Aeroelastic Model Helicopter Rotor Testing In The Langley TDT

Wind-tunnel testing of a properly scaled aeroelastic model helicopter rotor is considered a necessary phase in the desiqn development of new or existing rotor systems. For this reason, extensive testing of aeroelastically scaled model rotors is done in the Transonic Dynamics Tunnel (TDT) located at the NASA Lanqley Research Center. A unique capability of this facility, which enables proper dynamic scaling, is the use of Freon as a test medium. The paper presents a description of the TDT and a discussion of the benefits of using Freon as a test medium. A description of the model test bed used, the Aeroelastic Rotor Experimental System (ARES), is also provided and examples of recent rotor tests are cited to illustrate the advantaqes and capabilities of aeroelastic model rotor testing in the TDT. This paper demonstrates the importance of proper dynamic scaling in identifying and solving rotorcraft aeroelastic problems, and affirms the importance of aeroelastic testing of model rotor systems in the desiqn of advanced rotor systems.