Aerodynamic Problems in the Calculation of Helicopter Airloads

The contributions of recent developments in rotary wing aerodynamic theory, particularly lifting surface theory and distorted wake geometry, toward improving the calculation of helicopter airloads are assessed. The difficulties of airloads calculations associated with the occurrence of dynamic stall are reviewed. Some problems involving both vortex induced loads and dynamic stall, and some related problems in blade motion calculation are discussed. It is concluded that there is a great deal of fundamental research remaining to be done into the phenomena involved in rotary wing aerodynamics. The aerodynamic problems still remaining in the calculation of airloads are discussed, and some suggestions are made of theoretical and experimental models which might be useful in future research into these problems.