A study of flutter in one degree of freedom

• Main Authors: Kiergan, Nova Babb, Tomamichel, Jack Jones
• Format: Others
• Published: 1942
• Online Access: https://thesis.library.caltech.edu/4653/1/Kiergan_nb_1942.pdf; Kiergan, Nova Babb and Tomamichel, Jack Jones (1942) A study of flutter in one degree of freedom. Engineer's thesis, California Institute of Technology. doi:10.7907/NX9K-JT57. https://resolver.caltech.edu/CaltechETD:etd-11242008-082928 <https://resolver.caltech.edu/CaltechETD:etd-11242008-082928>

The authors have attempted to develop a theoretical means of determining the amount of aerodynamic damping, positive or negative, existing on a symmetrical airfoil having freedom to oscillate only about an axis parallel to the span and on the zero camber line. Variables considered were oscillating frequency, wind speed, and hinge position (location of axis of oscillation.) Having developed what they considered a proper theoretical criterion for determining the value of aerodynamic damping, the authors have conducted an experimental investigation of an airfoil oscillating system having one degree of freedom, in an attempt to verify the theoretical criterion. It was concluded that for small oscillations the theoretical values of aerodynamic damping moment are correct except for hinge positions near the leading edge. Contrary to the theory, it was considered that the experimental investigation established the fact that negative damning does not occur for hinge positions at or near the leading edge. A general conclusion was made by the authors that an airfoil oscillating with only one degree of freedom will always have a positive aerodynamic damping moment provided the oscillations are small. It was found that an airfoil restricted to one degree of freedom (rotation) and pivoted about the 0.75 chord line will flutter when deflected to an amplitude approximating the stall angle. Flutter will be self-induced when the aerodynamic forces are sufficient to deflect the airfoil to the stall angle.