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.