[AR] Re: Precooled engine
- From: "John Stoffel" <john@xxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Sun, 5 Jun 2016 11:07:04 -0400
"John" == John Stoffel <john@xxxxxxxxxxx> writes:
"Henry" == Henry Spencer <hspencer@xxxxxxxxxxxxx> writes:
Henry> On Mon, 30 May 2016, Keith Henson wrote:
The Reaction Engines precooled engine may be the most advanced in the
world. It gets good performance up to 26 km on air before it switches
to internal LOX for the last 6 km/s to orbit.
Henry> ...on paper.
Henry> With the exception of the precooler, it's still a paper engine,
Henry> and a complex and novel one too. I'll grant that the precooler
Henry> was the trickiest (and least orthodox) bit, but there's still
Henry> plenty of room for development difficulties and
Henry> underperformance to happen along the road to flight.
Henry> High-supersonic jet engines are not easy at the best of times,
Henry> and this would be the *very first* one to operate all the way
Henry> from the ground to Mach 6-ish.
John> So what are they doing with all the cooled nitrogen they now
John> have sucked into the engine? To me that seems like a big
John> problem, where they have to cool all this incoming air down to
John> -195 deg, but the nitrogen will condence before the oxygen,
John> right?
Duh... I mis-read things, and O is liquified at 90K, N at 77K. So
they still spend alot of energy (mass, complexity) cooling air down
enough to liquifiy the Oxygen and start using it, while also cooling
down a ton of Nitrogen as well which they basically toss away, or put
into the thrust stream?
Seems inefficient. I know it works for all sorts of get engines and
ram jets, etc. But the complexity of the pre-cooler seems to outweigh
the simplicity of a second tank of oxygen.
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