Open hatches and HEAT

[BloodCat]

I heard, that in Afghanistan and Chechnya some tank/BMP crews preferred to drive (especially in convoy) with open hatches, 'cause it greatly improves crew chances of survival if the vehicle is hit with HEAT. 1) Is there any similar practice among the Western Tankers and 2) is this simulated in CMSF?

PS I didn't speak or write in English for some years -- so don't laugh too loud.

[bodkin]

Welcome to the forum.

I don't know about question 1, but I'm pretty sure question 2 is not simulated in CMSF.

I base my answer on nothing other than game time experience. Why would being unbuttoned improve survivability? Is it a physics thing? Yet even then the more available area for the explosive force to escape through would probably doom an occupant who sits near one the hatches. Just my thoughts.

[Lieste]

As peak overpressure inside a vented and closed chamber is to all intents the same there is no 'survivability' enhancement to the direct effects of the weapon.

More likely is the indisputable reasoning that a closed hatch can be jammed if it or the frame are damaged during the impact, either directly or by distortion of the hull. In the case of a fire this would result in potentially wounded crew being unable to evacuate in time.

With the hatches open there is reduced risk of being trapped.

The riding outside the vehicle was an anti-mine protection measure, as the rigid seats and poor optimisation (pax. facing outwards among other things) would result in a high risk of serious and life threatening lower extremity and neck injuries. Outside there is a higher risk of injury from direct fires, but there is a certain amount of protection afforded by vehicle structures, stowage and improvised armours, and gravity does assist getting off the vehicle quickly if taken under fire.

[hcrof]

Welcome to the forums!

I have heard that story too. I believe that it is supposed to reduce the heat and overpressure in the crew compartment. I don't believe that CMSF models this effect but you cant open all the hatches on a BMP anyway so any effect would be minimal.

As for western tankers, I should probably leave it to the experts but in Iraq/Afghanistan they are driving around with so much extra armour, especially on the sides that they would be pretty safe from RPG HEAT rounds. The main threat is IEDs.

It is an interesting question though

Edit: Lieste are you sure that there would be no difference with all the rear hatches open on a BMP? There is a lot of ventilation there!

[Elmar Bijlsma]

I do not see how the blast of a HEAT type warhead would be lessened by it exiting the vehicle. The shockwave would still do what it does to any object it encounters on the way out. Neither over-pressure nor heat would be diminished by the eventual freedom of the blast.

I would assume the open hatches preference is more likely due to a wish to exit a burning vehicle post-haste.

[Vark]

I remember a story about a Churchill being hit by a panzerfaust which caused all the hatches to be blown open, after the crew recovered, they shut the hatches and kept fighting. This would tend to suggest there is some blast that could be vented, by opening the hatches, but would not think it would reduce the effects of a faceful of molten steel/copper.

[Damian90]

It is myth...

In Iraq many M1 tanks were perforated over side, top and rear armor, by HEAT ammo from RPG's, sometimes with hatches closed, sometimes opened. In 99% of cases crew was only injured, tanks were most often only lightly damaged.

In fact there is no overpresure effect's, the main danger are spall and shaped charge jet.

But modern HEAT warheads are optimised to perforate better, and better armors, so after armor effects seems to be smaller and less deadlier... heh modern APFSDS ammo seems to be more deadly and generate more spall, especially DU ammo with it's piroforic effects can be extreme deadly for crew.

IRCC there were conducted tests in cold war times with animals inside tanks, and APFSDS ammo was more deadly than HEAT.

But I read about that in 2008 maybe 2007 and I can not remember everything correctly.

[Lanzfeld]

More likely is the indisputable reasoning that a closed hatch can be jammed if it or the frame are damaged during the impact, either directly or by distortion of the hull. In the case of a fire this would result in potentially wounded crew being unable to evacuate in time.

With the hatches open there is reduced risk of being trapped.

This is correct. It is the same when you ditch a light aircraft. The last thing we would do is pop open a door and wedge a shoe in it. Impact is going to deform the hull and you may not be able to open a door after. Same concept with tanks....kinda.

[John Kettler]

Bloodcat,

Welcome aboard!

