Shinji Suzuki met Takuo Toda in 1999, atop Mt. Yonami within the southern city of Jinseki-Kogen, Japan. Toda, the chairman of the Japan Origami Airplane Association, was there to launch a big paper plane from a tower he had built on the mountaintop for just that purpose.
Toda persuaded the local city council to construct the 85-foot-tall tower—with 360-degree views of Mount Daisen, Mount Dogo, and the Hiba Mountains—as a monument to paper airplane hobbyists. The primary floor of the tower features a showcase of precisely folded paper plane models, while the highest floor opens right into a veritable launch pad. When Suzuki first met Toda, he was launching the almost-seven-foot-long paper plane—modeled after the space shuttle Discovery—off that very flight deck. “He told me that he would really like to launch this paper plane from the space station,” Suzuki, now an emeritus professor in aviation on the University of Tokyo, says. “Everybody laughed at him.”
Toda’s lofty dream inspired Suzuki to take motion, and in 2008, the pair announced a project to launch paper airplanes from the International Space Station (ISS). Critics suggested these planes would burn up on their descent back to Earth, Suzuki says. Nonetheless, he predicted that with a protective coating and a controlled trajectory, they could actually have the ability to avoid burning up on reentry into Earth’s atmosphere. One other challenge? Determining where precisely the planes would land.
While Suzuki plotted the planes’ journey to the ISS, Toda would chart one other path, racking up Guinness World Records for his paper airplane designs. For a long time, he’s aimed to interrupt the 30-second record for time aloft of a paper plane. He’s come close multiple times.
At a Japan Airlines hangar near Tokyo’s Haneda Airport in 2009, Toda sent a paper plane soaring for a whopping 26.1 seconds. And he holds the present time aloft record, which he set in 2010 with an oblong design that lingered within the air for an astonishing 29.2 seconds. There are other records to be broken, too. As of April 2023, a trio of aerospace engineers currently hold the title for longest-distance throw of a paper airplane. Their dart-shaped plane traveled 289 feet and 9 inches, beating the previous record by almost 40 feet.
Our obsession with testing the boundaries of folded flight is comparatively recent, but our desire to explore and explain the complex world of aerodynamics goes back much further.
Chinese engineers are thought to have invented what could possibly be considered the earliest paper planes around 2,000 years ago. But these ancient gliders, normally crafted from bamboo and paper or linen, resembled kites greater than the dart-shaped fliers which have earned quite a few Guinness World Records in recent times.
Leonardo da Vinci would take a step closer to the fashionable paper airplane within the late 14th and early fifteenth centuries by constructing paper models of his aircraft designs to evaluate how they could sustain flight. But da Vinci’s knowledge of aerodynamics was fairly limited. He was more inspired by animal flight and, consequently, his design for craft just like the ornithopter—a hang-glider-size set of bat wings that used mechanical systems powered by human movement—never left the bottom.
Paper airplanes helped early engineers and scientists learn concerning the mechanics of flight. The British engineer and aviator Sir George Cayley reportedly crafted the primary folded paper plane to approach modern specifications within the early 1800s as a part of his personal experimentation with aerodynamics. “He was certainly one of the early people to link together the concept that the lift from the wings picking up the aircraft for stable flight have to be greater than or equal to the load of the aircraft,” says Jonathan Ridley, PhD, the top of engineering and a scholar of early aviation at Solent University within the U.K.
Greater than a century later, before their famous 1903 flight in Kitty Hawk, North Carolina, the Wright Brothers built paper models of wings to higher understand how their glider would sustain flight, explains Ridley. They then tested these models in a rudimentary, refrigerator-size wind tunnel—only the second to be in-built the U.S.
Paper planes are still illuminating the hidden wonders of flight. Today, these lightweight aircraft function a source of inspiration not just for aviation enthusiasts but in addition for fluid dynamicists and engineers studying the complex effects of air on small aircraft like drones.
At Cornell University, in a lab run by physics professor Jane Wang, PhD, paper gliders plunge, swoop, and flutter through the air. What might appear like child’s play to the untrained eye is definitely a part of a serious experiment conducted by Wang and her colleague Leif Ristroph, PhD, an associate professor of mathematics at Latest York University. Once the planes land, Wang and Ristroph analyze data from their flight and apply weights to alter the balance of those gliders. They hope doing so will help them higher understand how lightweight objects soar—something that might someday inform the long run of miniature drones and other robotic craft.
The team’s most up-to-date study, published within the Journal of Fluid Mechanics in February 2022, explored the mechanics of gliding and identified latest ways for paper gliders to attain stable flight. Insights gleaned from this research have practical applications, but additionally they make clear the aerodynamic principles that keep paper airplanes thrown by enthusiasts up within the air. All planes —powered and unpowered —are controlled by the 4 forces of flight: lift, weight, thrust, and drag. Lift is the aerodynamic force produced by the forward motion of an object through a fluid—on this case, air. Weight, or the force of gravity, is the opposing force and pulls the airplane toward Earth. Where the engines or propellers on a passenger aircraft generate thrust, the force of a paper plane pilot’s throw gives the aircraft the forward momentum. Drag, attributable to the friction a plane experiences because it moves through the air, acts in opposition to thrust.
Traditional airplanes have airfoil-shaped wings with a round vanguard. Air that passes over the wing conforms to its shape. Air flowing above the wing moves faster than air below the wing, forming a low-pressure zone above the wing that generates lift.
However the wing of a paper glider is flat, and air doesn’t flow easily around it. As an alternative, that air forms a small, low-pressure vortex immediately above the forefront of the wing. “This little vortex finally ends up changing a variety of the aerodynamic characteristics of the plane,” Ristroph says. “One thing it does is give the plane a natural stability, meaning that, in principle, it could and can glide.”
