HYDROFOIL FLUTTER PHENOMENON AND AIRFOIL FLUTTER THEORY. VOLUME 3. SWEEP AND TAPER

Measured decay rates and flutter speeds for a two degree-of-freedom hydrofoil model with sweep or taper do not agree with the decay rates and flutter speeds predicted by two-dimensional strip theory, whereas the measured and predicted frequencies are in agreement. Calculations based on the two-dimensional strip theory show that increasing sweep angle or decreasing taper yields higher flutter speeds as well as higher values of the critical density ratio. It is shown that flutter-speed predictions based on quasi-steady representations of the unsteady hydrodynamic forces are not valid.