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COMPETITIVE ASSESSMENT OF TECHNOLOGY 109 Aerodynamics In addition to the advances in aerodynamic computational procedures, significant potential exists for advances in aerodynamics in the areas of boundary layer management for cruise conditions and lift enhancement for takeoff and landing. Figure 5-1 indicates the gains to be realized from the successful attainment of laminar flow to reduce skin friction drag. In the past three decades extensive analytical and experimental work has been done in this country under NASA sponsorship to understand the laminar-to turbulent-flow transition and to develop methods for delaying this transition. Much more work needs to be done to adapt these methods to a large commercial transport in a practical, cost- effective manner. Current NASA plans call for testing the most promising configurations in actual flight conditions. Should these tests prove successful, adaptation of this technology to a new production aircraft is not expected before the mid-to late 1990s, 10 to 15 or more years from now. The status of active boundary layer management programs in Europe is unknown at this time, but the United States is thought to be ahead, based on the extensive NASA work discussed above. The Japanese are developing an experimental "Quiet STOL" research aircraft using the upper-surface blowing concept similar to NASA's QSRA aircraft and Boeing's YC-14 STOL Transport Demonstrator Aircraft for DOD. In the low-speed, high-lift flight regime, current transports incorporate a combination of leading edge devices and sophisticated flaps to vary wing camber to increase lift at low speeds. Significant advances in multielement airfoil analysis techniques are providing considerable insight into the behavior of high- lift systems and reducing the need for extensive experimental data. The United States and Europe are thought to be generally comparable in wing design, e.g., the Airbus A310 wing incorporates the latest in high-lift systems to provide excellent takeoff and landing performance. Extensive double curvature in the lower skin of the inner wing provides optimum lift characteristics. Precise altitude control, combined with thrust control through flight path computers, provides the capability for Category III automatic landing in which conditions are virtually zero ceiling, zero visibility. Improvements in aerodynamics are not receiving particular attention in aircraft for general aviation, but the strength of the United States in this field could accrue to U.S. manufacturers if it is applied. In rotorcraft, foreign capability is judged to be on a par with the United Statesâthough foreign manufacturers have been able to supply advanced technologies more rapidly.
