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Topic	ce i'd like to answer your most pressing questions - AMA
Harpie 10/12/17 9:33:27 PM #25:	Zeeak4444 posted... What is the airspeed velocity of an unladen swallow? To begin with, I needed basic kinematic data on African and European swallow species. left: South African Swallow right: European Swallow Although 47 of the 74 worldwide swallow species are found in Africa,1 only two species are named after the continent: the West African Swallow (Hirundo domicella) and the South African Swallow (Hirundo spilodera), also known as the South African Cave Swallow. Since the range of the South African Swallow extends only as far north as Zaire,2 I felt fairly confident that this was the non-migratory African species referred to in previous discussions of the comparative and cooperative weight-bearing capabilities of African and European swallows.3 Kinematic data for both African species was difficult to find, but the Barn or European Swallow (Hirundo rustica) has been studied intensively, and kinematic data for that species was readily available. Its a simple question of weight ratios A 54-year survey of 26,285 European Swallows captured and released by the Avian Demography Unit of the University of Capetown finds that the average adult European swallow has a wing length of 12.2 cm and a body mass of 20.3 grams.4 Because wing beat frequency and wing amplitude both scale with body mass,5 and flight kinematic data is available for at least 22 other bird species,6 it should be possible to estimate the frequency (f ) and amplitude (A) of the European Swallow by a comparison with similar species. With those two numbers, it will be possible to estimate airspeed (U). In order to maintain airspeed velocity, a swallow needs to beat its wings forty-three times every second, right? Actually, wrong. By comparing the European Swallow with bird species of similar body mass, we can estimate that the swallow beats its wings 18 times a second with an amplitude of 18 cm: SpeciesBody massFrequencyAmplitude Zebra Finch13 g27 Hz11 cm European Swallow20 g 18 Hz? 18 cm? Downy Woodpecker27 g14 Hz29 cm Budgerigar34 g14 Hz15 cm Note that even the tiny Zebra Finch flaps its wings no more than 27 times a second while cruising. If we ignore body mass and look only at bird species with a similar wingspan, we can estimate an average frequency of 14 beats per second and an amplitude of 23 cm: SpeciesWingspanFrequencyAmplitude Budgerigar27 cm14 Hz15 cm European Swallow 2830 cm 14 Hz? 23 cm? Downy Woodpecker31 cm14 Hz29 cm European Starling35 cm14 Hz26 cm By averaging all 6 values, we can estimate that an average European Swallow flies at cruising speed with a frequency of roughly 15 beats per second, and an amplitude of roughly 22 cm. --- hi there :3 1264-1315-8952 \| Anna <cite>Harpie posted [p:888328243] in ce i'd lik... [t:75873011]...</cite> <quote><cite>Zeeak4444 posted...</cite> <quote>What is the airspeed velocity of an unladen swallow?</quote> To begin with, I needed basic kinematic data on African and European swallow species. left: South African Swallow right: European Swallow Although 47 of the 74 worldwide swallow species are found in Africa,1 only two species are named after the continent: the West African Swallow (Hirundo domicella) and the South African Swallow (Hirundo spilodera), also known as the South African Cave Swallow. Since the range of the South African Swallow extends only as far north as Zaire,2 I felt fairly confident that this was the non-migratory African species referred to in previous discussions of the comparative and cooperative weight-bearing capabilities of African and European swallows.3 Kinematic data for both African species was difficult to find, but the Barn or European Swallow (Hirundo rustica) has been studied intensively, and kinematic data for that species was readily available. Its a simple question of weight ratios A 54-year survey of 26,285 European Swallows captured and released by the Avian Demography Unit of the University of Capetown finds that the average adult European swallow has a wing length of 12.2 cm and a body mass of 20.3 grams.4 Because wing beat frequency and wing amplitude both scale with body mass,5 and flight kinematic data is available for at least 22 other bird species,6 it should be possible to estimate the frequency (f ) and amplitude (A) of the European Swallow by a comparison with similar species. With those two numbers, it will be possible to estimate airspeed (U). In order to maintain airspeed velocity, a swallow needs to beat its wings forty-three times every second, right? Actually, wrong. By comparing the European Swallow with bird species of similar body mass, we can estimate that the swallow beats its wings 18 times a second with an amplitude of 18 cm: SpeciesBody massFrequencyAmplitude Zebra Finch13 g27 Hz11 cm European Swallow20 g 18 Hz? 18 cm? Downy Woodpecker27 g14 Hz29 cm Budgerigar34 g14 Hz15 cm Note that even the tiny Zebra Finch flaps its wings no more than 27 times a second while cruising. If we ignore body mass and look only at bird species with a similar wingspan, we can estimate an average frequency of 14 beats per second and an amplitude of 23 cm: SpeciesWingspanFrequencyAmplitude Budgerigar27 cm14 Hz15 cm European Swallow 2830 cm 14 Hz? 23 cm? Downy Woodpecker31 cm14 Hz29 cm European Starling35 cm14 Hz26 cm By averaging all 6 values, we can estimate that an average European Swallow flies at cruising speed with a frequency of roughly 15 beats per second, and an amplitude of roughly 22 cm. --- hi there :3 1264-1315-8952 \| Anna</quote> ... 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