Anthony B. Wight
-
“The airplane is of course only a machine, but what an instrument of analysis! This instrument has shown us the oral face of the earth . . . Up here, observing man from our portholes, we find ourselves judging him on a cosmic scale . . .
We find ourselves rereading our own history.
’’
____
—Antoine de Saint-Exupery (Canby, p.6)
“Rereading history’’ is really the underlying task of our Daedalus odyssey. What we seek to establish or perhaps simply remind ourselves of is the connectedness between human imagination and human powered flight. With Cayley’s publishing in 1809 (Canby, p.16) of the first realistic theory of the airplane, a means was available for analyzing all previous attempts at flight and for scientifically pursuing all subsequent developments. Taking the four forces into account, we can go back even to the first Daedalus “flight’’ and see that his thrust and lift devices were inadequate for the task of overcoming the burdens of his weight and drag. It is also possible to see why Cayley is the “father of the modern airplane’’. Though he did not build a successful prototype, he made clear the obstacles to be overcome and even provided the design formula: lighten the ship’s weight; make a rigid wing (airfoil) to provide lift; provide a separate mechanism (engine) to produce thrust; stabilize (and also reduce drag) with a tail assembly.
All that was needed after Cayley were relatively small advances in the airfoil and engine design and the modern airplane was born. Our story could end here with the triumphal inauguration of the era of motorized flight at Kitty Hawk. However, one final chapter in the Daedalus cycle must be accounted for. While the vast majority of aircraft design and development followed the route of harnessing ever larger engines to larger and more streamlined airfoils, another path of development pursued the design of radically increased lift and reducing weight to enable the thrust required to fit within the scale of output by a “humane engine’’. Only in the past 25 years has the human powered aircraft come into its own, relying on advances in a combination of essential technologies: aerodynamics, propulsive, and structural.
A series of international competitions sponsored by a few organizations and individuals did much to stimulate human powered flight. The first great competition took place in France between 1912 and 1922, sponsored by the Peugeot company. It resulted in aircraft that were described more as “jumping bicycles’’—the pilot pedaled hard to get up ground speed and then the craft would glide in the air for about 12 meters. Once airborn there was no way to add to the thrust. In 1935 German, Italian and Russian prizes were offered for the first human power flight around two posts set 500 meters apart. None of the prize money was claimed, but new designs were shown capable of several hundred meters of propeller driven flight if launched by catapult.
The most renowned competitions and the ones which have spurred significant technological progress have been sponsored by a British manufacturer, Henry Kremer. In 1959 he offered a prize of 5,000 pounds to the first entrant to fly around a one-mile, figure eight course under human power alone. 18 years passed and the prize money increased to 50,000 pounds before Bryan Allen of the United States successfully flew Paul MacCready’s
Gossamer Condor
around such a circuit. Kremer then offered the largest prize in aviation history, 100,000 pounds for a human-powered flight across the English Channel. Again the winner was Allen, pedalling the
Gossamer Albatross
across the 21 mile strait on June 12,1979. Seeking to encourage smaller and faster craft, Kremer offered yet another prize, 20,000 pounds to the first contestant who would complete a 1,500 meter triangular course in less than 3 minutes—an average speed of nearly 20 miles per hour with some technically challenging turns. This prize was won in May, 1984 by Frank Scarabino in the
Monarch
, a craft designed and built at the Massachusetts Institute of Technology.
In each Kremer competition, the designers faced a common problem: how to reduce the power required by the aircraft to the amount available from a human being. This amount varies widely according to the person’s age, training and motivation. A well-conditioned athlete can produce up to one kilowatt (about 1.3 horsepower) for short periods of time or a few hundred watts for several hours. (Drela and Langford,
Scientific American
, Nov’85)
Since the power required by an aircraft is the product of its aerodynamic drag and its velocity, low power can be obtained by building a craft with low drag and flying slowly. The wing is an aircraft’s main aerodynamic surface. Since it creates most of the drag, its shape must be as efficient as possible. New materials such as graphite and graphite-epoxy have enabled builders to make large, lightweight fixed wings and by covering surfaces with mylar film drag can be minimized.
Following the successful capture of the Kremer prize in 1984, the MIT design team began to prepare for their ultimate challenge—the reenactment of the Daedalus flight from Crete. Preparations were extraordinary. To build and test the 70 pounds aircraft took 15,000 hours and one million dollars. Five athletes—bicycling champions—were selected and put through rigorous training and endurance tests. The pilot of the craft would pedal a mechanism which operated through two gear boxes and turned an 11-foot, superlight propeller to provide thrust for the craft. The length of the flight and low speed required that the operator maintain a high level of pedalling power for nearly five hours—not unlike running two back-to-back marathons. Even a new beverage was developed for the flight to replace the perspiration and minerals sweated off by the pilot.
Finally, at 7:06 A.M. on a sunny Saturday last April, the ultralight
Daedalus 88
was propelled down the runway of an airfield in Heraklion, Crete, bound for the volcanic island of Santorini 74 miles away. The pilot and “power’’ of the plane was Kanellos Kanellopoulos, 31, winner of 14 Greek national cycling championships. Aided by a mild tailwind, the plane advanced at a graceful 18.9 miles per hour. Just three hours and 54 minutes after takeoff, the craft approached the beach of Santorini. Suddenly an offshore gust caught the craft bringing it up into a stall and snapping off its tail. The Daedalus plunged into the sea 30 feet from shore. Undaunted, Kanellopoulos swam to shore, the holder of three world human-power flight records:
____
1. Longest straight-line flight (74 miles).
-
____
2. Longest absolute distance flight (74 miles).
____
3. Duration aloft: 3 hours, 54 minutes.
Perhaps, we might say, in the spirit of this unit, he also attained the record for completion of the longest known odyssey!
