A Boeing 727 jetliner is shown in this 1974 NASA Flight Research Center photograph taking part in a wake vortex study. Smoke from "smoke generators" installed on the tips of the aircraft's wings is shown being entrained by the wing tip vortices. A Piper PA-30 Twin Comanche and/or an F-104 or Lear Jet model 23 would fly behind the 727 to measure the effects of the airliner's wake vortices during landing approaches. A series of flight tests using a Boeing 727 jetliner was conducted in 1973-1974 at the NASA Flight Research Center (FRC), which became the Dryden Flight Research Center in 1976, to study the effects of wake vortices emanating from the trailing edges of the wings. The NASA study in conjunction with the Federal Aviation Administration (FAA) was in response to the hazards being encountered when small aircraft trailing behind new large jumbojets experienced "upset" problems.