Bloodcat and bodkin,

Regarding question 1, if you're talking well-protected modern western AFVs, probably not, since they have automatic fire suppression systems which can put out a HEAT detonation in milliseconds. A lot depends on the tactical environment, the perceived threats, and the temperature. Places like Iraq can be unbelievably hot and humid simultaneously, and U.S. tanks (at least through M1A2) aren't air conditioned, so thermal issues, for crew and electronics alike, matter. In MOUT, multiple weapons need to be manned and sectors searched in order to keep RPG teams from wreaking havoc. This necessitates opening hatches in order to see out and work the weapons, but that's a combat effectiveness decision rather than a thermal issue one. Certain AFVs, such as the baseline Stryker, have remotely operated weapon stations. I don't know the answer to question 2, but I do know that open hatches convey very real survivability advantages in the event of mine/IED attack from below and HEAT attack. The whys are explained in a somewhat gory well-illustrated thread called Casualties inside vehicles (see particularly my posts):

http://www.battlefront.com/community/showthread.php?t=89881

Armor crewmen have certainly been blown out of hatches and killed or seriously wounded when operating unbuttoned, but lots have survived relatively unscathed, whereas their compatriots, located in the fighting compartment proper, didn't. Now, go back and look at what mines and RPGs are capable of doing and imagine what it would be like inside a vehicle hit so hard the roof welds rupture, then the roof armor buckles. Care to be flung through that roof? Open hatches help keep blast overpressure and temperature within survivable ranges when an AFV is hit.

Regards,

John Kettler

[John Kettler]

Lieste,

Assuming no intervention from a state-of-art automatic fire suppression system, and concentrating purely on blast and temperature, ignoring spall and such, there's the almost instantaneous rise of both, but you fail to consider the vital issue of dwell time, or phenomenon duration. The human body can withstand incredible abuse; for only short periods of time. Thus, for a pilot, it might be 5 Gs sustained, but as much as 14 Gs for a very limited time. Open hatches act not only to rapidly dissipate that pressure and heat, but also limit the total time the AFV crew's exposed to it, in turn limiting casualties. A very simple demonstration of this may be found when shooting a given weapon at an indoor range as opposed to an outdoor one. The difference is considerable, and as explosions go, muzzle blast from even a .44 Magnum is nothing compared to an RPG projectile detonating. Standing at the next stall indoors while someone fired said .44 resulted in palpable concussive forces on my body, whereas the vastly more powerful rifle cartridges, fired outside, did nothing of the sort, even when I was the shooter. The difference lies in blast trapping and reverberation from the reflected pressure wave. When an AFV is hit by HEAT, the open hatch helps rapidly restore the status quo, as well as limiting effects from things like being blown into the overhead, resulting in what's known as translation injury. Likewise, a grenade going off outdoors is far less of a threat, holding range constant, than one going off inside. The walls and ceiling not only help contain the blast and echo it, but they and everything in the zone can become secondary missiles. Modern housebusting munitions exploit the structural integrity of the target to destroy it, and a HEAT strike or mine can do the same thing in a closed AFV. Even modest overpressure applied to interior walls can cause structural failure, as seen in the recent MythBusters where a sealed jail cell was destroyed using the carbon dioxide gas from thousands of antacids.

Damian90,

As noted in the link I gave, the M1 has a state-of-the-art automatic fire suppression system and spall protection, radically altering the AFV survival probabilities. The RPG detonation is basically strangled at birth once it enters the fighting compartment, creating no real opportunity for large scale blast or thermal effects. If you look at the Bill impact vid in the same thread, you can quite clearly see what an unhindered HEAT penetration to do to a combat loaded tank, both in terms of primary damage from the immediate effects, and from ammo cook off.

As for APFSDS, the Silver Bullet of Gulf War fame is made from depleted uranium and is pyrophoric on impact, filling the fighting compartment with displaced armor and a cloud of flaming, toxic, radioactive particles which demolish crew, men and gear alike. See this vid from minute 3-4 for a chilling look at what DU can do.

The fireworks show you see here is what DU looks like when it penetrates. You already know what it does inside.

Regards,

John Kettler

[Lieste]

I did consider the increased dwell time, but the blast size of the minor fraction of energy delivered by a small HEAT warhead through the penetration channel do not support a generally lethal direct blast effect when the internal volume of a typical vehicle. The only way to obtain significantly increased behind armour impulse loading would be to greatly augment the delivered blast energy by burning of fuel or ammunition subsequent to perforation of same by (high KE) fragments or the jet.

When the blast loading is larger, then the confined space does indeed increase the dwell time in a significant way - now an increased positive phase duration does increase the risk to solid organs. I still consider this effect to be minor though for external impacts compared to the risk to light vehicles from fragment perforations, shock loading via the structure (speed of sound in steel is much higher than in air, and severe damage can be caused to the lower extremities of crew in contact with the floor in IED etc), acceleration/deceleration injuries by bulk movement of structure and vehicle overall, and by tertiary objects (ammo cans/small arms not strapped into racks etc) which can be thrown (at slow speeds) by impact loadings.

I consider the movement from floor to roof to be more in consideration of these random unpleasantnesses by mines and IED, rather than to be related to light AT weapons.

