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McDonnell Douglas MD-XX

The MD-XX designation was used by McDonnell-Douglass to refer to a variety of aircraft configurations studied in the 1980s and 1990s.

In 1991 the planned MD-XX 0-3308-4 configuration aircraft was intended to compete with the Airbus Industrie A321 and Boeing 757. One variant of the McDonnell Douglas MD-XX advanced technology twin-engined aircraft configuration, with a wingspan of 129 feet, was designed to carry 192 passengers in a two-class arrangement.

Another later MD-XX was a derivative of the MD-11 proposed in 1996. Preliminary MD-XX design features include a 31-foot stretched 234-foot long fuselage, redesigned wing with a 212-foot wingspan, three post main landing gear, and three higher thrust engines. Aside from the stretched fuselage, the operational and physical dimensions of the aircraft would be comparable to those of the MD-11. Passenger capacity would increase by 25 percent, up to 360 passengers.

The MD-XX replaced the double-deck MD-12X that was under consideration by McDonnell Douglas in the early 1990s. The MD-XX LR was a proposed derivative of this baseline MD-XX that would include many of the improved modifications of the MD-XX, with a reduction in the fuselage length to 204 feet. The wingspan would remain the same for the LR version. The MD-XX LR program remained under study by McDonnell Douglas and was not been scheduled for launch.

Plans for a new high capacity, long range three-engine jetliner for the 21st century were unveiled by McDonnell Douglas Corp. at the Farnborough International Air Show on 04 September 1996. Details of the new aircraft were disclosedby Walt Orlowski, MD-XX program vice president-general manager for the Douglas Aircraft division of McDonnell Douglas. He introduced the MD-XX as a new member of the company's family of long range, wide cabin trijets that includes more than 550 MD-11s and DC-10s now in service.

The aircraft, designated the MD-XX, was planned in two initial models -- a 375-seat stretch version to accommodate growing world air traffic and a long range variant to meet airline demands for greater non-stop capability. Both would use a newly developed, highly efficient wing with increased span and total area. The decision to develop two variants of the new aircraft responds to discussions with potential airline customers. McDonnell Douglas expected to begin offering the aircraft to airlines later this year, with a formal launch anticipated in early 1997.

The stretch version of the MD-XX would have the same or greater range than the MD-11, while carrying 25 percent more passengers and baggage. The aircraft would seat 375 passengers in typical three-class arrangement. With all-economy seating, it would carry up to 515 passengers. The long range model was being designed to fly 20 percent farther than the MD-11, with a full load of 309 passengers and baggage. The MD-11 typically carries 298 passengers, with a maximum range of more than 7,000 nautical miles (8,050 statute miles or 12,950 km).

MD-XX capabilities rode on an advanced design wing with a span of 213 feet (64.9 m), and total area of 5,200 square feet (483.1 sq m). A patented supercritical air foil shape would make it the most aerodynamically efficient wing in the airline industry. The MD-XX design had evolved in intensive studies started in April 1996 by Douglas President Mike Sears. To meet future traffic growth, the carriers are demanding aircraft with more passenger capacity and also want more range capability than current jetliners.

The MD-XX would be a wide cabin luxury airliner. The stretch model would be 233.8 feet (71.2 m) long, 32 feet (9.7 m) more than the long range version, which had the same fuselage length as the MD-11. Design studies include plans for using lower deck space for a sky lounge or for sleeping compartments or airborne offices for business travelers.

For pilots, the new aircraft would feature the McDonnell Douglas advanced common flightdeck now being developed for the new MD-95 transport and other McDonnell Douglas commercial aircraft. In the MD-XX, it would offer complete operational commonality with today's MD-11 cockpit. All flight, navigation and systems information would be presented to the two-person crew on six large liquid crystal display screens. Automatic system controllers doing much of the routine of flight would reduce crew workload. Fly-by-wire systems would drive flight control surfaces and engines.

Power for the MD-XX would be provided by three advanced high bypass ratio turbofan engines operating in the 65,000 pounds thrust range. With the new wing, they would give the aircraft exceptional takeoff performance and the ability to climb quickly to an altitude of 35,000 feet, where it would cruise efficiently at a speed of about Mach 0.85.

Composites would make up 39% of the airframe weight, a significant increase from the MD-11 or MD-80/90 series aircraft. With composite wing and tail, the composite content of the MD-XX would grow to over 20 percent of empty weight. If the MD-XX were to also have a composite fuselage, the percent composite would be over 40% of aircraft empty weight.

