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From: Henry Spencer <>
Subject: SSTO costs (was Re: tourism)
Date: Fri, 5 Jan 1996 03:28:28 GMT

In article <4cgkbl$> (Marcus Lindroos INF) writes:
>Hm... In any case, SSTOs will be much more expensive to operate than
>airliners because they require huge amounts of exotic fuel to lift a
>comparable payload. Even kerosene/oxygen would be quite expensive. So
>it certainly won't be as cheap and easy as buying a plane ticket 
>from London to New York.

Actually, fuel is cheap -- it's the hardware and people that cost you.

If using LOX/kerosene, you need about 20 pounds of mix to lift a pound
into orbit, and maybe, oh, a fifth of those pounds are payload, so you
need 100 pounds of fuel+oxidizer.  Now, LOX costs about 4c/pound, and
is about 3/4 of the mix.  Kerosene costs depend on grade, but expensive
rocket-grade stuff is maybe 25c/pound.  So the average mix cost is 
circa 10c/pound, and total propellant costs are about $10 per pound of 

Figuring me at 200 pounds, that's $2000.  Not quite as cheap as London to
New York, agreed, but not much more than what I paid for a round trip from
Toronto to Australia some years ago. 

If you insist on using liquid hydrogen, it's expensive stuff, but now the
mixture ratio is 6:1 and you only need about half as much of the mix, so
your bottom line is maybe $25 per pound of payload.  Still pretty low. 

It is to be devoutly hoped that we can reach the point where we have
to seriously worry about propellant costs.
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |

Date: 10 Apr 91 01:49:51 GMT
From: van-bc!rsoft!mindlink!a752@ucbvax.Berkeley.EDU  (Bruce Dunn)
Subject: Re: Launch Technology

> writes:
> Person: James Davis Nicoll
>         What's the cost per tonne of lithium, fluorine and hydrogen,
> what's the cost of storing and using them and how do those two costs
> compare to the costs associated with standard fuels? A wild guess might
> that the higher Isp is nice, but that the problems of handling fluorine
> drove costs up above the level of standard fuels.
>                                                         James Nicoll

Selected data from "Advanced Liquid Propellant Systems for Chemical Propulsion"
by John Q. Weber of Rockwell (Rocketdyne Division); published in "Orbit Raising
and Maneuvering Propulsion: Research Status and Needs", Leonard H. Caveny ed.,
Volume 89 of the series Progress in Astronautics and Aeronautics, American
Institute of Astronautics and Aeronautics, N.Y. (1984):

Propellant    Density      Cost per lb. (1982)
N2O4          1.433        $   0.45
O2            1.149        $   0.43
F2            1.505        $  20.00
H2            0.071        $   4.50
MMH           0.870        $   6.60
RP-1          0.802        $   0.27
N2H4          1.004        $   7.00
NH3           0.607        $   0.10
Li            0.512 (Liq)  $  20.00
Be            1.85         $ 166.00

MMH is monomethyl hydrazine, and RP-1 is Rocket Propellant-1 (a special grade
of kerosene-like hydrocarbon).

The quoted cost per pound presumably includes the cost of handling the
material.  The lithium is presumed to be injected as a liquid into the
combustion chamber - however this introduces all sorts of problems such as how
do you keep the lithium lines hot so that they don't plug with solid lithium at
the end of a test stand run.

In considering first stage launchers, the choice generally seems to have
settled down to three systems: solid fuel, RP-1 and O2, and some form of
hydrazine burned with N2O4.  RP-1 and O2 are clearly the cheapest, but this
seems to be outweighed by the hassles of handling a cryogenic propellant.  The
Ariane chose a hydrazine/N2O4 system in spite of the vastly greater costs of
the propellants (relative to RP-1 and O2), presumably because of the fact that
both propellants are storable.  Interestingly, both hydrazines and N2O4 are
quite toxic, so it seems that the launch industry is already handling some
materials that would cause a fair size disaster if there were a tank rupture.

     Adding lithium in any manner helps the performance of propellant systems
which use fluorine, but does nothing for systems in which oxygen is the
oxidizer.  In theory, adding beryllium to propellant systems in which oxygen is
the oxidizer improves performance, however beryllium can't be injected as a
liquid, suffers from incomplete combustion, forms a solid oxide which gives
two-phase flow losses in nozzles, is extremely toxic, and costs a fortune.  In
spite of this, I have been told that the technology exists for high performance
solid rocket motors incorporating beryllium as solid metal particles
(presumably for use in space where the toxic exhaust won't give an
environmental disaster).
Bruce Dunn   Vancouver, Canada    a752@mindlink.UUCP

From: Henry Spencer <>
Subject: Re: Fuel Cost
Date: Thu, 9 Apr 1998 00:13:01 GMT

In article <>,
James Nicoll <> wrote:
>	Something I haven't seen a source for: what's the
>cost of the fuel in modern rockets? ...

Jeff Greason gave a very interesting talk about this at one of the
Space Access conferences.  He'd gone to the trouble of actually digging
up bulk suppliers and getting numbers.

It depends a whole lot on which fuel you are using.  For the more exotic
things, it also depends somewhat on timing, because the chemical industry
changes processes a lot, and anything that's a product or byproduct of one
of this year's favorite processes is dead cheap.  Space is not usually a
big enough customer to dominate the market -- even liquid hydrogen is
primarily an industrial chemical nowadays.

Liquid oxygen costs almost nothing in large quantities.

Common hydrocarbon fuels are very cheap.  RP-1 is a bit pricier, but even
so, LOX/hydrocarbon costs are dollars per kilogram of payload to orbit.

Liquid hydrogen is more expensive.  Now we're talking tens of dollars.

Hydrogen peroxide is somewhat more expensive, although there are some
differences of opinion about details.  One headache is that high-purity
peroxide is not available in bulk as a standard product right now.

Solid fuels and N2O4/hydrazine combinations are seriously expensive.
Titan IV is the only current US launcher whose fuel costs aren't down in
the noise.  Even for it, while they're noticeable, they're not a large
fraction of the price.  Maybe a hundred or two per kilogram.

Exotic chemicals, especially things containing boron or fluorine, are
insanely expensive... although their prices could be expected to drop
if serious demand appeared.

Finally, do bear in mind that current launch costs are dominated by
salaries, not fuel prices.
Being the last man on the Moon                  |     Henry Spencer
is a very dubious honor. -- Gene Cernan         |

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