... at average downstroke velocity (31.8 rad s −1 ), whereas P9 and P1 feathers never produced tones. P10 feathers had significantly lower coefficients of resultant aerodynamic force ( C R ) when spun at peak angular velocity than at average angular velocity, revealing that production of tonal sounds incurs...

... in the literature are due to the use of different techniques for determining flight power or due to inter-specific differences. Here we compare the power–speed relationships in cockatiels ( Nymphicus hollandicus ) determined using both an aerodynamic model and measurements of in vitro performance of bundles...