Levin: Flying Machines
Many birds of the Northern Hemisphere are now migrating southward. Every year I marvel at how they manage to stay aloft over such vast distances. Riley Griffin, a graduate of Woodstock Union High School, and now an aerospace engineer, has always been fascinated by what he calls the species-specific nature of flight; each species an engineering marvel honed to near perfection.
As a boy he loved owls; their feathers muffle the sound of flight; their parabolic faces redirect sound. So his mother took him to the Vermont Institute of Natural Science to see a great gray owl - with burning yellow eyes and enough shades of gray to appeal to the ground-breaking black and white photographer, Ansel Adams. Today, Griffin designs manned and unmanned aircraft. “My interests converged,” he says happily.
He tells me that both birds and planes employ thrust to move forward and lift to overcome gravity. An engine gives the plane thrust; wings muscles and flapping give the bird thrust. Both have a thick leading edge to their wings, a shape known as an airfoil. Birds redirect the air with the feathers of their thumb-like alula, mixing high-pressure air from under the wing with low-pressure air from above, critical when a bird slows to land and approaches stall. Planes use leading-edge slats for the same purpose.
To control their aircraft, the Wright brothers studied vultures; their flexing wings inspired the brothers to twist the wings of their aircraft to turn.
To celebrate the hundredth anniversary of the landmark federal Migratory Bird Treaty Act, the National Geographic Society, the National Audubon Society, and the Cornell Laboratory of Ornithology designated 2018 “The Year of the Bird.”
In 1918, Great Britain and the United States agreed to protect North American migratory birds. Mexico joined in 1936, and over the years the law has safeguarded more than eight hundred species, their body parts, nests, eggs, and feathers. But many species are still losing ground, due to human behavior, from habitat destruction to pesticides and everything in between.
And while Griffin reminds me that birds are a source of engineering insight, artwork like Leonardo da Vinci’s sketches of wings proves they have lasting aesthetic value as well.