Incidentally the suppression of fire by Halon extinguishers initially can do nothing except increase current internal pressure. Any suppression and cooling effect can only be related to flame-speed and mixing, and must be a much longer duration effect than those related to blast. They will act by preventing deflagration of fuel/propellant/HE filling of vehicle ammunition, rather than any reduction in incident weapon effects.

[Damian90]

As noted in the link I gave, the M1 has a state-of-the-art automatic fire suppression system and spall protection, radically altering the AFV survival probabilities.

Automatic fire supression systems not always work as tehy were designed unfortunetly.

And spall linear is only in newest variants like M1A1SA, M1A1FEP and M1A2SEP, older ones doesen't have spall linear.

In Iraq 90% of M1 tanks were older M1A1HA, M1A1HA+ and M1A1HC variants, still even if armor was perforated, crew members were often injured not killed, the real killer of tank crews were big IED's and snipers.

As for APFSDS, the Silver Bullet of Gulf War fame is made from depleted uranium and is pyrophoric on impact, filling the fighting compartment with displaced armor and a cloud of flaming, toxic, radioactive particles which demolish crew, men and gear alike. See this vid from minute 3-4 for a chilling look at what DU can do.

Almost everything in here are right... besides that BS about radioactive DU. Depleted Uranium is just heavy metal, it is not radioactive only toxic if someone is enough stupid to i.e. eat small DU piece.

If DU was radioactive You can be sure that Yanks were not use it as ammo and armor.

And if someone claims that DU is radioactive, for me that person is total idiot, and should back to school learn chemestry.

[Elmar Bijlsma]

Almost everything in here are right... besides that BS about radioactive DU. Depleted Uranium is just heavy metal, it is not radioactive only toxic if someone is enough stupid to i.e. eat small DU piece

DU is radio active, just so weakly that it's not a significant threat unless something silly is done with it.

However, it is highly toxic and inhalation of small airborne particles (which given the circumstances of military DU usage is pretty easy) or water contamination can lead to all kinds of nasty ailments. It's toxicity is considered by most research to be a significant risk to health.

[c3k]

Well, for that matter, granite is radioactive. And if we're being pedantic, we could include bananas; each one contains enough radioactive potassium to give the eater a 1 millirem dose.

DU is a heavy metal. Any heavy metal which is ingested is bad. That's why we don't like mercury in our fish.

Ken

[Damian90]

DU is radio active, just so weakly that it's not a significant threat unless something silly is done with it.

It is radioactive like every normal thing, like TV in your room (maybe even less than TV). So talking about it like about some radioactive rod from nuclear reactor is BS.

[Elmar Bijlsma]

It is radioactive like every normal thing, like TV in your room (maybe even less than TV). So talking about it like about some radioactive rod from nuclear reactor is BS.

Except I didn't say that. It is however mildly radioactive, more so then typical materials. To claim otherwise is ignorance. Indeed, in close proximity it can be hazardous, though such danger would require prolonged close proximity.

FYI, and I think I may have mentioned it before on this forum, DU is, like lead, a great radiation shield material. It can block significant radiation while it's own can be blocked with not much more then a coat of paint.

[Vark]

Given that most super heroes develop their super-human powers as a direct result of exposure to radiation what powers would you get by only eating bananas? I will look at these fruit now with a greater respect and not mock my wife when she calls the forgotten, smelly brown ones "radioactive". Final thought, why do so many arms videos have music akin to porno films of the 70's?

[dan/california]

DU emits small quantities of ionizing radiation as several people have noted. The quantity however is quite small and essentially harmless. Remember the thing that DU has been depleted of is the more radioactive isotope of uranium. DU is basically a byproduct of producing nuclear fuel. The chemical toxicity effects of inhaling small particles, however, are quite significant and in no way healthy.

Most of the debate though is somewhat silly, the goal of war is to convince the other side that sitting down and shutting up is a better course of action than being a pain the &^^&$#. Nasty pyrophoric effects are good at that, all the other issues are secondary. If you don't want DU particles in the water, don't make a U.S. armored division pay you a visit.

[John Kettler]

Lieste,

If I forgot to do so earlier, welcome aboard!

Very impressive post! You seem to have considerable familiarity with the issues under discussion, obviously have a strong technical background, and beyond that, seem to be at home with explosives phenomena.

