Five Inventions of Powered Flight
I will restrict myself to cases where the inventors themselves either do the flying or else can be carried by their inventions. This is intended to rule out such cases as bird lice, berry seeds in bird stomachs, and model airplanes.
I also rule out gliding and parachuting, though these are very common. Spores and pollen are often dispersed by wind, and some plants have seeds with wings (maple-tree seeds;
Acer) or strands (dandelion seeds;
Taraxacum officinale). Likewise, several spider species disperse themselves by "ballooning", spinning strands of silk and letting the wind blow them. Animals adapted for gliding include "flying squirrels" (
Glaucomys), "flying lemurs" (Dermoptera), and "flying lizards" (
Draco); their wings are flaps of skin along their sides. "Flying fish" (
Exocoetus) have their pectoral fins modified into wings for gliding.
The first of the inventions was by insects, back in the Carboniferous Period, 354 to 290 million years ago. Exactly what they developed their wings from has been a source of some controversy, but a solution is emerging: wings are modified gills. Interestingly, some insects grow winglike gills as larvae, and they flap those gills in order to "ventilate" them.
An interesting curiosity of insect wings is that while they have three thoracic segments, with a pair of legs on each one, they only have two pairs of wings, on the two rearward thoracic segments. However, some early insects in Paleodictyoptera (looked something like big cockroaches) had three pairs of wings, though the wings on the first thoracic segment were often much smaller than those on the other two segments. So insects could have started out with growing a wing and a walking limb on each of their thoracic segments, and then suppressing the frontmost wings as they have suppressed their abdominal limbs.
Some early insects grew large wings -- the aforementioned paleodictyopterans with wingspans out to 50 cm and early dragonflies (Protodonata) out to 75 cm. The present-day size champions are some butterflies and moths (lepidopterans), with wingspans out to 30 cm. But most insects, then and now, are much smaller.
Insect wings are usually thin and semitransparent, but many insects have modified their wings from that original structure. Beetles have modified their front wings, making them covers for their hind wings. Dipterans (flies, mosquitoes, etc.) have turned their hind wings into small halteres, which they use as balancing organs. Lepidopterans' wings are covered with small scales, which are colored in a variety of patterns.
And some insects have lost their wings. Ants are wasps whose workers no longer grow wings, and termites have a similar relation to cockroachlike insects. Only the sexually-reproducing phase of aphids has wings; their parthenogenetic phase is wingless. Fleas and lice never have wings.
Some sites on early insects:
Palaeos: Page not foundPalaeos: Page not foundPaleodictyoptera
Advancing to the late Triassic, about 200 million years ago, we find the second invention, by pterosaurs or pterodactyls. Their origin is obscure, though they are likely descended from Triassic two-legged running archosaurs, the sort of reptiles that also became the ancestors of the dinosaurs. Their wings are modified front limbs, with finger 4 extended outwards, and 1,2,3 keeping their claws. The wing surface is outstretched skin. Pterosaurs were diversified, extending from pigeon-sized to huge soarers like
Quetzalcoatlus with a wingspan of over 10 meters. They went extinct in the K-T mass extinction, however.
By the Jurassic, about 150 million years ago, the third invention, by birds, started to appear, notably as the famous fossil
Archaeopteryx (also at
UCMP). This pigeon-sized creature looked much like the small theropod dinosaur
Compsognathus, though with feathers. Its flying ability was likely limited, though later birds made up for that with a larger breastbone and flight muscles. It also had a long tail and teeth -- unlike present-day birds, which have a short tail, no teeth, and a beak.
Bird wings are modified front limbs, with the bulk of their area coming from their long flight feathers. Birds' tails also have long flight feathers; their bodies are covered with shorter feathers.
Birds diversified in the Cretaceous, survived the K-T mass extinction, and diversified again, with flightlessness emerging numerous times in the process.
Also after the K-T extinction was the fourth invention, by bats. They emerged from primitive mouse-ish mammals in the early Eocene, about 50 million years ago, and since then, they have become fairly diversified. Most bats reflect their primitive-mammalian heritage by being nocturnal, but some bats ("flying foxes" or fruitbats) have become diurnal. Their wings are modified front limbs, with skin stretched between their fingers and also their trunk. Nocturnal bats navigate by echolocation; they chirp and listen for their chirps' echoes.
For more, see
UCMP's exhibit on vertebrate flight.
Now for the fifth invention of flight, this time consciously as opposed to emerging by evolution. Being able to fly has been a centuries-old human dream; an early reference to it is the story of Daedalus and his son Icarus in Greek mythology. Daedalus and Icarus wanted to escape from Crete, so Daedalus constructed wings for him and his son, gluing them together with wax. Daedalus warned Icarus to avoid flying too high and getting too close to the Sun, but Icarus did so anyway. His wings' wax got soft, making them fall apart, and he plunged to his death.
Looking back, it's clear that they would not have gotten anywhere near the Sun -- and that the most that could have been constructed with Mycenaean-Greek technology was a hang glider constructed from cloth stretched over a wood frame.
Advancing forward in time, Leonardo da Vinci had scribbled concepts of flying machines in his numerous notebooks, but he never followed up on them. In the eighteenth century, the Montgolfier Brothers made their first hot-air-balloon flight, but that was a sidetrack. But experimentation with gliders and study of bird flight picked up in the nineteenth century, with Otto Lilenthal building and flying an early hang glider in the 1890's -- and being killed when his craft got out of control.
Two bicycle makers, Wilbur and Orville Wright, learned of this aeronautical experimentation, and they decided to join the effort. They did an abundance of R&D:
A wind tunnel, complete with instruments for measuring lift and drag
Movable surfaces for controlling the airplane
Treating propeller blades as a kind of wing
Aluminum-block engines
They selected Kitty Hawk in North Carolina as a good place to experiment with flying, because of its strong winds.
They were not alone; Samuel Langley was also developing a powered airplane. But his two tests, on October 7, 1903 and on December 8, were embarrassing flops, with his airplanes splashing into the Potomac.
On December 14, the brothers tried flying; starting from a downhill run, Wilbur traveled 105 ft before losing control.
But on December 17, both brothers flew four flights.
Orville, 10:35 am, 120 ft, 12 secs
Wilbur, 11:20 am, 175 ft
Orville, 11:40 am, 200 ft
Wilbur, 12:00 noon, 852 ft, 59 secs
Their airplane was wrecked by a gust of wind after their fourth flight, but in the years to come, they flew longer and farther -- and were eventually joined by a lot of competition.
There's some nice history at
http://www.first-to-fly.comFirst Flight Page RedirectionThe Early History of FlightSpecial Collections and Archives | Wright State University Libraries
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