Space launch company Stratolaunch has parted ways with manufacturer SpaceX, dissolving a partnership dating from the project's inception.

"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.

Stratolaunch

According to a source familiar with the matter, the design changes necessary would have forced SpaceX to make substantial modifications of their manufacturing process, which would effectively negate crucial commonalities with the company's signature Falcon 9 launch vehicle.

Orbital Sciences is tasked with "evaluating multiple concepts that utilize both new and existing components," says Wentz. Orbital confirmed the study contract but deferred further questions to Stratolaunch. Orbital Sciences is among the most experienced air-launch companies in the world, having built and launched the much smaller Pegasus launch vehicle from a modified Lockheed L-1011.

Stratolaunch is planning to build the largest aircraft ever built, a twin-fuselage aircraft capable of launching a large rocket. The SpaceX-designed rocket, a winged, five-engine modification of the Falcon 9, was designed to lift 6,200kg (13,500) into low Earth orbit. Should the project reach fruition, it will be by far the largest air-launched spacecraft ever built.

SpaceX did not immediately respond to questions.

Source: Flight International