The development of transport aircraft composite primary wing structure had been under study at McDonnell Douglas since 1975. The original design concept was based on the prepreg tape material designed to the ultimate micro-strain level of 4500 for damage tolerance. However, it become evident that this conventional prepreg approach was not likely to lead to a cost effective application of composite materials to primary wing structure. The stitched dry preform/resin film infusion process was selected as having the best potential for achieving target weight and cost goals.

Ownership costs (to the operator) are directly related to the vehicle price which, in turn, depends on the manufacturer's cost. Structure costs are larger than propulsion, avionics, or equipment costs. The largest components of structure costs are the fuselage and wing. These two components provide the largest potential for a significant impact on ownership cost and total operating cost. McDonnell Douglas elected to focus its initial effort on the wing. Success with a composite wing would yield two benefits: reduced weight and reduced drag. Reduced drag results from the stiffness characteristics of composite which allows higher aspect ratio without attendant weight penalties.

A primary objective of the "Innovative Composite Aircraft Primary Structure" (ICAPS) program was to develop the technology to allow the incorporation of an all-composite wing on a commercial transport aircraft. Conventional composite construction reduces weight but at increased cost. McDonnell Douglas studies of a wing box unit show a 25 percent weight savings but a 50 percent or greater cost increase for a conventional composite unit. Using the ICAPS methodology, the weight savings would be retained with a goal of achieving better than a 40 percent improvement in cost compared to the conventional composite unit.

A key feature of the MD-XX aircraft was the high aspect ratio composite wing which was aerodynamically more efficient than the comparable metal wing. The more efficient and lighter wing would require smaller control surfaces, smaller engines and lighter support structure. The entire aircraft resized would weigh 7300 lb less than its metal wing counterpart. The combined effect of a lighter and more efficient aircraft was to reduce the direct operating cost (DOC) by 2.1 percent, translating into more than 100 percent profit increase for the airlines.

By 1995 the forecast by McDonnell Douglas was that long-term fuel prices would remain fiat in constant dollar terms at about 60 cents per gallon. This was based upon an abundant oil supply remaining (over 40 years supply at present consumption) and the short-term nature of dramatic fluctuations due to political events. Therefore, ownership costs were expected to continue as the largest element in the Direct Operating Cost [DOC] equation.

It was possible, through incorporation of several new technologies, to achieve a one-third reduction in aircraft fuel consumption. However, a full one-third reduction in fuel burned exclusively was not enough to achieve a ten percent reduction in DOC. An all-new aircraft with a thirty-three percent reduction in fuel burned would provide an economic benefit of only four to eight percent in DOC depending on fuel price.

Discussions were under way with all three major engine manufacturers -- General Electric, Pratt & Whitney and Rolls-Royce -- about using their powerplants on the aircraft. The MD-XX was being designed not just to meet, but to beat, the most stringent environmental regulations. With expected noise levels a cumulative 20 decibels below current limits, it would be the quietest airliner in its class.

Program plans aimed at gaining permission from the McDonnell Douglas board of directors to make formal MD-XX offers to airlines later in 1996. A 44-month development schedule would lead to first deliveries before the end of the year 2000 if orders needed for formal launch of the program are booked early in 1997. Following a six month review of potential risks and advantages, McDonnell Douglas announced on 28 October 1996 that it was terminating this advanced technology medium-range airliner. The termination of the MD-XX led industry observers to think the move may seal Douglas' fate. Management faced up to market realities and retreated from its 'commitment' to the commercial aircraft business.

In making the announcement that the proposed jumbo jet, called the MD-XX, would not be developed, McDonnell Douglas Chief Executive Officer Harry Stonecipher outlined a new strategy for the commercial aviation division. He said the Long Beach division would quit trying to compete head to head against industry giants Boeing Co. and Europe's Airbus Industrie, and instead concentrate on its existing line of commercial aircraft. The commercial aircraft division, Stonecipher said, would become a niche player rather than trying to keep up with Boeing and Airbus in the race to develop new aircraft.

On 25 July 1997 McDonnell Douglas Corporation's shareholders voted to approve the merger with The Boeing Company. The merger received regulatory approval by the U.S. Federal Trade Commission on July 1 and was expected to receive European Commission approval by July 30. The merger closed on Aug. 1, with the first day of operations for the new Boeing Company on Aug. 4.



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Page last modified: 12-07-2014 18:07:43 ZULU