Design The now defunct aircraft manufacturer McDonnell Douglas studied improved versions, long and most powerful trirreactor MD-11, known as MD-12X momentarily. This extended version would have had a length of 72 m and a wingspan of 64 , 39 m, and probably would have included a lower deck passenger front with panoramic windows. The board of directors of McDonnell Douglas in October 1991 agreed to offer the then new design of the MD-12X to airlines. Furthermore, in November 1991, McDonnell Douglas and Taiwan Aerospace Corporation signed a “memorandum of understanding”, to form the company that produced the new design. The new company would have conformed to McDonnell Douglas as the majority shareholder, although only 51 of the capital. Taiwan Aerosp.For its part, would have remained with 40 of ACTIONS, while other smaller Asian companies had been allocated the remaining 9 . The design later led to the much larger MD-12 with four engines instead three. This was because, since it would require a combined thrust of over 100,000 kgf, would have been necessary to place a turbofan engine or blower of 35,000 kgf (for example, a GE90) below the vertical stabilizer, which would have placed a potentially excessive weight on the stern or rear of the plane. Another of its outstanding characteristics, but the most remarkable, lay in its double cabin along the entire fuselage. The length of the main and basic variant of the MD-12 was 63 m, while it had a wingspan of 64.54 m. For its part, the proposed fuselage oval measuring 7.4 m wide and 8.5 high. McDonnell Douglas finally unveiled in April 1992, the design of the MD-12 to the specialized public.According to the optimistic agenda at the time of the company, the first flight of the new plane was to take place towards the end of 1995 and first delivery to an airline, two years later (in 1997). This was similar in concept to Airbus and Boeing NLA A3, and had been a little larger and of greater capacity than the Boeing 747-400, which would have been its natural and direct competitor. Meanwhile, Douglas had also made early studies, and during the 1960s on a design of double cabin. Despite the aggressive marketing (marketing) and the initial excitement, especially among some magazines specialized aviation, no airline reached any real checkout of the new aircraft.MDC would be without the necessary financial resources after the company associated with the project, Taiwan Aerospace, decides to leave. Furthermore, the development and construction of a commercial aircraft giant double-decker passenger has proved a task too complex and expensive, even for Airbus and Boeing, the two aerospace giants residual (after the acquisition of McDonnell Douglas by Boeing in 1997). Boeing just come to study even larger variations of classic Boeing 747, which basically consisted of a fuselage of greater length (about 80 m) and the extension of higher passenger cabin along all the same, which would have resulted in the disappearance of their traditional hump.By the European consortium Airbus Industrie, a plane even larger than the hypothetical MD-12, the mammoth A380 finally entered service in 2007, not before he had several financial problems, not only because of the implicit cost of development, but the delay in delivery of the first units to buyers airlines. . Indeed, Airbus is having more difficulties in achieving achieve the 200-250 orders for giant aircraft due to their specific niche. Just between the number of units the company could recover from the financial drain of over U.S. 9,000 million allocated to developing the project, from initial conceptual designs by computer to its first test flight in April 2005.With the cancellation of MD-12 program, McDonnell Douglas preferred to focus on the development of derivatives of MD-11, in the range of medium-high capacity., The order of 300-400 passengers.And so, during the 1996 international air show in Farnborough, the company decided to bet on a new trirrector bigger than the MD-11, MD- named momentarily. However this aircraft would ever materialize. . The MD- was offered in two variants: the MD- Stretch ( “stretched or extended), which had a larger fuselage length, and the D- LR (Long Range), which gave even greater scope for a plane that already offered considerable autonomy.