On Tue, 5 Aug 2003 20:19:18 +0000 (UTC), in a place far, far away,
(Greg Kuperberg) made the phosphor on
my monitor glow in such a way as to indicate that:

Ummmm...no. I said nothing about cost per mile--I said cost per
transcontinental trip.

Well that's cheating in a different way. First, you changed 1200 mph
to 500. 1200 mph is a Concorde, not a jumbo jet. A transcontinental
Concorde trip is a full order of magnitude more expensive than by car
at 120 mph.

Sorry, I didn't pay close attention to the speed you wrote. I thought
you were talking about conventional air transports.

Concorde is more expensive for two reasons--it has much higher drag
(mostly due, directly or indirectly, to shock) resulting in several
times the unit fuel consumption (its L/D ratio is less than half that
of a modern subsonic transport), and it's not flown very much, so it's
difficult to amortize the fixed costs (the same problem we have with
launch costs).

And in fact, I would argue that physics is a much stronger factor in
keeping the costs of supersonic flight high than it is in keeping
launch costs high. There are things we can do to dramatically reduce
launch costs with known physics, but there's little we can do to
reduce supersonic flight costs without a better understanding of
supersonic aerodynamics and vehicle design.

Second, you are comparing a Concorde to a space rocket on the Concorde's
distance scale, 3,000 miles, rather than on the rocket's distance scale,
which is 300,000 miles (at least!).

As you pointed out yourself (or at least it seemed, cost per distance
is an absurd measure to compare space transport with ground or air
transport. I don't know why you do it.

So let's compare the Concorde to
a car on the car's distance scale, 30 miles. One would be 5 dollars
per passenger, the other would be $500 (maybe). So that's two orders
of magnitude right there.

Yes, because it would be idiotic (and not possible, in a business
sense) to fly a Concorde thirty miles. My point was that under
realistic circumstances (which short haul on a Concorde is not, though
many people drive, or take trains, across the country) the costs of
cars and aircraft aren't that different, so the comparison on which
you're basing your comparison between air and space is invalid.

You're really flaunting your own ignorance of the source of high
launch costs, here, Greg.

--
simberg.interglobal.org * 310 372-7963 (CA) 307 739-1296 (Jackson Hole)
interglobal space lines * 307 733-1715 (Fax) http://www.interglobal.org

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