Another Step On The Path To X-Prize

Burt Rutan's Scaled Composites has reached another milestone along its path to the X-Prize competition. Scaled hopes the hybrid rocket will boost its SpaceShipOne on a suborbital path that could mean $10 million in prize money and a new era in space travel.

Earlier this month, workers on the super-secret Rutan project fired up SpaceShipOne's motor, lighting up the Mojave Desert and shaking it with the sound of man-made thunder. It was the second of two engine tests from companies hoping to give SpaceShipOne a lift.

Hybrid Technology: How It Works

The designs tested by SpaceDev of Paveway (CA) and Environmental Aerospace Corporation (eAc), share some common characteristics, at least, on the drawing board. Both combine the advantages of solid- and liquid-fuel. The pilot has two switches -- one to arm, the other to fire. There is no throttle.

Rutan and crew have been working on the design for more than two years. The composite nitrous oxidizer tank and CTN (unitized motor case/throat/nozzle) passed their qualification tests by late last year.

Scaled Composites isn't talking much about the results of engine testing. The company cites the competitive nature of the rocket ground test program, saying details about engine performance won't be released until either eAc or SpaceDev is chosen.

While hybrid motors are nothing new, Rutan's design is. He's applied for a patent to cover the fuel case and the cantilevered nozzle that leads to the main oxidizer tank. As for the oxidizer itself, SpaceShipOne uses laughing gas -- N2O. That's combined with HTBP (hydroxy-terminated polybutadiene) to create the propellant. The advantage of these two substances is that they can be stored separately and safely, without reacting until they're ignited.

The use of nitrous oxide as an oxidizer means SpaceShipOne doesn't need complicated turbo pumps, or specialized plumbing to get it into the firing chamber. There's no chance that a hybrid motor will start by accident, in the way a Brazilian rocket did recently, killing several people in the launch area. The byproducts of the Rutan fuel combination are considered much more environmentally friendly than the byproducts of traditional fuels, such as those used by NASA. They include water vapor, carbon dioxide, a bit of carbon monoxide, hydrogen and nitrogen.

Space: The Final Frontier

When Rutan announced the SpaceShipOne project back in April, he called the effort “the beginning of a renaissance for manned space flight. This might even be similar to that wonderful time period between 1908 and 1912 when the world went from a total of 10 airplane pilots to hundreds of airplane types and thousands of pilots in 39 countries. We need affordable space travel to inspire our youth, to let them know that they can experience their dreams, can set significant goals and be in a position to lead all of us to future progress in exploration, discovery and fun."

While Scaled Composites has twice drop-tested the SpaceShipOne vehicle by separating it from its mother ship, White Knight. Next on the apparent agenda is the selection of a propulsion system and its airborne testing.

FMI: www.scaled.com