The Douglas DC-8 (sometimes McDonnell Douglas DC-8) is an early long-range narrow-body jetliner designed and produced by the American Douglas Aircraft Company. Work began in 1952 toward the United States Air Force's (USAF) requirement for a jet-powered aerial refueling tanker. After losing the USAF's tanker competition to the rival Boeing KC-135 Stratotanker in May 1954, Douglas announced in June 1955 its derived jetliner project marketed to civil operators. In October 1955, Pan Am made the first order along with the competing Boeing 707, and many other airlines soon followed. The first DC-8 was rolled out in Long Beach Airport on April 9, 1958, and flew for the first time on May 30. Following Federal Aviation Administration (FAA) certification in August 1959, the DC-8 entered service with Delta Air Lines on September 18.
Permitting six-abreast seating, the four-engined, low-wing jet aircraft was initially produced in four long variants. The DC-8-10 was powered by Pratt & Whitney JT3C turbojets, and had a MTOW; the DC-8-20 had more powerful JT4A turbojets, for a MTOW. The intercontinental models had more fuel capacity, and had an MTOW of up to ; it was powered by JT4As for the Series 30, and by Rolls-Royce Conway turbofans for the Series 40. The Pratt & Whitney JT3D powered the later DC-8-50 and Super 60 (DC-8-61, -62, and -63) as well as freighter versions, and reached a MTOW of . A stretched DC-8 variant was not initially considered, leading some airlines to order the competing Boeing 707 instead.
The improved Series 60 was announced in April 1965. The DC-8-61 was stretched by for 180–220 seats in mixed-class and a MTOW of . It first flew on March 14, 1966, was certified on September 2, 1966, and entered service with United Airlines in February 1967. The long-range DC-8-62 followed in April 1967, stretched by , could seat up to 189 passengers over with a larger wing for a MTOW up to . The DC-8-63 had the long fuselage and the enlarged wing, freighters MTOW reached .
The DC-8 was produced until 1972 with 556 aircraft built; it was superseded by larger wide-body airliners including Douglas' DC-10 trijet. Noise concerns stimulated demand for a quieter variant; from 1975, Douglas and General Electric offered the Series 70 retrofit, powered by the quieter and more fuel-efficient CFM56 turbofan engine. It largely exited passenger service during the 1980s and 1990s, but two re-engined DC-8s remain in use as freighters.
Development Background At the end of World War II, Douglas was the dominant North American aircraft producer in the commercial aviation market. Douglas produced a succession of piston-engined aircraft (DC-2, DC-3, DC-4, DC-5, DC-6, and DC-7) through the 1930s, 1940s, and 1950s. While de Havilland flew the world's first jet airliner, the Comet, in May 1949,Dick and Patterson 2010, pp. 134–137.Green and Swanborough April 1977, p. 174. Douglas initially refrained from developing a jet airliner.
De Havilland's pioneering Comet entered airline service in May 1952. Initially, it appeared to be a success, but the Comet was grounded in 1954 after two fatal accidents which were subsequently attributed to rapid metal fatigue failure of the pressure cabin.Darling 2001, p. 33. Various aircraft manufacturers benefited from the findings and experiences gained from the investigation into Comet losses; specifically, Douglas paid significant attention to detail in the design of the DC-8's pressurized cabin.“Damage Tolerance in Pressurized Fuselage”, 11th Plantema Memorial Lecture, 14th Symposium of the International Committee on Aeronautical Fatigue (ICAF), New Materials and Fatigue Resistant Aircraft Design, Ottawa, Canada, June 8–12, 1987.Faith 1996, p. 72. By 1952, Douglas had continued its success as a commercial aircraft manufacturer, having received almost 300 orders for its piston-engine DC-6 and its successor, the DC-7, which had yet to fly.Norris and Wagner 1999, p. 10. The Comet disasters, and the airlines' subsequent lack of interest in jets, seemed to validate the company's decision to remain with propeller-driven aircraft, but its inaction enabled rival manufacturers to take the lead instead.Norris and Wagner 1999, pp. 9-10.Anderton 1976, p. 78.
As early as 1949, rival company Boeing had started design work on a pure jet airliner. Boeing's military arm had experience with large long-range jets, such as the B-47 Stratojet and the B-52 Stratofortress strategic bombers. While producing and supporting these bombers for the United States Air Force (USAF), Boeing had developed a close relationship with the USAF's Strategic Air Command (SAC). The company also supplied the SAC's refueling aircraft, the piston-engined KC-97 Stratofreighters, but these proved to be too slow and low flying to easily work with the new jet bombers. The B-52, in particular, had to descend from its cruising altitude and then slow almost to its stall speed to refuel from the KC-97.Cook 1991, pp. 212-213. Believing that a requirement for a jet-powered tanker was a certainty, Boeing started work on a new jet aircraft for this role that could be adapted into an airliner. As an airliner, it would have similar seating capacity to the Comet, but the use of a swept wing enabled a higher cruising speed and better range. First presented in 1950 as the Model 473-60C, Boeing failed to generate any interest from airlines, yet remained confident that the project was worthwhile and pressed ahead with a prototype, the Boeing 367-80 ("Dash-80"). After spending $16 million of its own money to build it, the Dash-80 rolled out on May 15, 1954.Irving 1994, p. 173.
