February 21, 2007

Maglev assisted launch

The future goal of maglev launch assist would be to build a space vehicle and maglev sled—together weighing 100 tons—and accelerate them to a velocity of 255 m/s (918 km/hr). The main cost-saving areas would come from reduced fuel consumption and the reduced mass of the spaceship. This idea could be combined with hypersonic skyhooks, which would help raise cargo from Mach 10 vehicles to orbit (orbital velocity is Mach 24). Going from Mach 1.5 to Mach 10 could be done with a dual mode ramjet/scramjet vehicle. Its fuel weight would be 90% less since oxygen would be taken from the atmosphere. SpaceshipOne type systems could also be used to go from Mach 1.5 to Mach 10.

More details in this pdf on the hypersonic skyhook The early stage skyhook could be a rotovator that is 900km long or a cardiorotovator that is 1800mk long and has a rendevous speed of 8.7 Mach.

“The energy result would be about 2600 kw•hr, which is a very small energy cost compared with other launch technologies, such as a pneumatic acceleration system,” Yang explained. “Key challenges for this maglev launch assist are the linear motor’s acceleration system and its power supply system, which are required to provide an acceleration of 2g-3g (gravity).”

In their model of a test vehicle on a seven-meter-long track, Yang’s group used a suspension system based on bulk high temperature superconductors, which achieve highly stable levitation due to their diamagnetic and flux pinning properties. The researchers used an arrangement of YBCO bulk superconductors, which achieve their remarkable property of zero resistance at 77 K. When the superconductors were cooled to this temperature, the test vehicle levitated freely over the track.