Estimating the Airspeed Velocity of an Unladen Swallow

“In order to maintain airspeed velocity, a swallow needs to beat its wings forty-three times every second, right?”

Actually, wrong. By comparing the European Swallow with bird species of similar body mass, we can estimate that the swallow beats its wings 18 times a second with an amplitude of 18 cm… Jonathan CorumEstimating the Airspeed Velocity of an Unladen Swallow (Style)

This pop-cult reference is, of course, to Monty Python and the Holy Grail.