The world’s largest aircraft, the Stratolaunch “Roc” air-launcher vehicle built by Scaled Composites, completed its maiden flight today from Mojave Air and Space Port in California.





The six-engined twin-fuselage all-composite design (registration N351SL) was created by Scaled Composites as a purpose-built air-launch vehicle for US-based Stratolaunch, which was set up by the late Paul Allen. Today’s first flight follows more than a year of ground testing, including high-speed taxi runs.



The Roc took off at 06:58L and during the 2h 29min flight achieved a maximum altitude of 17,000ft and a speed of 165kt (305km/h), says Stratolaunch. During the test flight the crew evaluated aircraft performance and handling qualities, before landing back at Mojave.

Tests included various flight control manoeuvres to calibrate speed and evaluate flight-control systems, including roll doublets, yawing manoeuvres, pushovers and pull-ups, and steady heading sideslips. Test crew Evan Thomas and Chris Guarente also flew simulated landing approach exercises at an altitude of 15,000ft.

“Today has been great. The airplane flew as predicted. It was a very smooth flight and the team had a lot of fun,” said Thomas.

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Scaled Composites

The Roc, designated Scaled Model 351, is powered by six Pratt & Whitney PW4056 turbofans, as fitted to the Boeing 747-400. The twin-fuselage high-wing configuration enables the Stratolaunch platform to accommodate and deploy launch vehicles more safely in a central position, says the company.

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Scaled Composites

Each fuselage is 73m (238ft) in length and they are 29m apart, while the wingspan of 117m makes Stratolaunch the largest aircraft ever to fly. As with the powerplant, many of the systems are derived from the 747-400 such as avionics, flightdeck and landing gear, to reduce development costs. The crewed cockpit is incorporated into the right fuselage while the left fuselage is empty and unpressurised.



The Stratolaunch platform has a maximum take-off weight of 589.7t and can carry an external payload of 250t. Its operational range is 1,000nm (1,850km).

Scaled has been working with Stratolaunch for more than six years to design, build and test the Roc, which is being developed “to make access to space more convenient, reliable, and routine”, it says.

“What a fantastic first flight,” says Stratolaunch chief executive Jean Floyd. “Today’s flight furthers our mission to provide a flexible alternative to ground launched systems.”