The Measurement of the McDonnell-Douglas DC9 Trailing Vortex System Using the Tower Fly-By Technique
Abstract
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1974
- Accession Number
- ADA001456
Entities
People
- David Lawrence
- Leo J. Garodz
- Nelson Miller