[AR] Re: Flying to Orbit with Hydrogen?
- From: Keith Henson <hkeithhenson@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 24 Dec 2019 12:06:44 -0800
On Date: Tue, 24 Dec 2019 00:11:11 -0500 (EST) Henry Spencer
<hspencer@xxxxxxxxxxxxx> wrote:
snip
Flying to orbit in the atmosphere is a wish-fulfillment fantasy for the
aviation crowd, not even remotely practical at this time. Hydrogen or no
hydrogen, at Mach 15, an oxygen atmosphere is not your friend.
It's rare indeed that I disagree with Henry Spencer.
I followed Reaction Engines's Skylon project closely, reproduced many
of their graphs and discovered that it flys up the constant dynamic
pressure line. It also makes no attempt to get to orbit in the
atmosphere. It carries 250 tons of LOX and switches to pure rocket at
26 km and Mach 5.5. An interesting feature is that the wings unload
the gravity drag for quite a while even after going to rocket mode.
The high-risk part of Skylon is the engines. They are a radically new
design that cools ram into the engines to where it can be compressed
to rocket chamber pressure. So far all the news about their progress
has been positive. (They have been firing a large jet engine with
afterburner through a test heat exchanger.)
So my disagreement with Henry is one of degree. I think Skylon or
something like it might be practical to develop over the next ten
years or so.
It's true the payload isn't very high, slightly under 5%. But
Reaction Engines was the only company to project cargo to LEO at under
$100/kg at high launch rates.
They also passed an NOAA analysis of the ozone damage up to a million
flights per year.
Keith
Other related posts: