From: "Jeff Greason" <jgreason@hughes.net>
Newsgroups: sci.space.policy
Subject: Re: HMX gets NASA contract
Date: Wed, 6 Sep 2000 10:01:50 -0700

Rand Simberg <simberg@interglobal.org> wrote in message
news:39B628F7.1FA75393@interglobal.org...
> Vehicle design is a second-order factor.  Lots of dumb expendable vehicles
> will be much cheaper than today's expendables.  Lots of flights of
> complex reusable vehicles will be much cheaper than today's expendables
> (including Shuttle).  OTOH, whatever you design, if you hardly ever fly
> it, it will not be cheap.  That's the fundamental flaw with the
> NASA/Lockmart approach.

Rand has the crux of the problem spelled out here.  The DC-3 was
sucessful during its heyday because its size was well matched to the
traffic requirements, so that each DC-3 (even before WW2) could fly with
reasonable load factors.  Today, the DC-3 is far too small for general
traffic.  As the available market for air transport has expanded, the
airplanes have gotten bigger. An airplane which isn't carrying payload at
least half of the time is an underperforming asset.

The air transport industry is currently going through a serious
reevaluation of the economically favored size of airplanes.  The
increasing traffic in regional jets are exploring what you can do with
smaller airplanes, and the Airbus Axxx and Boeing 747X efforts will, if
launched, explore what you can do with bigger airplanes.  However, both
elements are a reflection not of the "first order" effects of sizing
(traffic volume & minimum cargo unit size), but of "second order"
effects.  Specifically, both regional jets & super jumbos are different
attempts to deal with airport & air traffic congestion.  One approach is
to leave the hubs, which leads to less traffic per airport and (to fly
full) requires smaller aircraft.  An alternative is to fly bigger
airplanes so that the same number of departure slots hold more
passengers.

Cheap access to space requires a match between the vehicle and the
traffic requirements so that vehicles fly often (if reusable), or production
rates (in launchers produced per month) are high (if expendable).

----------------------------------------------------------------
"Limited funds are a blessing, not         Jeff Greason
a curse.  Nothing encourages creative      President & Eng. Mgr.
thinking in quite the same way." --L. Yau  XCOR Aerospace
   <www.xcor-aerospace.com>                <jgreason@hughes.net>