Monty Python and the Holy Grail still continues to amuse today, and the question remains, what is the airspeed of an unladen swallow?
If you are having trouble remembering, be sure to watch the short clip above of the comedic scene. The discussion also arises when questioning how 2 halves of a coconut ended up in Europe, with the proposition that a swallow carried a coconut from the tropics. This discussion can be found in the video below.
With the background out of the way, let’s calculate what the airspeed of an unladen swallow is.
First, we need to determine which birds to examine as best fits for those discussed in the movie. There is, in fact, a European swallow, but there is no swallow specifically named the African Swallow. However, there is a South African swallow which is likely the best fit when discussing an African swallow. One problem arises when discussing the African swallow, there is almost no data recorded that can give us any indication of its airspeed. Rather than make blind guesses, we will look into the European swallow’s capabilities.
Believe it or not, the European swallow has been extensively studied throughout history. According to research from the Avian Demography Unit of the University of Capetown, the average European swallow has a length of 12.2 cm and a mass of about 20 grams. Gathering information mentioned in the videos above, it is estimated that a European swallow flaps its wings 43 times every second in order to maintain the necessary airspeed velocity. Examining research by C.J. Pennycuick titled Predicting Wingbeat Frequency and Wavelength of Birds, we can find relevant data to the European swallow. While the European swallow wasn’t examined exactly in his study, a swallow of the same average weight was. This 20-gram swallow was found to flap its wings about 12 times every second with an amplitude of 20 cm each time. Strike one for Monty Python.
Now that we have the number of beats per second of the swallow’s wings and the amplitude, we can begin estimating the airspeed. Each beat of the swallow’s wings carries it some distance forward. There is no way to know exactly how far the average European swallow’s wing flap propels it, but we can estimate about .75 meters per beat according to various studies. When we take the number of beats per second (12) and multiply it by the distance per beat (.75), we get a value for velocity of 9 meters per second. Translating this into miles per hour, we see that the airspeed velocity of a European swallow is 20.1 mph.
Now that we understand the airspeed, let’s assume that theoretically, a European swallow could find a coconut in its normal habitat. Would it even then be possible for a swallow weighing 20 grams to pick up a coconut and transport it to Europe?
Since we’re already dealing with an absurd scenario, let’s imagine that the swallow found the world’s smallest coconut ever recorded, weighing in at 3.847 grams, according to the India Book of Records. So then, the question becomes can a 20-gram swallow carry a 3.387-gram coconut?
Despite the incredible improbability of the scenario, it would theoretically be possible for a large European swallow to somehow come across an incredibly small coconut and carry it to the destination where King Arthur would have found it. As it turns out, Monty Python has a little bit of truth in it, but only just barely.