A kerosene-fueled X-33 as a single stage to orbit vehicle.

Consider a vehicle that masses 7.45 kg empty and 175.00 kg full. It
is equipped with a propulsive skin made of an array of micro-
thrusters. Think of an inkjet print head that sprays rocket fuel.
The engines occur in clusters of three - each oriented orthogonally to
the other - pointing outward from the normal to the sphere. There are
millions of them, as finely and quickly controlled as the dots on your
HDTV screen.

http://www.youtube.com/watch?v=mzXwctPXT4c

They have a thrust to weight ratio of 1,000 to 1 and are as efficient
as any macroscopic engine.

Using hydrogen and oxygen a sphere like this has an exhaust speed of
4.4 km/sec.

Here is a sketch of what I have in mind;

http://www.scribd.com/doc/40623446/Disk-Moonship-2
http://www.scribd.com/doc/40549127/Disk-Moonship

Now with an exhaust speed of 4.4 km/sec and a propellant fraction of
0.957428571428572 this system will achieve 13.88892 km/sec. With air
drag and gravity losses 12.7 km/sec final speed.

Greater than orbital velocity.

Greater than escape velocity.

This system also carries significant sensing and computing capability
with MEMS based fuel cells and microscopically sized cameras, phased
array antennae built into the propulsive skin, along with computing
and gyros, etc.

It is also capable of performing ballistic flight to any spot on
Earth, and returning.

http://www.youtube.com/watch?v=2g7TWx8s8LQ
http://www.youtube.com/watch?v=jNPV285B4Bc
http://www.youtube.com/watch?v=SuuTVLS6eVg

Using software and hardware developed for flight systems that mass
only a few grams.

http://www.youtube.com/watch?v=MvRTALJp8DM

http://www.vicon.com/products/t20.html

On Jul 19, 9:22*am, Jeff Findley wrote:
In article , says...



But it's all moot anyway. Investing in a reusable SSTO craft makes sense
only with high launch frequencies and there are just no customers and
payloads for that. You'd need to outright create a market (for space
tourism, SPS or whatever) and to do this you'd need to drive down the
costs per flight massively and this would require lots of money to
invest first with a very high risk to burn it.

Classic chicken and egg problem. *Without cheap launches, demand for
access to space stays low. *Without high demand for access to space,
developing a fully reusable launch vehicle is simply too expensive to
pay off.

It's possible that the "build it and they will come" approach would
work, but this would require new markets to be opened up by the new
vehicle. *Considering that SpaceX has taken a step down the road to
lower launch costs (without reusing any hardware), we'll have to wait
and see if they've dropped the price enough for this to start to happen. *
If it does start to happen, I'd expect SpaceX to ramp up its efforts to
recover hardware.

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011

You solve the chicken and egg problem by creating a consortium of
buyers. A launch provider gets orders for and participates in what he
or she is helping to build.

Motorola approached a number of manufacturers with their Iridium
idea. The aerospace community in unison dragged their feet and
refused to participate in the revenue stream. As a result, Iridium
lost a lot of money by under performing and being late to market.

Teledesic approached a number of manufacturers with their network.
The aerospace community ignored them. They again refused to
participate in the project as an equal partner.

haha - if Wall Street really worked the way I imagined it did in the
1980s - someone like Buffet and Gates and Turner could form a
consortium, arrange financing, and buy up Boeing and Lockheed. They
would then strip the companies of the space faring assets, and turn
out three or four specialty companies with higher revenues than the
combined companies - and use the profits to organize a private space
program. They would already have in place customers - like Microsoft
and Turner Broadcasting and others - to take delivery of services
delivered from space. They would borrow against these orders to
build a commercial RLV and deliver the satellites, and enjoy a
percentage of the profits to further perfect and develop space based
assets and resources.

Of course, Wall Street doesn't work like that today, if it ever did.

The DC-X never burned up its tail. The landing gear failed to deploy
on the DC-X leading to its demise after it fell over.

http://www.youtube.com/watch?v=wv9n9Casp1o
http://www.youtube.com/watch?v=JzXcTFfV3Ls

The USA may have stopped supporting this, but the Japanese are
developing a version of their own.

http://www.youtube.com/watch?v=-irOfrXy4N4

In neither case did they burn up their tails as Jeff wrongly asserts.

On Jul 20, 7:29*pm, William Mook wrote:
The DC-X never burned up its tail. *The landing gear failed to deploy
on the DC-X leading to its demise after it fell over.

http://www.youtube.com/watch?v=wv9n9...?v=JzXcTFfV3Ls

The USA may have stopped supporting this, but the Japanese are
developing a version of their own.

http://www.youtube.com/watch?v=-irOfrXy4N4

In neither case did they burn up their tails as Jeff wrongly asserts.

This approach of vertical take off and vertical landing - VTOVL - can
easily be applied to multi-stage systems. A booster can land
downrange, be refueled there and bounced back to the launch center.
The orbiter deploys its payload and lands.

This was the idea behind my original Greenspace proposal in the 1990s
- which I pitched to Teledesic and Iridium. The system uses an SSME
or RS-68 pump-set in the first stage - as part of a zero height
aerospike engine. Very similar to Rocketdyne's construction of an
aerospike engine around the J2 turbomachinery.

Okay, so using this approach the first stage has an exhaust speed of
4.1 km/sec and produces 370 tonnes of thrust. The vehicle ideally
should weigh 289 tonnes at lift off.

To reach the same orbits as the Shuttle, requires the vehicle attain
9.2 km/sec. Dividing this equally between the two stages means each
will add 4.6 km/sec. Since the exhaust speeds between the two stages
are equal, this is a good thing to do. If they did not, things would
be more difficult and we'd use Calculus of Variations to show we're
best when the stage speed is in proportion to the exhaust speed.

