The Convair 990 Coronado was a 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 feet, which increased the number of passengers from between 88 and 110 in the 880, to between 96 and 121 (depending on the interior). This was still considerably fewer than the contemporary Boeing 707 (110 to 189) or Douglas DC-8 (105 to 173), although the 990 remained some 25 to 35 mph faster than either in cruise.
Design and development
American Airlines requested that Convair design an aircraft suitable for coast-to-coast shuttle flights. The aircraft needed non-stop capability westbound from JFK to LAX, the direction it which it would encounter greatest headwinds. They also wanted somewhat larger passenger capacity than the 880, which was the smallest of the first-generation US jet-powered airliners. The 990 entered production in 1961.
One interesting change from 880 was the addition of large anti-shock bodies on the upper wings (often referred to as 'Küchemann carrots', after their designer at Convair), to increase their critical Mach and reduce transonic drag. This allowed the heavier 990 to go slightly faster than the 880, cruising at about Mach 0.91, making it the fastest passenger jet when it was built. Originally there were plans to use the bulges as fuel tanks, but during test flights the extra weight caused the tanks to vibrate excessively. Instead the inner set of bumps also served a secondary role as fuel dump for the fuel tanks in the fuselage.
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 as found in the Pratt & Whitney JT3D that powered the 990's competitors. The engine was a simplified civilian version of the J79, used in military fighters. Like the J79, the CJ-805 was very smoky. Although other early jet airliners were smoky, the 990 is especially remembered for it. There are stories of people calling fire departments after seeing a 990 fly over to report seeing an airplane on fire. Indeed, when viewed from an airport, where the point of view was looking the long way through the smoke trail, a 990 on final approach looked as if it were burning.
Like the 880, 990s were later modified with a "raceway" added to the top of fuselage to hold the wiring for additional instrumentation.
Early versions of the 990 did not meet the specifications promised American Airlines, who reduced their order as a result. The modified 990A was an engineered solution to speed related shortfalls, though the aircraft never did live up to its promise of coast to coast non stop capability westbound from JFK to LAX. American Airlines began to dispose of its 990As in 1967, having found the 707 and 720 more suited to its routes in spite of their larger capacity.
The 990's market niche was soon to be destroyed entirely by the Boeing 727 and the Boeing 720 (a derivative of the 707), and by the time the line was 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 the Convair 880 and 990 to be accepted by the airlines led Convair to suffer, at the time, the largest corporate losses in history until then.
Several 990s have survived. A former Swissair Convair 990 is on display in the Swiss transportation museum, the Verkehrshaus in Luzern, while two are owned by the Mojave Spaceport. Of these, one is on display at the airport's entrance, and the other is used for movie and television filming projects.
Specifications (Convair 990)
Published in July 2009.
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