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Post by peasant on Nov 20, 2023 11:40:00 GMT
So, I was wondering about how long it would take for a projectile shot out of a railgun to cool as they travel in the cold vastness of space. Turns out, a freaking long time! Here is an example with a 10g copper sphere (12.9mm in diameter). After flying for 30 seconds it's still very hot. This is bad, as the hotter it is, the easier it will vaporize on impact with the whipple shield of the target. Try it out yourself: www.desmos.com/calculator/grgkyw08ajData on specific heat capacities of some materials which can be used in railgun projectiles: www.engineersedge.com/materials/specific_heat_capacity_of_metals_13259.htm
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Post by sage on Dec 9, 2023 2:58:18 GMT
Interesting find, and other reason I have moved away from railguns and coilguns to missiles and Lasers.
But more important, how do you post pictures on this forum? I have been trying for years to do so.
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Post by peasant on Dec 10, 2023 17:35:55 GMT
Interesting find, and other reason I have moved away from railguns and coilguns to missiles and Lasers. But more important, how do you post pictures on this forum? I have been trying for years to do so. I upload image on a separate image hosting site: postimages.organd then use the "Insert Image" button on top of the reply form to insert it into my reply.
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Post by zuthal on Dec 30, 2023 4:59:09 GMT
This is actually a lot less bad than it seems. 10 g of copper at 650 K has, even taken relative to 0 K, about 2.5 kJ of heat. If it were moving at 5 km/s, it would already have a kinetic energy of 125 kJ. Hypervelocity projectiles impact with an energy so far in excess of what is required to vapourise them that their pre-impact temperature only matters if it is hot enough for the projectile to melt and as a result disperse.
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