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MD11 # |
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Photo: Robert Deering
2/15/2013 San Francisco International Airport (SFO) San Francisco, California |
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he McDonnell Douglas MD-11 is a
three-engine medium- to long-range widebody
jet airliner, manufactured by McDonnell
Douglas and, later, by Boeing Commercial
Airplanes. Based on the DC-10, it features a
stretched fuselage, increased wingspan with
winglets, refined airfoils on the wing and
smaller tailplane, new engines and increased
use of composite materials. Two of its
engines are mounted on underwing pylons and
a third engine at the base of the vertical
stabilizer. It also features an all-digital
glass cockpit that decreases the flight deck
crew from the three required on the DC-10 to
two by eliminating the necessity for a
flight engineer. Although the MD-11 program was launched in 1986, McDonnell Douglas started to search for a DC-10 derivative as early as 1976. Two versions were considered then, a DC-10-10 with a fuselage stretch of 40 feet (12 m) and a DC-10-30 stretched by 30 feet (9.1 m). That later version would have been capable of transporting up to 340 passengers in a multi-class configuration, or 277 passengers and their luggage over 5,300 nautical miles (9,800 km). At the same time, the manufacturer was searching to reduce wing and engine drag on the trijet. Another version of the aircraft was also envisaged, the "DC-10 global", aimed to counter the risks of loss of orders for the DC-10-30 that the Boeing 747SP and its range were creating. The DC-10 global would have incorporated more fuel tanks. While continuing their research for a new aircraft, McDonnell Douglas designated the program DC-10 Super 60, previously known for a short time as DC-10 Super 50. The Super 60 was to be an intercontinental aircraft incorporating many aerodynamic improvements in the wings, and a fuselage lengthened by 26 feet 8 inches (8.13 m) to allow for up to 350 passengers to be seated in a mixed class layout, compared to 275 in the same configuration of the DC-10. Following more refinements, in 1979 the DC-10 Super 60 was proposed in three distinct versions like the DC-8. The DC-10-61 aimed to be a medium-range aircraft, able to carry 390 passengers (mixed class) or 550 passengers (all-economy) on an airframe lengthened by 40 feet (12 m), similar to the Boeing's later 777-300 and Airbus A340-600. Like for the DC-8, the series 62 was proposed as a long-range aircraft stretched by 26 ft 7 in (8.10 m) and capable to carry up to 350 passengers (mixed class) or 440 passengers (all-economy), similar to the later Boeing 777-200 or the Airbus A330-300/A340-300/500. And finally, the series 63 would have incorporated the same fuselage as the DC-10-61 as well as all the aerodynamic refinements of the -62. After three high-profile accidents in the 1970s (Turkish Airlines Flight 981, American Airlines Flight 191, and Air New Zealand Flight 901), the trijet's reputation was seriously damaged by doubts regarding its structural integrity. For these reasons, and due to a downturn in the airline industry, all work on the Super 60 was stopped. In 1981, a Continental DC-10-10 (registration number N68048) was leased to conduct more research, particularly the effects the newly-designed winglets would have on aircraft performance. Different types of winglets were tested during that time in conjunction with NASA. McDonnell Douglas was again planning new DC-10 versions that could incorporate winglets and more efficient engines developed at the time by Pratt & Whitney (PW2037) and Rolls-Royce (RB.211-535F4). The manufacturer finally rationalized all these studies under the MD-EEE (Ecology-Economy-Efficiency) designation, that was later modified to MD-100 following some more changes. The MD-100 was proposed in two versions: the Series 10, having an airframe shorter by 6 ft 6 in (1.98 m) compared to the DC-10 and seating up to 270 passengers in a mixed class configuration; and the Series 20, incorporating a fuselage stretch of 20 ft 6 in (6.25 m) over the DC-10 and able to seat up to 333 passengers in the same kind of configuration as the Series 10. Both versions could be powered by the same engine families as the actual MD-11 plus the RB.211-600. But the situation for the manufacturer, and the airline industry in general, did not look bright. No new DC-10 orders were received, and many among the observers and customers doubted that the manufacturer would be around for much longer. Thus, the Board of Directors decided in November 1983 to once again cease all work on the projected new trijet.[2] The following year no new orders for the DC-10 were received. The production line was kept active thanks to an earlier orders from the U.S. Air Force for 60 KC-10A tankers. McDonnell Douglas was still convinced that a new derivative for the DC-10 was needed, as shown by the second-hand market for their Series 30 and the heavier DC-10-30ER version. Thus, in 1984 a new derivative aircraft version of the DC-10 was designated MD-11. From the very beginning, the MD-11X was conceived in two different versions. The MD-11X-10, based on a DC-10-30 airframe, offered a range of 6,500 nautical miles (12,000 km) with passengers. That first version would have had a Maximum Take-Off Weight (MTOW) of 580,000 pounds (260,000 kg) and would have used CF6-C2 or PW4000 engines. The MD-11X-20 was to have a longer fuselage, accommodating up to 331 passengers in a mixed class layout, and a range of 6,000 nautical miles (11,000 km). As more orders for the DC-10 were received, McDonnell Douglas used the time gained before the end of DC-10 production to consult with potential customers and to refine the proposed new trijet. In July 1985, the Board of Directors authorized the Long Beach plant to offer the MD-11 to potential customers. At the