The world's first flying ornithopter
Last Updated Oct. 12, 2006
Canadian aeronautical engineer and University of Toronto professor emeritus James DeLaurier with the Flapper, the first ornithopter to achieve sustained flight.
It's a bird, it's a plane … actually, it's a plane that flaps like a bird. And it was developed in Canada.
Flapping-wing aircraft, or ornithopters, are one of humanity's oldest aeronautical dreams. Long before Leonardo da Vinci first sketched his human-powered ornithopter design in 1490, people pictured themselves reaching the skies in the same way they observed it occurring in nature — by flapping.
About three centuries after Leonardo, however, the discovery that lift and thrust could be engineered separately made fixed-wing flight possible. It was a breakthrough that relegated the concept of ornithopters to the sidelines of aircraft design.
But something about the possibility of humans achieving flapping-wing flight continued to stir the imagination of innovative souls. A few, like Canadian aeronautical engineer and University of Toronto professor emeritus James DeLaurier, never stopped believing it could be done. That belief led him to build the first ornithopter able to slip — however briefly — the surly bonds of Earth.
DeLaurier's interest in ornithopters surfaced during his teenage years, when he constructed small rubber-band-powered models. After focusing on other things for a few years, his interest was ignited once more by Jeremy Harris, whom he met while both were working as research engineers at Battelle Memorial Institute in Columbus, Ohio. Their designs were built on centuries of ideas — many of them innovative and sound — but none were able to achieve sustained motorized flight.
DeLaurier admits that when he first started seriously considering the problem of building an aircraft that flapped its wings back in the 1970s, "I didn't anticipate it would take nearly this long. It was really difficult."
From the time he started building his ornithopter in 1995, it's been a matter of constant modification, structural strengthening, and overcoming myriad electronic and engine challenges.
It also required funding from more than 20 sources over the years. The total cost is hard to estimate, DeLaurier says, because some donations were not in the form of cash and others were made on the understanding that they would remain undisclosed. The main funding for construction came from Harris, who made a $100,000 donation that was matched by the Canadian government's Industrial Research Assistance Program. Crucial storage and work space was provided by the Toronto Aerospace Museum, and Bombardier provided use of its runway.
DeLaurier's eventual success certainly had much to do with his determination, but it's also a result of the technology now available to aircraft builders. He was able to use this era's electronics, lightweight but strong composite construction materials, and the vast storehouse of aeronautic knowledge developed by the fixed-wing aircraft industry.
For example, the ornithopter's wings are attached to a central section along the fuselage that is moved vertically by the drivetrain of a 24-horsepower König engine, a model often used in ultralight aircraft. And although the ornithopter's wings appear similar to those of a normal aircraft, they are actually built much stronger because of the far greater stresses that must be withstood during flight. To achieve this level of strength while minimizing weight, DeLaurier had the wings constructed of a lightweight but strong composite of carbon fibre and Kevlar.
Even with these advanced materials to work with, he met many challenges before hitting on a successful ornithopter design. By 1999, for example, the Flapper (as it's affectionately known) was able to successfully accelerate by flapping along over flat ground to reach the necessary liftoff speed, 82 km/h, working at a rate of about one flap per second. The problem he still faced, however, was involved with the run-up to liftoff itself.
"First of all," says DeLaurier, "it takes a goodly amount of runway to get to liftoff speed, and we didn't have that much runway." He adds that a conventional runway is about two kilometres long, and the Flapper needed more than that to reach takeoff velocity.
But the bigger problem was that the flapping of the wings produced an oscillating vertical force that caused the aircraft to rise off the ground during the wing's downstroke and come back down during the upstroke.
DeLaurier notes that this bouncing effect, as the ornithopter approached takeoff speed, "is not only extremely stressful to the structure, it also causes the acceleration to cease."
The engineering team was at an impasse. Then one day in 2004, during a visit to his favourite hobby store near Toronto, DeLaurier was introduced to newly available miniature jet engines.
