Additional technical areas that merit focused research include composite structures with the following characteristics: Technological approaches to the above goals include the use of boundary layer control to reduce profile drag and parasite drag and the use of new materials, such as modern carbon-based or metal matrix composites, to reduce structural weight fraction. However aircraft productivity and efficiency are measured, they can be improved through advances in aircraft aerodynamics, materials, structures, and other disciplines that improve performance parameters such as lift-to-drag ratio (L/D), ratio of empty weight to MTOW, and specific fuel consumption. For the same aircraft, utilization rates and block speeds vary by airline and route, so these factors are beyond the direct control of manufacturers and design engineers. A more complete understanding of aircraft productivity and efficiency should include additional factors, such as availability (the average number of hours per day, week, etc., that an aircraft can be operated, taking into account servicing and maintenance requirements), utilization (the actual number of hours per day, week, etc., that a particular aircraft is operated), operational range (which ideally should be matched to the routes on which a particular aircraft is employed), and fuel consumption. Design efficiency is then indicated by the ratio of productivity to maximum takeoff weight (MTOW) high design efficiency is reflected in lower MTOW. However, estimating the ultimate effect that long-term research and advanced technology may have on operational cost is often difficult at best.Ī basic measure of aircraft productivity can be computed by multiplying payload by block speed (the average gate-to-gate speed for a given mission leg).

For airlines, operational cost (i.e., cost per seat-mile) is a key measure of aircraft performance. Improvements in aircraft performance are critical to achieving necessary improvements in almost every aspect of the overall performance of the air transportation system (see Chapter 1). The effects of a diminished or misdirected aeronautics research program will not be significant in the near term, but eventually the result will be a diminished U.S. widebody aircraft, were developed over 20 years ago. Technologies used to support the launch of the Boeing 777, the most recent model of U.S. Commercial jet aircraft produced in the United States are highly competitive, but they are also the result of technology investments made a long time ago.

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