Iraqi soldiers and Darth Vader helmets?
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haha go find 1 1st hehe best is still a concrete helm!Originally posted by Viper52:Make no mistake, your Kevlar helmet will stop bullets ONLY UNDER CERTAIN CONDITIONS!!!
If you're struck by a 5.56, 7.62 or 12.7mm round fired at close range and strikes your at anywhere near 90 degrees, it'll go right through your brain, kevlar helmet or not! What the kevlar does is to offer better protection(can stop rounds flying at higher velocity and at steeper angles) and lighter weight than the steel pot. The Brit squaddie was probably hit by rounds fired from a distance at low angle of penetration. That and the helmet saved his noggin (to use a British term)
We ran the old steel pot through 5.56 mm rounds at 100m, the rounds went through the front and back the outer shell and inner lining(both steel) EVERYTIME. Thats penetrating 4 layers of steel. That thing'll keep out no more than fragments and the falling rain.
Will like to run the test through the kevlar helmet sometime
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Erm, I think you mixed up your laws of physics liao. Firstly, the energy imparted to the bullet will includes all the propulsive kenitic energy afforded to it by the expanding gases, and that sum total of KE is obtained after subtracting all the other energy conversions (light, sound, heat). If the KE of the bullet as you suggested, that would violate the law of conservation of energy.Originally posted by |-|05|:the shot gun will not fly......but the recoil of it is very very heavy....i've fired 1.....the shotgun was made to basicly maim a person.....and it's effective range is a mere 20m!!
As for bullets the recoil force is less then what is given off when u fire due to energy being dissipated to sound and also cuz it's expending gases that propels the bullet not pure brute force....also the length of barrel also plays a part in how much recoil there is and how much power is needed blah blah.....
The "pure brute force" you refered to here is not a seperate entity from the expanding gases, they are one and the same. As the gases expand and the projectile is propelled forward, the reaction force in the opposite direction generated will always be the same as the force throwing the projectile forward. That means the recoil force will be equal to the force of the bullet.
As of such, it is impossible to have a recoil force less then the propulsive force of the bullet because that would violate newton's law of motion, which is completely seperate from the law of conservation of energy. You appear to have the concepts mixed up.but on the whole steel helmets can and stop bullets cuz the soft tip bullet which is built the kill infantry will smash on inpact.......
As far as I note, most armies used jacketed bullets as opposed to the hollowpoints you suggested. They will blast through the steel helmet will no problem and it will be nothing more then a pot for spilled brains.
As a matter of fact, I suspect even hollowpoints can penetrate a steel helmet, the steel is thin enuff to allow that. That's becos a typical rifle bullet contains about 1,500-3,000 joules of energy, concentrated on a spot, more then enuff to exceed the mechnical strength and thickness of the steel helmet. The inner lining is no problem. -
It appears 12.7 mm will blast right through any kind of helmet.
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Erm, I think you mixed up your laws of physics liao. Firstly, the energy imparted to the bullet will includes all the propulsive kenitic energy afforded to it by the expanding gases, and that sum total of KE is obtained after subtracting all the other energy conversions (light, sound, heat). If the KE of the bullet as you suggested, that would violate the law of conservation of energy.
hmm.......well what i do know is that the initial force used is more then what is needed but when the gas expends that energy is quickly disapated to light sound heat blah blah but from what i understand the rifling and barrel length has something to do with the recoil....
The "pure brute force" you refered to here is not a seperate entity from the expanding gases, they are one and the same. As the gases expand and the projectile is propelled forward, the reaction force in the opposite direction generated will always be the same as the force throwing the projectile forward. That means the recoil force will be equal to the force of the bullet.
As of such, it is impossible to have a recoil force less then the propulsive force of the bullet because that would violate newton's law of motion, which is completely seperate from the law of conservation of energy. You appear to have the concepts mixed up. i'm not sure though as i do not study engineering mechnics yet -
Think you are refering to the peak gas energy. When the bullet is fired, the gases expand to propel the bullet down the barrel, but as the gases expand throughout the barrel, the pressure drops after building up a peak. The bullet can only move as fast as the lowest gas velocity.Originally posted by |-|05|:hmm.......well what i do know is that the initial force used is more then what is needed but when the gas expends that energy is quickly disapated to light sound heat blah blah but from what i understand the rifling and barrel length has something to do with the recoil.... i'm not sure though as i do not study engineering mechnics yet
This however, has little bearing on the recoil force generated. What our preception of recoil is however, affected by gun mass and other factors. Whatever it may be, recoil (as in the actual force generated) remains the same as the force of the bullet when it strikes (disregarding other factors) -
then how about the 5.7mm ? Tests shown on the p90 and i think a few layers of kevlar at around 100yards... the bullets went through all of them..Originally posted by SingaporeTyrannosaur:It appears 12.7 mm will blast right through any kind of helmet.
12.7mm.... yea it'll blast thru...
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Depends on how many layers of Kevlar... level 2 armor usually contains only 12 layers, can stop most handgun rounds.
I think for heavier threats, levels 5 can stop most rifle rounds.
The crazy swat armor which is level 9 provides protection equal to 56 layers of kevlar, and even more when they put in those composite plates on the front, that one can probably stop shotgun copper slugs, though not without trauma to the body below the impact point.