[ExI] emerging technologies may lead to a revolutionary horizontal space launcher

[spike]

________________________________

	... On Behalf Of Adrian Tymes
	Subject: Re: [ExI] emerging technologies may lead to a revolutionary
horizontal space launcher
	
	
	>...up to Mach 10
	
	Orbital speed is roughly Mach 25, so this is about right for the
first stage of a two
	stage solution.  However, Mach 10 is about 7500 mph, and they say
the aircraft would
	only reach about 600 mph on the rail - which doesn't have that much
total impact...

Ja, the way I would look at that is the rail system lets you out of wheels
if you go horizontal launch, and it gets you to a speed in which you could
light up your ramjets.

	...still needs its own engines to reach the remaining 9/10ths of its
final speed...

Ja again.  The rail launch system has its advantages, but it is not a
miracle.  Otherwise we would have done it before now.

	
	>...Though, acceleration would be a problem if it went for Mach 10,
limiting it to cargo
	launches only...

I have in mind these kinds of systems will always be for cargo only.  But
cargo only craft have their advantages too: the engineers can shave the
margins closer, accept a bit more risk.

...
	
	>...What this does do, is sneak in reusability, instead of
rebuildability as championed by
	the Space Shuttle, or explicitly discardable spacecraft that are
traditional rockets.
	That could significantly reduce the cost of launching things into
orbit, even if the
	second stage is discarded every time.

All the concepts that look real to me have at least two stages with at least
part of one stage as a throwaway.  Doing a no-throwaway cargo ship to orbit
is a holy grail we are unlikely to find any time soon.

spike