The Lockheed Martin F-35B Lightning II short takeoff/vertical landing (STOVL) stealth fighter engaged its STOVL propulsion system in flight for the first time yesterday. The successful test is the first in a series of planned STOVL-mode flights that will include short takeoffs, hovers and vertical landings.

“The joint F-35 industry and government team has already shown during extended ground tests that the STOVL propulsion system performs well, and thousands of hours of component testing has validated its durability. Now we are seeing early proof that the system operates in flight as our team predicted,” said Dan Crowley, Lockheed Martin executive vice president and F-35 program general manager.

The aircraft is powered by a single Pratt & Whitney F135 engine driving a Rolls-Royce LiftFan®. The system, which includes a Rolls-Royce 3-bearing swivel duct that vectors engine thrust and under-wing roll ducts that provide lateral stability, produces more than 41,000 pounds of vertical thrust. The F135 is the most powerful engine ever flown in a fighter aircraft.

During the flight, F-35 Lead STOVL Pilot Graham Tomlinson of BAE Systems engaged the shaft-driven LiftFan propulsion system at 5,000 feet and 210 knots (288 mph), then slowed to 180 knots (207 mph) with the system still engaged, before accelerating to 210 knots and converting back to conventional-flight mode. The STOVL propulsion system was engaged for a total of 14 minutes during the flight. The successful test is the first in a series of planned STOVL-mode flights that will include short takeoffs, hovers and vertical landings. Tomlinson took off at 1:53 p.m. EST, engaged the STOVL propulsion system for a total of 14 minutes and then landed at 2:41 p.m. EST.

STOVL-mode flights will continue, with the aircraft flying progressively slower, hovering, and ultimately landing vertically. Most STOVL-mode testing will be conducted at NAS Patuxent River.