Douglas X-3 Stiletto
As speeds of aircraft began to reach Mach 2, a new aircraft was needed to explore these exceptionally high speeds. Such an aircraft would need to be streamlined with as little drag as possible. Douglas, which had already built a Mach 2-capable aircraft in the D-558-2 Skyrocket, got the contract to build two aircraft specifically for Mach 2 research, which became the X-3 Stiletto. As needed, the X-3 had a long, streamlined fuselage with a narrow nose, stubby wings, and titanium used throughout the airframe to ward off the expected heat burden caused by consistent high speed flight. Unlike the D-558-2 and X-2 aircraft, the X-3 would not be dropped from a mothership aircraft, but take off under its own power, climb to about 40,000 feet, achieve Mach 2, and then land. The first X-3 flew in October 1952; the second would be scrapped midway through building and used as spare parts.
Immediately it ran into trouble. The X-3 had been designed for the Westinghouse J46 engine, but the J46 was plagued with development troubles and never was a success; instead, the X-3 had to use less powerful J34 engines. As a result, the X-3 could barely go over Mach 1, and then only in a dive—one that was difficult to pull out from, because of the Stiletto’s design. Because of its lack of wing area, the Stiletto was also very difficult to fly. Simply put, the X-3 would never make Mach 2, or even Mach 1.5.
It did, however, contribute to aviation technology, albeit more or less accidentally. Its titanium structure introduced new metallurgy techniques into building high-speed aircraft, which would contribute to the failed CF-105 Arrow project and very successful SR-71 Blackbird. The small wing design and streamlining was studied closely by Lockheed as they designed the F-104 Starfighter. When it was found that the X-3 did have a high roll rate at supersonic speeds, testing was switched to roll rate experiments, and in October 1954, test pilot Joseph Walker suddenly experienced complete loss of control, as the X-3 pitched upwards at supersonic speed and nearly somersaulted before Walker could regain control. The same problem, known as roll inertia coupling, had caused the loss of several F-100 Super Sabres by this time, and the X-3’s experience was to solve the problem.
As the airframe had been overstressed by Walker’s flight, the X-3 Stiletto program rapidly came to an end, and the only aircraft, 49-0892, was retired in 1956 to the National Museum of the USAF, where I saw it in May 2017. My camera's battery had given out by this time (after 400 pictures at the NMUSAF!) and I was using a friend's smartphone, which was not capable of getting all of the X-3 in one shot. I was unable to back up on account of the F-107A behind me. It sits in its overall gloss white test colors, underneath the starboard wing of the XB-70 Valkyrie.
Douglas X-3 Stiletto
As speeds of aircraft began to reach Mach 2, a new aircraft was needed to explore these exceptionally high speeds. Such an aircraft would need to be streamlined with as little drag as possible. Douglas, which had already built a Mach 2-capable aircraft in the D-558-2 Skyrocket, got the contract to build two aircraft specifically for Mach 2 research, which became the X-3 Stiletto. As needed, the X-3 had a long, streamlined fuselage with a narrow nose, stubby wings, and titanium used throughout the airframe to ward off the expected heat burden caused by consistent high speed flight. Unlike the D-558-2 and X-2 aircraft, the X-3 would not be dropped from a mothership aircraft, but take off under its own power, climb to about 40,000 feet, achieve Mach 2, and then land. The first X-3 flew in October 1952; the second would be scrapped midway through building and used as spare parts.
Immediately it ran into trouble. The X-3 had been designed for the Westinghouse J46 engine, but the J46 was plagued with development troubles and never was a success; instead, the X-3 had to use less powerful J34 engines. As a result, the X-3 could barely go over Mach 1, and then only in a dive—one that was difficult to pull out from, because of the Stiletto’s design. Because of its lack of wing area, the Stiletto was also very difficult to fly. Simply put, the X-3 would never make Mach 2, or even Mach 1.5.
It did, however, contribute to aviation technology, albeit more or less accidentally. Its titanium structure introduced new metallurgy techniques into building high-speed aircraft, which would contribute to the failed CF-105 Arrow project and very successful SR-71 Blackbird. The small wing design and streamlining was studied closely by Lockheed as they designed the F-104 Starfighter. When it was found that the X-3 did have a high roll rate at supersonic speeds, testing was switched to roll rate experiments, and in October 1954, test pilot Joseph Walker suddenly experienced complete loss of control, as the X-3 pitched upwards at supersonic speed and nearly somersaulted before Walker could regain control. The same problem, known as roll inertia coupling, had caused the loss of several F-100 Super Sabres by this time, and the X-3’s experience was to solve the problem.
As the airframe had been overstressed by Walker’s flight, the X-3 Stiletto program rapidly came to an end, and the only aircraft, 49-0892, was retired in 1956 to the National Museum of the USAF, where I saw it in May 2017. My camera's battery had given out by this time (after 400 pictures at the NMUSAF!) and I was using a friend's smartphone, which was not capable of getting all of the X-3 in one shot. I was unable to back up on account of the F-107A behind me. It sits in its overall gloss white test colors, underneath the starboard wing of the XB-70 Valkyrie.