(Plume effects were a new experience for aircraft.) The number three aircraft also gathered information about the effects of external stores (bomb shapes, drop tanks) upon the aircraft's behavior in the transonic region (roughly 0.7 to 1.3 times the speed of sound). The three aircraft gathered a great deal of data about pitch-up and the coupling of lateral (yaw) and longitudinal (pitch) motions wing and tail loads, lift, drag and buffeting characteristics of swept-wing aircraft at transonic and supersonic speeds and the effects of the rocket exhaust plume on lateral dynamic stability throughout the speed range. The goals of the program were to investigate the characteristics of swept-wing aircraft at transonic and supersonic speeds with particular attention to pitch-up (un-commanded rotation of the nose of the aircraft upwards), a problem prevalent in high-speed service aircraft of that era, particularly at low speeds during takeoff and landing, and in tight turns. Martin made the first flight at Muroc Army Airfield (later renamed Edwards Air Force Base) in California on 4 February 1948 in an aircraft equipped only with the jet engine. Once the forward fuselage had decelerated sufficiently, the pilot would then be able to escape from the cockpit by parachute.ĭouglas pilot John F. Like its predecessor, the D558-1, the D558-2 was designed so that the forward fuselage, including cockpit, could be separated from the rest of the aircraft in an emergency. This resulted in a greater profile area at the front of the aircraft, which was balanced by an additional 14 inches (36 cm) of height added to the vertical stabilizer.
The Skyrocket was configured with a flush cockpit canopy, but visibility from the cockpit was poor, so it was re-configured with a raised cockpit with conventional angled windows. A total of 250 US gallons (950 L) of aviation fuel, 195 US gallons (740 L) of alcohol, and 180 US gallons (680 L) of liquid oxygen were carried in fuselage tanks. This engine was rated at 6,000 lbf (27 kN) static thrust at sea level. For high speed flight, a four-chamber Reaction Motors LR8-RM-6 engine (the Navy designation for the Air Force's XLR-11 used in the Bell X-1), was fitted. This engine was intended for takeoff, climb and landing. The Skyrocket was powered by a Westinghouse J34-40 turbojet engine fed through side intakes in the forward fuselage.
The wings and empennage were fabricated from aluminum and the large fuselage was of primarily magnesium construction. The Skyrocket featured wings with a 35-degree sweep and horizontal stabilizers with 40-degree sweep. A contract change order was issued on 27 January 1947 to formally drop the final three D558-1 aircraft and substitute three new D558-2 aircraft instead. When it became obvious that the D558-1 fuselage could not be modified to accommodate both rocket and jet power, the D558-2 was conceived as an entirely different aircraft. The eventual D-558-3 design, which was never built, was for a hypersonic aircraft similar to the North American X-15. 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.
The phase-one aircraft, the D-558-1, was jet powered and had straight wings. The "-2" in the aircraft's designation referred to the fact that the Skyrocket was the phase-two version of what had originally been conceived as a three-phase program.