Sil - ZL2CIA wrote: > Bob Bruninga wrote: > > >> 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. >> >> >> > Bob, > > I hesitate to say this, but I'm almost certain that re-entry heating is > not caused by friction (well may be 10%). Most reliable sources, NASA > included, attribute re-entry heating to shock wave compression of the > air in front of the descending craft. > > Sil > ZL2CIA > Wikipeadia reckon 80% of the heating experienced by a re-entering orbiter (shuttle) is the result of compression, leaving 20% to friction.
The 90% figure might be more correctly applied to the Apollo re-entry vehicle. It was a very different shape. Some highspeed vehicles did experience severe heating, notably the amazing X-15 craft. The question is a good one, but the answer has needs to consider far more than frictional heating, since that accounts for only a small part of the energy that is converted to heat during re-entry. I have no idea what the equivalent ratio is on the way up, but it is a delightful puzzle. Thanks Joe. Sil ZL2CIA Sil _______________________________________________ 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