Early design phase
During mid-1952, Douglas opted to covertly begin work on definition studies for a jet-powered transport aircraft. The company's design team examined various arrangements, including some that closely resembled the Comet. By mid-1953, the team had settled on a form similar to the final DC-8; an 80-seat, low-wing aircraft powered by four Pratt & Whitney JT3C turbojet engines, 30° wing sweep, and an internal cabin diameter of to allow five-abreast seating. The use of podded engines was seen as highly beneficial for maintenance purposes as well as to increase wing volume for accommodating fuel.Norris and Wagner 1999, pp. 10-12. The fuselage featured a double-bubble cross-section that produced relatively low drag while providing for a relatively spacious passenger cabin along with a large cargo deck that was sufficiently tall as to permit ground crews to stand up within it.Norris and Wagner 1999, p. 12.
While Douglas remained lukewarm about the jet airliner project, it believed that the USAF tanker contract would go to two companies for two different aircraft, as several USAF transport contracts in the past had done. In May 1954, the USAF circulated its requirement for 800 jet tankers to Boeing, Douglas, Convair, Fairchild Aircraft, Lockheed Corporation, and Martin Marietta. At the time, Boeing was only two months away from having its prototype in the air. Just four months after issuing the tanker requirement, the USAF ordered the first 29 KC-135 Stratotankers from Boeing. Donald Douglas was reportedly shocked by the rapidity of the decision which, he claimed, had been made before the competing companies even had time to complete their bids. He protested to Washington, but without success.
Having already started on the DC-8 project, Douglas decided that the best option was to press on than abandon the project.Norris and Wagner 1999, pp. 12-13. Following consultations with the airlines, several design changes were made, such as the fuselage being widened by to permit six-abreast seating, which in turn led to larger wings and tail surfaces being adopted along with a lengthening of the fuselage. The existence of the DC-8 was formally announced on June 7, 1955; at the time of the announcement, the development costs had been forecast to be roughly $450 million.Norris and Wagner 1999, p. 13. Four versions were offered to begin with, all with the same long airframe with a wingspan, but varying in engines and fuel capacity, and with maximum weights of about 240,000–260,000 lb (109–118 metric tons). Douglas steadfastly refused to offer different fuselage sizes. The maiden flight was planned for December 1957, with entry into revenue service in 1959. Aware that the program was lagging behind Boeing, Douglas began a major marketing push to promote its new jetliner.
First orders Douglas' previous thinking about the airliner market seemed to be coming true; the transition to turbine power looked likely to be to turboprops rather than turbojets. The pioneering 40–60-seat Vickers Viscount was in service and proving popular with passengers and airlines: it was faster, quieter, and more comfortable than piston-engined types. Eden 2016, p. 112. Another British rival was the 90-seat Bristol Britannia, and Douglas's main rival in the large airliner market, Lockheed Corporation, had committed to the short to medium range 80–100-seat turboprop Electra, with a launch order from American Airlines for 35 and other orders flowing in.Francillon 1982, pp. 396–397. Meanwhile, the Comet remained grounded, the French 90-passenger twin jet Sud Aviation Caravelle prototype had just flown for the first time, and the Boeing 707 was not expected to be available until late 1958. The major airlines were reluctant to commit themselves to the huge financial and technical challenges of jet aircraft; however, none could afford not to buy jets if their competitors did.
There the matter rested until October 1955, when Pan American World Airways placed simultaneous orders with Boeing for 20 707s and Douglas for 25 DC-8s.Eden 2016, p. 76. To buy one expensive and untried jet-powered aircraft type was brave: to buy both was, at the time, unheard of. In the closing months of 1955, other airlines rushed to follow suit: Air France, American Airlines, Braniff International Airways, Continental Airlines, and Sabena ordered 707s; United Airlines, National Airlines, KLM, Eastern Air Lines, Japan Air Lines, and Scandinavian Airlines System (SAS) chose the DC-8. In 1956, Air India, BOAC, Lufthansa, Qantas, and TWA added over 50 to the 707 order book, while Douglas sold 22 DC-8s to Delta, Swissair, TAI, Trans Canada, and UAT. By the start of 1958, Douglas had sold 133 DC-8s compared to Boeing's 150 707s.
Production and testing
Donald Douglas proposed to build and test the DC-8 at Santa Monica Airport, which had been the birthplace of the DC-3 and home to a Douglas plant that employed 44,000 workers during World War II. To accommodate the new jet, Douglas asked the city of Santa Monica, California to lengthen the airport's runway. Following complaints by neighboring residents, the city refused, so Douglas moved its airliner production line to Long Beach Airport. (Registration required)Norris and Wagner 1999, pp. 13-14. In September 1956, production of the first prototype commenced. The first DC-8 N8008D was rolled out of the new Long Beach factory on 9 April 1958 and flew for the first time, in Series 10 form, on 30 May for two hours and seven minutes with the crew being led by A.G. Heimerdinger.Norris and Wagner 1999, p. 9.