Date of Award
Master of Science in Zoology
There has been much speculation about the significance of avian formation flight, yet it's purpose is still unknown. To explain the phenomenon, two hypotheses have been proposed. The first describes linear formations, such as vee formations, as a function of the visual, social and spacial needs of the particular bird. The second hypothesis proposes that formation flight exists to conserve flight energy for the formation as a whole. The proposed conservation of flight energy is achieved by an overall reduction of in-flight drag, or by taking advantage of lift components of the vortex wake produced by the preceeding bird in the formation.
To confirm basic aerodynamic considerations of flapping bird flight, and to clarify the sequential wing actions during such flight, a Budgerigar (Melopsittacus undulatus) was taught to fly in a wind tunnel. Airflow characteristics around the bird were made visible by directing a stream of chemical smoke into the tunnel. The bird was photographed during flight.
The photographic flight data were used in conjunction with data on formation flight geometry to construct a hypothetical model of a five bird vee formation. The model was subjected to analysis using standard aerodynamic principles to determine the extent of drag savings available to the birds in the formation.
The reduction in aerodynamic drag was much less than previously hypothesized, and the use of a fixed wing analogy for flapping flight was determined as an oversimplication. Previous aerodynamic studies of formation flight are discussed and compared to the results of this study, and investigation methods are proposed for further work which may provide answers to the question of a possible aerodynamic advantage to formation flight.
Haffner, John D., "A Flapping Wing Model for Avian Formation Flight" (1977). Open Access Master's Theses. Paper 738.