time, the aircraft was still proposed in two versions, both with the same fuselage length, a stretch of 22 ft 3 in (6.78 m) over the DC-10 airframe, as well as the same engine choice as the MD-11X. One version would have a range of 4,780 nautical miles (8,850 km) with a gross weight of 500,000 pounds (230,000 kg) and transport up to 337 passengers, while the second would carry 331 passengers over 6,900 nautical miles (12,800 km). A year later, as several airlines had committed for the MD-11, the situation was looking optimistic. The aircraft was now a 320 seater baseline and defined as an 18 ft 7 in (5.66 m) stretch over the DC-10-30 powered by the new advanced turbofans offered by the major engine manufacturers and giving it a range of 6,800 nautical miles (12,600 km). Other versions, such as a shortened ER with a range of 7,500 nautical miles (13,900 km), an all cargo offering a maximum payload of 200,970 pounds (91,160 kg) and a Combi with a provision for ten freight pallets on the main deck, were proposed. Further growth of the aircraft was also foreseen, such as the MD-11 Advanced. Finally, the MD-11 was launched on December 30, 1986 with commitments for 52 firm orders and 40 options in three different versions (passenger, combi and freighter) from ten airlines (Alitalia, British Caledonian, Dragonair, FedEx Express, Finnair, Korean Air, Scandinavian Airlines System, Swissair, Thai Airways International, and VARIG) and two leasing companies (Guinness Peat Aviation and Mitsui). Orders from Dragonair, Scandinavian and UTA, an undisclosed customer, were canceled by 1988. Assembly of the first MD-11 began on March 9, 1988, and the mating of the fuselage with wings occurred in October that year. First flight was originally planned to occur in March 1989, but numerous problems with the manufacturing, delays with suppliers producing essential components and labor industrial actions delayed the ceremonial roll out of the prototype until September of that year. The following months were used to prepare the prototype for its maiden flight, which finally happened on January 10, 1990. The first two aircraft manufactured were intended for FedEx and thus, were already fitted with the forward side cargo door. They remained with the manufacturer as test aircraft until 1991 before being completely converted to freighters and delivered to their customer. FAA certification was achieved on November 8, 1990 while the European Joint Aviation Authorities (JAA) certified the MD-11 on October 17, 1991 after approximately 200 separate issues were resolved. Yugoslav Airlines, already flying several DC-10s, became the first customer of the MD-11. Three aircraft were manufactured but were never delivered due to war in Yugoslavia. The first MD-11 was delivered to Finnair on December 7, 1990 and it accomplished the first revenue service by an MD-11 on December 20, 1990, carrying passengers from Helsinki to Tenerife in the Canary Islands. MD-11 service in the U.S. was inaugurated by Delta Air Lines, also in 1990. It was during this period that flaws in the MD-11's performance became apparent. It failed to meet its targets for range and fuel burn. American Airlines in particular was unimpressed, as was Singapore Airlines, who canceled their order for 20 aircraft. American Airlines cited problems with the performance of the airframe and the Pratt & Whitney PW4000 engines as reasons for the cancellation while the Singapore Airlines stated that the MD-11 could not operate on the airline's long haul routes. Pre-flight estimates indicated that the P&W-powered MD-11 was to have a 7,000 nautical miles (13,000 km) range with 61,000 pounds (28,000 kg) of payload. With the Phase 1 drag reduction in place then, the aircraft could only achieve its full range with 48,500 pounds (22,000 kg) of payload, or a reduced range of 6,493 nautical miles (12,025 km) with a full payload. In 1990, McDonnell Douglas, along with Pratt & Whitney and General Electric began a modification program known as the Performance Improvement Program (PIP) to improve the aircraft's weight, fuel capacity, engine performance and aerodynamics. McDonnell Douglas worked with NASA's Langley Research Center to study aerodynamic improvements. The PIP lasted until 1995 and recovered the range for the aircraft. However, by this point sales of the MD-11 had already been significantly impacted. The MD-11 was one of the first commercial designs to employ a computer-assisted pitch stability augmentation system that featured a fuel ballast tank in the tailplane, and a partly computer-driven horizontal stabilizer. Updates to the software package made the plane's handling characteristics in manual flight similar to the DC-10, despite a smaller tailplane to reduce drag and increase fuel efficiency. After McDonnell Douglas merged with Boeing in 1997 the new company decided that MD-11 production would continue, though only for the freighter variant. However, in 1998 Boeing announced they would end MD-11 production after filling current orders. The last passenger MD-11 built was delivered to Sabena in April 1998. Assembly of the last two MD-11s were completed in August and October 2000; they were delivered to Lufthansa Cargo on February 22, and January 25, 2001 respectively. Production ended because of lack of sales, resulting from internal competition from comparable aircraft, such as the Boeing 777 and Boeing 767-400 and external competition from the Airbus A330/A340. McDonnell Douglas and later Boeing performed studies on the feasibility of removing the tail engine and making it a two engine plane, but nothing came of it. McDonnell Douglas originally projected that they would sell more than 300 MD-11 aircraft, but only 200 planes were built. The MD-11 was assembled at McDonnell Douglas's Douglas Products Division in Long Beach, California (later Boeing's facility). |
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