When I was at Hughes Aircraft Company's Missile Systems Group, I had the chance to watch footage of the Kidde Automatic Fire Extinguishing System (AFES) in action. This system relied on super fast optical triggering from detectors made by our then subsidiary Santa Barbara Research Center. The test was a direct comparison of what happened when an RPG projectile shaped charge jet penetrated a fighting compartment which had and didn't have the AFES. The ultra high speed footage told an unmistakable story. Without AFES, the penetration became an almost instantaneous fireball, wrecking the interior and setting it ablaze. With the AFES, you could watch as the Halon stifled the explosion before it could even get going, leaving the compartment both intact and not burning. The difference was so astounding you could hear gasps in the room. This is the system on U.S. M1 Abrams, M2/M3 Bradleys and other AFVs. SOFAIK the RPG jet didn't go through a fuel tank first in the test.

http://www.army-technology.com/contractors/protection/kidde/

I've tried and so far failed to find any test footage online that I could better use to make my point.

Damian90,

I wish you were right, but the facts belie your wishes. If you watch the videos by Dr. Doug Rokke, you will learn a great deal about DU, which is radioactive and an emitter even before it's fired into the targeted AFV.

http://www.youtube.com/results?search_query=dr.+rokke&search_type=&aq=f

It was a known hazard, as the good doctor shows, well before the first Gulf War, yet except for a handful of specialized EOD soldiers, most were given no protection or cautions against its effects. NATO was ultimately forced to clean up its DU mess in Kosovo, but the hundreds of tons expended in Iraq alone and never cleaned up will blight the region for ages to come, and the resulting birth defects are simply horrific and readily available for viewing at YouTube. DU is an inhalation, ingestion and wound penetration threat which, once inside, subjects the body areas in contact to high radiation doses not considered by whole body exposure dose models used in such things as film badge dosimeters.

Regards,

John Kettler

[Damian90]

Oh another good source, another good doctor that makes another nuclear panic!

DU is toxic, and this is only real problem with it... and it is toxic as any other heavy metal, like lead and... the "natural envirvorment friendly tungsten "...

Besides this, DU in ammo and armor is not pure DU but DU alloy with few other metals and materials.

Damn here in Poland, in our WarPac times civilains used DU made hammers... oh my, in such case my nation should be dead right now or on street of Warsaw we should see radioactive mutants.:eek:

You should be more critic to opinions from such good doctors and other people that takes money from cancer of our times... lefties, pacifists and other morons...

But I agree, we should clean areas from DU ammo, it is not good if toxic metals can be a threat to civilians.

[flamingknives]

Given that most super heroes develop their super-human powers as a direct result of exposure to radiation what powers would you get by only eating bananas?

One from the British nostalgia albums:

http://www.youtube.com/watch?v=cNknWT-agT0

Regards DU, IIRC it is an alpha emitter and hence essentially harmless when it is outside the body as the alpha particle will not penetrate the skin. If ingested then it can cause severe damage to the soft tissues. However, that it is a very toxic heavy metal is probably more of a concern. As a bulk material the radioactivity is unlikely to be particularly hazardous, anymore than a cellar in a granite region.

[JonS]

... here in Poland, in our WarPac times civilains used DU made hammers... oh my, in such case my nation should be dead right now or on street of Warsaw we should see radioactive mutants.:eek: ...

You mean it's not because of the radiation, that's just the way you lot look naturally?

Oh.

Oh dear.

[John Kettler]

Damian90,

That was the U.S. Army's own medical expert talking, and if you watch the first video I gave a link to, he says he himself is officially classified 40% disabled by DU. Might want to listen to the man!

Using DU for hammers is hardly the same thing as slamming and blasting 350 tons of DU across a large chunk of Iraq, to name just one locale. Mind, I'm talking about actual DU content here, not weight of expended munitions.

Recommend you read this DU Wiki, which presents a wealth of material, from a variety of perspectives.

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

What the IAEA has to say about DU. See particularly answers to questions 9, 10 and 12.

http://www.iaea.org/NewsCenter/Features/DU/du_qaa.shtml

Here's some info on civilian issues associated with DU.

http://www.wise-uranium.org/dviss.html

I close with this valuable compilation of articles on various military and civilian aspects of DU, to include the news to me that the U.S. is quietly doing spot cleanup in Iraq in support of its own bases. Discussed are long term contamination, mutagenic and toxicity issues, known hazard status, whopping jump in background radiation, damage to offspring and more. See particularly what the SpecOps guy has to say in DU--Don't Ask-Don't Tell.

http://www.prorev.com/du.htm

Regards,

John Kettler

[flamingknives]

Strangely enough, the IAEA article does not support your picture of DU as a huge threat.

[John Kettler]

flamingknives,

It confirms what I said about how DU enters the body, states it's both radioactive ( a point Damian90 disputes) and toxic. It also addresses where the DU concentrates in the body, such as the kidneys. Interestingly, a lot of GIs who claim DU exposure injuries have big time kidney issues. I tried to provide a range of information sources, rather than only providing that which served my argument. The IAEA seemed like a logical group to include in the information array.

Regards,

John Kettler