The Convair 990
Although the performance of both the CV-880 and CV-880M could not be disputed, it still fell short of its design goals; its narrower fuselage, only affording sufficient width for five-abreast coach seating, deviated from the then-standard six; the sudden appearance of the 720 provided unexpected competition; and the intermediate-range market had neither evolved nor even defined itself, resulting in in a paltry production run of 65. Because of these factors, the program seemed on the verge of financial collapse, but Convair made a final attempt to rescue it with a version that was more extensively modified.
Guided by American Airlines, which was viewed as its launch customer, the aircraft was designed to provide higher-speed, all-first class transcontinental service in competition with TWA’s 707s and United’s DC-8s, a strategy that American implemented in the 1930s when it asked Douglas to design the Douglas Sleeper Transport (DST), or night version of the DC-3, to offer passenger-attracting comfort on its transcontinental routes in competition with United’s slower, narrower B247s. In this case, American intended to reconfigure its 707-120s with all-coach cabins.
Initially designated Model 30 and then CV-600, it was given the definitive CV-990 name when Convair decided to reflect its 990 kilometers-per-hour cruise speed by it.
Its modifications were far more extensive than those incorporated in the CV-880M. A 10.1-foot-longer fuselage, for instance, resulted in a new 139.5-foot overall length, but its width remained the same, and its cabin, with its own 98.9-foot length, 1,007-square-foor floor area, and 6,114-cubic-foot volume, could accommodate 96 four-abreast, first class passengers or 121 five-abreast economy ones. Maximum, single-class capacity was 149, which was 16 less than that of the competing Boeing 720.
Underfloor baggage, cargo, and mail hold capacity also marginally increased-in this case, to 928 cubic feet.
The type’s most significant modification-and also its most visually apparent-was its wing. As the thinnest airfoil ever used on a commercial aircraft, it introduced a 39-degree sweepback-or two degrees more than that of the later widebody Boeing 747-thinner, tabbed, double-slotted, trailing edge Fowler flaps, and four anti-shock fairings that appeared like upside-down canoes on the upper wing surface’s trailing edge.
Alternatively called area rule fairings, speed bumps, conical fairings, Whitcomb fairings, and blisters, they measured two-feet-wide by 24-feet-long and prevented shock waves from forming at high speeds, thus reducing drag. The area rule itself, devised by Richard T. Whitcomb in 1953, stated that the cross-sectional area of an aircraft should uniformly increase from nose to tail, providing that the area of a complete airframe smoothly varies along its length.
The fairings themselves, installed to regain the original Convair 880’s promised performance, served several purposes, including improving the air flow pattern, increasing cruise speed without a coincident increase in engine thrust, provide greater wing cross-sectional area, and serve as additional fuel tanks, which themselves increased range. It was the first time such a configuration was employed by a jet airliner.
The wing, with a 2,250-square-foot area and a new maximum loading of 108.5 pounds-per-square-foot, also introduced all-speed ailerons between the fairings and the spoilers ahead of the trailing edge flaps.
Overall height increased to 39.6 feet.
Power was now provided by quieter, more economical, new-technology General Electric CJ-805-23B aft-fan engines rated at 16,100 pounds of thrust, each of which incorporated a turbine- and fan-comprised additional stage. As the first commercial airliner to be turbofan powered, it attained its capability by means of air that bypassed the core, or hot section, of the powerplant, was routed around it, and exited the double-jet nozzle at lower velocity. So-configured, it was able to offer a 40-percent increase in efficiency, eliminating the need for sound suppressors. Greater thrust, combined with lower fuel consumption, resulted in improved economy.
The CV-990 also introduced proportional anti-skid brakes, which gradually applied pressure. Again, it was the first commercial jetliner to feature such an innovation.
First announced on July 30, 1958 after receipt of a 25-firm and 25-optioned order from American Airlines, it first flew three years later, on January 24. A second aircraft followed suit on March 30 and FAA type approval was granted that December after a full production standard flight test program.
