🚀 go-pugleaf

In article <1992Dec30.211506.19286@netcom.com> ckp@netcom.com (Charles Pooley) writes:
>So, for the 1st environment, the 1st stage should have the durability to
>cope with the aerodynamic loads and have engines optimised for use in
>atmpsphere...

In practice, even first-stage engines are necessarily a compromise between
atmosphere and vacuum operation.  If you look at the cutoff altitudes of
typical first stages (ignoring little strap-ons and the like), a substantial
fraction of their burn time is spent in near-vacuum.

>The general idea, it seems, is not to take any component or capability
>of the rocket past the point it is needed.  ie, wings, landing gear,
>parachutes, rugged construction etc for low altitude conditions not go
>beyond staging point...

Of course, the same is true for aircraft.  The design of an aircraft's
wings, in particular, is heavily driven by takeoff and emergency-landing
requirements.  (Normal landings, at least for long-haul aircraft, are
made at substantially lower weights than takeoffs and worst-case emergency
landings.)  Would it make sense to build two-stage aircraft, with the
upper stage optimized for high speed at high altitude (plus landing at
relatively low weights after fuel is burned)?  Well, yes, in a way, and
it's even been done occasionally, for research aircraft like the X-15.
But nobody would buy a commercial aircraft built that way, even though
performance would be better, because staging is simply too much trouble
and expense when one-stage designs work fine.

There will be a place for staging throughout the foreseeable future.
No propulsion system likely to be practical soon would be capable of
launching a short-flight-time mission to Pluto without staging; even if
the DCs work perfectly, missions like that will use upper stages.

But it's not necessary or desirable for hauling payloads into low
Earth orbit; we have the technology to do without it, and doing so
has potential to reduce costs quite substantially.
-- 
"God willing... we shall return."       | Henry Spencer @ U of Toronto Zoology
       -Gene Cernan, the Moon, Dec 1972 |  henry@zoo.toronto.edu  utzoo!henry