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September 17, 2009

A More Affordable, High G force Magnetic Space Launcher Proposal

A magnetic space launcher is proposed by Bolonkin.

If this magnetic launcher costs 50 millions of dollars, lifetime of installation is 10 year and mountain is $2 millions of dollars per year. The launcher operates 350 days and launches 100 kg payload every 30 min (This means about 5000kg/day and 1750 tons/year). Then additional cost from installation is $2.86/kg then total cost is $6/kg.

The installation consists of a space apparatus, power drive stations, which include a flywheel accumulator (for storage) of energy, a variable reducer, a powerful homopolar electric generator and electric rails. The drive stations accelerate the apparatus up to hypersonic speed. The estimations and computations show the possibility of making this project a reality in a short period of time (for payloads which can tolerate high g-forces). The launch will be very cheap at a projected cost of 3 ─ 5 dollars per pound.

A homopolar generator is a DC electrical generator that is made when a magnetic electrically conductive rotating disk has a different magnetic field passing through it (it can be thought of as slicing through the magnetic field). Relatively speaking they can source tremendous electric current (10 to 10000 amperes) but at low potential differences (typically 0.5 to 3 volts). This property is due to the fact that the homopolar generator has very low internal resistance.

The engine accelerates the flywheel to maximum safe rotation speed. At launch time, the fly wheel connects through the variable reducer to the homopolar electric generator which produces a high-amperage current. The gas gun takes a shot and accelerates the space apparatus up to the speed of 1500 – 2000 m/s. The apparatus leaves the gun and gains further motion on the rails where its body turns on the heavy electric current from the electric generator. The magnetic force of the electric rails accelerates the space apparatus up to speeds of 8000 m/s. (or more) The initial acceleration with a gas gun can decrease the size and cost of the installation when the final speed is not high. An affordable gas gun produce a projectile speed of about 2000 m/s. The railgun does not have this limit, but produces some engineering problems such as the required short (pulsed) gigantic surge of electric power, sliding contacts for some millions of amperes current, storage of energy, etc.

The current condensers have a small electric capacity 0.002 MJ/kg ([2], p.465). We would need about 10^10 J energy and 5000 tons of these expensive condensers. The fly-wheels made of cheap artificial fiber have capacity about 0.5 MJ/kg ([2], p.464). The need mass of fly-wheel is decreased to a relatively small 25 – 30 tons. The unit mass of a fly-wheel is significantly cheaper then unit mass of the electric condenser.



Bolonkin ideas to reduce costs:

1. Fly-wheels (25 tons and 710 m/s max rotating speed) from artificial fiber.
2. Small variable reducer with smooth change of turns and high variable rate.
3. Multi-stage monopolar electric generator having capacity of producing millions of amperes and a variable high voltage during a short time.
4. Sliding mercury (gallium) contact having high pass capacity.
5. Double switch having high capacity and short time switching.
6. Special design of projectile (conductor ring) having permanent contact with electric rail.
7. Thin (lead) film on projectile contacts that improve contact of projectile body and the conductor rail.
8. Homopolar generator has magnets inserted into a disk (wheel) form. That significantly simplifies the electric generator.
9. The rails and electric generator can have internal water-cooling.
10. The generator can return rotation energy back to a flywheel after shooting, while rails can return the electromagnetic energy to installation. That way a part of shot energy may be returned. This increases the coefficient of efficiency of the launch installation.

A short rail way (412 m) would launch 7500 Gs into orbit.

A manned rail launcher must be 1100 km for acceleration a = 3g (untrained passengers) and about 500 km (a = 6g) for trained cosmonauts.

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