Aerojet Rocketdyne has received a contract from Stratolaunch Systems Corp. to supply engines for an unmanned space rocket being developed in the Antelope Valley, the company announced Wednesday. Stratolaunch, based in Huntsville, Ala., is building its launch vehicle – an airplane powered by six 747 engines and a wingspan the length of a football field – in a massive hangar at the Mojave Air & Space Port north of Lancaster. Stratolaunch, founded by billionaire Microsoft co-founder Paul Allen, is partnering with Scaled Composites, also in Mojave, to construct the plane. Orbital ATK Inc., in Dulles, Va., is building the Thunderbolt rocket. Aerojet Rocketdyne, in Sacramento, will provide six RL10C-1 engines for use by Stratolaunch with an option to supply another six engines in the future. The RL10C-1 engine, made in West Palm Beach, Fla., will power the rocket that will carry payloads into earth orbit. The RL10 engine has a long history of reliability carrying satellites into orbit and powering space-probe missions, said Steve Bouley, vice president of Space Launch Systems at Aerojet Rocketdyne. “This contract expands our reach into commercial ventures and builds greater volume, providing more affordable propulsion to all of our customers,” Bouley said in a prepared statement.