# how fast would a magic rail/coil gun need to fire to melt its tungsten bullet

In my story magic allows for the creation of accelerators that can multiply the speed of any object that passes through them. These accelerators allow for modified conventional weapons to fire at rail gun velocity and beyond. My question is how fast would a tungsten .50 BMG bullet need to be found in order for it to melt from air resistance?

Currently I’m running on the assumption that anything past 50,000 fps will melt the tungsten well before getting to any target.

Notes:

The accelerators do not touch the objects they accelerate and ignore Newton’s third law of motion, meaning that while they magically accelerate an object to a multiple of their current speed they do not physically interact with the projectile. The world has earth-like gravity, air etc. The projectile weighs 1218 grains and has a ballistic coefficient of 1.088.

• Atmosphere is close enough to earth same with gravity. The magic bends or in some cases allows for the complete avoidance of some fundamental laws to an extent, however this is isolated to the magic and the objects created with it. Thanks for the tips Commented Oct 26, 2019 at 22:08
• It is only the accelerators that ignore the third law of motion since they increase the speed of objects without physically touching them meaning you have the same recoil as a conventional weapon that uses the same round. The accelerators are effectively enchanted rings mounted in a frame so that the projectile passes through them. Commented Oct 26, 2019 at 22:15
• "Increase the speed of objects without touching them" describes a coilgun, specifically one that magnetically levitates the projectile away from the coils. This isn't in violation of Newton's Third Law; the rings will recoil as they impart force on the projectile, but there will be no conduction of heat. Commented Oct 26, 2019 at 23:55
• Practically speaking, how the bullet gets to melting speeds is completely irrelevant. The question, simplified, is "How fast can a tungsten bullet go without melting from air friction?" - Which, sadly, I have no idea how to calculate. Commented Oct 27, 2019 at 0:23
• @Andon incidentally, the major source of heating will not be friction, but compression of air in front of the projectile. A magical frictionless supersonic projectile would still be subject to compression heating, because the air in front of it simply can't get out of the way fast enough. Commented Oct 27, 2019 at 10:14