US-based aerospace company Stratolaunch has successfully completed the third test flight of its Roc carrier aircraft.

With a 385ft wingspan, the Roc aircraft flew for four hours, 23 minutes over the Mojave Desert in the latest test flight.

According to the company, the aircraft reached an altitude of 23,500ft at an indicated airspeed of 180k.

Stratolaunch president and chief operating officer Zachary Krevor said: “Today’s successful flight demonstrates and validates improvements to the carrier aircraft’s systems and overall flight performance.

“We will take the data we gathered and continue to advance the aircraft’s operational performance to support hypersonic testing in 2022.”

Initial results achieved during the tests include continued evaluation of the aircraft’s performance and tackling characteristics at increased speeds and altitude.

Also included is the validation of the left mid-main gear operations such as door operations, and alternate gear extension of the left mid-main gear.

Krevor added: “The partial gear retraction seen during the flight is a graduated approach to building confidence in the landing gear and gear door hardware.

“Testing the left main landing gear individually mitigated risk and provided our aircrew with options for landing the aircraft in the event the hardware didn’t perform as expected.

“We’ll review the data and determine when we can get back into the air to continue advancing our unique, hypersonic architecture.”

According to Stratolaunch, this flight test further prepared the Roc carrier aircraft to support launches of its first Talon-A hypersonic vehicle.

The Talon-A vehicles are rocket-powered, autonomous, reusable testbeds that can carry customised payloads at speeds over Mach 5.

Last month, Stratolaunch won a research contract by the US Missile Defense Agency (MDA) to supplement flight testing resources.