published on: 2015-03-28 17:57:06
nytvideo: The force generated by a flapping wing on the downstroke
sickpage:Raphaël Bourelly
nyrpea.tumblr.com/post/114858194275/
nyrpea.tumblr.com/post/114858379120/
nyrpea.tumblr.com/post/114858423775/
nyrpea.tumblr.com/post/114858440900/