Answer: 11 to 16mls
Explanation:
It's obvious, you'll be thinking of African or European swallow; we might consider the West African swallow, or the South African Cave swallow, however, choosing one between these two would be completely arbitrary- and neither is it sufficiently studied to provide the absolute data we need.
Notwithstanding, there is an accepted way to estimate the airspeed of a bird using Strouhal ratio's equation. This states that "the frequency of wingbeats multiplied by their amplitude and divided by the airspeed of the bird provides a semi-constant value." This is known as the Strouhal number and averages between 0.2 and 0.4 for most birds, with a higher number denoting a less efficient flight pattern.
Flight is (for those poor people who we're not opportune to watch it) clearly very efficient, seeming almost effortless. So we’ll go for the lower end of Strouhal numbers in our working, giving us (drumroll please), an airspeed velocity of 11–16 metres per second. That’s 40–60 kilometers per hour.
