Douglas D-558-1 Skystreak
The D-558-I "Skystreak" was among the early transonic research airplanes like the X-1, X-4, X-5, and XF-92A. Three of the single-seat, straight-wing aircraft flew in a joint program involving the National Advisory Committee for Aeronautics (NACA), the Navy-Marine Corps, and the Douglas Aircraft Co. from 1947 to 1953. In the process, the Skystreaks set two world speed records.
The division of responsibility among the partners was that Douglas flew a contractor program on the first Skystreak to investigate its performance, handled major maintenance and performed any modifications. The NACA's Muroc Flight Test Unit, redesignated the High-Speed Flight Research Station in 1949 and now named the NASA Dryden Flight Research Center, purchased fuel and oil from the Army Air Forces (Air Force after September 1947), provided and installed instrumentation, performed the flight research on the number two and three aircraft, and took care of routine flight maintenance and inspection on them. The Navy paid the expenses of Douglas Aircraft, including engine overhaul and replacement, and its pilots did some of the flying.
The (Roman numeral) I in the aircraft's designation referred to the fact that the Skystreak was the phase-one version of what had originally been conceived as a three-phase program, with the phase-two aircraft having swept wings. The third phase, which never came to fruition, would have involved constructing a mock-up of a combat-type aircraft embodying the results from the testing of the phase one and two aircraft.
Douglas pilot Eugene F. May flew the number one Skystreak for the first time on April 14, 1947, at Muroc Army Airfield (later renamed Edwards Air Force Base) in Calif. The goals of the program were to investigate the operation of a straight-wing configuration in the lower third of the transonic speed range (which extended from roughly 0.7 to 1.3 times the speed of sound) and to obtain data about flight in that speed range that were not available from existing wind tunnels.
The three aircraft, equipped with Allison J-35-A-11 turbojet engines, gathered a great deal of data on handling qualities, tail loads, buffeting, pressure distribution, plus static and dynamic longitudinal as well as lateral stability and control and the effects of vortex generators on undesirable handling characteristics. Together with other transonic research airplanes, the D-558-I research results validated the data from wind tunnels then being developed by the NACA, which required basic data for comparison to ensure there were no unforeseen errors in their development. Both kinds of data were then available for use by designers of new military aircraft, such as those in the century series of fighters (F-100, F-102, and so forth.) 
Oct 1949 - this NACA Muroc Flight Test Unit photograph of the Douglas D-558-1 #3 Skystreak was taken in front of the NACA hangar at South Base, Edwards Air Force.
Design: The need for transonic research airplanes grew out of two conditions that existed in the early 1940s. One was the absence of accurate wind tunnel data for the speed range from roughly Mach 0.8 to 1.2. The other was the fact that fighter aircraft like the P-38 "Lightning" were approaching these speeds in dives and breaking apart from the effects of compressibility-increased density and disturbed airflow as the speed approached that of sound, creating shock waves. People in the aeronautics community-especially the NACA, the Army Air Forces (AAF), and the Navy-agreed on the need for a research airplane with enough structural strength to withstand compressibility effects in the transonic region. The AAF preferred a rocket-powered aircraft and funded the X-1, while the NACA and Navy preferred a more conservative design and pursued the D-558, with the NACA also supporting the X-1 research.
August 24, 1953 -The Douglas D-558-1 Skystreak is seen close-up in this early 1950s inflight photograph. What a beautiful airplane!
Program History: The three Skystreaks flew a total of 229 times from 1947 to 1953, including 101 contract flights in the number one aircraft (Bureau No. 37970-NACA 140), 46 by the Skystreak number two (Bureau Number 37971-NACA 141), and 82 by the number three aircraft (Bureau Number 37972-NACA 142). NACA 140's flights were all completed as part of the contractor program, although Caldwell flew it on four passes on August 20, 1947, averaging 640.663 miles per hour over a measured course, setting a new world airspeed record. Five days later, however, Marine Major Marion Carl surpassed the record, flying NACA 141 an average 650.796 miles per hour in four passes over the course. The NACA never flew the number one airplane, using it instead for spares support of the number three aircraft.
The Skystreaks were approximately 35 feet long, 12 feet high, and 25 feet across the wing span. They were powered by one Allison J-35-A-11 engine (developed by General Electric as the TG-180), which was rated at 5,000 pounds of static thrust. The airplane carried 230 gallons of aviation fuel (kerosene).
NACA 140 is located at the Naval Aviation Museum in Pensacola, Fla. NACA 142 is at the Marine Corps Air Ground Museum, Quantico, Va.
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