Moffett Field, Calif.—Significant advances in charting the details of super-sonic aerodynamics plus new transonic research techniques were revealed in the second biennial inspection of the Ames Memorial Laboratory of the National Advisory Committee for Aeronautics. More than 800 aircraft manufacturing executives and engineers plus top Tanking Air Force and Naval Aviation brass attended the two-day session.
A more distinct detailed picture of the aerodynamic phenomena encountered in the range between Mach .8 and Mach 2.0 has emerged as a result of the last year's NACA research in this previously undefined area. Most important advance of the year—the first piloted supersonic flights by USAF and NACA test pilots in the Bell X-1 rocket powered research plane—was significantly omitted from any of the discussions.
► Sweep vs Straight—Perhaps the most interesting delineation offered by the NACA researchers was the assignment of proper places to swept back and straight wings in the supersonic picture.
The supersonic flights of the X-1 proved it is possible to achieve these speeds with extremely thin, straight wings. But wind tunnel research and flight test data indicate that the swept back wing still offers the most promising possibilities in the transonic range between Mach. 0.8 and about Mach 1.8.
In this area the sweep back of the wing delays the formation of shock waves across the wing allowing a subsonic airflow over the wing while the aircraft is travelling at supersonic speeds.
At about Mach 1.8 the shock waves catch up with the swept back wing and send drag soaring beyond the capabilities of any power plants that are likely to be available in the foreseeable future.
A straight wing encounters shock waves below Mach 1.0. Above Mach 1.8 the straight wing becomes more efficient than the swept back wing.
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Aviation Week | July 26, 1948
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