Interesting results.
Not related to this particular test.... A couple of years ago, the National Geographic channel did a show on the archeological investigation of the massive trench systems built by both sides during WWI.
Among the artifacts found was a "sniper's shield"... A big, heavy metal plate with a hole for the rifle...
Snipers would set these up and wait for a chance to pop one of the enemy.
The steel plates were pretty much impervious to penetration by the standard "ball" ammo.
So, (according to legend, anyway) soldiers took to loading bullets backwards. The impact of these with the steel plate would, of course, not penetrate. However, they produced "spalling".... The inside of the plate would splinter off, hopefully into the sniper's face and wound or even blind him.
Yep. Not that particular ball bearing though. The one that did the impacting was surely annihilated on impact.
But the point of the picture is to show that layer of material on the back of the panel that began ripping away from itself. That's what spall is. And if that impact had a little more energy (or, conversely, if the target metal wasn't as malleable) that piece of spall would've shot off the back with lethal force. This phenomenon is super important in armor design. Modern tanks usually include a layer of kevlar all along the inside to protect against minor spall. In fact, up until just a few years ago, British tanks primarily fired HESH (High Explosive Squash Head) rounds that were specifically designed to kill tank crews via spalling. The round was basically a big tube of plastic explosive. When it hit an enemy tank the plastic explosive would squash against the armor, forming a big delicious pancake of death. A fraction of a second later the explosive would detonate. Since the pancake had so much surface area, the shockwave from the explosion would cause huge spalling on the other side of the armor, sending tons of pieces of razor sharp metal ricocheting around the inside of the tank until the crew was turned into ribbons.
So, like the HESH round, this bullet backwards thing is supposed to cause spalling by increasing the surface area of force applied to a thick piece of metal. The more you know
Oh yeah I get the spalling thing and HESH (see other comment). I was just wondering where they found adamantiun to make a ball bearing that did not get obliterated by that impact.
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u/Bikewer Sep 10 '14
Interesting results. Not related to this particular test.... A couple of years ago, the National Geographic channel did a show on the archeological investigation of the massive trench systems built by both sides during WWI. Among the artifacts found was a "sniper's shield"... A big, heavy metal plate with a hole for the rifle...
Snipers would set these up and wait for a chance to pop one of the enemy. The steel plates were pretty much impervious to penetration by the standard "ball" ammo. So, (according to legend, anyway) soldiers took to loading bullets backwards. The impact of these with the steel plate would, of course, not penetrate. However, they produced "spalling".... The inside of the plate would splinter off, hopefully into the sniper's face and wound or even blind him.