Re: Multiple Engines???

[EMAIL PROTECTED] (Henry Spencer) wrote in message news:<[EMAIL PROTECTED]>...
> In article <[EMAIL PROTECTED]>,
> Mike Miller <[EMAIL PROTECTED]> wrote:
> >I suspect the TSTO can glide back. Even at mach 8 separations, is the
> >first stage all that far down range, more than 100-200 miles?
> 
> For an orthodox trajectory, a Mach 8 separation will bring it down more
> like 300mi from the launch site.  That tends to require powered return.
> And that's not a particularly high separation speed.
> 
> >It'll
> >have a lot of energy from altitude and speed that can be spent turning
> >around and gliding back.
> 
> Not unless it has truly excellent aerodynamic performance, which is
> another nasty can of worms.  It's not all that high up by the time it
> can get turned around.

That always seems like the sticky wicket for RLV TSTOs.  There are
ways to go about solving the problem but none of them are simple.  One
idea I kinda like is a hopping sub-orbital first stage.  Build a
nearly orbital single stage RLV (but enough less than orbital to
realize substantial savings design and operations wise), set up
several launch/landing sites around the world and then hop the
sub-orbital vehicle from one to another for each launch.  For example,
a ring of 2, 3 or more spaceports along the equator.  Since you are
(or should be) running a high flight rate launch service with these
vehicles there isn't much downside to not having them all piled up at
one centralized launch complex.  The other idea I like is a simple
drop tank on a quasi-SSTO.  Though with orbital rocketry there's very
little that's ever simple.