They’ve been stiff as boards and nearly as flexible as wet noodles, and a group of Victoria students is determined to make them all fly.
Working in partnership with Boeing, researchers and students at the University of Victoria’s Centre for Aerospace Research are helping design and fly unmanned aircraft constructed with flexible materials in the wings and rear stabilizers.
Researchers at Boeing originally thought such a plane could work if the flexible wings, front and rear, were joined together, making for some extra stiffness. Now, the Victoria students have spent years working up a series of flying, unmanned aircraft to demonstrate Boeing’s flexible- and joined-wing idea is workable.
“Boeing has always been hyped about this particular configuration, the joined wing,” said Jenner Richards, a UVic PhD and the research and development manager at the Centre for Aerospace Research. “They see all sorts of applications for commercial aircraft, transport aircraft, all sorts of things.
“But in addition to the benefits, it has some weird potential flight behaviour,” Richards said. “You can hit a gust, and the flexible wing can bend in a weird way and nobody is sure exactly how it will behave.”
So the students, mostly UVic engineering graduates, but also two Camosun students, one high-school co-op student and an exchange student from Portugal, have been designing, building and documenting the flight behaviour of various joined-wing aircraft.
Driving the whole effort to build these flexible aircraft with joined wings is the age-old quest in aerodynamics to construct lighter aircraft with better energy efficiency.
Boeing wasn’t so much interested in flexible aircraft. It was interested in lighter aircraft. But the lighter the material, the more flexible it becomes.
Frode Engelsen, research fellow at Boeing, said traditionally, aircraft have been designed with an eye to keeping the wings and other aerodynamic surfaces as stiff as possible.
With a physical shape made to remain firm and consistent while undergoing the aerodynamic forces in flight, aircraft wings will allow a craft to perform in a predictable manner. But rigid materials are heavy.
“You can always make an aircraft more stiff, but eventually, you are going to have something like a flying brick,” Engelsen said.
“But when you make them lighter, you will have an aircraft that uses less fuel.”
At this point, Boeing has an idea that very light, flexible, joined-wing aircraft could be constructed as big as airliners to be used at high altitudes, for things such as survey work or even surveillance.
Problems have arisen, however, because when a flexible aircraft wing bends, or otherwise becomes deformed, its aerodynamics change. Directional control becomes difficult; even remaining aloft can become a challenge.
“Eventually, the wing will start buckling until it becomes a very large deformation,” said Engelsen.
“Does the deformation make the airplane fly up or down or whatever?” he said. “Can you even still fly it when these deformations happen?”
So back at the UVic Centre for Aerospace Research, the students are powering through questions such as how to keep these aircraft flying steadily even when the wings are being bent under the force of something like a gust of wind.
In the quest for answers, said Richards, the centre has built its aircraft with many control surfaces — ailerons, flaps, rudders. One model has 15 separate ailerons on the front wing alone.
When these are all operated independently, they can deflect the passage of air across the wings and combine to keep the plane flying steadily. It would, however, be impossible for one person to manipulate all these flaps and control surfaces at the same time.
But Richards said the enormous increase in the computing power of small systems, the sort of thing that puts a mobile phone in your hand, supplies an auto-pilot solution.
Sensors on board the aircraft could recognize things such as wind speed or a change in the shape of the wing. And the small onboard computer would adjust the various control surfaces independently to keep the plane in the air.
So a human pilot flying the aircraft via radio control can move a joystick to signal the plane to do something simple, such as turn right or left, go up or down. The computer on board, however, signals all the control surfaces at once, with different instructions, to make the aircraft follow the pilot’s direction.
“Watch the pilot fly the thing and he will hold it to the right and make a nice banked turn,” said Richards.
“But if you were watching the ailerons or the other control surfaces, you would see them just going crazy to hold the plane there,” he said.
The autopilot can also take over and fly in a prearranged pattern or course, say a triangle or a box grid, and even land.
But during operation, the human pilot could take control now and then to keep the aircraft moving as planned and then hand it back to the autopilot.
“So the autopilot flies around for a bit and the pilot relaxes and then takes over for a sec and does some manoeuvre,” Richards said. “That’s kind of how we are using it now.”
“If the pilot was handling it on his own, he would be white-knuckled the whole time,” he said.
“He’s tired in about 20 minutes, just mentally fried.”
Much of the work Richards and his team are doing involves computer programs to keep the experimental aircraft aloft.
But he said the joined-wing configuration has never been built or tested before. So nobody has even put one through a wind tunnel, and no one has extensively tested the design in real flight.
Also, Richards said the joined-wing design presents some tricky aerodynamics all on its own. Even when the test craft have been constructed out of rigid material, the configuration creates some challenges.
So the team is also collecting data and measurements that ultimately will allow the joined-wing plane to fly even more autonomously.
For example, if the autopilot can anticipate how the craft will react and adjust control surfaces accordingly, the craft becomes even more aerodynamically reliable.
“One of the things they are finding is they are getting weird things happening with the joined wings,” Richards said. “But nobody has been able to study them because you don’t see any of them flying around.
“So what [Boeing] wanted us to do was build a very flexible aircraft, put all kinds of sensors on it and put it through different flights it might do in reality,” Richards said. “Then we can build a database of real-world responses and [Boeing] can simulate that with their software and see how well it matches reality,” he said.
CENTRE FOR AEROSPACE RESEARCH
The Centre for Aerospace Research at the University of Victoria is contributing to an up-and-coming industry in B.C.
Prof. Afzul Suleman, who founded the centre two years ago, said Victoria, with Viking Air and its proximity to big aerospace firms such as Boeing in Washington state, is in a good location for constructive feedback.
Suleman, an aerospace engineer, said the centre has seven full-time engineers, 15 graduate students and several undergrads and high-school co-op students.
The federal government has assisted with grant money from the Western Economic Diversification Fund to get the centre going.
Since then, the provincial government has been supportive.
Suleman said the centre has already delivered some projects with industrial partners, including Boeing and Bombardier.
“We’ve been doing some original research,” said Suleman.
“We’ve also been getting support and funding to develop some new technologies,” he said.