This group is working out themechanics of bird flight across the species and reading through just this bitreveals astounding possibilities. Some ofit may one day find it into equipment humanity can use.
A good start would be the designof an artificial pectoral muscle capable of the power output needed. The geometry and configuration is able toprovide flight security to the user and make such an artificial flight systemvery attractive.
Recall my posting on the flightdynamics of the great horned owl and its likely family member, also known asMothman. We still need an order ofmagnitude scaling to achieve human flight capability, but that is no longer impossibility. Nature does come close and we do want trueflight capability.
Such a system would allow landingon any open space with modest training and extended flight times burning energyonly to gain height. Of course, this isa true pleasure device whose practical value will be marginal in terms ofpersonal transport, though its availability will certainly create the optionfor true aerial commutes.
Perhaps the ultimate replacementfor personal commuting is such a device. A sky full of giant ‘birds’ is not a dumb idea and the advent of electricalcars is getting us close to the energy supply technology.
Flying Machines, Amazing at Any Angle
Bret Tobalskes
ON THE WING The wake of a hovering rufous hummingbird, top. Yellowvectors show air velocity, revealed by particle image velocimetry. The mist inthe background is a cloud of laser-illuminated olive oil droplets.
By JIM ROBBINS
Published: January 3, 2011
MISSOULA, Mont. — The flying abilities of even the most prosaic birdput airplane maneuvers to shame, and experts here at the University of Montana Flight Laboratory arecognizant of that every day.
“Birds can do some pretty spectacular things,” said Kenneth P. Dial, a biologistwho, in 1988, founded the lab at a field station near the University of Montana
Dr. Dial and BretW. Tobalske, a biologist and the director of the lab, are obsessed withtrying to bridge the gap in flying abilities between humans and birds. At alaboratory filled with wind tunnels, high-speed cameras, lasers, surgicalequipment and a device that generates clouds of olive oil, they and severalgraduate students try to divine the secrets of bird flight.
In a quiet field, Dr. Dial, 57, with a shaved head and goatee, standsout with his evangelical zeal about understanding bird flight. He has hosted atelevision show on adventures in bird-watching, and is so enthusiastic aboutflight that he and his son, Terry, also a biologist, are planning to fly aroundthe world as pilot and co-pilot.
Dr. Dial’s 28 years of studying the functional morphology of all kindsof birds have led him and others at the lab to numerous insights into ecology,biodiversity, airplane design, aerospace and even paleontology. In a recentpaper, Dr. Dial and a graduate student, Brandon E. Jackson,presented a novel idea about how some dinosaurs used their proto-wings — apossible step in the evolution of flight. They based their paper on theobservation of day-old Australian brush turkey chicks.
The laboratory, at Fort Missoula , was once a stable for the United States Montana
Dr. Dial says some of his most important observations have been madewatching a bird glide by while he is fly fishing, and then heading back to thelab with a new theory to test.
After observing woodpeckers in the lab’s wind tunnel both flying and“bounding” — gliding missilelike with their wings tucked, a behavior notpreviously identified in these birds — Dr. Tobalske was able to see the samegliding a few hundred yards out the door, which confirmed it was not a productof lab conditions.
One key to the insights here is a small, dark room with two1,000-frames-per-second cameras, developed by the military to study ballistics,which slow high-speed action in high resolution. Wild birds in flight aremisted with a fog of vaporized olive oil, which is illuminated by a greenstrobing laser operating in tandem with the camera. The system allowsresearchers to track the movement of misty air around the birds, showing wherethey are generating lift and drag. It led to the discovery here of a vortex onthe leading edge of bird wings, which adds to a bird’s lift.
The birds, ranging from delicate diamonddoves to burly ravens, have crystal sensors surgically implantedin their pectorals and elsewhere that measure muscle contractions as they fly.
“Pectorals are the motor for 80 percent of flight,” said Dr. Tobalske,which explains why they are the largest part of the anatomy. “That’s how birdsgenerate enormous power and can resist fatigue, and why some can fly from onepole to the other” without stopping.