Despite its promise, the Convair 990 only became representative of the earlier Convair 880 situation: its performance guarantees failed to be met during a 12-month development period because of higher than anticipated drag created by the wider engine nacelles and outer engine pod oscillation during full-fuel anti-shock fairing conditions. While remedies required both time and expense, the situation hardly aided the problem-plagued program.
Modifications were numerous. The four leading edge slats were replaced with Krueger flaps, for instance, resulting in full-span ones, which, in turn, decreased the airfoil’s leading edge droop and thus overall camber. Air flow separation was discouraged with the installation of a modified fairing at the wing-to-fuselage joint. The engine mount was covered with a leading edge glove. The length of the outboard engine pylons was reduced, the clamshell thrust reversers were covered, each inboard engine nacelle terminal fairing was extended aftward, and the pylon and engine pod shapes were streamlined to reduce air resistance and drag.
Although these post-production changes required some 400 additional hours of testing, they ultimately achieved the projected speed, performance, and range parameters.
Redesignated Convair 990A, the improved variant offered a 29,245-pound payload capability and a 239,200-pound gross weight, requiring a 5,350-foot runway for takeoff when loaded for a 2,000-mile flight. Rate-of-climb at its maximum weight was 3,250 fpm.
The anti-shock fairings, serving as additional fuel tanks and incorporating 320 and 300-gallon capacities in, respectively, their in- and outboard ones, increased total aircraft capacity to 15,119 US gallons and range to 4,300-statute miles. Consumption was calculated as 1,530 gallons per hour at 30,000 feet. Service ceiling was 41,000 feet and maximum speed was 640 mph, qualifying t as the fastest commercial jet airliner ever built.
Stalling speed was 105 mph.
Now offering a 180,000-pound maximum landing weight, it required a 4,770-foot field length after a 2,000-mile sector. FAA certification was achieved in January of 1963.
Intended for US domestic operation, it served as the counterpart to the export model, designated CV-990A Coronado, which lacked the pylon contour fairings and the inboard engine side exit nozzle terminal fairings and resultantly featured slightly higher figures, including a 15,675-US gallon fuel capacity and a 244,200-pound gross weight. Contrasted with the domestic variant, whose primary advantage was speed, its principle advantage was range. It was certified in October of 1962.
American Airlines, whose own input and influence shaped this higher-speed counterpart, was not bestowed with the honor of inaugurating the new version into service. Instead, Swissair was.
Taking delivery of its first three unmodified aircraft in January of 1962 and a fourth the following month, it designated them Convair 990 Coronados and gained initial service experience by operating them on an intra-European network that encompassed Vienna and London from Zurich.
March 9 marked the commencement of the type’s intended route coverage, to the Middle and Far East and to Africa and South America. Returning its two leased CV-880s, it placed its CV-990s, in a 16-first and 84-coach configuration, on the multi-sector route from Zurich to Tokyo via Cairo, Karachi, Calcutta, Bangkok, and Hong Kong.
Dispensing with the Convair modifications, it converted all seven aircraft, registered HB-ICA through HB-ICH, to CV-990A standard itself by early 1964. Meeting all performance targets, they had 3,595-mile, full-payload ranges, facilitating Switzerland-Brazil service by means of Dakar, Senegal, and the South Atlantic. Their capacity was later increased to 116, comprised of 14 first and 102 coach passengers.
Relegated at the end of their career to the short-range European sectors they had briefly served at the beginning of it, they were progressively replaced with DC-9-30s and -50s on short routes and DC-8s and DC-10-30s on intercontinental ones between late-1974 and January of 1975 after 13 years of reliable service.
American Airiness finally took delivery of its first still-unmodified Convair 990, registered N5605, on January 7, 1962, but it was only used for crew familiarization and route-proving purposes until March 18, at which time it inaugurated scheduled service with two daily round-trips between New York-Idlewild and Chicago-O’Hare with a quartet of them.
As with other carriers, increased coach class demand and the need to maximize revenue resulted in progressive, less-luxurious cabin configurations-from an initial 92-passenger, all-first class one with a six-place lounge to a dual-class, 42-first and 57-coach one with a four-place lounge to a final 34-first and 67-coach one without any lounge.
Like Swissair, it performed the CV-990 upgrades on its 20-strong fleet itself at its Tulsa maintenance base.
