Accession Number : ADA018366

Title :   Flight Test Investigation of the Vortex Wake Characteristics behind a Boeing 727 during Two-Segment and Normal ILS Approaches.

Descriptive Note : Final rept.,


Personal Author(s) : Garodz,L. J. ; Barber,M. R. ; Kurkowkski,R. L.

Report Date : OCT 1975

Pagination or Media Count : 136

Abstract : A series of flight tests were performed to evaluate the vortex wake characteristics of a Boeing 727 (B727-200) aircraft during conventional and two-segment ILS approaches. Twelve flights of the B727, equipped with smoke generators for vortex marking, were flown wherein its vortex wake was intentionally encountered by a Lear Jet model 23 (LR-23) or a Piper Twin Comanche (PA-30); and its vortex location during landing approach was measured using a system of photo-theodolites. The tests showed that at a given separation distance there were no readily apparent differences in the upsets resulting from deliberate vortex encounters during the two types of approaches. Timed mappings of the position of the landing configuration vortices showed that they tended to descend approximately 91 meters (300 feet) below the flight path of the B727. The flaps of the B727 have a dominant effect on the character of the trailed wake vortex. The clean wing produces a strong, concentrated vortex. As the flaps are lowered, the vortex system becomes more diffuse. Pilot opinion and roll acceleration data indicate that 4.5 nautical miles would be a minimum separation distance at which roll control could be maintained during parallel encounters of the B727's landing configuration wake by small aircraft. This minimum separation distance is generally in scale with results determined from previous tests of other aircraft using the same roll control criteria. (Author)

Descriptors :   *Vortices, *Wake, *Commercial aircraft, *Instrument landings, Turbulent flow, Smoke generators, Aircraft landings, Jet aircraft, Flight control systems, Roll, Flight testing

Subject Categories : Civilian Aircraft
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE