Paper airplanes have unlocked the science of flight for centuries. Now, they could inspire the design of future drones.
Paper airplanes are great fun to make, and fly. However, I had no idea the lengths to which people would go to launch their paper creations: There is a plan afoot to launch a paper airplane from the International Space Station (ISS), believe it or not.
Chinese engineers are thought to have invented the equivalent of paper airplanes over two thousand years ago, but these efforts resembled kites rather than what we know today as paper airplanes. There were probably many other undocumented incarnations in the art of making paper airplanes over the intervening years, both as examples of scientific research, and just as fun projects: more darkly, and most likely, someone would also have thought of using them in warfare, such is the way the human mind seems to think.
The major step forward, of which most of us are aware, came from Leonardo da Vinci, in the late 14th and early 15th centuries. He built paper versions of his aircraft designs so he could determine how, or if, they would fly. Some of his contraptions, mainly derived from observing how birds fly, had complicated mechanical aspects that tried to imitate birds’ wing motions – most of these designs never left the ground, which was probably fortuitous in that they would almost certainly killed him, and we would have lost much of his genius.
One of the first recorded examples of using paper airplanes to study aerodynamics, an unknown science at the time, was the British engineer and aviator Sir George Cayley in the early 1800’s. He realized that the “lift” of wings had to be greater than the weight of the flying machine. That seems somewhat elementary today, but it was a major break-through in aircraft design development. It took another century until the Wright Brothers used that concept for their flight at Kitty Hawk in 1903 – it is interesting that even the Wright Brothers used paper airplanes to design the wings of their aircraft.
The world record for the flight of a paper airplane, that is hand-launched, is currently (April 2023) 289 feet and 9 inches, which is 40 feet longer than the previous record, so the designs are improving. In terms of time aloft, the record is held by Takuo Toda – he launched his paper airplane in a Japan Airlines hanger in Tokyo (no wind) and it stayed in the air for an astonishing 29.2 seconds.
Toda and his associate, Shinji Suzuki, are the ones designing a paper airplane to launch from the International Space Station – the design is apparently around seven feet long. The only problems they have are getting it up there in one piece, laminating it in some way so that it doesn’t burn up coming down through the earth’s atmosphere, and, most important, predicting where it will land – obviously minor worries!
Technically, there is a difference between paper airplanes and today’s real ones, and that is in how the wings produce lift. The wings of paper airplanes are flat and the lift is created by a small air vortex that forms just above the leading edge of the wing when it is launched. The design of that leading edge directly affects the lift and the stability of flight.
In today’s aircraft, the leading edge is rounded with the top being more rounded than the bottom. That means the air passing over the top of the wing is moving slightly faster than the air going underneath. The differential produces the required lift. You can sometimes see that curved flow if you look out of the plane’s window when it is taking off on a very humid day.
Some scientists are now predicting that, for small, unpowered, aircraft – some drones and gliders – paper airplane technology may be more relevant than current powered-flight technology. One of the results of this thought process is the proposed launching a large paper airplane from the ISS, crazy at that sounds.
Inevitably, the military is getting involved: The concept that an unpowered drone, carrying ordinance, could glide silently to its target is just too enticing a concept to ignore. Paper airplanes could well become weaponized yet, two thousand years after they first flew.
