“Ultra Slow Motion Grenade Expanding” https://www.youtube.com/watch?v=L5kaNanGV0I
If you’re unable to watch it, the video starts with two camera angles of the same hand grenade. The pin is pulled, the lever of the grenade comes off, and the casing begins to expand until it resembles a balloon. It expands to probably 3 times its original size, at which point it bursts like an overfilled water balloon.
Is this expansion a real representation of what happens when a frag grenade explodes? Seems silly to make a grenade so perfectly able to evenly accommodate the pressure, then fail, rather than just failing all over the place right from the start.
Yes, it is real. That is the way it needs to fail in order to build up the desired destructive energy. Explosives of that type work by burning very quickly in a small space and then releasing through through the point(s) of least resistance. With firearms, the rapidly expanding gasses push the bullet out of the barrel extremely quickly but grenades are different. You want the entire device to build up as much pressure as possible before the whole casing fails catastrophically and releases a destructive explosion. Any weak spots in a grenade design would allow the gas to release prematurely and not build up the necessary pressure to do nearly as much damage.
I bet that wasn’t a frag grenade. It looks like the casing split in 3 places, not burst into a bunch of smaller fragments.
Plus, frag grenades are packed with high explosive; I’m pretty sure the brisance of the filling will mostly shatter the grenade case on explosion, not blow it up like a balloon.
I see plenty of similiar videos at work. Aircraft bombs, artillery projectiles, shaped charge warheads and the like all respond in a similar manner. The blow up like a balloon to between two and three times original diameter before wall failure.
The old WWII “John Wayne” pineapple grenades with the pre-sectioned exterior pineapple grenade - Bing images actually didn’t work as intended. If you looked at a cross-section, the “arch” of the grenade wall is toward the explosive. Arches are strong - hardly any fragments actually were produced.
Besides metal balls imbedded like a claymore mine, other methods like pre-fragmented walls on the inside (artillery ICM grenades) and steel coils with crimped/weakened sections (M67 hand grenade) are used.
Why didn’t they figure it out then? They had high speed cameras in ww2, and they could have set up target surfaces to catch the fragments to figure out the fragment distribution. How many soldiers died because they threw ineffective grenades?
The reason for the grooves on the surface was to get a good grip; it had nothing to do with fragmenting.
I must say, I have seen plenty of shards from exploded grenades, in museums and private collections, and while they may sometimes be twisted and bent, I have never seen an example of the metal being stretched, as the video implies. Heck, even the letters on the shells are sometimes left, perfectly readable!
Actually, I believe this was one of the problems metallurgists faced in WW1 or thereabouts, when high explosives were introduced: the crude alloys used for shells tended to give rather than shatter, which resulted in a few, big, twisted peels rather than a storm of small but deadly fragments…
I recall there was some difference in steel used in artillery shells between US and UK manufacture. I think the values were referred to in tons and one type was 18 ton and the other type 21 ton.
Quite what those numbers meant I don’t know but it was directly related to fragmentation characteristics. In both cases the shell was intended to fragment on detonation with particular size fragments. Too many fragments reduce the blast effect of a shell and blast is the primary destructive mechanism rather than fragments. This resulted in artillery shells fragmenting into a few relatively large pieces
In the case of hand grenades which are anti-personnel, blast is less important and lots of fragments are desired. That’s why the have notched wire or equivalent wrapped in a low strength casing
The propellant in firearm cartridges deflagrates quickly, but the high explosive in a grenade detonates. This is why a suicide vest, in which naked bricks of HE have ball bearings and hex nuts embedded in them, are so effective: the reaction need not be contained in any pressure vessel, as it happens so quickly that the reaction products can’t get out of their *own * way fast enough, resulting in the production of a shock wave that accelerates the shrapnel to high speeds.
This makes it hard to believe that the average grenade does the inflating-trick the video demonstrates. It’s not possible the casing shards would spring back to their original size, would they?
Does anyone have a reference or a cite for expandy-grenade?
