Aircraft capable of very high altitude flight are desirable for atmospheric research and for military reconnaissance. Vehicles envisioned to cruise at altitudes from 70,000 to 100,000 feet must be designed with state-of-the-art structures, propulsion and aerodynamics in order to carry any meaningful payload for a significant loiter period. Because of the low Reynolds number inherent in flying at such high altitudes, recent aircraft designs have taken advantage of natural laminar flow (NLF) airfoils to reduce skin friction drag. The extent of NLF is limited by the need to recover the pressure by the trailing edge. The advantages of NLF airfoils can be enhanced by including in the original design a miniature boundary layer mixing device (BLMD) system that allows airfoils to be designed with a much more aggressive pressure recovery profile. The advantage of such a design is an increase in the percentage of laminar flow, while at the same time increasing the design lift coefficient. This combined increase in lift to drag ratio (L/D) will increase the performance of high altitude vehicles and can help to reduce the vehicle size, and hence the cost, required to carry a fixed weight payload.
Potential Commercial Applications:Laminar flow airfoils are in use for a variety of aircraft including high altitude long endurance unmanned air vehicles (UAV's), general aviation aircraft, business jets, and some commercial aircraft. The ability to enhance airfoil performance would be of great value to aircraft manufacturers that use laminar flow airfoils. This technology may also be applied to propeller airfoils. It is possible that with the use of Boundary Layer Mixing Devices, new applications for laminar flow airfoils will become available where it was once not practical because of boundary layer separation concerns.
