The Measurement of the McDonnell-Douglas DC9 Trailing Vortex System Using the Tower Fly-By Technique
Final rept. 11 May 1972-12 May 1974
NATIONAL AVIATION FACILITIES EXPERIMENTAL CENTER ATLANTIC CITY NJ
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The results are presented of a series of low-altitude approximately 200 feet above ground level fight tests in which the trailing vortices of the McDonnell-Douglas DC9 airplane were investigated, using a 140-foot instrumented tower. Data presented consists of plots of vortex tangential velocity distribution, peak velocity as a function of time, airplane configuration and windspeed, vortex descent rates, and lateral transport rates. Principal findings were that 1 Within the time period 30 - 100 seconds after vortex generation, the peak velocities within the vortices were bounded by the function V sub theta 396exp-.0347t, with a half-life of 20 seconds 2 Vortex cores were uniformly small 1 - 2 feet in both configurations tested takeoff and landing , and little or no growth with time was found 3 Vortex lateral transport velocities correlated well with the crosswind measured at 140 feet and 4 The presence of a temperature inversion markedly retarded the vortex descent rates. The highest peak recorded tangential velocity was 120 - 130 feet per second, found to occur in both configurations tested.
- Transport Aircraft
- Fluid Mechanics