What's the temperature (°F) of a machine gun barrel after prolonged firing? Are there studies on it? Is there a average temperature range?
>>61491485hot
>>61491485Machine guns do not do "prolonged firing" in any real life circumstance
>>61491485Naturally, they will slowly approach the temperature of the exhaust gases produced by the deflagration of whatever specific propellent is being used. At the same time, they're also radiating heat and passing it off to the surrounding air by convection. If you want to spend an hour learning some basic thermodynamics, you could pretty easily get general estimates for a specifically sized barrel of a known alloy firing a certain number of rounds per minute, with a specific atmospheric temperature.
>>61491534Oh they absolutly do, but not to the point that they glow redt. former machinegunner
>>61491553While I'm no machinegunner by best guess would be once thermal expansion started to shrink the bore you get more friction heating, more thermal expansion more friction heating.There would be a point where the temp started to runway even ignoring cookoff making it belt dump on closed bolt MGs.
>>61491485Yeah ºFYeah DOIs/AD about internal ballisticBruhBack of the napkin calculation with simplification should be enough for most whats:>Short burst at high ROF (no heat loss by radiation/conduction)>Barrel temperature is uniform>Heat from propellants is similar to muzzle energy of bullets (because it's like that irl https://en.wikipedia.org/wiki/Physics_of_firearms)>Specific heat of steel 0.5 J/(ºC.g), in globohomo unitsFor a ~ 2Kg MG barrel (like the MG42/38) it's like 4ºC/7ºF per round. After 100-200 rounds it'll need a new barrel >2000 * 0.5 = 1000 J/ºC>4000 J muzzle energy -> ~4000 J barrel heat (total propellant energy ~12000 J) >4000/1000 = 4 ºC / rnd
>>61491534>>61491556Seconded. That "Short delayed bursts" is a training mindset. In an actual twoway live fire you send that shit. t. 249/mk48/m2 gunner circa 2009/2010
>>61491485Given an unlimited supply of ammunition it will keep heating up until it can't fire anymore, either because the metal expands too much and causes the mechanism to jam, or because it loses too much strength and causes the mechanism to break.
>>61491590Why do you think getting a tube hot makes the inside smallerThat's not what happens
>>61491556>>61491624>ywn fire a vickers gun for 5 days straight in the trenches of WWI:^(
>>61491724>Why do you think getting a tube hot makes the inside smallerBecause the walls expand in all directions don't they?Hang on, I'm a fucking idiot, I have literally heated bearings to get them on and off.I'll see myself out.
>>61491753the expansion is really really small. but it's enough with stuff like rusted bolts or tight fits because you only need a tiny gap to open.but yeah the hole does also get larger. > a steel post that is exactly 1 meter long at 0 C is 1.2 millimeters longer at 100 C. This seems negligible until we discover that it would take a 15 ton force to keep the post from expanding>If the ocean becomes 1 degree (F) warmer, its volume will increase by 0.01%. Since the ocean is several miles deep, this implies that the surface will rise about a foot, giving a change in the sea level. In the process, the beach line moves landwards 20 feet.
>>61491724It's pretty intuitive to assume that an expanding tube would close shut as the heat expansion occurs.I blame the 1-dimensional examples of heat expansion in school textbooks. It's always a bar of metal whose expansion is visually shown in a single direction.
>>61491485>How how do machine gun barrels get?^the absolute state of this ESL board
>>61491895bro it's a one letter typo
>>61491485A machine gun barrel will literally melt if you overuse it.
>>61491485not very how
>>61491729I hear scientists are really close to figuring out a time machine. You'll be able fulfill your dream of dying in a trench really soon
>>61492046>You'll be able fulfill your dream of dying in a trench really soonthe afu is hiring
>>61491553This is more specifically heat transfer then thermo
>>61491596Doesn’t sound right. You’d have a better time finding Qdot from the expanding gasses and then setting that =kA(T2-T2)
>>61492677T2-T1*
>>61492291this. hell, the vatniks are hiring as well. you have options.
