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From: dietz@SLB-DOLL.CSNET (Paul Dietz)
Newsgroups: net.space
Subject: HOTOL Airbreathing Rocket
Message-ID: <8603042348.AA14915@s1-b.arpa>
Date: Tue, 4-Mar-86 08:35:18 EST
Article-I.D.: s1-b.8603042348.AA14915
Posted: Tue Mar  4 08:35:18 1986
Date-Received: Fri, 7-Mar-86 04:08:23 EST
Sender: usenet@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 9

I agree, the icing problem makes air liquification implausible.  I
speculate the HOTOL engine does the following: it has a (or several)
rocket-like fuel injectors burning a hydrogen-rich LOX/LH mixture
(the LOX is from onboard tanks).  Some of the hydrogen flows through
heat exchanger pipes in an air intake.  This cools the incoming air
as it is compressed, but only enough to keep the engine from melting.
The air is then mixed with the hydrogen-rich rocket exhaust in the
aft section of the engine.  Above Mach 12 the vehicle leaves the
atmosphere and the fuel injectors serve as conventional rockets.