Iwo Jima
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Re: Iwo Jima
"wouldn't you have to have a direct hit on the opening"
In simplistic terms yes. I remember charts and tables for estimating this damage, have collected a few. The fast rule of thumb is if the projectile crater in 'average' soil covers the item it will damage it. ie: US 105mm howitzer projectile, 3kg explosive, must hit within a meter of a trench to have chance of collapsing the wall; A 155mm projectile, 7kg of HE about 1-5 meters. Thats surface bursts.
It changes when the projectile has a delay fuze. The energy from the expanding gas is transfered in a larger part to the soil, thus more against the target structure. So if you know you are attacking subsurface or hardened surface structure delay fuzes are preferable and perhaps AP or penetrating ammunition.
Still, even with 600kg+ HE charges we can be talking single digit distances from the target structure if well built.
Buried in the pages of the US Field artillery Journal are text and photos summarizing reports of test against a steel reinforced concrete bridge in the 1920s. Even the 240mm projectiles took suprisingly small bits off the bridge. A meter or two, the 105mm left scorch marks around chipped surface. With penetrating rounds you got holes completely through and a broken steel rebar or two. A single hit with a 20 or 35 cm projectile on a tunnel entry may leave it repairable in a few hours. For a target like that you need two or more damaging hits.
It is late and my notes are not here. but one more bit of trivia. 'Battleships' can do plunging fire. All projectiles follow a parabolic path modified by air resistance. It is a matter of having the appropriate range. For way to many reasons the navy gunners of 1945 did not always take advantage of this. Ok its time to go, next class we talk about skip or ricochet rounds and how to achieve a 40% rate in those.
In simplistic terms yes. I remember charts and tables for estimating this damage, have collected a few. The fast rule of thumb is if the projectile crater in 'average' soil covers the item it will damage it. ie: US 105mm howitzer projectile, 3kg explosive, must hit within a meter of a trench to have chance of collapsing the wall; A 155mm projectile, 7kg of HE about 1-5 meters. Thats surface bursts.
It changes when the projectile has a delay fuze. The energy from the expanding gas is transfered in a larger part to the soil, thus more against the target structure. So if you know you are attacking subsurface or hardened surface structure delay fuzes are preferable and perhaps AP or penetrating ammunition.
Still, even with 600kg+ HE charges we can be talking single digit distances from the target structure if well built.
Buried in the pages of the US Field artillery Journal are text and photos summarizing reports of test against a steel reinforced concrete bridge in the 1920s. Even the 240mm projectiles took suprisingly small bits off the bridge. A meter or two, the 105mm left scorch marks around chipped surface. With penetrating rounds you got holes completely through and a broken steel rebar or two. A single hit with a 20 or 35 cm projectile on a tunnel entry may leave it repairable in a few hours. For a target like that you need two or more damaging hits.
It is late and my notes are not here. but one more bit of trivia. 'Battleships' can do plunging fire. All projectiles follow a parabolic path modified by air resistance. It is a matter of having the appropriate range. For way to many reasons the navy gunners of 1945 did not always take advantage of this. Ok its time to go, next class we talk about skip or ricochet rounds and how to achieve a 40% rate in those.
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Re: Iwo Jima
The CEP, Circular Error Probability, for the BBs rounds when using plunging fire was way too large to take out the entrance to a tunnel, for example. To get plunging fire they'd have to be well away from the target and distance increases the CEP. Even when firing at something the size of a battleship most of the rounds missed.
Re: Iwo Jima
sounds logicalOpanaPointer wrote:The CEP, Circular Error Probability, for the BBs rounds when using plunging fire was way too large to take out the entrance to a tunnel, for example. To get plunging fire they'd have to be well away from the target and distance increases the CEP. Even when firing at something the size of a battleship most of the rounds missed.
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Re: Iwo Jima
The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
Re: Iwo Jima
I was in the USMC at Vieques Island [sic spell ] late 80s.......we were about 4000 yards away from impacts of USS Wisconsin[ I believe ] 16 inchers and they were MONSTROUS from that far away.....however, as we see in hsitory, it takes a close hit to kill well dug in troops....OpanaPointer wrote:The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
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Re: Iwo Jima
During the Korean War the NK accused us of using nukes on them. Just a little old battleship round, ya'll. Like this one.bronk7 wrote:I was in the USMC at Vieques Island [sic spell ] late 80s.......we were about 4000 yards away from impacts of USS Wisconsin[ I believe ] 16 inchers and they were MONSTROUS from that far away.....however, as we see in hsitory, it takes a close hit to kill well dug in troops....OpanaPointer wrote:The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
Re: Iwo Jima
Comparing to:
http://www.google.com/imgres?q=battlesh ... =192&ty=77
or
http://www.google.com/imgres?q=battlesh ... =146&ty=96
I suspect that the above round is a 14" round.
http://www.google.com/imgres?q=battlesh ... =192&ty=77
or
http://www.google.com/imgres?q=battlesh ... =146&ty=96
I suspect that the above round is a 14" round.
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Re: Iwo Jima
At what range? When you consider that lethal fragments from a 8 inch howitzer go 1,000 meters, what would it be for a 16 inch gun??OpanaPointer wrote:The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
Mike
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Re: Iwo Jima
The marine sitting on that projectile. . .is he crazy?? Or has gone past the point of giving a shit?? Or both??
Mike
Mike
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Re: Iwo Jima
The range I remember was 16 miles for that figure. The blast radius would depend on the round. I'd have to dive deep for that information and my big box is in the shop.Delta Tank wrote:At what range? When you consider that lethal fragments from a 8 inch howitzer go 1,000 meters, what would it be for a 16 inch gun??OpanaPointer wrote:The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
Mike
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Re: Iwo Jima
Just a smoking cup of macho, that's all.Delta Tank wrote:The marine sitting on that projectile. . .is he crazy?? Or has gone past the point of giving a shit?? Or both??
Mike
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Re: Iwo Jima
Carl,
What was the CEP on the 155mm M109A1 Howitzer? Could you break the CEP into Range and Deflection Probable Error? I do not recall any conversations on CEP, we always talked about Range and Deflection Probable Error.
Mike
What was the CEP on the 155mm M109A1 Howitzer? Could you break the CEP into Range and Deflection Probable Error? I do not recall any conversations on CEP, we always talked about Range and Deflection Probable Error.
Mike
Re: Iwo Jima
50 feet? Wow, that’s good. On Hyperwar you have a USMC doctrine manual from pre-WW2 giving 8” cruiser gunfire a spread of, I think it was, about 300 yards. For 50 feet, I’m thinking the ship has to be pretty close in.The New Jersey's CEP was 50 ft. during the Vietnam era. So you could figure the safe zone was the blast radius plus 50 feet. The sane zone was a bit larger.
In the Technical Missions to Japan info, if you look hard enough you can find a table that gives the effective AA radius of Japanese HE shells up to 18.1”. That's a rough guide on how far splinters travel (but doesn’t give you information on the density of splinters as you move out from the blast).At what range? When you consider that lethal fragments from a 8 inch howitzer go 1,000 meters, what would it be for a 16 inch gun??
Re: Iwo Jima
isn't that spread from all the 8 inchers at once?
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Re: Iwo Jima
I'm pretty sure that's how it went, but I haven't seen the page in question lately.bronk7 wrote:isn't that spread from all the 8 inchers at once?