Although it never fulfilled its intended, coveted, and competitive, all-first-class transcontinental purpose, it saw dual-class operation on the 2,143-mile route between New York and Phoenix, its longest.
American operated its last Convair 990A flight in October of 1968.
There were several other original CV-990 operators, albeit with much smaller fleets.
SAS Scandinavian Airlines System, for example, leased two aircraft from Swissair, registered SE-DAY and SE-DAZ, which featured dual-class, 42-first and 57-coach arrangements. They were operated between 1962 and 1966 when Swissair acquired them itself, and served the Copenhagen-Tokyo route flow with several intermediate stops.
Varig Brazilian Airlines, which refused to take delivery of its three ordered CV-990As until they were modified to performance-restoring “A” model standard, received its first on March 1, 1963 and placed it into intercontinental service from Los Angeles to Porto Alegre with intermediate stops in Mexico City, Bogota, Lima, and Rio de Janeiro. It operated the type for eight years.
Garuda Indonesia Airways took delivery of three CV-990As intended for American Airlines between September of 1963 and January of 1964. Despite the small fleet, it covered considerable distance-from Jakarta to Tokyo via Bangkok, Manila, and Hong Kong; to Australia; and to Europe through then-named Bombay, Cairo, Rome, and Amsterdam. They were replaced with DC-8s in 1972.
A trio also constituted the Aerolineas Peruanes (APSA) fleet. Configurated for 119 passengers with a forward lounge, its Convair 990As were inaugurated into service on December 23, 1963, spanning the Americas between Miami and Buenos Aires, but intermittently touching down in Bogota and Lima. The second aircraft, placed into service two years later, on March 1, connected Lima with Mexico City via Guayaquil, but the route was later extended to Los Angeles.
Overexpansion and under-capitalization accounted for the carrier’s sudden demise and consequent cessation of its CV-990A operations.
Convair logically tried to interest existing CV-880 customers in the higher-performance CV-990.
Consistent with its tumultuous involvement in the program, Howard Hughes actually ordered 13 aircraft for TWA. But, reflecting his erratic behavior and inability, at times, to commit to anything, he reversed his decision, claiming that neither it nor the CV-880 was appropriate for the airline’s medium-range routes. In what could be considered the ultimate gall, he ordered the competing Boeing 720 instead. TWA, in the end, took delivery of neither.
With its own sizeable fleet, Delta was considered another logical operator of the type, but it felt that it was only appropriate for transcontinental routes on which its speed could be exploited and it currently had none of them in its mostly short- to medium-range system.
Although the CV-990’s design attracted interest, it attracted few sales. Its protracted, two-year development program, during which Convair implemented the series of previously discussed performance restoring changes, damaged its reputation. Completed aircraft, known as “white tails,” sat on the ramp outside of the San Diego production factory, awaiting interested buyers. In what could be considered the ultimate and exasperating irony, those carriers that had ordered the CV-990 and then cancelled them, turned to Boeing and its competing, Pratt and Whitney JT8D turbofan-powered 720B for aircraft.
As had or would be later demonstrated throughout commercial airliner history, aircraft designed for a specific carrier had little application for those whose payload and range requirements significantly differed, which was proven the case with the VC10 Vickers had designed for BOAC and with the HS.121 Trident Hawker Siddeley had designed for BEA British European Airways in the UK. In the US, the CV-880 had essentially been created for TWA and its CV-990 successor was principally intended for American.
Total Convair 880, 880M, and 990 production barely eclipsed the 100-unit line, of which the latter accounted for only 37 orders, leading to program discontinuation in early 1964, General Electric’s own civil pure-jet engine production cessation, and a $500 million loss, the largest in commercial aviation history.
Lewis, W. David, and Newton, Wesley Phillips. Delta: The History of an Airline. Athens, Georgia: The University of Georgia Press, 1979.
McClement, Fred. It Doesn’t Matter Where You Sit. New York: Holt, Rinehart and Winston, Inc., 1969.
Proctor, Jon. Convair 880 and 990. Miami: World Transport Press, Inc., 1996.