KENT, Wash. (Reuters) - Privately owned Blue Origin is years ahead of competitor Aerojet Rocketdyne Holdings Ltd (>> Aerojet Rocketdyne Holdings Inc) in developing a rocket engine to replace now-banned Russian engines used on rockets launching U.S. military missions, company founder Jeff Bezos said on Tuesday.

Blue Origin's BE-4 rocket engine under development would be used by United Launch Alliance, a partnership of Lockheed Martin Corp (>> Lockheed Martin Corporation) and Boeing (>> Boeing Co), to launch military satellites, said Bezos, the founder of Amazon.com Inc (>> Amazon.com, Inc.)."I’m very confident," Bezos said. "They have selected our engine. They are designing the Vulcan (rocket) around our engine. It's a big course change for them to switch to their backup engine."

On Monday, UAL said it would pick a rocket by the end of the year and its preferred supplier is Blue Origin with Aerojet as a backup.Blue Origin, which has been developing its BE-4 engine for four years, is scheduled to test-fire a full-size engine by December.

The liquid oxygen and methane-burning engine is expected to be ready for use on United Launch Alliance’s Vulcan rocket by 2019. United Launch Alliance, which currently has a near-monopoly on launching U.S. military and national security satellites, plans to retire its workhorse Atlas 5 rocket, which uses Russian-made RD-180 engines to power its first stage.

Two years ago, Congress banned imports of the RD-180s as part of trade sanctions to punish Russia for annexing Ukraine’s Crimea peninsula.

The U.S. Air Force last week awarded contracts worth a combined $160 million to Blue Origin and Aerojet Rocketdyne for work on the new engines. Blue Origin also intends to use the BE-4 on its as-yet unnamed orbital launch vehicle.

Bezos said he doubts Blue Origin will use its booster to compete against United Launch Alliance for the military's launch business, but it will vie for commercial customers against United Launch Alliance, Elon Musk’s SpaceX and other companies.

“Space is really big and there’s room for lots of winners. It’s very rare that you see new industries built by single companies. Typically industries rise and fall together … and I think space is going to be like that,” Bezos said.

(Reporting by Irene Klotz; Editing by Lisa Shumaker)

By Irene Klotz