MIAMI – Today in Aviation, the Convair 990 Coronado, an American four-engine narrow-body jet airliner, performed its maiden fight in 1961. The CV-990 was developed by General Dynamics’ Convair division. the type was a stretched version of its previous Convair 880 and was produced in response to an American Airlines (AA) order.
The CV-990 went on to fly with Aerolineas Argentinas (AR, Alaska Airlines (AS), Cathay Pacific (CX), SAS (SK), Swissair (LX) and VARIG (RG), among others. Both Convair jets were incredibly fast compared to their peers, but their operating cost became prohibitive during the oil crisis of the 1970s and the number built was limited by dwindling orders. Only 65 CV-880s and 37 CV-990s were built.
The Convair 990A is still considered one of the fastest commercial non-supersonic transport ever produced. In May 1961, one of the 990 prototype pre-production aircraft set a level flight record of .97 Mach at an altitude of 22,500 feet (6.9 km), equivalent to a true airspeed of 675 miles per hour (1,086 km/h).
In order to satisfy the performance that Convair had promised AA, numerous aerodynamic drag-reduction improvements were introduced to the later 990A.
Design and Development
American Airlines asked Convair to develop a coast-to-coast flight aircraft capable of flying nonstop against the wind from New York City to Los Angeles. They needed a much greater capacity for passengers than the 880, the smallest of the U.S. jet airliners of the first generation. On January 24, 1961, the CV-990 began flight testing.
The aircraft was lengthened by 10 ft (3.0 m), raising the number of passengers from 88 to 110 in CV-880 to 96 to 121 in CV-990. This was still fewer pax than the Boeing 707 (110-189) or Douglas DC-8 (105-173) while the CV-990 was 25-35 mph (40-56 km/h) faster than any cruise.
The wide anti-shock bodies on the upper trailing edge of the wings were another improvement from the CV-880 to raise the critical Mach and reduce transonic drag. For additional fuel tanks, the inboard shock bodies were often used, which were bigger.
Later, Convair changed the design to include fuel in the outboard pods, but the extra weight caused the outboard engines to oscillate under some conditions during the initial test flights. Once again, the pods were redesigned and shortened by 28 inches (710 mm), which caused 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.
Furthermore, just like the CV-880s, the CV-990s incorporated a dorsal “raceway” to house the two ADF antennas and one VHF antenna at the top of the fuselage.
In the end, the CV-990 did not meet the promised requirements and, as a result, AA reduced its order. The aircraft never lived up to its promise of coast-to-coast nonstop capability from JFK to LAX, despite the modifications from the basic CV-880 and those in response to drag issues in testing.
In contrast to the fan stage at the front of the engine used on the Pratt & Whitney JT3D that powered the CV-990’s competitors, the engines were also modified to the upgraded General Electric CJ-805-23s, which were unusual in that they used a fan stage at the rear of the engines.
The engine was a simpler, non-post-combustion civilian variant of the J79, which was used by military fighters. Like most variants of the J79, the CJ805 and CJ805-23 were smoky, while secondary operator Spantax (BX, 1959-1988) eventually had their CV-990 aircraft refitted with smokeless combustion chambers in the 1970s.
For the higher cruising speed and longer range CV-990A model, the aircraft had fairings added to the engine nacelles.
As of 1962, LX had bought eight CV-990s, operating them on long-distance routes to South America, West Africa, the Middle East and the Far East, as well as on heavy-duty European routes. In 1975, the CV-990 fleet was withdrawn from service. Coronados were also flown by SK on its long-haul schedules to Tokyo and other destinations in the Far East.
The Boeing 720 and Boeing 720B, derivatives of the Boeing 707, and later the Boeing 727, soon seized CV-990’s niche. Just 37 990s had been produced by the time the assembly line shut down in 1963, taking the entire production of commercial jet airliners by General Dynamics to 102 airframes.
The inability of airlines to widely embrace the Convair 880 and 990 led the company to suffer what was one of the biggest corporate losses in history at the time. As a consequence, Convair left the jet airliner market, although the McDonnell Douglas DC-10, KC-10 and MD-11 fuselages were later profitably constructed by there company.
When the major airlines retired their Convair 990s, the type found a second life on charter airlines. Spanish operator Spantax had a large fleet until the mid-1980s and so did the now defunct US private airline, Denver Ports of Call. In 1967, AS purchased Convair 990 PP-VJE from Varig, and operated it in scheduled service until 1975.
Featured image: A Swissair Convair 990 low-wing airliner in flight with its four underwing turbofans. Photo: wiki Commons. Article sources: Proctor, Jon (June 1996). Convair 880 & 990 (First ed.). Miami: World Transport Press. ISBN 0-9626730-4-8, Convair Jet Airliners. San Diego: General Dynamics: Customer Service Dept. December 1961.