.

 

OK. None of this germane to the new game. Back to your regularly scheduled programming inquiring about developer's plans for the damage model!

 

PS. I now have the Premium pre-buy. No idea what I need to do to make it show under my avatar.

Edited February 9, 2014 by =69.GIAP=C0NAN

[LLv34_Flanker]

S!

 

 C0nan, I work on F/A-18C and D. If I recall right the air is taken from the 3rd stage of the compressor. Can check it tomorrow at work. The OBOGS should provide oxygen to the pilot up to the operational ceiling with ease. What also strikes in those fatalities is that if the pilots did have symptoms of hypoxia and suspected OBOGS failure, maybe even had an advisory of the malfunction on the screens(at least F/A-18 has OBOGS advisory), why did they not switch to emergency oxygen from the ejection seat? That is a common procedure and saves your life while getting to lower altitude.

 

 Another thing pilot can accidentally do with the OBOGS is not turning oxygen flow fully open. Again from F/A-18C and D there is the OBOGS panel in the cockpit and first you turn on the OBOGS with a 2-position switch and after that turn Oxy Flow to ON. Failure to fully turn the Oxy Flow to on can possibly cause problems thus hypoxia at higher altitudes. There is a warning to make sure the Oxy flow is fully turned on.

[Rama]

Thread cleaned of Raaaid's science-fiction off-topic stuff.

 

@Raaaid, please keep your creativity for the Free Subject forum. And I sugest you try to read forum rule #15. It apply to everybody, including you. Next time I will give you some time to think about.

[=69.GIAP=C0NAN]

Makes sense to pull it from the low pressure section Flanker. Thanks for the info.

 

Older oxygen panels had a similar problem. The switches (looking remarkably like light switches) could be confusing. It might look like it was "on" or "100%" but the switch was somewhat like a circuit breaker and wasn't actually "on" unless you pushed it through a clicking detent. Of course my memories are fading but I would not be surprised if that was an issue. Of course, by the time you recognize hypoxia - if you are lucky enough to sense it - you are already in a degraded state and if it is a bad enough situation, you may not have time to do anything before lights out. Bummer. And much worse than GLOC for recovery time.