🚀 go-pugleaf

In article <PAULI.RAMO.93Jan24190410@vipunen.hut.fi>, Pauli.Ramo@hut.fi (no, I don't repeat it!) writes:

|> If someone has the velocity change requirements for the rest of our trip
|> to moon, we can continue this little number game.

OK, here's a table from Sutton

Mission			Ideal velocity		Approx actual velocity
			(km/sec)		(km/sec)

Satellite orbit 		 7.9-10			9.1-12.5
Escape from earth		11.2			12.9
Escape from moon		 2.3			 2.7
Earth to moon (soft landing	13.1			16.1
   on moon, no return)		
Earth to Mars (soft landing)	17.5			20
Earth to Venus (soft landing)	22			26
Earth to moon (soft landing
   on moon, return to earth)	15.9			18.6
Earth to Mars (soft landing	22.9			27
   and return)


Oh well.  Not quite what we need, but interesting, regardless.  Anyway, call
it 3.2 km/sec for TLI, .7 km/sec for LOI, another .7 for TEI, and aerobrake
somehow for reentry.

Someone must have posted the empty and full masses of the ET--i seem to have
missed them.  Anyway, if you assume a mass ratio of between 4 and 5 for
shuttle + ET, you get a delta v of between 6 and 7 km/sec.  Plenty for TLI.
I don't think OMS is sufficient for LOI, however, so you'd need to restart
the main engines.  And again for TEI.  You aren't going to have enough left
over at reentry to bring you down to normal LEO reentry speeds, but maybe
you can do a couple of skips to burn off some speed.


david rickel
drickel@sjc.mentorg.com