DOC Farrow
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Q

What is the average airspeed of an African Swallow?


DOC Farrow responded on 04/27/2015
A

Depends on which of the 47 Varieties in Africa. About 24 MPH
What kind of African Swallow? There are 47 varieties of swallows found in Africa. I will assume you mean either the West African Swallow (Hirundo domicella) or the South African Swallow (Hirundo spilodera) as they have "African" in their common names. Lucky for us, they are roughly the same size in terms of body mass, wing span, and flight mechanics.
In order to figure this out, we want to establish a Strouhal ratio which is the frequency (f) of wing beats and amplitude (A) of each wing flap. With those two numbers, it will be possible to estimate airspeed (U) for a cruising bird. (fA/U) if you will. So, with a frequency of wing flaps of about 7 times per second (which has played itself out in the Philos-O-Tron Wind Tunnel Testing Area) and an amplitude of .18m per flap (given that the average wingspan of this particular avian is around 29cm) that would yield an airspeed of roughly 11 m/sec or 24 mph assuming the swallow is u

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