Using structural steel for spacecraft

Here are the design guidelines for structural steel repairs on Ships a Sea.

http://www.shipstructure.org/pdf/443.pdf

And we can see that we can make significant super structures and outfit them to a high standard at prices that are small compared to the prices associated with aerospace applications.


http://www.fraseryachts.com/Charter/...chtID=Y7414_MC

The difference is the total weight involved!

2,479 tonnes - of which 326 tonnes are diesel fuel. Quite the reverse of aerospace structures - the Space Shuttle External tank masses 23 tonnes empty, and carries 760 tonnes of propellant!

Yet, these propellant weights, are adequate for nuclear pulse ships. Which let's us use pretty standard procedures... like this;

https://www.youtube.com/watch?v=acy8bdHg2qA

This is according to Freeman Dyson who said nuclear pulse propulsion makes it possible to use steel and conventional methods and equipment, to build spacecraft!

http://www.patrickmccray.com/wp/wp-c...-a-Project.pdf

Now, since the 1950s, we have developed micro-nuclear fusion pulse units using aneutronic reactions of Lithium-6 and Deuterium - have the potential to create micro-pulse rockets capable of producing 23,300 km/sec exhaust speeds.

http://nuclearweaponarchive.org/News/INESAPTR1.html


23,300 km/sec exhaust speeds means that to achieve 9.2 km/sec delta vee required to achieve Low Earth Orbit - with air drag and gravity losses - requires 979 kilograms of propellant for a 2,479 tonne take off weight!

To accelerate at two gee from the surface of the Earth, maintaining one gee half way to the moon and then one gee acceleration slowing down and landing at one and one sixth gee means that that ship has to achieve 272.6 km/sec for a round trip to the moon and back in 6.95 hours. This takes 28.8 tonnes of fusion propellant.

Taking 12 people in luxury to the moon and back ever day, at a cost of $20 million, earns $240 million per day! Flying 300 days - that's 360 people - and $72 billion per year!

So, just one of these ships, outfitted for lunar travel and exploration, could earn more money than all the space programs of the world combined! Which is pretty awesome!

How far could this ship go?

This ship (take off weight 2,479 tonnes with 326 tonnes of fuel) has the capacity to travel at one gee across a distance of 137.56 million km! All in 2 days per trip each way.

Reducing gee forces to 1/10th gee - increases distance for a given delta vee 10x - to 1.3756 billion km! The time here is 64 days per trip each way.

So, this gives us access to the entire solar system really. With spare propellant modules, trip time could be reduced as well for long distance journeys.

Something the shape of the fictional shuttle craft Argo is interesting... as a sight model, but would have to be way bigger, with three levels, to be as big as the ocean going yacht above.

http://38.media.tumblr.com/6f14a3588...zo3_r1_250.gif

Four fusion pulse engines one at each corner, like a quad rotor on steroids, provide accurate control during boost. Each producing up to 625 tonnes of lift (6.13 MN) so together they can pull two gee if need be. But can be scaled back to 5% thrust. This means throttling the mass flow from 13 grams to 265 grams per second. With a Lithium-6 Deuteride spherical pulse unit that is 0.88 grams/cc and 5 mm in diameter pulse rate varies from 225 per second to 4,600 per second. Two axis gimballing of each corner engine along with variation of thrust, gives the ability to do any sort of maneuver, especially if you're in a gravity field.

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

Getting a ship yard to build three of these air frames, and outfit it for space travel - similar to building a submarine - and then equipping each airframe with a fusion pulse engine - makes it go!

Three ships costing $200 million each - with one dedicated to lunar tourism - and one dedicated to cargo - and emergency back up - for shipping pressure vessels to the Moon for deployment and rescue if needed. One dedicated to solar system exploration.

A $2 billion programme to build the ships, and develop the engine - has a reasonable expectation to earn $72 billion per year as mentioned above from 3600 people (12 people to the moon and back for $20 million - charters for $24 million per day beyond that). Since there are over 40 million millionaires in the world, this is not a very large market penetration - and given the response to one way trips to Mars, its likely that one or both boats would be busy ferrying people to the moon and back, and the cargo ship would be shipping places to party, and party supplies...

