Stratolaunch’s Roc Completes Third Flight Test

The Roc on final approach
Credit: Hartman/Stratolaunch

Stratolaunch says it is on track to begin its first Talon hypersonic vehicle flight test by the end of 2022 following the successful completion of the Roc carrier aircraft’s third test flight from Mojave Air & Space Port in California on Jan 16. 

The six-engine behemoth was airborne for 4 hr. 23 min., marking the longest single sortie for the twin-fuselage, 385-ft.-wingspan aircraft since its flight debut in April 2019. The aircraft made its second test flight in April 2021, and now faces an intense flight campaign through the rest of this year as the focus begins to switch from envelope expansion to preparations for payload tests.

Zachary Krevor, Stratolaunch president and chief operating officer, says the flight met all objectives and takes the company “one step closer to hypersonic flight with our Talon vehicles.” The mission, which included two practice low approaches to Mojave’s runway 30, was flown by pilots Mark Giddings and Evan Thomas, with flight engineer Jake Riley. The carrier aircraft departed Mojave at 8:47 a.m. PST. and returned at 1:10 p.m.  

The crew continued evaluation of the aircraft’s performance and handling characteristics at altitudes up to 23,500 ft. and airspeeds up to 180 kt. The flight included validation of the left mid-main gear, including door operations, and alternate gear extension. The complete gear is expected to be cycled on the upcoming fourth test flight.

The mid-main gear tests included several retraction and extension cycles at nominal altitudes as well as after cold soaking the gear at higher altitudes above 20,000 ft. Tests also evaluated gear cycling during maneuvers with varying yaw and beta angles. Operating well below its design maximum take-off weight (MTOW), the test flight was performed at an MTOW of 750,000 lb., of which 200,000 lb. was fuel. 

Following further envelope expansion on the next flight, the fifth mission will see the large payload attachment pylon flown on the mid-span position between the fuselages. These will clear the way for the first drop test of the unpowered Talon-A, dubbed TA-0, and the first flight of the initial rocket-powered Talon variant, TA-1. Stratolaunch is assembling both vehicles and the pylon and completed initial power-on tests of TA-1 in late December. 

Stratolaunch is designing the Talon as a reusable testbed carrying customizable payloads at speeds above Mach 5. This capability will enable routine access to the hypersonic flight environment and initially is targeted at technology developments as well as component demonstrations for military applications.

“Before the end of the year we plan to and hope to launch our first hypersonic test vehicle, TA-1,” says Daniel Millman, chief technology officer of Stratolaunch. “It will also land—we will flare it into the Pacific. Our goal is to prove we can go hypersonic. We will do that envelope expansion first and then with the first reusable Talon—TA-2, which will fly in 2023—we will begin with glide tests, probably into Vandenberg [Space Force Base, California].”

Production of the company’s next pair of follow-on reusable Talon vehicles—TA-3 and TA-4—“will also begin later this year and early next year,” Millman says. “By the end of 2024 we are targeting to have a fleet of three fully reusable hypersonic testbeds providing services for the nation in advancing hypersonic payloads and other things that we’ll be able to test them.”

Guy Norris

Guy is a Senior Editor for Aviation Week, covering technology and propulsion. He is based in Colorado Springs.