by Douglas Messier
MOJAVE, Calif. — Stratolaunch’s Roc — the world’s largest airplane by wing span at 385 ft (117.3 m) — flew for the fourth time on Thursday. In a sign of just how complicated the massive air-launch platform is to fly, one of the main objectives of this flight test was to retract and lower the plane’s landing gear at altitude for the first time ever.
Roc flew for 1 hour 43 minutes and reached an altitude of 15,000 feet (4,572 m) before landing back at the Mojave Air and Space Port, Stratolaunch said in a press release. In addition to retracting and lowering the landing gear, the pilots evaluated the twin fuselage aircraft’s performance and handling characteristics.
“Today’s successful flight demonstrates and validates improvements to the carrier aircraft’s systems and overall flight performance,” said Dr. Zachary Krevor, Stratolaunch president and chief operating officer. “The full landing gear retraction and extension brings the carrier aircraft closer to operational status, a milestone that is necessary to ready the aircraft for Talon-A separation and hypersonic flight tests later this year.”
Stratolaunch is developing two rocket-powered Talon-A hypersonic test vehicles, TA-0 and TA-1, that will be capable of carrying customizable payloads at speeds exceeding Mach 5. Roc will carry the vehicles to a high altitude before dropping them for flights.
“This capability enables routine access to the hypersonic flight environment, which is critical for scientific research, technological development, and component demonstration,” Stratolaunch said.
“The team has also started fabrication of a third vehicle, TA-2, the first fully reusable hypersonic test vehicle. The company anticipates beginning hypersonic flight testing in 2022 and delivering services to government and commercial customers in 2023,” the company added.
Roc’s test on Thursday was Roc’s second in just over a month and third in the past year, signaling an increase in the flight cadence in a program unveiled more than a decade ago.
Scaled Composites founder Burt Rutan and Microsoft co-founder Paul Allen plans for Roc in December 2011 with the goal of orbiting satellites using air dropped rockets. The aircraft was built by Scaled Composites for the Allen-funded Stratolaunch Systems.
While development proceeded, Stratolaunch had difficulty developing a medium-lift rocket it was supposed to launch. When Allen died in October 2018, Stratolaunch was facing an expensive effort to develop a family of rockets to launch from the aircraft as it lost its main financial backer.
Stratolaunch conducted Roc‘s first flight test from Mojave on April 13, 2019. The company subsequently ceased operations. The sale of the company to Cerberus Capital Management was announced in October 2019. The new owners dropped “systems” from the company’s name and pivoted development from satellite launches to hypersonic test vehicles.