Douglas Skystreak
| D-558-1 Skystreak | |
|---|---|
 |
|
| Role | research aircraft |
| National origin | United States |
| Manufacturer | Douglas Aircraft Company |
| First flight | 14 April 1947 |
| Status | Retired |
| Primary user |
United States Navy National Advisory Committee for Aeronautics |
| Number built | 3 |
| Developed into | Douglas D-558-2 Skyrocket |
The Douglas Skystreak (D-558-1 or D-558-I) was an American single-engine jet research aircraft of the 1940s. It was designed in 1945 by the Douglas Aircraft Company for the U.S. Navy Bureau of Aeronautics, in conjunction with the National Advisory Committee for Aeronautics (NACA). The Skystreaks were turbojet-powered aircraft that took off from the ground under their own power and had unswept flying surfaces.
The D558 program was conceived as a joint NACA/U.S. Navy research program for transonic and supersonic flight. As originally envisioned, there would be three phases to the D558 program: a jet-powered airplane, a mixed rocket/jet-powered configuration, and a design and mockup of a combat aircraft. A contract for design and construction of six D558-1 aircraft for the first phase was issued on 22 June 1945. The original plan had been for six aircraft with a mixture of nose and side inlets and varying wing airfoil sections. That plan was quickly reduced to three aircraft of a single configuration with a nose inlet. Plans for the second phase with mixed rocket/jet propulsion were also dropped. Instead, a new aircraft, the D558-2, was designed with mixed rocket and jet propulsion for supersonic flight.
Construction of the first 558-1 began in 1946 and was completed in January 1947. The fuselage used magnesium alloys extensively, while the wings were fabricated from more conventional aluminum alloys. The airframe was designed to withstand unusually high loads of up to 18 times gravity due to the uncertainties of transonic flight. The forward fuselage was designed so that it, including the cockpit, could be jettisoned from the aircraft in an emergency. The aircraft was configured to carry more than 500 lb of test equipment, including sensors (primarily strain gauges and accelerometers) in 400 locations throughout the aircraft. One wing was pierced by 400 small holes to enable aerodynamic pressure data to be collected.
The Skystreaks were powered by one Allison J-35-A-11 engine (developed by General Electric as the TG-180) — one of the first axial-flow turbojets of American origin — and carried 230 US gallons (871 l) of aviation fuel (kerosene).
All the Skystreaks were initially painted scarlet, which led to the nickname "crimson test tube." NACA later had the color of the Skystreaks changed to white to improve optical tracking and photography. The first of three D-558-1 Skystreaks, BuNo 37970, made its maiden flight on 14 April 1947, at Muroc Army Air Field (later named Edwards AFB). Less than 4 months later, on August 20, this aircraft with Commander Turner Caldwell, USN, reached 640.744 miles per hour (1,031.178 km/h) flying D-558-1 #1. This was recognised as an official world speed record, as the World War II-era German Me 163A Komet rocket fighter that reached 1004 km/h (624 mph) in October 1941 did so in secrecy. The D-558-1 #1 Skystreak's record lasted 5 days, and was broken by then-Lieutenant Colonel Marion Carl, USMC, going 10 miles per hour (16 km/h) faster in D-558-1 #2, BuNo 37971. This aircraft was delivered to the NACA Muroc Flight Test Unit in April 1949 after 101 flights had been completed by the Navy, Air Force, and Douglas. This aircraft was never flown by the NACA. The D-558-1 #1 is located at the National Naval Aviation Museum at Naval Air Station Pensacola, Florida.
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