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| | | WAS IT A BIRD OR WAS IT A PLANE
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Go to the Listen Again page | | | | | Designers of modern aircraft can learn much from the avian experts. | | | |
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Howard Stableford celebrates the centenary of the first powered flight by investigating the influences that birds have had on the way we fly. From the earliest observations of Aristotle weβve always been fascinated by the act of flight, but itβs taken us many centuries to work out how birds do it, and even longer to reproduce their methods.
| | |  | | Howard Stableford
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Aristotle believed that birds flew by compressing the air beneath their wings, using it as a way to propel themselves forward. Thanks to the discoveries of Isaac Newton, we now know that every downstroke has an opposite reaction which lifts the wing and so, provided that the bird is powerful enough and light enough, it can move forward by creating airflow over its wings.
Birds are not only light, but very strong and their muscles have evolved to push themselves through the resistant air. Early human fliers believed that they could fly simply by attaching large wings to their arms, but discovered to their cost, that it wasnβt that simple. Itβs been calculated that a person would need a six-foot breastbone to accommodate the muscles to help him or her fly. For Howard the nearest thing to becoming a bird is to first observe them at the sea-cliffs of South Stack on Anglesey. Here he watches fulmars, cruising without flapping, in the upwelling air around the cliff-face and sees choughs tumble effortlessly in the turbulence.
And later, he gets airborne himself as he joins glider pilot Danny Goldsworthy over the Cotswold Hills, where buzzards and pilots join each other in the same thermals.
The real key to successful human flight has been the separation of the means of lift from the means of propulsion. The Wright brothers at Kitty Hawk had developed gliding wings by watching turkey buzzards soaring near their home, but their first powered flight in 1903 was a step away from influence by birds. Now we understood the principles of powered flight, we could develop bigger and faster aeroplanes capable of travelling farther and carrying more weight.
Airbus engineer Neil Scott tells Howard about the aerodynamics of the new Airbus which can seat around 600 passengers and travel huge distances. Its fuel load can be distributed around the wings and tailfin, but even so, there are birds which do it even better. The Bar-tailed Godwit, a delicate wading bird breeding in the Alaskan tundra, flies 10,000 kilometres to its wintering grounds in New Zealand, sometimes virtually non-stop. It puts on weight before it sets off, but can also burn its own guts and other internal organs if it needs to, the equivalent of a plane burning its own engines or sacrificing several rows of passengers.
Now birds are coming into their own once again, as flying machines become smarter and smaller. Scientist still have a lot to learn about how air flows over the wings of birds, especially small ones. Until recently this wasnβt important, but now as smaller and smaller craft are developed, their aerodynamics may depend on the observations of how birds fly in wind-tunnels. Dragonfly-sized reconnaissance planes which can fly through air-ducts are now being developed and the methods used to power them may well draw on real birds or insects. The movement of feathers has implications for developers of so-called βsmart materialsβ which adjust to tiny changes in air pressure.
As our mastery of the air becomes ever more sophisticated, we leave the birds behind at our peril.
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