Application of Temperature Sensitive Paint for High Altitude Transonic Natural Laminar Flow Design

Otto Aviation recently completed (Nov. 2024) a test entry at the European Transonic Windtunnel to support ongoing design and tool validation of their natural laminar flow design optimization for high altitude transonic flight. As part of this testing the use of cryogenic temperature sensitive paint was applied to a subscale wind-tunnel model to capture and evaluate boundary layer transition across a wide range of test conditions including variations in Mach number and Reynolds number. The design, development and fabrication of the wind-tunnel model were completed to provide the best possible conditions to characterize boundary-layer transition. Test results were compared to computational predictions and show good comparison and indicate specific areas for improvement and refining of our numerical methods and tools.