The Scaled Composites Model 351 Stratolaunch, or "Roc", is a solitary testbed aircraft built by Scaled Composites for Stratolaunch Systems to carry air-launch-to-orbit (ALTO) rockets, and subsequently repurposed to offer air launch hypersonic flight testing after a change of ownership. It was announced in December 2011, rolled out in May 2017, and flew for the first time on April 13, 2019, shortly after the death of founder Paul Allen. The aircraft features a twin-fuselage design and the longest wingspan ever flown, at 385 feet (117 m), surpassing the Hughes H-4 Hercules "Spruce Goose" flying boat of 321 feet (98 m). The Stratolaunch is intended to carry a 550,000-pound (250 t) payload and has a 1,300,000-pound (590 t) maximum takeoff weight. Stratolaunch ceased operations in May 2019, shortly after the first flight of the Roc, and placed all company assets, including the aircraft, for sale by June 2019. In October 2019, Cerberus Capital Management acquired Stratolaunch Systems, including the Stratolaunch aircraft. Stratolaunch announced in December 2019 that it would be focusing on offering high-speed flight test services.
History
Early development In early 2011, Dynetics began studying the project and had approximately 40 employees working on it at the December 2011 public announcement. Stratolaunch originally planned to airlaunch the Falcon 9 Air by SpaceX, whose efforts began shortly before December. Launching medium-sized payloads with the Falcon 9 dictated the aircraft size but SpaceX departed a year later. In May 2012, its specially constructed hangar was being built at the Mojave Air and Space Port in Mojave, California. In October 2012, the first of two manufacturing buildings, an 88,000 sq ft (8,200 m2) facility for construction of the composite sections of the wing and fuselage, was opened for production. In August 2013, the Pegasus II was selected for the air-launch vehicle. In August 2014, all-solid-fuel propulsion was selected, rather than liquid as for the Orbital Sciences launcher. In August 2015, 200,000 lb (91 t) of structure was assembled. By June 2016, Scaled Composites had 300 people working on the project. Virgin Orbit also planned to launch small satellites with the LauncherOne from a 747. Orbital ATK dropped its Thunderbolt rocket project for medium-class payloads. In October 2016, the Pegasus II was replaced by multiple Pegasus XLs mounted underneath the carrier aircraft, developments of the original Pegasus rocket, which had been launched 42 times since 1990.
Testing By May 1, 2017, Stratolaunch had already spent hundreds of millions of dollars on the project. On May 31, 2017, the aircraft was rolled out for fueling tests, and to be prepared for ground testing, engine runs, taxi tests, and ultimately, first flight. The company stated that it was aiming for a 2019 first-launch demonstration. The Register newspaper in 2017 reported that Stratolaunch may have competition from the DARPA XS-1 or from Vector Space Systems by 2019. By September 2017, engine testing was underway as well as testing of "control surfaces and electric, pneumatic and fire detection systems." In December 2017, its first low-speed taxi test took it to 25 knots (46 km/h) on the runway, powered by its six turbofans, to test its steering, braking, and telemetry. Higher-speed taxi tests began in 2018, reaching 40 knots (74 km/h) in February, and 78 knots (144 km/h) in October. On January 9, 2019, Stratolaunch completed a 110 knots (200 km/h) taxi test, and released a photograph of the nose landing gear lifted off the ground during the test. In January 2019, three months after the death of Stratolaunch founder and Microsoft co-founder Paul Allen, Stratolaunch abandoned the development of its PGA rocket engines and dedicated launchers. This left the Northrop Grumman Pegasus XL as the sole launch option for an orbital capability of 800 lb (360 kg). Stratolaunch was then reported to be aiming for a first flight within a few weeks and a first launch from the carrier in 2020. The aircraft first flew on April 13, 2019, at the Mojave Air and Space Port, reaching 17,000 feet (5,200 m) and speed of 165 knots (306 km/h) in a 2-hour-29-minute flight.
Development halt and sale The future of Stratolaunch had been in doubt since the death of company founder Paul Allen in October 2018, with speculation that Stratolaunch Systems could cease operations. Allen had been the source of funds for the capital-intensive development program since the project began in 2010, and the company founding in 2011. In January 2019, Stratolaunch announced it was halting development of its air-launched family of launch vehicles. On May 31, 2019, the company announced that it would cease operations and that sale of its assets was being explored. An asking price of US$400 million was reported, which would include the sole aircraft, the company facilities, equipment, the designs and other intellectual property. In June 2019 the Stratolaunch Systems company and assets were put up for sale by Vulcan for $400 million. By October 11, Stratolaunch announced it had new ownership and that it would continue regular operations, but did not disclose the identity of the investors. In December, the new owner was revealed to be Cerberus Capital Management, a specialist in the acquisition of distressed companies. After the acquisition, Stratolaunch is now focusing on offering high-speed flight test services.
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