Swept-wing laminar flow control studies using Cessna O-2A test aircraft
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abstract
This paper presents the results of a series of flight tests using a test wing section, mounted on a pylon of a Cessna O-2A aircraft, to study the effects of micron-sized spanwise-periodic distributed roughness elements (DRE) on a 30 swept-wing model. Laminar to turbulent transition data were acquired at a chord Reynolds number of 6.5 to 8 million at angles of attack between 2. The swept-wing test article was mounted vertically from the hard points located on the wing. The modification to the original aircraft design resulted in a campaign of flying quality tests and flutter clearance tests up to 170 KIAS and sideslip angles of 7 degrees. The flight test results are presented in three categories: flying qualities with the test article, freestream turbulence measurements, and laminar to turbulent transition studies on the test article. Flying qualities with the test article showed changes in static stability, but very little change in dynamic stability of the aircraft. Freestream turbulence measurements demonstrated turbulence intensity values suitable for boundary-layer stability experiments in the location of the test article. Transition results showed substantial amounts of natural laminar flow beyond the pressure minimum with a polished leading edge. An infrared camera was used as the laminar to turbulent transition diagnostics tool. This unobtrusive, qualitative imaging technique has proven valuable in a flight test environment, where weight and simplicity were a driving factor. Copyright 2008 by the American Institute of Aeronautics and Astronautics. All rights reserved.
