> at take off we go from zero to 17580 Mph > in what 10 minutes or so and are in orbit. > Yet the other way around going from 1780 > to zero in 45 minutes causes the fireball > effect with the friction. > > Why not on the way up?
It does, its just that all the energy is being burned at the rear end of the rocket to produce the acceleration... see the flames... On the way down, you have to decelerate that same amount of acceleration in the opposite direction and remove all that LAUNCH energy, to come back down.... hence the flames. The difference is that going up, you are going slowly in the higher density atmosphere which is continually lessening as you go up letting you go faster and faster with less and less friction. THus, no multiplying build up of friction. Coming down, everything is against you. As you come down, into denser and denser atmosphere, the friction is increasing and increasing, the temperature building and building you are going slower and slower and falling faster and faster. Into one ultimate fireball. > we can go from zero to 17580 in ten min > on the way up with no fireball, but take > a slower, 450% slower return rate and it > almost fries to a crisp. Thats why I'm thinking there might be a way to change your drag coefficient as you come down to reduce the crescendo build up of heat and spread out the descent. But still, for something as small as a cubesat you still have to disipate about 300KWH of energy and even if you do this over an hour, thats still 300 killowatts of heat... (a number they used here in the presentation.. I'd like to see confirmation)... Still seems like a fireball.. Bob, WB4APR _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
