TDIH July 21, 1946, Lieutenant Commander James Jennings Davidson, U.S. Navy, flying the second prototype McDonnell XFD-1 Phantom, made four takeoffs and landings aboard the Midway-class aircraft carrier USS Franklin D. Roosevelt (CVB-42). This was the very first time that an all-jet aircraft had operated from a U.S. Navy aircraft carrier.

-The Douglas X-3 Stiletto on the dry lakebed at Edwards AFB in 1954. | Photo: NACA

FLIGHTLINE: 109 - DOUGLAS X-3 STILETTO

The Douglas X-3 was built for NACA to research designs suitable for sustained supersonic flight, but the available engines proved to be underpowered.

The X-3 was built by the Douglas Aircraft company for NACA, the National Advisory Committee on Aeronautics (predecessor of NASA) to develop an aircraft capable of flying at Mach 2 for long periods. The Stiletto was slender and long, with small, low-aspect-ratio wings. The long, pointed nose and small, buried windscreen were designed for the minimum possible aerodynamic heating. Douglas built the plane with the intention of using two Westinghouse J46 afterburning turbojets, making the Stiletto the first X-Plan designed to takeoff and land under its own power. Development of the J46 stalled, however, and lower powered J34s were substituted. The frame and skin of the aircraft were aluminum, but the underside of the tail boom and horizontal stabilizers were titanium, the first time the metal was used on an aircraft in such large amounts.

-Orthograph of the X-3 Stiletto. | Illustration: NASA

-The Stiletto being towed out of the Douglas Corp hangar prior to being shipped out. | Photo: Douglas Aircraft Corporation

The X-3 was trucked to Rogers Dry Lake in California, home of Muroc (later Edwards) AFB and the USAF and NACA flight test facilities. The Stiletto flew for the first time unofficially on 15 October 1952, when a high-speed taxi run turned into a one mile flight. The first official flight occurred fifteen days later, lasting 20 minutes. Douglas' builder trials lasted until December 1953, covering 26 flights before the plane was turned over to the USAF. The contractor tests showed that the X-3 was difficult to control, with an unusually high takeoff speed (260kts) and was underpowered, unable to break Mach 1 in level flight. Plans were made to refit the plane with either uprated turbojets or rocket motors, but were later dropped.

-Douglas' NACA planes in 1954. Clockwise from front: X-3, D-558-I, XF4D-1 and the first D-558-II.

-A rare color photo of the X-3 on the dry lake, surrounded by support vehicles. | Photo: NACA/USAF

The USAF test program began in December of 1953, but given the plane's poor performance only a limited number of flights were attempted. USAF test pilots Frank Everest and Chuck Yeager made only three flights each, mainly to gain experience in aircraft with low-aspect wings. With Yeager's last flight in July 1954, the X-3 was turned over to NACA, who planned an abbreviated test plan for the Stiletto, concentrating on longitudinal stability and control, wing and tail loads, and pressure distribution. Additional flights to research lateral and directional stability were also added, with the aircraft abruptly rolled at trans- and supersonic speeds. It was during these that the X-3 made its most significant contributions to aviation, allowing NACA researchers to study the causes and consequences of inertial coupling, a condition encountered during high-speed flight where movement in one axis will cause uncommanded and uncontrolled movements in others. It was during Chuck Yeager's flight in the X-1A in 1953 that inertial coupling was first documented, and the phenomena had claimed Captain Mel Apt's life during a flight of the X-2 in 1956. The F-100 Super Sabre, F-101 Voodoo and F-102 Delta Dagger were also vulnerable to the effect until modifications were made.

-The X-3 in flight. The Stiletto cut a rakish figure, even if its performance couldn't match. | Photo: NACA

-The instrument panel of the X-3. As expected from its design, the pilot's forward view is exceptionally poor. | Photo: USAF Museum

The X-3 was retired after just 51 test flights. The aircraft's highest achieved speed was Mach 1.208, in a 30° dive. Though unable to perform its intended task of exploring sustained Mach 2 flight, the Stiletto provided copious data on a diverse range of subjects including roll coupling, construction techniques for high-speed aircraft, improvements in tire technology, and low-aspect wings. Lockheed utilized data from the program to design the F-104 Starfighter, which also featured small, unswept and highly-loaded wings to achieve high-speed flight.

-The X-3 sits as the centerpiece of a group of NACA/NASA aircraft in 1953. | Photo: NACA

After the end of the program, the X-3 was transferred to the USAF Museum in Dayton, where it remains on display in the Research & Development hangar alongside other X-Planes and experimental aircraft.

-The X-3 Stiletto on display at the USAF Museum. In the background are the Bell X-1B and North American Aviation XB-70. | Photo: USAF Museum