Airspeed Velocity of an Unladen Swallow - Wolfram|Alpha
http://www.wolframalpha.com/input?i=Airspeed+Velocity+of+an+Unladen+Swallow
"there is unfortunately insufficient data to estimate the velocity of an African swallow (even if you specified which of the 47 species of swallow found in Africa you meant) (asked of a general swallow (but not answered) in Monty Python's Holy Grail.)"