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Flight test experiments were conducted to measure the extent and nature of natural laminar flow on a smoothed test region of a swept-wing business jet wing. Surface hot film aneraometry and sublimating chemicals were used for transition detection. Surface pressure distributions were measured using pressure belts. Engine noise was monitored by a microphone attached to the wing surface to study possible acoustic effects on stability of the laminar boundary layer, Side-slip conditions were flown to simulate changes in effective wing sweep. Flight instrumentation and ground data analysis techniques and a method for measuring intermittency of turbulence are described, Correlation was obtained between the hot film gage signals and chemicals for transition detection. Cross-flow vortices were observed for some flight conditions. Results of spectral and statistical analysis of the hot film signals for various flight test conditions are presented.

Full scale flight tests of a wing designed for natural laminar flow (NLF) have provided insight into the aerodynamic characteristics of the airfoil used (NLF(1)-0414F), and into the effects of transition location on airfoil lift, drag, pitching moment and overall aircraft performance. Results of these tests help answer questions pertaining to the development of aircraft using NLF airfoils such as the one tested. These data also provide comparisons of predictions based on computational and wind tunnel test methods. Instrumentation methods used to gather data during these tests include flush mounted airfoil pressure orifices, hot film anemometers and a wing mounted integrating wake rake.

A noise control strategy for a small twin engine turboprop aircraft is evaluated. The noise control strategy consisted of a composite shell suspended inside the aircraft on isolation mounts. The evaluation consisted of a ground test program on component panels to select the shell material and a flight test program on the aircraft with and without the interior shell installed. Results from both phases are presented.