Wing flap frequency varies inverse logarithmically with wing span in flying animals, see https://www.researchgate.net/profile/Jeremy_Rayner2/publication/1390466

Wing flap frequency varies inverse logarithmically with wing span in flying animals, see https://www.researchgate.net/profile/Jeremy_Rayner2/publication/13904663/figure/fig3/AS:667179653558283@1536079433659/Wingbeat-frequency-versus-wing-length-For-comparison-the-slopes-of-two-predicted.png https://www.researchgate.net/profile/Jeremy_Rayner2/publicat... It's amazing how this carries over across species. Hummingbirds fly more like insects than eagles.