Just because its cool!

Cubli...
https://www.youtube.com/watch?v=n_6p-1J551Y

On to fabrication technologies:

Remote laser welding
https://www.youtube.com/watch?v=H0BV0CDuGRI
https://www.youtube.com/watch?v=d_SNCRKdnDI

5-axis laser cutting & welding
https://www.youtube.com/watch?v=4TJur00-R8k

Flexible fabrication assembly module
https://www.youtube.com/watch?v=_rWT5fQLq4Y

So, instead of thousands of steps, with a tool for each step, assembly processes take place in a small volume of space.

When combined with custom forming of sheet
https://www.youtube.com/watch?v=GxysBla3NyI
https://www.youtube.com/watch?v=Wl5_wUVxRvw

We can fabricate an airframe fairly easily and quickly.

Something along these lines.

Argo Shuttlecraft (fictional)
http://img2.wikia.nocookie.net/__cb2...go_shuttle.jpg

Length: 21.66 m
Beam: 6.97 m
Height 4.45 m

Made with 1.8 mm thick aircraft aluminum, stamped into shape, cut and laser welded, the airframe masses 2,640 kg (5,810 lbs)

There are four fusion pulse engines that are mounted on an inverted Stewart platform to generate a controlled thrust.

https://www.youtube.com/watch?v=1GM2C8yqqeQ
https://www.youtube.com/watch?v=j4OmVLc_oDw

A super powerful version of a quad-rotor design.

In atomic physics, a ridged mirror (aka ridged atomic mirror, or Fresnel diffraction mirror) is a kind of atomic mirror, designed for the specular reflection of neutral particles (atoms) coming at a grazing incidence angle to reduce the mean attraction of particles to the surface and increase the reflectivity, this surface.

The de Broglie theory of wave properties of reflected atoms shows very high efficiency of quantum reflection of waves from ridged mirror. Ridges enhance the quantum reflection from the surface by reducing the effective constant of the van der Waals attraction of atoms to the surface.

For efficient ridged mirrors, high reflectivity is achieved.

The reflectivity of a ridged atomic mirror is nearly perfect. The use of a ridged mirror as an atomic hologram has been demonstrated. In Shimizu's and Fujita's work,of atom holography is achieved as the atomic mirror itself.

An ellipsoidal ridged mirror is the focusing element for an atomic optical system with submicrometre resolution to implement an atomic nanoscope.

In fusion pulse applications the high efficiency means orders of magnitude reductions in erosion and improved thrust efficiency and beam formation.

MEMS based fusion pellets detonated by a focused neutron beam in a compact device, provide a means to reliably detonate 2 mm diameter disk 21 microns this containing 53.6 micrograms of Li6-Deuteride. Each pulse releases 14.56 megajoules of energy and produces a collimated beam 500 mm in diameter moving at 23,300 km/sec! Each of the four thrusters produce 400,000 Newtons. This requires a mass flow rate of 17.17 grams per second. A detonation rate of 320,335 units per second. This requires a wafer launcher capable of achieving 200 km/sec - which is achieved with laser sustained detonation of a plastic coating on the Li6-D wafer. The laser propulsion of the wafer guides it to the focal point of the neutron source - where the wafer detonates - and the resulting pulse of high speed plasma is directed by the atomic hologram described previously.

A portion of the stream passes through an MHD generator in each engine, to provide power for the laser system, and provide power for the other on board systems. Up to 1 MW of power may be generated by each of the four lift engines.

Thrust may be reduced to as little at 1/1000th gee or rise above 2 gees by changing detonation rate.

MEMS based life support, cryogenic, and energy systems populate the walls of the spacecraft.

http://sbir.gsfc.nasa.gov/SBIR/abstr...3.03-8236.html

160 metric tons force - of thrust. 78 metric tons total weight. 3 ton inert weight. 75 ton payload/propellant weight.