Full-Configuration CFD Analysis of the S-97 RAIDER

The S-97 RAIDERTM is a next-generation light tactical helicopter which uses a coaxial dual main rotor and aft-mounted propeller for auxiliary propulsion. This advanced configuration presents challenges for aerodynamic modeling, particularly with regard to the interactions between various components and their dependency on flight condition and trim state across a wide envelope. This paper describes continued research into the aerodynamics of the coupled aircraft components. Computational simulations of multiple combinations of components have been conducted for a series of pitch sweeps and flight conditions. These computational fluid dynamics (CFD) results are compared to available scale-model wind-tunnel test results. As is typical with development programs, changes were made between the original small-scale testing and analysis, and the current flight-test aircraft. In addition, the available computational methods and processing capabilities have improved significantly since the program started in 2010.