Lockheed fighter for Marines flies for first time

WASHINGTON (Reuters) - The Marine Corps variant of Lockheed Martin Corp's F-35 fighter jet completed its first conventional flight on Wednesday, with a flight in the short takeoff/vertical landing (STOVL) mode planned for later this year.

The first flight of the F-35 aircraft designated BF-1 began at 10:17 a.m. CDT (1517 GMT) and lasted 44 minutes, according to John Smith, a spokesman for Lockheed.

Lockheed and its partners are developing three variants of the F-35 or Joint Strike Fighter for the Air Force, Marine Corps and Navy, and to sell to other countries. All three variants are based on a common design.

Development is led by the United States, but includes Britain and seven other international partners. A former British military pilot was the first to fly the new jet.

The Pentagon estimates the overall F-35 program, including research and development, will cost $298.8 billion. The cost of each plane is forecast at almost $70 million, based on plans for the U.S. military to buy 2,443 F-35 fighter jets through 2034.

The aircraft flown on Wednesday was powered by an engine developed by Pratt & Whitney, a unit of United Technologies Corp. The company had several engine blades snap off during earlier ground tests of the STOVL mode.

The problem never affected the engine during conventional flight mode, and Pratt & Whitney says it is on track to begin testing of the engine in STOVL mode later this year.

"We are working closely with our customers, Lockheed Martin and the joint program office; we have identified the root cause, and we are working toward a STOVL mode flight later this year," said Stephanie Duvall, a Pratt & Whitney spokeswoman.

The F-35 program is the world's largest military project, involving 11 countries -- nine working on the development effort and two additional security partners. It employs about 20,000 people worldwide.

The F-35 is a single-seat, single-engine military strike fighter that can perform close air support, tactical bombing and air superiority fighter missions.

Northrop Grumman Corp and Britain's BAE Systems are Lockheed's main subcontractors on the program. A team comprising General Electric and Britain's Rolls-Royce is developing an alternate engine.

(Reporting by Andrea Shalal-Esa; editing by Jeffrey Benkoe)