The airspeed velocity of an unladen swallow depends on the species of the swallow. If you are referring to the African Swallow, there is a famous reference from the movie "Monty Python and the Holy Grail" in which the airspeed velocity of an unladen African Swallow is said to be about 24 miles per hour or 11 meters per second. However, if you are referring to a different species of swallow, the airspeed velocity may be different.