Stratolaunch Confirms Repeat Hypersonic Test Milestones

MOJAVE and COLORADO SPRINGS—High-speed test company Stratolaunch has officially confirmed that its air-launched Talon TA-2 vehicle successfully exceeded Mach 5 on two hypersonic test flights before landing on each occasion at Vandenberg Space Force Base, California.

Stratolaunch says the flights, believed to have been conducted on Dec. 20 and March 24, validate Talon’s status as the world’s first autonomous, fully reusable hypersonic test aircraft. Both missions carried several payloads including experiments for the U.S. Defense Department Test Resource Management Center’s (TRMC) Multi-Service Advanced Capability Hypersonic Test Bed (MACH-TB) program under a partnership with Leidos.

Confirmation of the first two hypersonic flights and recoveries at Vandenberg, the first of which was reported by Aviation Week, marks a key milestone for Stratolaunch’s plan to develop the Talon into the first reusable hypersonic test system since the piloted North American X-15 of the 1960s.

Stratolaunch also is nearing completion of a second Talon vehicle, TA-3, and is modifying a Boeing 747-400 into a carrier platform under a U.S. Missile Defense Agency contract. When its two Talons and both the 747 and its existing Roc air launch aircraft become available from 2026 onward, Stratolaunch ultimately aims to fly up to 24 missions per year.  TA-3 is expected to make its first flight later this year while parts for a third Talon, TA-4, are in production. Assembly of that vehicle is due to begin later in 2025.

The Dec. 20 flight followed two earlier launch attempts over the previous week that were called off because of out-of-limit test conditions. The test sequence did, however, mark the fastest sortie rate yet achieved by the Roc, which flew three times in eight days. The mission also partially demonstrated an element of SkyRange—a new airborne test range instrumentation system funded by the U.S. Defense Department.

Commenting on the achievement, Scott Wilson, program manager for MACH-TB, says “the data collected from the experiments flown on the initial Talon-A flight has now been analyzed and the results are extremely positive. The opportunity for technology testing at a high rate is highly valuable as we push the pace of hypersonic testing. The MACH-TB program is pleased with the multiple flight successes while looking forward to future flight tests with Stratolaunch.”

George Rumford, director of the TRMC, adds that “demonstrating the reuse of fully recoverable hypersonic test vehicles is an important milestone for MACH-TB. Lessons learned from this test campaign will help us reduce vehicle turnaround time from months down to weeks.”

Although many details of the first and second flights are yet to be revealed, Stratolaunch says TA-2 was able to accelerate on both occasions to a sustained test condition at Mach 5-plus. It also says the first flight landed at Vandenberg with more than 200 lb. of propellant remaining. On the same Dec. 20 flight the Talon was released from the Roc at 35,000 ft. at 9:18 a.m. Pacific Time before the vehicle’s liquid oxygen/Jet-A-fueled Ursa Major Hadley rocket engine ignited and accelerated the TA-2 to Mach 1.15 as it passed 60,000 ft.

TA-2 achieved steady-state hypersonic flight at Mach 5-plus at an altitude of 104,000 ft. Stratolaunch’s previous highest speed was achieved with the first powered flight of TA-1, which is thought to have reached Mach 4. This earlier flight, which took place in March 2024, tested the performance of the Hadley motor, expanded the high-speed flight envelope and ended with a water landing off the California coast.

The top speed achieved on the Dec. 20 flight was “decently above Mach 5,” says Aaron Cassebeer, Stratolaunch chief product officer. “We also achieved tens of seconds of time on condition—it wasn’t one or two seconds. It flew exactly as we expected. It was a very nominal flight. We predicted certain performance and flight conditions, and we were within percentage points of what we planned, both time on condition and peak Mach.”

Cassebeer says within minutes of touchdown on the first flight the Stratolaunch recovery crew, with support from government and other “payload experimenters,” were able to approach TA-2 and begin the process of offloading data and hardware. The vehicle was then mounted onto a trailer and trucked back to the company’s Mojave Air & Space Port facilities by the following evening.

TA-2 itself was in good condition after the first flight, Cassebeer adds. Aside from some minor surface heat discoloration in areas of high thermal loads around the wing-fuselage junction, leading edges and vertical tail, the thermal tiles protecting the nose section “performed flawlessly with no replacements needed.” He adds that the thermal blankets around the remaining parts of the vehicle “worked as expected.”

Maintenance work on TA-2 between flights included replacement of some avionics and refurbishment of the thermal protection system. Future flights are expected to include efforts to reach speeds beyond Mach 6. “So you’ll see that,” Cassebeer says. “You’ll see us push maneuvers, because that’s something customers are interested in. We’ll push up peak Mach. We’ll push up time on conditions, or the amount of time in seconds above Mach 5. Those are three major domains that the customers have some interest in.”

Stratolaunch President and CEO Zack Krevor notes that “TA-2 was really a historic accomplishment and the culmination of a lot of hard work, not just at Stratolaunch, but at all of our external partners. And it really took everyone working together, not just the engineering, but all the operational aspects, to make it happen. This was the first reusable hypersonic aircraft ever to do it autonomously, and the first reusable aircraft dedicated to hypersonic flight since 1968, so we couldn’t be prouder.”