Microsoft co-founder Paul Allen, right, confers with airplane designer Burt Rutan during the 2011 unveiling of the Stratolaunch concept.

WASHINGTON — As Elon Musk hinted in an interview with Britain’s Royal Astronautical Society in mid-November, changes were indeed in the offing for Paul Allen’s Stratolaunch project. reported Tuesday afternoon (Nov. 27) that SpaceX has dropped out of the project and Orbital Sciences Corp. of Dulles, Va., has been engaged to evaluate alternatives to the Falcon 9 rocket that had been the baseline for the air-launched Stratolaunch system. Orbital Sciences has been flying air-launched Pegasus rockets since the early 1990s but has struggled in recent years to find payloads for the small rocket. 

“Stratolaunch and SpaceX have amicably agreed to end our contractual relationship because the current launch vehicle design has departed significantly from the Falcon derivative vehicle envisioned by SpaceX and does not fit well with their long-term strategic business model,” says Gary Wentz, Stratolaunch CEO, in a 27 November email.

“Moving forward, Stratolaunch has engaged Orbital Sciences Corporation to evaluate and develop alternative solutions with the objective of arriving at a design decision in the early spring timeframe. The other segment contractors will continue to proceed forward in accordance with existing plans since their interfaces have been defined,” he adds.

Despite the close relations, Stratolaunch’s updated designs required “significant structural mods to incorporate a fin/chine configuration,” according to Wentz. Initial concepts did not include a chine, which is a structural extension of the wing root along the sides of the vehicle, useful for providing lift at high speeds.

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Brian Berger is editor in chief of and the SpaceNews magazine. He joined in 1998, spending his first decade with the publication covering NASA. He was named senior staff writer in 2004, a position he held...