Stratolaunch Roc, the largest plane in the world, was returning from a four hour 'captive carry' test flight carrying the Talon-A hypersonic test vehicle with live propellant over the Pacific Ocean. (AFP)

Stratolaunch successfully tests new hypersonic vehicle with first powered flight off California coast.

On Saturday, Stratolaunch, a U.S. aerospace company, successfully completed the first powered test flight of a new unmanned craft designed for hypersonic research.

Hypersonic describes flight at speeds of at least Mach 5 or five times the speed of sound.

CEO Zachary Krevor said in a statement that the Talon-A-1 vehicle “reached high supersonic speeds approaching Mach 5 and collected a large amount of data at incredible value to our customers.”

Krevor said he could not disclose specific altitude and speed due to proprietary agreements with customers.

The company’s massive six-engine Roc carrier aircraft carried the Talon aloft, attached to the center of its gigantic wing, and released it from the central California coast.

Powered by a liquid-fueled rocket engine, Talon ended its flight by landing in the sea as planned. Although this Talon was expendable, a future version will be able to land on the runway for reuse.

Stratolaunch said the flight’s primary objectives included safe air launch of the vehicle, engine ignition, acceleration, sustained climb in altitude and controlled water landing.

The company called the result a significant milestone in the development of the United States’ first privately funded reusable hypersonic test capability.

Stratolaunch performed two captive transport flights in December and February, lifting Talon aloft with live propellant but not releasing it from the mothership.

Stratolaunch is located at the Mojave Air and Space Port in the Mojave Desert north of Los Angeles.

Named after the huge mythological bird, the Roc aircraft has a wingspan of 385 feet (117 meters) and twin fuselages that give the impression of two large jets flying side by side.

It was developed by Microsoft co-founder Paul G. Allen, who died just months before it flew for the first time in April 2019.

Allen intended to use it as an aircraft carrier for space launches, carrying satellite-laden rockets under the center of the wing and releasing them aloft.

This project was canceled and the new owners used Stratolaunch to launch reusable hypersonic research vehicles.

Stratolaunch has announced flight contracts with the U.S. Air Force Research Laboratory and the Navy’s Multi-Service Test Program as a subcontractor to technology company Leidos of Reston, Virginia.