Machine Design

The Second Space Age

Ready for a space cruise? The technology is taxiing to the runway.

Patrick G. Mahoney
Associate editor

In 2001, the first paying passenger traveled into space aboard a Soyuz space capsule. Four short years later, SpaceShipOne proved that a private company could make space travel possible. Suddenly, space tourism didn’t seem so crazy.

SpaceShipOne fired the imagination of millions. But that was nothing compared to what’s next. Get ready for SpaceShipTwo.

Virgin Galactic, the world’s first space line, recently unveiled a model of what may be the next big thing in space travel: WhiteKnightTwo and SpaceShipTwo. Virgin Galactic was formed in 2004 by SpaceShipOne designer Burt Rutan and Richard Branson, owner of Virgin Atlantic Airways. Galactic placed an order for the construction of five suborbital ships with Rutan’s company, Scaled Composites LLC, Mojave, Calif. And prospective passengers plunked down $190,000 apiece for the privilege of being the first tourists in space.

Passengers will get three days of training in weightlessness and the g loads of space flight before the 60-ft long SpaceShipTwo carries six of them plus two pilots about 62 miles above the Earth.

WhiteKnightTwo (the mother ship), a twin-fuselage airplane with a single 140-ft wingspan, and SpaceShipTwo will fly a different profile than SpaceShipOne. Instead of ascending straight up to launch altitude, the new plane will take off over land and fly to a launch point over the Pacific Ocean. There, WhiteKnightTwo will release SpaceShipTwo so it can fire its rocket engine. SpaceShipTwo will reenter the atmosphere some 20 miles from where it took off and glide to a landing at Mojave Spaceport. From takeoff to touchdown, the flight will cover 200 miles.

In January, Virgin Galactic President Will Whitehorn said WhiteKnightTwo was more than 70% complete, while SpaceShipTwo was about 60% finished. Scaled Composites hopes to begin test flights this summer.

Want to hitch a ride into space? Tickets for Virgin Galactic’s 2.5-hr flight are now going for $200,000. But Branson’s company is not the only one with its head above the atmosphere.

Rocket Woman
Reda Anderson expects to be Rocketplane Inc.’s first passenger. The Oklahoma City-based company is splicing together two Lear jet 25 fuselages to make room for the kerosene and liquid oxygen tanks that will power a 36,000-lbthrust rocket engine. The Lear’s horizontal stabilizers will be replaced with a V-tail to help raise the nose when it’s loaded with fuel. And a delta-shaped wing assembly will replace the standard wings. Tickets will cost $225,000 to $300,000, depending on how soon passengers fly and where they sit.

The Lear jet 25’s twin GE CJ610 jet engines will power the spaceship to a launch altitude of 25,000 ft. There, the pilot will shut down the jets and fire the rocket engine for a 70-sec, 4-g boost into space and a maximum speed three and a half times the speed of sound. After shutting down the rocket, passengers will experience 4 min of weightlessness and a view they won’t get anywhere else (unless they’re double booked with Virgin Galactic, that is).

Computerized flight controls will let Rocketplane XP’s pilot navigate the dynamic pressure and supersonic speeds of reentry. The RCS (Reaction Control System), interacting with the ship’s aerodynamic- control surfaces through its flight path outside the atmosphere and on the way back down, will provide seamless control, says the company. Computers will fly the ship from boost to reentry, with the pilot taking over only in an emergency and for landings. At 20,000 ft, the pilot will restart the jet engines for a powered landing. Total flight time: 1 hr.

Rocketplane’s plan to bolt two salvaged fuselages together and use a liquid-fuel rocket engine and fly-by-wire controls to guide the ship is the brainchild of Mitchell Burnside Clapp, an aerospace engineer and former test pilot instructor. Burnside Clapp, Robert Zubrin, and Chuck Lauer formed Pioneer Rocketplane in 1996. Zubrin left two years later. Under the direction of new president George French, the company sought a new prize: the so-called O (for Oklahoma) Prize.

In an effort to grab a piece of the space-tourism pie, Oklahoma offered transferable tax credits worth $18 million to any Oklahoma based space-launch company with at least $10 million of capital, among other criteria. Rocketplane, the winner, sold the tax credits for $13 million and the XP taxied closer to takeoff.

The Lear jet on which the XP is based could take 3+ gs and had an operational ceiling around 50,000 ft. The new delta-wing assembly and V-tail will let the craft handle 4 gs. Rocketplane’s designers replaced the engine inlets, nose, and leading edges of the delta wing with steel or titanium to protect against the heat of reentry.

