Accession Number : ADA113621

Title :   B-747 Vortex Alleviation Flight Tests: Ground-Based Sensor Measurements.

Descriptive Note : Final rept.,

Corporate Author : TRANSPORTATION SYSTEMS CENTER CAMBRIDGE MA

Personal Author(s) : Burnham,D C

PDF Url : ADA113621

Report Date : Jan 1982

Pagination or Media Count : 188

Abstract : In 1979, a series of B-747 flight tests were carried out to study the wake-vortex alleviation produced by deploying spoilers in the landing configuration. The alleviation achieved was examined by encounters of probe aircraft and by velocity profile measurements made by a ground-based Laser Doppler Velocimeter. For the first time these two types of measurements were analyzed in a way which allowed direct comparison; they showed reasonable agreement. The velocimeter measurements can be used to evaluate the vortex-induced rolling moment on any following aircraft at any separation. The spoiler alleviation was found to be insufficient to assure safe landings of small aircraft at reduced separation behind the B-747. The persistence of the alleviated vortices appears to be due to the wing-tip vortices which dominate the roll-up of the spoiler-alleviated wake. The addition of rapid roll inputs to the spoiler deployment produced much more effective alleviation, but at the expense of an unacceptable ride quality in the generating aircraft. (Author)

Descriptors :   *VORTICES, *BOUNDARY LAYER CONTROL, *SPOILERS, JET TRANSPORT AIRCRAFT, WAKE, REDUCTION, WING TIPS, RIDE QUALITY, FLIGHT TESTING, PROBES, LASER VELOCIMETERS, DOPPLER SYSTEMS, GROUND LEVEL, TRAILING VORTICES, DECAY, HAZARDS, AIRCRAFT LANDINGS, AVIATION SAFETY, ROLL

Subject Categories : Test Facilities, Equipment and Methods
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE