[AR] costs (was Re: Ozone layer was Re: Removing Coking Deposits)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 21 Sep 2016 23:02:27 -0400 (EDT)
On Wed, 21 Sep 2016, David Gregory wrote:
Indeed the Falcon 9 propellant cost comes in at about $40/lb of payload
with expensive RP. Commercial airlines do about 50% of their costs as
fuel.
It's more traditionally quoted as "operating cost three times fuel cost",
and even that can be low depending on which year you're looking at and
what you include. It's some small multiplier, anyway.
Moreover, rocketry ought to be *better*. Magically doubling the fuel
capacity of an airliner would not double its operating costs; a lot of the
non-fuel part is fixed overheads, or multiples of *dry* mass, that don't
scale much with fuel use. And our vehicles are far more fuel-intensive
than airliners, so fuel ought to be a larger part of our costs. Max
Hunter thought that rocket vehicles ought to be able to operate at circa
1.2x fuel cost eventually.
However, it's abundantly clear that we're a long way from that operating
regime. Launch costs are overwhelmingly dominated by overheads and ops
manpower (and replacement of expendable hardware); fuel costs are down in
the noise for any launcher except maybe a few oddballs. (Twenty years
ago, Jeff Greason's analysis said that Titan IV was the only US rocket
whose fuel cost was actually noticeable. Today, hmm, perhaps Delta IV,
because of all that LH2, although that's nowhere near as costly as solids
and toxic hypergolics.)
Fixing this requires reusable hardware, much-less-manpower-intensive
launch operations, and much higher launch rates (so fixed overheads don't
dominate, as they do for *anything* that flies only a few times a year).
Henry
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