Things That Fly
Flying has always fascinated me. Humans have only managed free flight for a few hundred years. For “heavier than air” flight (i.e. not a hot-air balloon) we’ve only done it for a little over a century. It took hard work for humans to make it happen. But birds, mammals, insects and even the occasional fish have been flying long before humans ever ever achieved it.
[G2:335 n=1 class=left] Making something fly means solving many engineering problems. One big problem with flying is weight – everything has to be light. A flying machine needs an “engine”, yet the engine can’t be too heavy. It needs to carry its own fuel, but the fuel can’t be too heavy. It needs aerodynamic flight surfaces with structural support. The materials used in the structural support must be strong enough to support the stresses of flight, but still light.
Finally, a flying machine needs to control the flight surfaces to make the thing go in the right direction to do something useful. We may laugh at the way a moth bangs around the front light in the evening, but amazingly, they survive and they do it with a minuscule bit of brain-power. On the other hand, many birds are sensationally beautiful to watch as they gracefully cross the sky.
Birds come in many shapes and sizes, and their design allows them to fly beautifully. Structurally, birds have bones that are light-weight yet strong. Some of their bones are hollow, and have air in the hollow space. The bones have internal “struts” to reinforce them, in a similar way to the struts inside an airplane’s hollow wings.
[G2:327 n=1 class=left]Bird feathers are exquisitely constructed micro-structures. A light hollow main shaft goes up the centre of the feather. From the shaft, soft barbs come off each side. Each barb has “barbules” that hook onto those of the neighbouring barb. The interlocking barbs provide a strong, light flight surface, and together the feathers hold the air on the bird’s downstroke. And yet on the bird’s upstroke, barbs and feathers “unlock” allowing air to pass through.
[G2:331 n=1 class=right]The bird’s feather design makes it possible for birds to fly by flapping. So the aerodynamic surfaces and structures are also the bird’s “engines”. The birds have strong muscles to pull the wings down for the downstroke, and relatively smaller muscles for pulling them back up. And on top of this, the wings and tail are the control surfaces, allowing the bird to control its flight.
After looking at the complex arrangement of bones, feathers and muscles that make up a bird’s wing, the wings of a human-designed airplane look crude in comparison. After looking at the darting flight of swallows, the acrobatics of wattlebirds and the elegant landings of most birds, the flight of airplanes looks simplistic in comparison. What human aircraft can hurtle through a forest, darting quickly and accurately between the branches of trees, to finally land with perfect balance on a particular twig?
We look at a plane and never have any doubt that it is the product of trained engineers, masters of their profession. Surely we must look at any bird and conclude that it has been designed by a master engineer.