Regarding parachute deployment, it actually began much closer to the ocean (about 16,000 feet) for a few reasons: denser air slowed the booster more and they didn't want the thing drifting too far while on the mains. Aero drag heated up the surface enough to require thermal protection on the major aluminum structures (350 degrees was the limit) while 500 was the limit on steel parts (like the motor case) and the white paint was often scorched brown on much of the structure. CG placement was very important-we didn't want it pointed nose-down as this would make 'chute deployment very difficult. There were 5 parachutes carried on each booster for a total weight of around 15,000 pounds. The recovery sequence was started by a baro switch at 15,500 feet (V= 540 fps) that triggered release of the nose cap and pulling out the 11' pilot chute. This pulled out the 54' drogue, orienting the falling booster more tail-down and slowing it to 360 fps. Then a shaped charge around the circumference of the frustum fired at about 5500 feet, separating the booster and pulling the 3 mains out from the slowing frustum. The 136 ft mains were kept partially closed by reefing lines so that they wouldn't be ripped apart by the air loads and were cut in 3 steps over about 15 seconds to allow the canopy to open gradually and slowing the beast from 360 fps to water impact of about 75 fps. It hung on the mains for almost 50 seconds, giving time to fire a shaped charge around the carbon-fiber nozzle just before impact and reducing damage to the very expensive flexible nozzle bearing and steering actuators. Everything was recovered by two ships standing nearby and reused except the nose cap and pilot 'chute, which usually sank. These ships left Port Canaveral two days before launch and waited about 160 miles off shore, usually within visual contact with the falling boosters but not too close as the boosters weighed around 100 tons and nobody wanted to be conked by a falling nose cap or other stuff.
We won't be seeing things like this again but that's what the Apollo guys said and the Gemini guys before them, and the Mercury guys before them. It is rather sad, though, to think that future returning astronauts will return this way, plopping into the ocean in a modified cannon ball to scramble out all wet, cold, and miserable into rubber rafts, probably getting seasick on the trip back instead of strolling with dignity down an air conditioned jetway into comfy ground transport. I'm told this is progress. Really?
RK
Topic: Ride the space shuttle booster! Awesome!!! (Read 2069 times)
