On Dec 15, 12:14 pm, (Rand Simberg)
wrote:
On Sat, 15 Dec 2007 09:00:37 -0800, in a place far, far away, John
Schilling made the phosphor on my monitor
glow in such a way as to indicate that:



On Fri, 14 Dec 2007 23:23:55 -0800 (PST), wrote:

There has been lots of interest in Scramjets because of their
potential to lower the cost of access to space, or Single Stage to
Orbit as a means of lowering cost of access to space.

"Has been", past tense. That interest went away when everyone
realized that the hypersonics people didn't have a clue how to
build a scramjet that would be useful for space launch. As John
Hare put it, there's an extra "r" in scramjet.

Anyone care to comment or check my numbers? Your feedback is
appreciated!

I didn't see anything wrong with them on a quick look, but your
numbers are based on the assumption that someone comes up with a
useful scramjet.

Actually, it looked to me like he was proposing an all-rocket system.

Yes, it does look like an all-rocket system.
However, I saw the word scramjet and didn't
bother reading further until your post.

There is a lot of potential range for the numbers
within the context of an all-rocket system--some
better and some worse, IMO. Our approach "wastes"
a lot more delta vee, but much more than makes up
for this waste in other structural, performance and cost
improvements. As a net result of our particular
approach, II think the bottom-line, overall goal
is actually quite modest and achievable, including
the "forgotten" factors pointed out by Sylvia.

Nothing makes much sense at low traffic levels
below 200 flight per year. At higher traffic levels,
I think that $500/kg is a quite achievable price,
not cost, goal. I think failure to take proper account
of traffic level is probably the main factor between
the "pessimistic" and "optimistic" posters on this
news group. And, as Fred points out, the chicken-and-
egg nature has to be addressed. However, this just
makes this problem a problem, not an un-surmountable
barrier.

Len