WASHINGTON — Designers and engineers at Scaled Composites in Mojave, Calif., are busily working on the large WhiteKnightTwo jet aircraft to get it ready for a special rollout ceremony now targeted for July 28 at the Mojave Air and Space Port. The massive plane is a key piece of the two-stage system that is intended to launch paying tourists into suborbital space.

The rollout will be followed by an extensive ground and flight test program of the airplane, which will be used as the first stage for SpaceShipTwo, the suborbital spacecraft Scaled is building for Virgin Galactic.

Powering the WhiteKnightTwo are four PW308 turbofan jet engines built by Pratt & Whitney Canada.

Pratt & Whitney Canada, based in Longueuil, Quebec, is a United Technologies company.

Those engines were selected for the mega-carrier plane that will transport SpaceShipTwo to an altitude of 15,167 meters where it will release the suborbital spacecraft so it can use its hybrid rocket system to take a group of paying tourists into suborbital space. SpaceShipTwo is being designed to accommodate six passengers and two crew members.

SpaceShipTwo is being built by Scaled Composites for The Spaceship Co. – a firm that is jointly owned by Virgin Galactic and Scaled Composites.

Virgin Galactic is part of the Virgin Group of companies established by British entrepreneur and billionaire, Sir Richard Branson, who is keen on creating the first spaceline business. Virgin Galactic is the launch customer for the SpaceShipTwo system, having ordered five spacecraft with options for seven-plus WhiteKnightTwo carrier aircraft.

According to Will Whitehorn, president of Virgin Galactic, the firm has some $36 million in escrow. That figure represents the total amount of full- and partial-deposits that would-be SpaceShipTwo customers have put down to reserve trips on the space plane.

Whitehorn told Space News in a May 29 interview that Virgin Galactic anticipates handling 500 to 600 passengers the first year of commercial suborbital operations. “The thing that has interested me the most about the customers is that they are almost all either scientists … or entrepreneurs who are interested in science,” Whitehorn said.

Meanwhile, loads of actors and individuals from the thespian world have approached the group seeking free rides in exchange for being an ambassador for the effort. “We can’t afford to go down that route … and have celebrities fly for nothing. Then we go bust. Virgin isn’t going to fund a business that isn’t a real business,” Whitehorn said.

Those early adopters of suborbital space travel via Virgin Galactic have provided an impetus to move forward on constructing the WhiteKnightTwo-SpaceShipTwo system. Branson would not have invested in the project if the business case could not be shown, Whitehorn added.

Both Branson and the Virgin Group “see something very exciting and a long-term business in space for Virgin,” Whitehorn said. “They understand what we understand. We’ve got a lot of markets we can go after.” Following the unveiling of WhiteKnightTwo, a series of ground evaluations of that vehicle – such as taxi tests and low- and high-speed tarmac runs – are slated, leading to an inaugural flight perhaps by early September from the Mojave Air and Space Port. Meanwhile, SpaceShipTwo will remain under wraps, with fitting to the WhiteKnightTwo occurring perhaps by early 2009.

Preparations to handle the testing of the WhiteKnightTwo-SpaceShipTwo system are under way at the Mojave Air and Space Port, which also is the home base for XCOR Aerospace. Stuart Witt, general manager of the Mojave Air and Space Port, has characterized 2008 as a “tipping point” in the emerging personal spaceflight business. Witt said in a June 12 e-mail there are a number of initiatives at the site to support flight testing of private suborbital activities, such as control tower radar display hardware, as well as extensions and widening of runways.

Scaled Composites founder Burt Rutan – newly named as chief technology officer and chairman emeritus of the company – remains tight lipped about the details of next month’s ceremony. “Hmmmmm … I have never been one to spoil the suspense of a rollout,” he said in a June 11 e-mail response.

Despite the air of secrecy surrounding the WhiteKnightTwo, it is clear that the aircraft is being eyed to handle more than public space tourism.

In an event earlier this year, Branson spotlighted the fact that the WhiteKnightTwo-SpaceShipTwo system will have the capability to launch small payloads and satellites at low cost.

“The other thing that I really admire about the system is that it has the architecture that could someday be developed into a passenger carrying vehicle, able to take people from A to B around the planet, outside of the atmosphere,” Branson said during a Jan. 23 event in New York to showcase scale models of WhiteKnightTwo and SpaceShipTwo.

Thanks to the open architecture design of the largely carbon composite WhiteKnightTwo, Virgin Galactic views the jet aircraft as the world’s most advanced payload carrier. “This thing has got incredible abilities. You can hang anything under there,” Whitehorn said.

Since WhiteKnightTwo can serve as a high-altitude flying launch pad to loft microsatellites, its owners are studying a wide range of other business ideas such as using it as a water-bombing aircraft to help quench forest fires.

Beyond supporting space passenger travel, WhiteKnightTwo “also allows us to start to develop the other markets,” Whitehorn said, be they carrying science experiments to high altitude or making microgravity-producing parabolic flights available for customers.

Leonard David has been reporting on space activities for nearly 50 years. He is the 2010 winner of the prestigious National Space Club Press Award and recently co-authored with Apollo 11’s Buzz Aldrin the book “Mission to Mars — My Vision for Space...