04-25-2006, 06:06 PM | #21 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Explosives: Lethality of 1 pount of TNT
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Static overpressure results from compressing the atmosphere, and shatters things but doesn't really move them about. Dynamic results from moving the atmosphere, and tends to throw things around but isn't too effective at destroying them. Typically, a blast wave on the building first breaks the building's structure, then the dynamic overpressure knocks the building down. On a human, the static overpressure might kill (at 50-100 psi, due to lung damage typically), the dynamic overpressure will not kill directly but can cause casualties by throwing objects or people around (shrapnel or translation injuries). Static overpressure is pretty much constant in duration, as it's a single wave, though it can be amplified by bouncing off of things; dynamic overpressure varies with the size of the explosion, and might last longer indoors due to being channeled about. My main objection to the chunky salsa effect, in any case, is the fact that humans are generally more resistant to overpressure than buildings, so unless you're in a hardened building, or the blast waves are too weak to hurt you anyway, blast waves don't reflect back on you, they just blow out the walls. |
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04-25-2006, 06:08 PM | #22 | ||
Grim Reaper
Join Date: Aug 2004
Location: Italy
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Re: Explosives: Lethality of 1 pount of TNT
Just to make sure we are on the same page: dynamic overpressure is what kicks things around (blast wave), static overpressure is what crushes sealed cans.
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bye! -- Lut God of the Cult of Stat Normalization Last edited by Luther; 04-25-2006 at 06:14 PM. |
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04-26-2006, 03:53 AM | #23 | ||
Join Date: Aug 2005
Location: Hamburg, Germany
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Re: Explosives: Lethality of 1 pount of TNT
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50psi are about 3,5 bar or 3,5 times the presure of the atmosphere at ground level. A diver will be exposed to this kind of presure if he dives about 25m (83ft) deep. Even long time exposure will not kill anyone. So it is not the overpressure itself but the speed at wich the pressure change occures - the speed at wich the front of the shockwave moves. The dynamic presure is a result of the kinetic energy of a body with a significant mass, wich is moveing. So i guess the shockwave (wich has a physically significant mass and is fast moveing) creates a sudden change of dynamic presure. Overpressure will not damage a building. Buildings can withstand the force of wind or the weight of water or snow. Furthermore pressure is force applied by area. If you have 50 psi in the hex of the explosion - wich means if the hex was a 3D-body 50psi would effect every square inch of its surface - that doesn't mean you have 50psi in the six surounding hexes. The surface area the 5m*5m*2,5m room i sugested is much bigger that the surface area of the hex the TNT is placed in. This is why explosive charges have to be embedded ( i don't know the english word: "verdämmt"). If you put down simple charges you will need a lot more explosives to simply damage a building. I have tables for sizeing breaching charges. But i can't find them right now. But i remember that about 1pound (500g) of TNT will only breach a load bearing brick wall (double layer standart bricks) if it will be properly embedded. Either by takeing some bricks out and place the charge into the wall or by useing sandbags. Furthermore even shaped charges of LAWs (Panzerfaust) or 120mm tank guns are not sufficient to make a building collapes with one hit. While it is possible that a part of the building will colapse and break away that is rather unlikely. There will be quite impressive holes in the walls though. |
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04-26-2006, 05:43 AM | #24 | |
Join Date: Aug 2004
Location: Wellington, NZ
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Re: Explosives: Lethality of 1 pount of TNT
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When discussing the damage a nuke does, and to how big an area the common blast radii in discussion are the 5 psi limit and the 2 psi limit. Inside the latter most wooden buildings will be severely damaged, and inside the former none will be standing and stone and concrete buildings will be considerably damaged. However, people won't be directly damaged such blast overpressures (but the fragments of buildings, etc will be very dangerous). Living beings are fairly resilient, buildings are not.
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04-26-2006, 10:12 AM | #25 | |||
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Explosives: Lethality of 1 pount of TNT
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04-26-2006, 12:13 PM | #26 | |||
Join Date: Aug 2005
Location: Hamburg, Germany
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Re: Explosives: Lethality of 1 pount of TNT
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But i still doubt that one pound of TNT can fill a room of 62,5 m^3 with enough gas to crate 50 psi over a significant part of the surface of the outer walls. I furthermore doubt that it can even create enough gas to blow a room appart if it is solid build out of stone (brick walls). Quote:
"...In any case, the 50 psi or so required to actually kill a human from overpressure will definately flatten anything not built like a bunker" Two different posts and it doesn't exactly say that. But i just wanted to point out that the area to wich the force is applied is very important. |
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04-26-2006, 12:29 PM | #27 | ||||
Join Date: Feb 2005
Location: Berkeley, CA
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Re: Explosives: Lethality of 1 pount of TNT
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04-26-2006, 01:35 PM | #28 |
Grim Reaper
Join Date: Aug 2004
Location: Italy
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Re: Explosives: Lethality of 1 pount of TNT
50 psi?
Boys, we just need 20-30 Psi in order to destroy the vast majority of non armored buildings! For 1 lbs of TNT this is the overpressure experimented at 1.5-2 yards from the explosion. I guess if you put 1 lbs of TNT in the middle of a 4x4yards room, that room is going to be severely damaged, if not destroyed.
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bye! -- Lut God of the Cult of Stat Normalization |
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