Military


Boeing 763 New Large Aircraft

In the mid 1990s airlines and aircraft manufacturers began discussing the future requirement for a new, larger aircraft capable of carrying between 500 and 1,000 passengers that, as a result, will weigh in excess of 1 million pounds. Deliveries of these types of aircraft were expected to begin in 5 to 10 years. Development of new large aircraft was explored by Boeing, McDonnell Douglas, and Airbus Industries. Each planned to develop its own family of "super-jumbo" jets. Many of the planned aircraft were larger derivatives of aircraft that are already flying. Other new aircraft, however, were based on completely new designs that are unlike anything currently in production. Announced specifications underwent continuous alteration with changes ranging from simple size adjustments to dramatic redesign of the entire aircraft. Some aircraft that were originally planned as a double-deck design were scaled down to traditional single-deck.

The average weight of commercial aircraft has increased consistently over the last thirty years. The trend in aircraft maximum takeoff weights for large aircraft introduced over the past 3 decades suggests that the upward trend in aircraft weight can be expected to continue to increase with the introduction of first and future generations of NLA (indicated by the clear and shaded boxes). Note how there are two separate trends depicted on this chart. One trendis the weight characteristics of the larger transport aircraft used for long international flights. A second trend is the weight trend of the large transports used on shorter routes. These lines are parallel and are most likely to continue on the same track in the future. By taking these trends and their associated values into consideration, one can predict that the weights of future long route NLA will increase to 1.6 million in the next 20 years, while the shorter route NLA will also rise to 1 million pounds during the same period of time.

Commercial transport aircraft have also increased in wingspan length over the last several years. Many NLA will be classified in the largest airplane design group category, Group VI, recognized by the FAA. The largest wingspan included in this design group category is 262 feet. Current trends in aircraft wingspans indicate that they will continue to grow but may be curved to remain within the parameters of current design Group VI criteria. It is anticipated that it will reach a plateau and result in maximum values at or below 262 feet for two reasons. The first is that the development of higher efficiency wings will permit the carrying of more weight without an increase in size. The second reason, actually an unavoidable restriction, is that airports will be unable to fit aircraft that are much larger than 262 feet on their taxiways and runways without compromising the required separation standards for aircraft operating at the airport. The future demand for faster transport aircraft may also influence the trend in wingspan length, as they will most likely be equipped with swept wings for faster flight.

Other design characteristics of future NLA that can be predicted based on historical trends are the fuselage length, tail height, and landing gear wheelbase. These three elements, in general, are very closely related to each other. The wheelbase of the aircraft is typically a function of the fuselage length; the longer the fuselage, the longer the required wheelbase. Likewise, as the size of the aircraft increases, the height of the aircraft increases. Future derivatives of NLA are also expected to continue to grow in size and may be expected to have fuselage lengths upwards of 280 to 300 feet. As a result, they can also be expected to have wheelbase values upwards of 140 to 150 feet and tail heights over 80 feet.

Current FAA airport design standards provide reference and guidance for airport designers and forecasters relating to construction and configuration of all runways, taxiways, aprons, and terminals. The design of these items is based primarily on the size, approach speed, and number of aircraft the airport is expected to serve. The FAA established the Airport Reference Code (ARC) system to aid designers in properly determining the size of the runway, taxiway, or terminal that is needed at an airport. Advisory Circular AC 150/5300-13, Airport Design, defines ARC as "a coding system used to relate airport design criteria to the operational and physical characteristics of the airplanes intended to operate at the airport." The geometry of all surfaces at an airport is designed specifically for the largest aircraft or group of aircraft that will be operating at the airport. This assures that all aircraft will be provided with the proper obstacle clearance and separation requirements while maneuvering on the airport's paved surfaces. An airport's ARC includes both a letter and a number for the critical aircraft approach category and the airplane design group, respectively.

The Boeing NLA, or New Large Airplane was a 1990s concept for an all-new airliner in the 500+ seat market. Somewhat larger than the 747, this aircraft was similar in concept to the Airbus A380 and McDonnell Douglas MD-12. The 763 concept not only provided room for 450 to 550 passengers, but could be equipped with sleeping berths in an upper deck for longer intercontinental routes up to 9,000 nm (16,740 km). Boeing chose not to pursue development of this concept, focusing instead on updates to the 747.



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