Ground Resonance and Whirl Stability Analysis Using CAMRAD

Various CAMRAD models for analyzing ground resonance and whirl stability have been developed and correlated with existing analyses using in-house code DART at Boeing Mesa. The landing gear system, rotor pylon and its support structure, as well as mast mounted assembly (MMA), need to be properly represented in CAMRAD in order to consider these types of aeromechanical instabilities. The results have shown that the CAMRAD models are fully capable of capturing the overall characteristics of ground resonance and whirl mode stability, thus could be used in routine design and analysis in order to prevent these potentially destructive behaviors. Results shown in the study indicate that the DART models are typically more conservative than CAMRAD in terms of predicted stability margins; however, the CAMRAD predictions may be more accurate.