Stratolaunch conducts 'captive carry' test flight of hypersonic vehicle

(In Feb. 24 story, corrects host aircraft name in second paragraph to 'Roc' (not modified Boeing 747-400 'Sprit of Mojave'))

By Mike Stone

WASHINGTON (Reuters) -Private U.S. company Stratolaunch conducted its second "captive carry" test flight of what it hopes will become a reusable hypersonic vehicle, it said on Saturday, as the Pentagon presses ahead with development of new hypersonic weapons.

The Stratolaunch Talon-A was loaded with live propellant and carried aloft by the company's launch platform, Roc, on a more than four-hour flight going over the Pacific Ocean.

During a captive carry test, the payload craft does not separate from the carrier aircraft.

The vehicle will be used to carry hypersonic weapons systems during their development. Component makers could test engines, sensors and communications equipment aboard future reusable versions of the Talon-A.

The U.S. and its global rivals are speeding up work on hypersonic weapons, the next generation of arms that rob adversaries of reaction time and can evade traditional defense mechanisms.

Hypersonic weapons travel in the upper atmosphere at more than five times the speed of sound, or about 6,200 km (3,853 miles) per hour.

Arms makers like Lockheed Martin Corp, Northrop Grumman Corp and RTX Corp have all touted their hypersonic weapons programs.

Defense contractors hope to capitalize on the shift to hypersonic weapons not only by building them but also by developing new systems to detect and defend against them.

Stratolaunch hopes to complete development of the reusable Talon-A this year.

(Reporting by Mike Stone in Washington; Editing by Cynthia Osterman)