The ship, which will weigh 19,500 lb at takeoff compared with the Lear jet 25’s 15,000 lb, will need something extra to get off the ground. Fortunately for Rocketplane, the former Strategic Air Command base (now Oklahoma Spaceport) in Burns Flat, Okla., has a 13,500-ft runway. XP’s Aircraft Rocket-36 will deliver 36,000 lb of thrust on liquid oxygen and kerosene. Regenerative cooling, which circulates kerosene along the combustion chamber’s outer wall before it’s burned, will make it possible for the engine to fire many times with little maintenance, similar to a jet engine.

According to Dave Faulkner, XP program manager, Rocketplane is “approaching a preliminary design review for the whole vehicle, but many of the systems are past this point in the design stage.” The company hopes to put passengers into space beginning in 2010.

Blooming in the desert
The Mojave, Calif., area is shaping up as a busy place for rockets. XCOR Aerospace, in Mojave, is working on its own two-seat rocket plane. Like Rocketplane XP, it will launch from a runway, but without jet engines.

XCOR’s first foray, the entirely rocket-powered EZ-Rocket (now retired), was a manned technology demonstrator for future vehicles. It flew 26 times using twin XR-4A3 (XCOR’s 400-lb thrust LOX/alcohol) engines in both up-and-away and cross-country mode. The alcohol was stored in an external composite fuel tank, and the LOX in an internal, insulated, aluminum liquid-oxygen tank. The engines and igniters used during the flight test program proved reliable, reusable, and restartable in-flight, says the company. The XR-4A3 engines made nearly 700 runs for a total of more than 165 min.

The EZ-Rocket was a modified Long-EZ home-built airplane with a canard layout, chosen for its pusher configuration and power-off glide capability. The Long-EZ was designed by Burt Rutan. EZ-Rocket pilots restarted the engines in midflight and performed touch-and goes, both firsts for rocket-powered aircraft. EZ-Rocket attained a maximum altitude of 11,500 ft.

While the EZ-Rocket helped work out the kinks in routine rocket-powered flight, the company’s ultimate goal is profitable transportation to Earth orbit. The initial target, to reduce per-flight costs to below $2,000, was reached and costs dropped to about $900. The groundbreaking EZ-Rocket went from paper to flight in only nine months.

XCOR has already begun preliminary design of its next craft, a suborbital vehicle called Xerus. The single-stage suborbital vehicle is designed for research, space tourism, and transporting microsatellites to low Earth orbit via a small secondary stage.

NASCAR without the track
Another opportunity for XCOR landed when The Rocket Racing League asked it to design and build an evolved EZ-Rocket for the first generation of X-Racers. The proposed league will race rocket powered aircraft (X-Racers) using liquid oxygen/kerosene fuel with a burn time of 4 min. Races will take place on a course 2 miles long, 1 mile wide, and 1,500 ft in the air. Spectators will watch the 1-hr-long race from multiple camera views.

Velocity of Sebastian, Fla., will build airframes to carry the XCOR XR-4K14 1,500-lb-thrust rockets. An LOX tank will replace the rear seats and strake tanks will store fuel. A rocket propellant piston pump will eliminate the pressurized fuel belly tank used on the EZ-Rocket.

The X-Racers will feature a single engine and a much brighter kerosene-burning plume. The single-pilot vehicles will have a gross takeoff weight of 3,000 lb, half of which is propellant weight. The first-generation Mark-1 XRacers will reach speeds of up to 230 mph, limited by airframe safety, not engine power. Electric ignition will start and stop the engine in flight, resulting in alternating 3.5-min engine boosts and 15-min glides.

In 2003, XCOR finished development of its third-generation igniter and tested an 1,800-lbthrust LOX/kerosene engine, the same class of engine that will power Xerus. XCOR developed the XR-4K14, a 1,500-lb-thrust regeneratively cooled LOX and pump-fed kerosene engine, and the rocket propellant piston pump that power the X-Racer. The same company built the initial version of a 7,500 lb-ft LOX/methane engine for NASA’s Crew Exploration Vehicle.

Perhaps one of these companies will emerge as the premier space line serving the space-tourism industry, but then space, like the future, is a pretty big place.


<em>Rocketplane XP</em> could start carrying passengers into space by 2010.


<em>SpaceShipTwo</em>, currently under construction at Scaled Composites in Mojave, Calif., will be named VirginSpaceShip Enterprise.


<em>WhiteKnightTwo</em>, Virgin Galactic’s mothership, carries SpaceShipTwo aloft in this artist’s conception.


Hybrids are among the safest and simplest rocket motors. Combustion occurs above the solid fuel surface inside the CTN and resulting hot gases exit out the nozzle, producing thrust. Hybrid rocket motors can be shut down at any point after ignition.


A conceptual representation of the exterior of <em>SpaceShipTwo</em> currently under construction at Scaled composites in Mojave, Calif. She will be named <em>Virgin SpaceShip Enterprise</em>

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