The Sea Dragon - 1.2 million pounds to LEO (was By-Pass the Moon?)

--- In spacesettlers 10459, ANTIcarrot wrote:
> Pretty much the best thing the next president could do
> is ... put up a ten billion dollar prize ... for the
> first organisation ... that can deliver a vehicle that
> can bring launch costs down to $500/kg or lower. ...
> private industry has repeatedly quoted a CATS
> development cost in the region of $5-$15 billion.

That vehicle has already been developed, many times over:
http://www.dunnspace.com/leo_on_the_cheap.htm

For example, from Chapter 10:

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Aerojet combined data derived from the SeaBee program with the newly
developed low-cost booster design rules to define a colossal launch
vehicle. Called Sea Dragon, it was intended to support NASA's manned
exploratory assault on Mars and interplanetary space (see table 9).

The Sea Dragon was to be a simple, reusable launch vehicle. Like the
SeaBee, it was to use a pressure-fed propulsion system; but it was
scaled to represent perhaps the largest space booster ever conceived.
It was to have a lift-off thrust of 356 million Newtons (80 million
pounds) and a lift capacity to low earth orbit of 544,000 kilograms
(1,200,000 pounds). The Sea Dragon was to be 168 meters (550 feet)
tall and to have a diameter of 23 meters (75 feet). Construction and
transportation of such a booster was more amenable to a shipyard than
an aerospace factory, and the vehicle's simple steel design with
water launch and recovery made shipyard manufacturing appropriate and
practical.

Aerojet designed the Sea Dragon to have two stages. The first stage
would use liquid oxygen and RP-1; the second stage, liquid oxygen and
liquid hydrogen. Both stages would be pressure-fed, and both would
use a single-engine thrust chamber. The first stage engine would be
rated at 356 million Newtons (80 million pounds) of sea-level thrust-
certainly the largest rocket engine ever seriously postulated.
Aerojet settled on single-thrust chamber stages because their studies
indicated it would be less expensive to develop and integrate single
large engines than to develop and cluster sets of smaller engines.
Also, analysis showed that even with near-exponential increases in
the size of simple engines and airframes, there is only a linear
increase in cost. The analysis results made a strong case for the
economy of very large and simple boosters with large engines, and Sea
Dragon was the consummate embodiment of this design philosophy.

Sea Dragon was to be constructed-and transported to the launch
location (at sea)-in a manner that was closer to a seagoing tanker
than an airplane. The vehicle would have been built horizontally in a
commercial shipyard, then staged out of a US coastal site. It was to
be fueled with RP-1 in a dry dock, then towed horizontally to the
launch point. Upon its arrival, propellant transport ships would have
loaded the vehicle with cryogenic propellants, and technicians would
have flooded a ballast device to position the booster vertically. The
booster would jettison the ballast at lift-off.

The first stage, which was to be recovered several hundred kilometers
downrange, would use an inflated drag chute to decrease its water-
impact velocity. The rigidity and strength of the heavy steel
tankage, which was designed for the pressure-fed propulsion system,
would have lent itself to surviving repeated water impacts with
little damage. The second stage had an optional reusability design
that would have employed retro-rockets, an ablative nosecap, and a
drag-inducing device for controlled reentry to a point close to the
refurbishment site.

Cost estimates for using the Sea Dragon to place a payload in low
earth orbit ranged from $59 per kilogram ($27 per pound) to $620 per
kilogram ($282 per pound). The booster researchers were able to
project these low costs because the booster had the benefit of a
significant economy of size, it depended on shipyard-type (as opposed
to aerospace) construction techniques, and it was reusable.
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