[AR] Re: Flying to Orbit with Hydrogen?
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Mon, 23 Dec 2019 23:08:43 -0500 (EST)
On Mon, 23 Dec 2019, Craig Fink wrote:
...The Wright Brothers a hundred years ago, chose the most
promising fuel at the time, and build their own engine using it. ...
Flying to Orbit, that fuel is Hydrogen. The physics of the problem shows
where to look.
The engineering of the problem, however, suggests that the physics is
being too simplistic and assuming too many spherical cows. As witness the
all-hydrogen Delta IV, which does less and costs more than the
part-hydrogen Atlas V. And then there's the the all-kerosene Falcon 9,
which handily beats both of them...
Getting rid of the Carbon increases Performance radically.
Getting rid of the carbon increases Isp radically. Performance, alas, is
not just Isp -- there are other variables in the rocket equation, and no,
they aren't independent of the choice of fuel. Not to mention the
annoying little fact that unless you're NASA or the USAF, it's cost you
really care about, not performance.
Henry
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