Return of the Pterosaur

By Jamie Murphy

For millions of years, gigantic flying reptiles with 36-ft. wingspans, believed to be the largest creatures ever to take to the air, soared on the warm thermal updrafts above the badlands of West Texas. Then, some 65 million years ago, along with their cousins the dinosaurs, pterosaurs disappeared from the earth forever. Well, not exactly forever. If Aeronautical Engineer Paul MacCready has his way, the winged reptile--or at least a good likeness of it--will fly again. MacCready, 59, designer of the Gossamer Albatross, the human-powered aircraft that flew across the English Channel in 1979, is building a full-scale, mechanical, wing-flapping pterosaur that he hopes will swoop slowly over the Washington Mall some time next summer.

Why resurrect the pterosaur? The Q.N. project (for Quetzalcoatlus northropi, the pterosaur's scientific name), says MacCready, represents an ideal meshing of zoo and museum. "If you can make something that moves around but gives you the feeling of a prehistoric creature, then people experience it; they feel it much better."

MacCready began thinking about the undertaking after the Albatross's successful channel crossing and in July 1984 assembled 25 experts in paleontology, aeronautics and other disciplines for a two-day workshop at the California Institute of Technology. Their consensus: the idea was possible, especially if MacCready was in charge. After the Smithsonian Institution's National Air and Space Museum and Johnson Wax Co. agreed to finance the $480,000 project, the engineer and a team of 20 technicians went to work.

The first phase, completed in February, was to begin aerodynamic testing by building several gliders with adjustable wings. In Phase 2, larger mock-ups were first mounted on vans, then flown from tethers like huge kites. MacCready's team will soon assemble a half-scale model of the creature, including flapping wings and flight-control mechanisms for stability. The technicians have already finished one wing, with rubbery skin pulled tight against tubular composite bones and a clawlike appendage halfway down one edge. They plan to achieve "fully controlled, climbing, flapping flight" by fall. By winter MacCready hopes to test a full-size replica with a finely detailed head and realistic skin and hair.

If all goes well, the mechanical reptile's first public flight will help promote the premiere of a Smithsonian film titled On the Wing. Says Brian Duff, the Air and Space Museum's associate director of external affairs: "If we can pull this off, it will be a beautiful exhibit of building a machine that replicates nature." But it will be much more. "We're getting a high scientific return as well," says Duff, "both in aerodynamics and on the paleobiologist's side."

Indeed, the construction of the first models raised questions for the project's paleontological team, headed by University of Texas at Austin Professor Wann Langston. MacCready's engineers wanted to know how the animal moved and how far forward it could swing its wings. Did it have webbed feet? (Answer: no.) Did it have a tail? (No.) Could its head have been shaped differently from what was previously thought? (Unresolved: only a few fragments of the skull have been recovered.) Each question sent the paleontologists back to examine the fossilized remnants of the giant pterosaur, which were discovered in 1971 scattered over a half-acre of West Texas arroyo. Says Langston: "The project has refined our observations on the way the pterosaur's joints functioned and how the joints were oriented."

To fly, the huge creature had to be remarkably light for its size, possibly only about 140 Ibs. Its wing bones were hollow tubes, and its body structure must have evolved for minimum weight. To emulate nature, MacCready's design team is using strong but lightweight parts made of carbon-fiber tubing and Kevlar cloth.

The pterosaur's lack of a tail posed another serious challenge to the engineers; a movable, horizontal tail surface increases the stability and control over pitch (the nose angle, up or down) of a flying object. But MacCready observed that other flying creatures, like the albatross, achieve stability and pitch control by instinctively making small fore and aft movements with their wings. His solution: the latter-day pterosaur will have an onboard computerized autopilot that will effect similar corrections in the attitude of its mechanical wings. That will take some doing. Explains MacCready: "Nature's creatures are very good at active control. Artificial creatures are very bad. For example, any dumb person can walk across a rough field, but to make a robot who can walk across that same field is really difficult."

In spite of the many challenges, MacCready has little doubt that by recreating the original pterosaur's design, the Q.N. team will succeed. Says he: "Nature does nothing that is stupid. The only purpose of those huge wings would be to fly, and there is a certain amount of evidence that the pterosaur could fly pretty well." Paleontologist Langston is equally optimistic: "We fully expect this model to fly," he says. "If anyone can do it, MacCready can." --By Jamie Murphy. Reported by Jay Branegan/Washington and Melissa Ludtke/Los Angeles

With reporting by Reported by Jay Branegan/Washington, Melissa Ludtke/Los Angeles