Because the angle at which a glider’s wing cuts through the air—generally known as the angle of attack—changes, so too does the scale and placement of the vortex above the wing. This affects where the middle of pressure, or the precise location where lift is targeted, lies along the wing and the way responsive it’s to disturbances. If, for instance, the plane encounters a gust that pushes its nose down, the middle of pressure will slide forward, pushing the nose back up and right into a stable position.
“The magic of a paper airplane is that every one of those little flight corrections are happening constantly throughout its flight,” Ristroph says. “The plane is hanging under a vortex that’s continually swelling and shrinking in only the proper ways to maintain a smooth and level glide.”
The middle of pressure for an airfoil, nonetheless, is locked in place and doesn’t change with the angle of attack. This implies it has trouble self-correcting if destabilized. Ristroph says the team tested this in a few of their experiments by folding the sheets into an airfoil. These sheets quickly crashed after temporary, erratic flights because they may not stabilize after being perturbed.
This phenomenon changes at different scales, Ristroph adds. As an example, for those who were to construct a paper plane the scale of a Boeing 747, the vortex above the wing could be much larger and behave otherwise. “That vortex wouldn’t just stay on the plane and sit there, it could jump off, reform again, and do something somewhat turbulent and somewhat crazy,” he says. “You may not have the ability to depend on that vortex to present you stability because it might not all the time be there.” Conversely, for those who created a paper airplane lower than, say, a millimeter long, the aerodynamics would change—together with the behavior of that vortex.
The central focus of Ristroph and Wang’s work—and, as their research suggests, the true secret to a stable glide—is identifying and making adjustments based on a glider’s center of balance. The middle of balance lies at the purpose where a plane could be perfectly balanced if suspended in midair. (You possibly can locate the middle of balance on a paper airplane by balancing it between the ideas of your thumb and forefinger.) For an unfolded sheet of paper just like the ones Wang and Ristroph tested, the middle of balance is directly in the course of the page.
The team experimented with tweaking the middle of balance by placing strips of copper tape on their paper gliders and studying their flight. If the weights were placed too near the middle of the sheet, the gliders would tumble uncontrollably to the bottom. If the weights were placed too far forward, they’d immediately nose-dive.
Through trial and error, they found that placing these weights halfway between the center of the sheet and the forefront created a stable glide, meaning that even when the glider was disturbed during its flight, it could still have the ability to right itself. Wang says this discovery was particularly surprising because previous work done on this topic had only ever identified “neutrally stable” modes of flight, which turn into unstable if perturbed and can’t self-correct.
Ristroph hopes the findings from their work will help engineers design latest varieties of small aircraft that benefit from passive modes of flight like, say, windsurfing craft that sail high above cities to observe air quality. “Over the past 20 years, there’s been increasing interest in smaller-scale flight,” Ristroph says. “Small-scale flying robots [could] do things like ride on the wind relatively than having some type of engine or spinning rotors like a helicopter.”
The push to develop low-cost and low-impact alternatives to traditional aircraft has grown in recent a long time. For instance, in 2017 the San Francisco–based research and development firm Otherlab announced it had won a grant from the Defense Advanced Research Projects Agency (DARPA) to work on a light-weight cardboard glider that might someday deliver blood, vaccines, or other critical cargo to distant locations inaccessible via other modes of transportation.
The gliders, constructed from flat-packed pieces of cardboard, could be released from an airplane and, with the assistance of an onboard computer, navigate to a preprogrammed set of coordinates. Otherlab and DARPA shelved the project, however the central idea—tapping into the realm of unpowered flight to unravel difficult problems—lives on.
Future small aircraft can also veer away from mimicking airplanes altogether, Wang says. Along with studying paper gliders, much of her research focuses on types of passive flight and gliding we already find in nature, resembling insects and seeds that twirl off tree limbs. Using these techniques to create small craft could create much more possibilities in years to return.
Even after locating a glider’s center of mass, Wang cautions that this discovery won’t necessarily make solving future problems facing paper craft experts or engineers any easier. She and colleagues try to unravel these problems mathematically. Applying these mathematical revelations to a working glider? Well, that’s one other challenge entirely.
Paper airplane enthusiasts, she suggests, might need higher luck crafting gliders using intuition and experimentation as an alternative. “People could make very, superb paper airplanes now,” Wang says. “It’s a tremendous art. They construct their intuition by making them.”
Suzuki, Toda, and their collaborators spent 18 months testing multiple designs. They coated each plane in a protective glasslike substance that may raise the warmth resistance but still allow for crisp, complex folds. With this design, Suzuki hoped that they could have the ability to check applications for other small-scale reentry vehicles.
The team then tested a prototype glider within the University of Tokyo’s hypersonic wind tunnel, subjecting the plane to speeds as high as Mach 7 and temperatures of virtually 450°F—conditions much like those a paper plane might face when reentering Earth’s atmosphere.
With these tests under their belt, the team reached out to Japan Aerospace Exploration Agency, who agreed to fund the project. Certainly one of the agency’s astronauts, Koichi Wakata, even expressed interest in launching them from the orbiting outpost himself. Ultimately, because of budget cuts, Suzuki and Toda’s paper planes never made it to space.
As researchers explore the sector of aerodynamics, and latest technology continues to model this kind of flight, there’s still a likelihood we could see paper gliders pushing boundaries in years to return.
Weird Ways to Generate Lift
Here’s how strangely shaped objects—from Frisbees to honeybees—generate lift to soar through the air.