Wednesday, August 3, 2011
Are we capable of launching projectiles on Earth's surface at speeds sufficient for friction to vaporize them?
By inertia alone, I'm not sure, & I doubt that any solid gun propellant can go off w/ sufficient velocity to even accelerate its own combustion gasses into their thermal "thicket", let alone any projectile they launch. I believe aluminum oxide is the solid fuel for the sssrb's, & has a Isp of about 200, meaning the gasses are capable of about 6500fps, or 4200mph, which should be sufficient to vaporize something dense enough to take its time slowing down to "cooler speeds". A projectile being launched by ssme propellant(lh2/lox) out of a "gun" bore could-theoretically- reach velocities of around 10,000fps. Come to think of it, the projectile would be subject to a lot more heat from the initial launch to that speed than it would slowing down from it. Lead is dense & should hold its speed well, has a low melting point, but I'm not sure of its boiling point. Anything w/ a vacuum would have to be sealed at the bore to keep air from rushing in. The projectile, from where I'm standing would have to blast its way through that seal, possibly disintegrating, which may or may not defeat your purpose. Either way, there most likely would have to be a lot of propellant-by mass-relative to the projectile.(Mass ratio) I'm pretty sure it would be "easier" vaporize a projectile than to have it escape Earths gravity. Also-atmosphere or not-I believe it would be impossible to get an object into orbit purely from velocity gained from the surface, because it would either escape into outer space(too fast) or impact the Eath at the launch point or before after onr revolution at most. An orbiting object's lowest point is always where it stopped accelerating. I know you didn't ask that. I'm just pointing out where it stands in the likelihood of possibilities. It's the most likely scenario among the 3 possibilities-assuming there are propellants powerfull enough to achieve it. There's a good chance that a propellent powerful enough to acheive your goal would be likely to vaporise the projectile b/4 the atmosphere does. In that sence, the chain of likelihood would be 1)burn up by propellant's heat. 2) Same by atmospheric friction,3)Escape into deep space, & (least likely-if at all) 4)orbit Eath more that 1 time. From Earth's surface there appears to be NO intermediate launch speed from the surface to allow that to happen.
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