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) and carried 230 US gallons (871 l) of aviation fuel (kerosene). General characteristics Crew: one pilot Payload: 500 lb of instruments (227 kg) Length: 35 ft 8 in (10.87 m) Wingspan: 25 ft 0 in (7.62 m) Height: 12 ft 1 in (3.68 m) Wing area: 150.7 ft² (14.00 m²) Loaded weight: 9,750 lb (4,423 kg) Max takeoff weight: 10,105 lb (4,583 kg) Powerplant: 1× Allison J35-A-11 turbojet, 5,000 lbf (22 kN) Performance Maximum speed: 650 mph at sea level (1,050 km/h) Stall speed: 137 mph (221 km/h) Service ceiling: 45,700 ft (13,900 m) Rate of climb: 9,220 ft/min (2,810 m/min) Wing loading: 67 lb/ft² (330 kg/m²) Thrust/weight: 0.51
