Stratolaunch has confirmed that the sixth test flight of the world’s largest aircraft by wingspan, Roc, ended earlier than expected. The test flight was planned to last for around three and a half hours, but instead came to an end after just under 90 minutes.

During the test flight, which took place over California’s Mojave Desert on June 9th, the aircraft reached an altitude of 15,000 feet.

Stratolaunch later tweeted the following, including a video of Roc coming in to land at the end of its test flight:

The test flight

Although Stratolaunch was not able to complete its full objectives, Thursday’s test flight was not completely wasted. It focused instead on continued evaluation of both the aircraft’s general performance and handling characteristics, and its landing gear functionality.

The test flight looked specifically at Roc's flight envelope to note any changes following the recent addition of the pylon on the aircraft's center wing.

An aircraft’s flight envelope is the range of combinations of speed, altitude, and angle of attack, within which it is aerodynamically stable.

The pylon will be used to safely carry and release Talon-A rocket-powered hypersonic vehicles. Talon-A is Stratolaunch’s 28-foot-long (8.5m) hypersonic vehicle prototype, designed to fly as fast as Mach 6, or six times the speed of sound. The company hopes to develop reusable versions of its Talon-A vehicles by the end of 2023.

Dr Zachary Krevor, Stratolaunch CEO and president, said,

"Today's flight builds on previous successful flights and hardware enhancements. We will leverage this flight experience as we complete integrated testing in the coming months and prepare for Talon-A test flights."

An earlier tweet from the company showed the pilots boarding the distinctive-looking aircraft (both the pilot and co-pilot sit in the cockpit of the right-hand fuselage to fly the aircraft):

Scaled Composites Model 351 Stratolaunch

Roc also goes by the not-quite-so catchy name of Scaled Composites Model 351 Stratolaunch. With its twin fuselage and six engines, Roc’s unique appearance has been grabbing the attention of aviation enthusiasts worldwide ever since its first test flight on April 13th, 2019.

Roc also boasts the largest wingspan of any aircraft in the world – an impressive 385 feet (117m). For comparison, an American football field is 300 feet wide.

Stratolaunch is headquartered in Seattle, Washington, and was founded by Microsoft co-founder Paul Allen over a decade ago. In 2011, the company hit the headlines when it began developing Roc, the world’s largest aircraft by wingspan.

Stratolaunch has designed Roc to carry payloads to a high cruising altitude before releasing them to rocket into orbit – essentially using the aircraft as a flying launch pad.

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