Newsgroups: sci.space.history,sci.space.tech
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: Re: Apollo/Saturn 5 "lofting" ?
Date: Thu, 23 Apr 1998 14:02:54 GMT

In article <353AE61E.FFF93E0F@seinf.mail.abb.com>,
bert.alm <xxxx.yyy@seinf.mail.abb.com> wrote:
>...shuttles overshoot the target altitude and then descend back
>in a shallow 2-minute descent back toward earth...
>Were the Apollo missions doing something similar ?

Yes.  This is fairly normal for launcher trajectories.  The main problem
of getting into orbit is accelerating to orbital velocity, which is most
efficiently done horizontally.  Oversimplifying, it's more efficient to
give the rocket a good hard boost upward at the beginning, and then do the
horizontal accelerating before it falls back into the atmosphere, than to
constantly fight gravity during the ascent.  Even after optimization, the
usual result is that the peak altitude is slightly higher than the final
orbital altitude.
--
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         | henry@zoo.toronto.edu