Boeing designed the X-32 around a large one-piece carbon fiber composite delta wing and a direct-lift thrust vectoring system (similar to the AV-8B) for the Marines’ STOVL requirement. Due to the heavy delta wing design of its prototypes, Boeing demonstrated STOVL and supersonic flight in separate configurations. Lockheed’s X-35B used a more complex alternative, incorporating a remote shaft-driven lift fan powered by the main engine. The design generated more lift thrust than possible with only direct exhaust gases, greater payload, and greater range.
The X-35 prevailed in large part thanks to its performance flexibility in a single configuration (converted from the X-35A) – able to take off in a short distance, go supersonic, and land vertically in one flight. Though costlier, the X-35 was judged to have better mission potential across three variants.
Fifteen years later, NAVAIR is still at work refining the F-35B/C, the latter having accomplished its first arrested landing on an aircraft carrier on Oct. 2, 2015.
A footnote is that two of the JSF demonstration aircraft, Boeing’s X-32B and Lockheed’s X-35C, now reside at the Patuxent River Naval Air Museum.
CH-53E Super Stallion
“Biggest” is a relative term, but when you’re talking helicopters, there’s nothing larger in the American military than the CH-53E. The Super Stallion grew out of an early 1960s Marine requirement for a heavy-lift helicopter. The Sikorsky CH-53A Sea Stallion met that requirement, but the need for even heavier lift in a variety of environmental conditions led to the development of the CH-53E Super Stallion, the largest helicopter NAVAIR has yet tested and developed.
NAVAIR ultimately developed the MH-53E Sea Dragon for the airborne mine countermeasures role, modifying the aircraft’s digital flight control system and increasing its fuel capacity and endurance. MH-53Es became operational in 1986.
In October 1967, the Marine Corps issued a requirement for a helicopter with a lifting capacity 1.8 times that of the CH-53D that would fit on amphibious warfare ships. Sikorsky had been at work on a heavier capacity version of the CH-53D, which added a third turboshaft engine and a more powerful rotor system with an additional (seventh) rotor blade. The Marines funded development of a prototype in 1968, and by 1970 the Navy joined the program.
The first YCH-53E flew in 1974. It featured a fuselage stretched 6 feet, 2 inches over the Sea Stallion. New rotor blades, a stronger transmission, a larger, canted vertical tail-rotor assembly, and a third engine yielded a helicopter that could lift 17.8 tons and reach 170 knots. In August 1976, two CH-53E prototypes arrived at the Naval Air Test Center at Patuxent River for flight test. The first production CH-53E flew in 1980, and fleet introduction began a year later.