Saving Private Ryan & chin straps

[pete]

.

I'd like to add another observation too, when I was trained in the army for nuclear attacks if you were out in the open, the drill was to lie down flat with your feet pointing towards the blast if i recall correctly and shield your head and helmet with your arms, that was 1991 if I have it reversed I dont think it would matter eithr way. If you were in that position there would be a shock wave approaching at ground level, same idea.


Best,

Pete

[Jean-Loup]

So it seems like in some particular situations, neck injury is a risk?
I wonder what they figured out with the British helmet; its huge rim must act as a perfect blast catcher.

Anyhow, whatever the reasons, nobody wants to have a solid chinstrap going around their neck ready to strangle them: its just asking for trouble.

[pete]

.

Well the basic idea is anything resistant to blastwave is bad, so helmet and head would be equally involved, I dont think its specifically only the helmet doing it but the helmets solid mass certainly probably enhances the effect. Helmets of now days are all with solid chin straps and never worn loose anymore, yet the same design of shells land. I am going to go with the "low to the ground" with only head and helmet exposed, and NOT curled up in max protective position like on d day behind a berm but facing a blast, thus restricting the shockwave. It seems to be the only logical explanation. If you have a whole frontal body exposed then it goes to the type and size of explosion and proximity for the various effects. J

Just an example if a 155mm shell lands 20-50m from the man standing in the open, if he miraculously is not vapourized or turned to burnt ground meat parts already from the frag wave, blast wave (intense heat) , and blast over pressure you can be certain there will be more high level injuries as cause of death then just the neck as a result of a chinstrap. Even if a guy is curled up in protective position laying flat, if his helmet is touching the ground and even if he is not looking towards (restricting) the shockwave he still will probably suffer some injuries as the shockwave is transmitted through the ground and ill go throgh his helmet too and into his body and head also in close contact with the ground. For example when you get rid of a bomb next to a house, you need sometimes to make a trench to stop the blast wave (earth shock) from wrecking services, that trench can have no reinforcing wood etc that will transmite the blastwave past it ad into somthing you dont want to damage like a foundation.

In most times when a shell is landing, like common mass ww2 bombardment, the troops woud be flat, or in trenches anyhow IMO, if they werent running for cover or attacking through the artilery wave to get out of it before guns can be adjusted possibly this is where this came from- reports from guys being flat or head and neck exposed, which filtered over into a myth or "every position" for the purpose of incomplete information or a "cover all the bases" remedy, shell, close contact etc. There is certainly relevance for some positions and also for close contact. Commandos and even basic infantry are still taught how to make use of a buckled up helmet to take ut an enemy easier or to use the helmet in close quarters to smash with, throw etc.


Best,

Pete


New email

Dear Pete,

If you want to share my answer, here is a slightly better version....

QUESTION: Question: does a solid fastened chinstrap (without any sort of
special release) always cause a neck injury in a blast?

ANSWER: No, but it probably depends on the size of the blast. Most mine
blasts are very small compared to bomb blasts encountered in combat. In
demining, there have been no instances of neck injury recorded when wearing
a fastened helmet in a blast - but there have been only a few where a
combat-helmet was worn and it was not recorded whether it was fastened in
most cases. There has been an instance where the chin-strap on a MedEng
plastic visor/helmet slipped and severely damaged a man's nose as the blast
front passed. This kind of helmet/visor breaks in a blast more often than
others - probably because it is held rigidly in place by the chin strap. The
breaking does not seem to cause injury - it is usually (but not always) just
the "wings" where the visor attaches to the helmet that snap.

With small blasts in demining, I don't think it matters.

With all blasts, unless you are on top of the device, the fragments strike
before the blast wave (it's a tiny timespan, but long enough). An unsecured
visor stops the fragments of earth, mine casing, etc just as well as a
secured one. [You can see the fragment marks on the unsecured visor face in
tests and after accidents - but 5mm polycarbonate is often holed by metal
fragments, of course.] The blast wave passes after the fragments have
already been stopped and it usually removes the visor and headframe. The
low-pressure behind the expanding blast wave causes turbulence and the visor
often flies high - but it had already stopped the fragments. Dust is drawn
into the low-pressure area as the pressure equalises and the victim
generally gets dust in his eyes - nothing that cannot be washed out if the
visor was in place when the fragments associated with an AP blast mine
struck.

The general rule with blast is - don't try to stop it. The forces are
immense. The HE in a large AP mine can lift a tank that bellies out on it
(while not damaging it, of course). Let the blast go - and let it take the
visor with it. It seems obvious that this is easier on the neck - but there
is no proof of that in the accident
record. Whiplash does not occur because the blast wave expands as a dome and
hits the kneeling deminer low down fractionally before hitting his head -
his whole body is pushed up and back. If the deminer were lying down so that
the head was the only thing to take the blast wave, this would not be true
and severe whiplash should be anticipated.

According to one report from MedEng, combat helmets can "trap" the blast and
increase the probability of severe hearing damage. I have no evidence of
this in the accident record. The company's research has (as you might
expect) reached conclusions that favour its own PPE designs in other cases,
so I treat their claims with skepticism. (It seems obvious to me that
commercial companies should not be expected to conduct objective research.)
But it may be true that helmets that flare over the ears to allow normal
hearing increase the risk of damage to the tympanic membranes.

For a deminer, being separated from his visor is not an issue after an
accident. The blast and fragment strike was a single event and he is not
going to pick up tools and work again immediately. For a soldier, being
separated from his helmet when all hell is still breaking loose around him
might be a different issue.

Based on my experience with small blasts and mine fragmentation (which I
acknowledge is not entirely relevant), my belief is, if the helmet is meant
to protect against shrapnel or bullets, it might deflect them slightly
easier if it could move away - but I would want to keep it in place because
more might be coming! If the soldier is going to be close to a single blast,
he should unfasten the helmet and let it go where it wants.

This opinion is empirically based, and subject to review as more evidence
becomes available.


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