Convair CV-990 Coronado
Archive Photos 1
[Convair 990-30A-5 "Coronado" (N810NA) at the Mojave Airport, Mojave, CA (Photo by John Shupek)]
The Convair 990 Coronado is an American narrow-body four-engined jet airliner produced by the Convair division of General Dynamics, a stretched version of their earlier Convair 880 produced in response to a request from American Airlines. The 990 was lengthened by 10 ft (3.0 m), which increased the number of passengers from between 88 and 110 in the 880 to between 96 and 121 in the 990. This was still fewer passengers than the contemporary Boeing 707 (110 to 189) or Douglas DC-8 (105 to 173), although the 990 was 25–35 mph (40–56 km/h) faster than either in cruise.
Design and Development 2
American Airlines asked Convair to design an aircraft for coast-to-coast flights, able to fly nonstop from New York City to Los Angeles against the wind. They wanted a somewhat larger passenger capacity than the 880, which was the smallest of the first-generation U.S. jet airliners. The 990 began flight testing January 24, 1961.
One change from the 880 was the large anti-shock bodies on the upper trailing edge of the wings to increase the critical Mach and reduce transonic drag. The inboard shock bodies, which were larger, were also used for additional fuel tankage. Later during the design period, Convair modified the design to include fuel in the outboard pods as well, but during the initial test flights the extra weight caused the outboard engines to oscillate in certain conditions. The pods were redesigned once more, and shortened by 28 inches (710 mm), causing increased drag. The inner set of pods also served a secondary role as fuel dumps for the fuel tanks, and the outlet pipe is prominent.
The engines were also changed to the uprated General Electric CJ-805-23s, which were unique in that they used a fan stage at the rear of the engines, compared to the fan stage at the front of the engine found on the Pratt & Whitney JT3D that powered the 990's competitors. The engine was a simplified, non afterburning civil version of the J79, used in military fighters. Like most versions of the J79, the CJ805 and CJ805-23 were smoky, although secondary operator Spantax eventually had their 990 aircraft refitted with smokeless combustion chambers in the 1970s.
Like the 880, 990s incorporated a dorsal "raceway" added to the top of the fuselage to house the two ADF antennas and one VHF antenna
Operational History 2
The 990 did not meet the specifications promised, and American Airlines reduced their order as a result. The 990A was developed by adding fairings to the engine nacelles, among other changes. Despite the modifications from the basic 880 and those in response to drag problems in testing, the aircraft never lived up to its promise of coast-to-coast nonstop capability from JFK to LAX. American Airlines' timetables show little or no difference in scheduled time between 707 and 990A flights; AA began to dispose of their 990As in 1967.
The Convair 990A is still the fastest non-supersonic commercial transport to have ever been produced. During May 1961, one of the pre-production 990 prototype aircraft set a record of .97 Mach in level flight at an altitude of 22,500 ft. (6.9 km), equivalent to a true airspeed of 675 mph (1 086 km/h). This was before the various aerodynamic drag-reduction changes were applied to the later 990A in order to meet certain performance guarantees which Convair had made to American Airlines. These subsequent modifications made to the later 990A (consisting of the four wing-mounted anti-shock body "speed capsules" and substantial streamlining of the engine pylon/wing interface) increased the velocity at which onset of transonic drag would occur by 0.09 Mach. As such, the 990A would have been capable of speeds slightly in excess of 700 mph (1,130 km/h).
In 1963, the 990A was reported to burn 13,750 pounds (6.24 t) per hour of fuel at Mach 0.84 (483 knots, 895 km/h) at 35,000 ft (10.7 km) at a mass of 200,000 lb (90.7 t). In contrast, a modern Boeing 737 MAX 8 typically carries 162 passengers and burns 4,460 lb (2.02 t) per hour at Mach 0.78 (450 kn; 833 km/h) at sub-optimal parameters.
Swissair bought eight 990As beginning in 1962, operating them on long-distance routes to South America, West Africa, the Middle and Far East, as well as on European routes with heavy traffic. Their fleet was withdrawn from service in 1975. Scandinavian Airlines also operated Coronados on their long-haul schedules to Tokyo and other destinations in the Far East.
The 990's niche was soon captured by the Boeing 720 and Boeing 720B, derivatives of the Boeing 707, and later by the Boeing 727. By the time the assembly line shut down in 1963, only 37 990s had been produced, bringing General Dynamics' entire production of commercial jet airliners to 102 airframes. The failure of airlines to broadly accept the Convair 880 and 990 led Convair's parent company, General Dynamics, to suffer what at the time was one of the largest corporate losses in history. As a result, Convair exited the jet airliner business, although they later profitably built fuselages for the McDonnell Douglas DC-10, KC-10 and MD-11.
When the major airlines retired their Convair 990s, they found a second life on charter airlines. Spantax of Spain had a large fleet until the mid-1980s and so did Denver Ports of Call. In 1967, Alaska Airlines purchased Convair 990 PP-VJE from Varig, and operated it as N987AS in scheduled airline service until 1975.
Convair CV-990A Coronado Specifications 2
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