Stratolaunch's huge Roc plane drops hypersonic test vehicle for 1st time (video)

The world's biggest airplane just notched another huge milestone.

Stratolaunch's Roc carrier plane aced its first-ever drop test on Saturday (May 13), successfully releasing a prototype of the company's Talon hypersonic vehicle high above the Pacific Ocean off the central California coast.

Everything went well, paving the way for an even more ambitious test in the coming months, Stratolaunch representatives said.

"With this significant milestone complete, we move on to preparing for our first hypersonic flight in late fall this year," Zachary Krevor, the company's CEO and president, said during a call with reporters today (May 15). "It's a very exciting time for our company."

Related: Stratolaunch test photos: The world's largest plane in action

Roc lifted off from the Mojave Air and Space Port in Southern California on Saturday a little after 9 a.m. local time, Stratolaunch representatives said, kicking off the plane's 11th test flight.

Roc, which has a wingspan longer than a football field, carried the company's Talon-0 separation test vehicle between its twin fuselages. The giant plane headed west, eventually dropping Talon-0 when it was off California's central coast.

Talon-0 isn't equipped with an engine, so it didn't make a powered flight on Saturday. But the vehicle did perform a variety of gliding maneuvers and continued sending telemetry back to the mission team until it hit the water, in a destructive impact that was all part of Saturday's flight plan.

"We got to watch it set up for a mock landing and eventually touch down on the water," Scott Schultz, Stratolaunch's senior director of engineering, said on today's call, referring to Talon-0.

"So, all primary objectives, secondary objectives, tertiary objectives — everything was accomplished," he said. "It was really, really a fantastic day."

Roc, meanwhile, returned for a touchdown at Mojave four hours and eight minutes after liftoff, bringing an end to Saturday's test flight.

Microsoft co-founder Paul Allen established Stratolaunch in 2011, with the initial goal of air-launching rockets carried high into the atmosphere, and then released, by Roc. Virgin Orbit and Virgin Galactic also employ an air-launch strategy, for satellite and space-tourism missions, respectively (though Virgin Orbit's future is murky; it recently declared bankruptcy).

The vision changed in 2019, a year after Allen's death: Stratolaunch turned Roc into a platform for hypersonic research and development, which it will conduct with the giant plane and the Talon series of robotic hypersonic vehicles. ("Hypersonic" refers to speeds of at least Mach 5, or five times the speed of sound.)

Thanks to Saturday's success, the company's first hypersonic flight may now be just a few months away.