dietz%USC-CSE%ECLA@sri-unix.UUCP (07/24/84)
The latest Aviation Week has the fifth (and final) article in their series on ballistic missile defense. The article discusses hypervelocity launchers, such as railguns. Some tidbits: Railguns have accelerated small (a few grams) lexan cubes to 10 km/sec with an energy efficiency of 40%. The next expermients are shooting for 20 km/sec and 50% efficiency. The ultimate goal is 100 km/sec at 100,000 gee's (with an accelerator 500 meters long), using a laser to drive a projectile with an ablative rear surface. (An aside: by launching deuterium-tritium pellets at one another at >= 100 km/sec one can possibly generate significant fusion energy.) In tests against actual ICBM components, gram size projectiles moving at 10 km/sec have been found to cause considerable damage (they can penetrate quarter-inch steel plate). The article includes a picture of a metal cylinder with a large, blackened hole in the side. Rail erosion problems during projectile startup have been solved by using gas injection. Studies have shown that hypervelocity launchers with homing projectiles deliver more energy per area at the target than lasers, particle beams, 25 KT nuclear ABMs or nuclear-pumped X-ray lasers (I'm not sure what systems they're comparing here). The military is considering using railguns as gatling gun replacements for close-in defense of ships against cruise missiles, and as long range artillery (50 miles) with terminally guided shells. Advances in active cooling are making very high velocity projectiles feasible in the atmosphere (this technology is borrowed from military reentry vehicle research). *** These things look much more technically feasible than laser BMD systems. At 100 km/sec you can reach LEO from GEO in under six minutes, which is fine for mid-course intercept.