surviving inside pillboxes

[john fox]

went to a lecture last night on WW1 archaeology and the guy stated that concrete pillboxes did not work because the concussion of the artillery strikes around them killed the defenders even though the box had not taken a direct hit, apparently this explains why the allied side did not use concrete boxes in the front line

 

anyone know if this is right (I was not overly impressed he knew what he was taking about outside his narrow but undoubted expertise area)

[Tony B]

The main problem with concrete pill boxes on the surface being hit was Spall. The inner wall being displaced by direct hits. The second world war ones were all lined with a thick plywood anti spall layer and or coverd with earth and rock, that was the old Victorian, Star Fort idea of a Bursting Layer. There was also a blue line painted round them, concussion and vibration could cause vertigo, the idea was the fixed line would alliveate this. The Allies did use concrete posts for flash spotting and sound ranging. The main differnce was one of emphasis, the Allies were all for pushing the German's back off their territory, the German view was even if we don't win, holding this ground gives us a political barganing point, hence you get a lot more Allied Offensives than German ones. If they had been that much of a death trap, why were so many built during WW2?

[john fox]

If they had been that much of a death trap, why were so many built during WW2?

 

thanks for the input - that was the point he was making about the GHQ line boxes in Surrey, he considered them to be death traps and a waste of time, owing far too much to Gen Ironside's influence rather than the lessons learned in WW1

[Tony B]

I think the gentleman had mis-interprated some information. During the Great War, British troops were not that keen on using captured pill boxes or any dugouts. Because THEY FACED THE WRONG WAY! Obvious really the entrance faced towards German Artillery etc. In that case it would make the occupants vunrable.

[AlienFTM]

The main problem with concrete pill boxes on the surface being hit was Spall. The inner wall being displaced by direct hits. The second world war ones were all lined with a thick plywood anti spall layer and or coverd with earth and rock, that was the old Victorian, Star Fort idea of a Bursting Layer. There was also a blue line painted round them, concussion and vibration could cause vertigo, the idea was the fixed line would alliveate this. The Allies did use concrete posts for flash spotting and sound ranging. The main differnce was one of emphasis, the Allies were all for pushing the German's back off their territory, the German view was even if we don't win, holding this ground gives us a political barganing point, hence you get a lot more Allied Offensives than German ones. If they had been that much of a death trap, why were so many built during WW2?

 

This effect is exactly that of the High Explosive Squash Head tank round used against all but the toughest targets.

 

The round is constructed so that when it strikes the armour, the explosive is squashed into a cowpat which is detonated by the fuze in the base of the round.

 

When the cowpat explodes, as we all know, the shock wave is perpendicular to the face of the explosive, i.e. through the armour across the area of the cowpat. When the chock of the explosion reaches the inside face of the armour, much of it reflects back on itself and the leading edge of the shock wave amplifies the trailing edge which is still incoming, causing metal fatigue and a cowpat shape similar that that of the explosive shears off inside and ricochets around inside, chopping up crew and causing secondaries.

 

In the first Gulf War, a 16/5 Lancers Scorpion was credited with a T55 kill. I'd be very surprised if it were not a HESH round, HESH being the usual anti-tank round in the 76mm gun.

 

Because the Germans and the Americans are so in love with the APFSDS ("Fin") round, which behaves better out of a smoothbore barrel, our Army, which can longer afford to make our own barrels, is to railroaded into dropping the HESH round, which needs a rifled bore to maintian accuracy over distance.

Edited November 14, 2008 by AlienFTM

[ford 369]

as Tony says spalling is the main danger involving the coming together of pillboxes and HE rounds ,the Germans got around this problem in thier atlantikwall bunkers by putting a steel plate in the roof of them to stop the shock wave penetrating and causing concrete to fall from the ceiling.Without this steel plate it was found that a cone shaped section of roof would come away when a bunker was hit from above

[Degsy]

The original question was nothing to do with direct hits, it was about the effects of concussion from near misses.

[Tony B]

As far as the Great War goes a lot of the soil was so wet the shells just sunk anyway and never went off on contact. The soloution was time fuses and base fuses. The time fuse to explode above the ground, shell fragments were the main danger, so you want to get under hard cover or deep underground. Base fuses allowed time for the shell to bury itself then explode underground. Concussion effects are extremly variable. It depends on the nature of the material the shock wave passes through. As with HESH, spaced armour or reactive armour both counter them. There was an historic precedent. Most old castles were made of stone. Along came cannon using stone later cast iron shot. Both these splintered on contact, lots of fragments, bad for people but no penetration on stone. Then explosive shells were developed and stone shattered, so later fortification used brick, this crumbled rather than shattered. As with offensive and defensive granades, the German stick grande had a light container for the explosive and relied on blast, you could throw it then run on, with little risk of large fragments. the blast might rattle your teeth but you'd still get up and fight. The British Mill's Grenade had a heavy case designed to fragment throw this and duck, large lumps of metal flying about at high speed. Another design is the 'Shaped Charge, using the Munro Effect. This was discovered by an American called Munro. He was testing explosves aginst various plates of diffrent types of armour. Some plates showed the letters US marked on them. Investigation showed that the charges had the letters US incised into them. If the void had been against the plate the letters were marked. It appears the space gives the gas time to accelerate and be focused by the outer edges of the explosive. The result was amongst other things the ubiquitous RPG.

[Adam Elsdon]

An explosion is a very rapid expansion of gases, causing shock waves, if you are behind something that will withstand that blast, that doesnt break up you are in the main fine, i would imagine that if you are in a re-inforced confined space i.e a pillbox, and a shell went off near the entrance, the gases would compress inside the box, as the rifle apertures are smaller, and compress anything else inside it momentarily, anything from milder effects of burst eardrums to the other end of the scale with the whole body in effect been crushed, causing massive internal organ failure.

 

Having been on the wrong end of a big mortar round, landing in reasonable proximity whilst undercover, the effect is like nothing else you can experience, it massively hits all your senses, even taste as fine dust is lifted.

I should imagine that the size of shells they were lobbing at each other in WW1, whether it was airburst or groundburst would have had quite an effect, even in a pillbox.

 

I would of thought pillboxes in a long term fixed position as per WW1 is pointless, it becomes a bullet magnet, and something to shell relentlessly, the lines of Pillboxes set up as per WW2 for defence is something else, as the enemy would of being coming up against them mainly unexpectedly and then held up until the pillbox and other defences were taken out, the idea to slow the enemy advance and use up their resources to buy time.

Edited November 15, 2008 by Adam Elsdon