While only in elementary school, Ken Blackburn settled on airplane design as a life study and began to shape his future in paper. He crafted reams of paper airplanes to learn the rudiments of aerodynamics. Experimenting for years with variations on a fundamental airplane made from a square sheet of paper, he learned about concepts that most people don’t encounter until they train to be pilots or study aerodynamics: dihedral angles, sink rates, and lift-to-drag ratios.
Through generations of folded aircraft, the youngster’s ideas evolved. He added pinpricks to wings, for example, to produce turbulent airflow so air wouldn’t “stick” to wing surfaces; later the tiny holes were dropped in favor of horizontal wing creases, which eventually gave way to diagonal creases.
In 1983, a year before earning a bachelor’s degree in aerospace engineering from North Carolina State University, Blackburn earned a spot in the Guinness Book of World Records for longest paper airplane glide time. He subsequently raised that Guinness standard three times, and his last record-setting flight—27.6 seconds—has stood for a decade. In 1994 he published several of his designs in The World Record Paper Airplane Book (Workman Publishing Company).
By some measurements, Blackburn has progressed little. Today a 45-year-old designer of military unmanned aerial vehicle prototypes, he works on pilotless craft so tiny their weight is measured in ounces and so slow they test the lower limits of aerodynamics. He and other engineers at the Air Force Research Laboratory, located at Eglin Air Force Base in Florida, labor in a branch of aeronautical engineering that in recent years has grown exponentially: Thousands of hand-launched UAVs, small enough to be carried in backpacks, have been deployed on surveillance missions in Iraq and Afghanistan.
Only a few inches in wingspan and about 15 ounces separate Blackburn’s recent professional project—BATCAM, an acronym alluding to the craft’s mission as an airborne battlefield camera—from the gliders he creates out of 8- by 11-inch sheets of paper. And, in fact, the bedeviling exigencies of low-speed flight are common to both types of craft and are studied and resolved in strikingly similar ways.
Blackburn, for example, designed paper airplanes systematically: A model was folded and flown, its flight assessed and its design tweaked accordingly. Then the redesigned airplane was flown, followed by more tweaking and more flying. Blackburn called it trial and error.
BATCAM, developed for the Research Laboratory’s Munitions Directorate, was engineered in much the same way, but professionals call it “the spiral method.” This development process also relies on iteration, albeit a more sophisticated variety, with an initial prototype being computer-designed, built, and tested, then an improved prototype built and tested, then a third, and so on.
When Blackburn joined Jacobs Engineering at Eglin, the original BATCAM prototype had been delivered. He helped develop the first improved model. Air Force Special Forces stationed at Hurlburt Field, Florida, tested eight of the aircraft in 2006.
“The Air Force and I are in agreement that you learn a lot by going out and testing,” Blackburn says. “I can generate a new tail shape, design it on the computer, and within a week have a prototype constructed and ready to fly. When you are working on a small airplane, and have all the tools, prototypes can come very quickly.” (Blackburn’s experience with flight is not limited to tiny aircraft. He has flown ultralights and at least once a week flies his Piper Warrior.)
Paper airplanes taught Blackburn that air is a real drag on light, slow-moving airframes. In order to be useful in the field, a small UAV must have an engine powerful enough to produce maneuvering thrust in buffeting winds. “Wind is a problem,” says Blackburn, and an especially daunting one for micro-vehicles. “For a bug, I guess going with the wind is okay,” he says, “but if you want to see what’s on the other side of the hill, an unmanned vehicle sometimes has to fly against the wind.”