Effect of Fuselage Dynamics on Helicopter Ground Resonance: Investigation of the Influence of Dynamic Properties on the Rotor to Fuselage Effective Mass Ratio and its Effect on Stability Boundaries

Of the parameters that may be adjusted to give the helicopter freedom from ground resonance, that which is ignored most frequently is Λ3 (ratio of effective rotor mass to effective fuselage mass). This is because it is usually impractical to change it on an existing helicopter. However, if it is considered sufficiently early in the design of the fuselage, the ground resonance problem can be greatly reduced or even eliminated by the consideration of this parameter alone. The paper investigates the effects of fuselage dynamic properties on Λ3 and also gives results for the effect of Λ3 on the stability boundaries for some simple helicopter configurations.