Alright, so, a 289 tonne vehicle accelerated to 4.6 km/sec by an
engine that has a 4.1 km/sec exhaust speed requires 194.9 tonnes of
propellant. The structure needed to carry this weight is 23.3
tonnes. This leaves a second stage 70.8 tonnes for the second stage.

Now, the turbomachinery from six RL-10 engines fashioned into a single
aerospike engine produces 67.3 tonnes of thrust. This is sufficient
for a vehicle moving at 4.6 km/sec and 25 km altitude, to continue on
to orbit.

Having the same exhaust velocity, this stage requires the same
propellant fraction as the first stage. With a 70.8 tonne total
weight this means 47.8 tonnes are propellant and 5.7 tonnes is the
structure of the second stage. This leaves 17.3 metric tons (38,060
lbs) useful payload.

Assuming launch from the Canaveral Air Station, the first stage will
come down South of the Azores. It will land vertically like the DC-X
- in the water. There it will be met by a tanker, carrying
sufficient hydrogen and oxygen to refuel the booster to 'bounce back'
to the launch center, where it will be ready for another flight in a
few hours. 48.3 tonnes of propellant are needed to boost the empty
first stage back to Canaveral. The entire operation will take only a
few minutes.

We have been launching large rockets from the ocean for years. There
is no reason rocket engines cannot be built to land in the ocean and
take off from the ocean as well.

http://www.youtube.com/watch?v=uljVI4m5e3c
http://www.spacefuture.com/archive/h..._systems.shtml

That's why early supporters of commercial SSTO operations, using the
Ithacus, the Pegasus, the Hyperion, the Rombus and the Nexus, showed
them landing and taking off from artificial pools of water.

So, landing on the ocean, being refueled by a waiting tanker, and then
flying out of the ocean, is a simple way to make TSTO work with
capabilities we already have in hand.

A fleet of three boosters and nine orbiters - would allow six flights
per day to be maintained of two satellites each. At this rate a large
network could be deployed in two months.

I would participate in the revenue stream from the network, and use
that to maintain the network and develop new uses for the launcher
system.

Of course, flights to sun synch Polar orbits from California would
have the booster drop down off the Pacific Coast in Chile.

I also explored the potential of the NEBA-III rocket. I envisioned an
unpiloted kick stage that operated with 9.5 km/sec exhaust speed using
pure hydrogen. This stage, once orbited would loiter on orbit and
automatically dock with a hydrogen tank carrying a satellite brought
to low orbit. The NEBA-III stage would drop from its parking orbit,
dock, then take the stage to GEO or whatever orbit was required. It
would then release the satellite, and take the tank back to its
parking orbit.

After several flights, the NEBA-III rocket would then take an
interplanetary payload to any planet of choice, powering it for a
number of years.

In this way the special fuels from the ROVER/NERVA programs could be
flown off for about $85 million per rocket. With 85 flights per
booster, the cost is competitive with existing kick stages. With 9.5
km/sec exhaust speed, the stage lifts far more payload to high orbit,
and is a good investment to increase payloads to high orbit.

I even spoke with the Clinton White House about getting Presidential
approval of this program. First Bank of Boston said they would fund
the entire program if I got it! lol. That would have led to an order
in 1995 from Iridium and Teledesic.

ah well.

A 10 MW thermal engine produces 107 kgf thrust with a 9.5 km/sec
exhaust speed. On orbit this has tremendous capability. The
system also produces 10 kW continuous power. Which is a plus. It
masses only 50 kg!! Not big at all.

A 17,300 kg payload - picked up by a 50 kg stage - accelerates at a
rate of 0.22 km/sec every hour. So, to add 2.95 km/sec to the speed
of the payload requires 13.4 hours. The advantage is that only 4.63
tonnes of propellant are needed to execute this maneuver.

This by the way is the speed needed to reach the moon from Earth
orbit.

To slow into lunar orbit with this tiny engine requires 3.2 hours of
boost. This requires another 0.91 tonnes of propellant.

We switch back to chemical rockets to fall from orbit safely to the
lunar surface. This requires 3.78 tonnes of propellant to land and
2.58 tonnes of propellant to return along with another 0.80 tonnes of
propellant to fly back to Earth.

The NEBA III attached by a long boom to the nose of the lander,
continues to operate and provides 10 kW of power to the spacecraft
while on the lunar surface.

On its way back to Earth, the NEBA III reactor separates, and takes
enough fuel to enter its parking orbit by rocket action alone. This
is another 0.16 tonne of propellant. The lander, equipped with
thermal protection, re-enters, aerobrakes, and lands on the Earth's
surface - and is available for reuse.

This leaves 10.8 tonnes of payload taken to the moon and back. The
empty weight of the payload module is 1.8 tonnes - 9 tonnes of
consumables on board.

A similar system carrying similar payloads to Mars, refuels on Mars
using local water supplies to make hydrogen and oxygen.

10 kW power supply can process 1 ton of propellant in 567 hours (24
days). A 9 tonne payload requires an 11.2 tonne propellant on Mars to
make orbit. Staying 264 days allows this propellant to be made from
15 cubic meters of ice found on the planet. This can be done in less
time if the power output is increased.

This is recognized as a version of Zubrin's Mars Direct idea.

The point is, these sorts of things are easily doable and easily
affordable if the right connections are made between the aerospace
industry and other industries.

It is interesting to note that Boeing moved its HQ from Seattle and
Chicago after destroying its Seattle HQ shortly after Gates and Condit
met at Seattle's country club and had conversation that led to
Teledesic.

Of course this is a very lightweight version of the ideas of the 60s,
but we could have had the first town on Mars and the Moon functioning
by now building from these modest beginnings.