He remembers commenting to the owner as a joke that one of these would most likely allow the Flapper to take off. Then he quickly realized he was probably correct. The thrust of the jets would add to the lift generated by the flapping of the wings.
The wings have three panels (a design patented by Harris); the middle panel of each wing, supported by an outboard vertical link, is moved up and down by the motion of each innermost panel, and in turn, drives each outer panel vertically. The wings of the Canadian ornithopter also passively twist in response to the flapping because of their unique structure, which DeLaurier calls "torsionally compliant in just the right amount … Too little twisting would cause massive stalling, and too much twisting could cause the wing to act in a ‘windmilling' mode, actually taking energy from the flow."
The team modified its computer simulation to incorporate the jet boost along with the wing design, and the resulting data pointed to success.
The day of reckoning approached. After initial testing with a tiny jet installed in June 2006, the Flapper was finally ready for the full test flight at Downsview Airport in Toronto. It was a critical moment in many ways, not least because it was the eve of DeLaurier's retirement.
The 65-year-old engineer was well aware before the test that yet another glitch could easily surface, and he says he remembers thinking, "I had been so inextricably linked to this project with my career … If it didn't fly, it would have been lame. Further, a mishap would have been hard to live with."We have liftoff
After several trial runs along the airstrip, the pilot went full throttle at 10:20 a.m. on July 8, 2006, flapping faster and faster down the runway. The ornithopter took off, flying about one metre above the ground for 14 seconds for a distance of about 300 metres — beating by two seconds the first flight of the Wright brothers' powered plane in 1903.
"I went nuts," laughs DeLaurier.
But it wasn't a perfect debut for the Flapper. After about 10 seconds of fairly straight and level flight, test pilot Jack Sanderson felt the plane roll suddenly due to a structural buckling of the left wing. Sanderson quickly throttled back and brought the Flapper down. However, the plane's roll angle was large enough that he could not prevent the left wing tip from touching the runway. The aircraft then spun around before hitting its nose on the ground and coming to a gradual stop.
DeLaurier says the expertise and feedback of a pilot like Sanderson, with considerable experience dealing with yaw-roll and flying ultralight aircraft, was invaluable in completing the first ornithopter flight safely.
For his part, despite the technical problem, Sanderson says that once the aircraft was in the air, "the ride was surprisingly smooth and stable."
The flight proved that an ornithopter design is able to take off from a ground roll. It was "largely due to using a boost from the jet engine," says DeLaurier, "but I should say that the jet alone could not even come close to sustaining the aircraft. The flapping still did most of the work."
Being the first to achieve successful, sustained flapping-wing flight has earned DeLaurier respect from the engineering community, and generated valuable aeronautic data. He considers his contribution to aviation history "a privilege … trying at times, stressful at times, but nonetheless a worthy quest."
However, the engineer says he won't miss the constant worry over the project, nor the well-meaning but misinformed suggestions he routinely received over the years. He also is glad he no longer has the stress of trying to operate on a minuscule budget. He estimates that those who try to take the project to the next level — using bigger wings to sustain flight without a jet engine — will need about $100,000 to fund research and construction. He knows of no other ornithopter research project currently taking place.
The Flapper's body currently sits in its hangar at Downsview, and the wings are being repaired in DeLaurier's university lab, which will remain open as long as DeLaurier can find a little funding.
If his ornithopter odyssey ends here, DeLaurier says he is satisfied. While the ornithopter has no foreseeable practical application in terms of commercial flight, DeLaurier's research has yielded valuable data on a number of important topics. Data gathered on unsteady aerodynamics may be used by researchers designing flapping-wing micro-aircraft in the years to come. Researchers will also be able to use DeLaurier's data on aero-elastic tailoring and the performance of composite materials under stress.
And then there's the personal sense of accomplishment, he adds. "The flight on July 8 crosses a psychological barrier regarding the feasibility of a full-scale flapping-wing aircraft … the Flapper's few seconds of sustained flight brings this notion from the realm of fantasy into the realm of reality."
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