Finding The Laminar-To-Turbulent Transition

Technical memorandum evaluates four techniques for determining location laminar flow about airfoil changes to turbulent flow. Studied in flight experiments on F-14 variable-sweep-wing aircraft. First technique involved measurements by hot-film anemometer sensors. Second, measurements by boundary-layer rakes, each array of pressure probes. Third, measurements taken by pitot tubes arrayed on airfoil, flush with surface, and fourth, test airfoil surface coated with pressure-sensitive liquid crystals, to make pressure pattern of flow visible.