Hank.Walker@UNH.CS.CMU.EDU (03/02/86)
An article in New Scientist briefly described the airbreathing rocket planned for use in the British Aerospace HOTOL. The basic idea seems to be to use liquid hydrogen to condense air, separate out the liquid oxygen, and then burn it with the hydrogen in a rocket. At higher altitudes, the engine would switch to onboard oxygen. The article didn't discuss it much, but there seem to be obvious problems with water and carbon dioxide ice buildup, as well as how to do the condensation rapidly and separate the oxygen and nitrogen. This all sounds very heavy. Does anyone know more? The CMU library copies of Aviation Week disappear or are read to shreds moments after arrival.
dietz@SLB-DOLL.CSNET (Paul Dietz) (03/04/86)
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.