This paper describes work done under a NASA-Langley grant at the university of Kansas Flight Research Laboratory in the area of natural laminar flow and regional aircraft. The focus of this paper is on the application of natural laminar flow over various major wetted areas. In particular, efforts were concentrated on analyzing the potential benefits of achieving extensive laminar flow on the wing, empennage, and fuselage. The effect of the presence of large amounts of laminar flow is evaluated in terms of performance and efficiency improvement over an all-turbulent baseline aircraft. An introduction is given to the concept of regional aircraft, and the aerodynamic characteristics are compared to those of other airplane classes. Some recent aerodynamic developments are presented that justify, to a certain extent, the assumptions made concerning the amount of natural laminar flow that is possible for each surface. Application of a cruise/climb flap to advanced medium-speed natural laminar flow airfoils is also discussed.
