re: #50 Gus 802

What, is the air-speed velocity of an unladen swallow?

Well it depends on the species, doesn’t it? For example :

The European Swallow has a body mass of 20grams, and beats its wings at a frequency of 18 hz and an amplitude of 18cm.

After solving the predicted pattern of cruising flight ranges

U ≈ 3fA
f ≈ 15 (beats per second)
A ≈ 0.22 (meters per beat)
U ≈ 3*15*0.22 ≈ 9.9

… to estimate that the airspeed velocity of an unladen European Swallow is 10 meters per second.

A different species of sparrow would have different results.