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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: HOTOL
Message-ID: <8602260354.AA00837@s1-b.arpa>
Date: Tue, 25-Feb-86 18:30:19 EST
Article-I.D.: s1-b.8602260354.AA00837
Posted: Tue Feb 25 18:30:19 1986
Date-Received: Fri, 28-Feb-86 06:40:59 EST
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 28

It looks like BAE will be going public with details on the HOTOL
soon.  According to reports in New Scientist and AWST, the vehicle
would begin 19 test flights in 1996 and begin commercial operations
sometime between 1998 and the early 2000's.  Amortizing the airframe
over 120 flights and the engines over 60 flights would give the HOTOL
an operating cost of $5.25 million/launch.  Payload size was not stated,
but judging from the illustration the payload bay would be a cylinder
approximately 30 feet long and 18 feet in diameter.

The vehicle would be automated but could carry a manned module in
its cargo bay.  The internal hydrogen tank must be pressurized for structural
integrity, limiting the time the vehicle could spend in orbit to
50 hours in a continuously illuminated polar orbit (the worst case).
The vehicle would take off horizontally on a wheeled trolley and land on
skids.  (Landing weight would be much lower than takeoff weight, since most
of the fuel would be gone.)  The vehicle would breathe air until it
reaches 26 kilometers, at this point it would have burned 18% of its hydrogen
and switched over to an onboard oxygen supply.  It would reach an orbit
of 300 kilometers.  Because the vehicle would be less massive than the shuttle
less heat would be dissipated on reentry, so tiles would not be used.  Instead,
carbon-carbon would be used on high temperature areas and titanium and nickel
sandwich elsewhere.

The designers project a turnaround time of two days.  The vehicle would
operate autonomously in orbit (this sounds dubious) and land using
conventional MLS guidance.

Development cost would be somewhere around $6 billion.