Re: "NASA Ends Project Intended to Replace Shuttle"

From: Doug Jones (
Date: Tue Mar 13 2001 - 12:51:21 MST

Spike Jones wrote:
> Michael Lorrey wrote:
> > c) scramjet/rocket chem or nuke insertion stage into orbit.
> >
> > What is the mass fraction a vehicle would need if it was already
> > travelling 1000 mph at 15,000 on a 30 degree trajectory, from the
> > equator?
> Ill look for my spreadsheet I wrote on this about 8 yrs ago.
> The 1000 mph and 15000 ft help less than I would have
> expected, so it was disappointing. As I recall, it reduced
> fuel needs by around 15%. Doug, do you have an active
> spreadsheet for this? spike

No, but Dan Delong does (Dan is chief engineer at XCOR). Whether we are
willing to release it into the public domain is another thing- it is a
valuable company asset. However, I should be able to get a copy of
Dan's analysis of the benefits of lobbed altitude launch; there are
about ten points where that choice allows improvements to the vehicle
design, from larger nozzles on the engines, to lower stresses on the
wing at full load (it need only be designed for .8 gee at 1.5 safety
factor, instead of a 2 gee pullup).

The combination of factors makes subsonic lobbed airlaunch *very*

Doug Jones, Rocket Engineer
XCOR Aerospace

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