Birds are also put in wind tunnels and photographed at high speed soresearchers can see in detail how they perform at 20 miles per hour or more.They are also fitted with tiny masks that measure metabolism.
CT scans are used on birds to tease out the hidden physics of flying.Using technology developed at Brown University, researchersscan birds’ bones and combine that with three-dimensional X-rays taken inflight. Together they create a very real animation of a bird in flight. “Itgives you three-dimensional joint movement,” said Ashley Heers, a doctoralstudent doing the work.
Dr. Tobalske said, “These tools allow us to see things that have alwaysbeen dreamed about.”
The lab has won National ScienceFoundation funding for 25 years, and published dozens of papers.
“This has been a classic area of research since Leonardo da Vinci,”said Richard O. Prum, aprofessor of ornithology and ecology and evolutionary biology at Yale. “Functional morphologyis being left behind in a lot of places, but it’s important and they are doingsome great stuff.”
Work at the Montana
For example, birds clap their wings together at the peak of theupstroke during takeoff — that’s the clatter of a pigeon taking off in the park— and rotate their wings on the way down to get lift. “The wings suck in air,like a fan,” Dr. Tobalske said, “and create a jet of air below it traveling at10 miles per hour.”
The most astounding fliers, in Dr. Tobalske’s opinion, are the world's350 or so species of hummingbirds, which, largely because of their size, havemastered flight like no other bird. The calliope hummingbird weighsonly as much as two paper clips, yet it migrates annually between Canada and Mexico
In fact, a major theme in research here is how the morphology of thebird influences its behavior. The smaller the bird, for example, the more agilethe flying — a swan may need the equivalent of two football fields to take offand get lift, while a hummingbird can rise like a helicopter. “It’s like aPorsche that can drive circles around a semi,” Dr. Tobalske said.
“The smaller the bird, the moreviscous the air is,” he said, which is partly why hummingbirds can maneuver sowell and for so long. They have evolved with greatly shortened wing bones, aswell as large pectorals that allow them to beat their wings 80 times a second.“A hummingbird can hover like a helicopter for one and a half hours, nonstop,”Dr. Tobalske said. “No other bird can do that.” By comparison, pigeons produceone-tenth the number of strokes.
Implanted sensors show that a hummingbird’s wing flaps so fast that thebrain is generating the muscle signal for the downbeat of its wing while thewing is still going up.
These new, deeper views into winged flight have affected other studies.Almost as an aside, the study of birds — which are widely believed to bedescendants of some dinosaurs — has led Dr. Dial to a novel hypothesis.
The one-day-old Australian brush turkey, hesays, may behave as theropods once did. Theropods were early winged andfeathered dinosaurs that walked mainly on their hind legs and were incapable offlight.
Ground-nesting birds like the brush turkey are precocial — they hit theground running when they are born, a crucial defense from predators. A day-oldbrush turkey can run straight up a rock wall or a tree, an ability thatdiminishes as the bird gets older.
A key to this early skill is flapping its small wings. This is not totry to fly, Dr. Dial said, but to serve the same role as a spoiler on a racecar: to keep the bird on the ground so it can generate more force with its feetand climb steep walls. Dr. Dial calls it “wing-assisted incline running” andhas high-speed videos of ground birds running up walls.
When the birds arrive atop a rock, and any threats have passed, theyjump to the ground using their wings to slow the descent; that is how Dr. Dialbelieves flight may have begun. “This form of behavior — independence, locomotorcapacity, parental care and development — could be similar to the life historyof the theropod,” he said.
Dr. Prum called the idea intriguing. “He’s demonstrated the phenomenaexists and it’s plausible,” he said. “But other plausible alternative claimsare out there.”
As far as birds informing human flight techniques, Dr. Dial said hebelieves that the future of human flight will incorporate birds’ remarkableshape-shifting abilities. “Birds are constantly morphing, and morphing ondifferent levels,” he said.
“A bird can look like a bullet, and two milliseconds later looks like ahang glider,” Dr. Dial said. “We have a lot more to learn about that. Imagine a747 blasting off its wings and tail to become a bullet.”
Post a Comment