Douglas DC-8 - Wikipedia

Background

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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,[1][2] Douglas initially refrained from developing a jet airliner.

De Havilland's pioneering Comet entered airline service in May 1952.[3][4] 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.[5] 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.[6][7] 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.[8] 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.[9][10]

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.[11] 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.[12]

Early design phase

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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.[8] 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 11 feet (3.35 m) 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.[13] 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.[14]

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.[15][14] 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.[16] Following consultations with the airlines, several design changes were made, such as the fuselage being widened by 15 inches (38 cm) 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 7 June 1955; at the time of the announcement, the development costs had been forecast to be roughly $450 million.[17] Four versions were offered to begin with, all with the same 150-foot-6-inch (45.87 m) long airframe with a 141-foot-1-inch (43.00 m) 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.[citation needed]

First orders

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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.[18][19] 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.[20] 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.[21] 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.[citation needed]

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.[22] 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.[17]

Production and testing

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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 5,000-foot (1,500-meter) runway. Following complaints by neighboring residents, the city refused, so Douglas moved its airliner production line to Long Beach Airport.[23][24] In September 1956, production of the first prototype commenced.[17] 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.[25][21]

Later that year, an enlarged version of the Comet finally returned to service, but had arrived too late to secure a substantial portion of the market: de Havilland secured just 25 orders. In August, Boeing had begun delivering 707s to Pan Am. Douglas made a massive effort to close the gap with Boeing, using no fewer than ten aircraft for flight testing to achieve Federal Aviation Administration (FAA) certification for the first of the many DC-8 variants in August 1959.[26] Several modifications proved to be necessary: the original air brakes on the lower rear fuselage were found to be ineffective and were deleted as engine thrust reversers had become available; unique leading-edge slots were added to improve low-speed lift; the prototype was 25 kn (46 km/h) short of its promised cruising speed and a new, slightly larger wingtip had to be developed to reduce drag. Also, a recontoured wing leading edge was later developed to extend the chord 4% and reduce drag at high Mach numbers.[27][28]

On August 21, 1961, a DC-8-43 broke the sound barrier at Mach 1.012 (668 mph/1,075 km/h) while in a controlled dive through 41,088 feet (12,524 m) and maintained that speed for 16 seconds. The flight was to collect data on a new leading edge design for the wing, and, while doing so, the DC-8-43 became the first civilian jet – and the first jet airliner – to make a supersonic flight.[29] The aircraft was DC-8-43 registered as CF-CPG, later delivered to Canadian Pacific Air Lines. The aircraft, crewed by Captain William Magruder, First Officer Paul Patten, Flight Engineer Joseph Tomich and Flight Test Engineer Richard Edwards, took off from Edwards Air Force Base in California and was accompanied to altitude by a Lockheed F-104A-10-LO Starfighter supersonic chase aircraft flown by Chuck Yeager and one North American F-100 Super Sabre also supersonic.[30]

Entry into service

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On September 18, 1959, the DC-8 entered service with Delta Air Lines and United Airlines.[31][32] According to the Delta Air Lines website, the air carrier was the first to operate the DC-8 in scheduled passenger service.[33] By March 1960, Douglas had reached its planned production rate of eight DC-8s per month. Despite a large number of DC-8 early models being available, all used the same basic airframe, differing only in engines, weights and details; in contrast, the rival Boeing 707 range offered several fuselage lengths and two wingspans: the original 144-foot (44 m) 707-120, a 135-foot (41 m) version that sacrificed space to gain longer range, and the stretched 707-320, which at 153 feet (47 m) overall had 10 feet (3.0 m) more cabin space than the DC-8.[citation needed]

Douglas' refusal to offer different fuselage sizes made it less adaptable and compelled airlines such as Delta and United to look elsewhere for short to medium range types. Delta ordered Convair 880s while United chose the newly developed short-fuselage 707-020. United prevailed on Boeing to rename the new variant the Boeing 720 in case the public thought they were dissatisfied with the DC-8. Pan Am never reordered the DC-8 and Douglas gradually lost market share to Boeing.[34] In 1962, DC-8 sales dropped to just 26 aircraft that year, followed by 21 in 1963 and 14 in 1964; many of these later deliveries were of the Jet Trader model rather than the more-prestigious passenger versions.[citation needed] In 1967, Douglas merged with McDonnell Aircraft, becoming McDonnell Douglas.[35][36]

Further developments

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During the early 1960s, Douglas began considering stretching the DC-8, a feat that was eased by its fuselage keeping the same dimensions across its length.[37] In April 1965, the company announced belated fuselage stretches for the DC-8 with three new models known as the Super Sixties. The DC-8 program had been in danger of closing with fewer than 300 aircraft sold, but the Super Sixties brought fresh life to it. By the time production of the DC-8 ceased in 1972, 262 of the Super Sixties had been completed, almost half of all models produced. With the ability to seat 269 passengers, the DC-8 Series 61 and 63 had the largest passenger-carrying capacity available. That remained so until the Boeing 747 arrived in 1970.[37][10] The DC-8-62 featured a shorter fuselage when compared with the Series 61 and 63, but was capable of nonstop long-range operations.[38]

All of the earlier jetliners were relatively noisy by modern standards. Increasing traffic densities and changing public attitudes led to complaints about aircraft noise and moves to introduce restrictions.[39] As early as 1966 the Port Authority of New York and New Jersey expressed concern about the noise to be expected from the then still-unbuilt DC-8-61, and operators had to agree to operate it from New York at lower weights to reduce noise. By the early 1970s, legislation for aircraft noise standards was being introduced in many countries, and the 60 Series DC-8s were particularly at risk of being banned from major airports.[citation needed]

 

In the early 1970s, several airlines approached McDonnell Douglas with requests for noise reduction modifications to their DC-8s. While third parties had developed aftermarket hushkits, there was initially no meaningful action taken by Douglas to fulfil these requests and effectively enable the DC-8 to remain in service. Finally, in 1975, General Electric began discussions with major airlines to fit the new and vastly-quieter Franco-American CFM56 engine to both DC-8s and 707s. MDC remained reluctant but eventually came on board in the late 1970s and helped develop the Series 70.[40] The Super Seventies proved to be a great success, being roughly 70% quieter than the 60 Series and, at the time of their introduction, the world's quietest four-engined airliner. As well as being quieter and more powerful, the CFM56 was up to 23% more fuel-efficient than the JT3D, which reduced operating costs and extended the range.[40] The largest single customer for the Series 70 was United, converting 29 of its Series 61 airliners at a reported cost of $400 million.[41]

United Airlines retired its last DC-8-71 aircraft on October 31, 1991, while Air Transport International all of its remaining DC-8-62, 71, 72, and 73 fleets between 2013 and 2015, and purchased several new Boeing 757 and Boeing 767 aircraft to replace them.[42]

By 2002, of the 1,032 Boeing 707s and 720s manufactured for commercial use, just 80 remained in service – though many of those 707s were converted for USAF use, either in service or for spare parts. Of the 556 DC-8s made, around 200 were still in commercial service in 2002, including about 25 50-Series, 82 of the stretched 60-Series, and 96 out of the 110 re-engined 70-Series. Most of the surviving DC-8s are now used as freighters. In May 2009, 97 DC-8s were in service following UPS's decision to retire its remaining fleet of 44.[43] In January 2013, an estimated 36 DC-8s were in use worldwide.[44] As a result of aging, increasing operating costs and strict noise and emissions regulations, the number of active DC-8s continues to decline, with the youngest airframes having exceeded 50 years of age in 2022.