Beauty in the Sky with Diamonds

Frode Engelsen stood with nervous anticipation as the countdown to the launch of an unmanned aerial vehicle (UAV) drew closer to zero.

Watching a UAV launch wasn’t new to him. Yet this launch, on a sparkling day in a field in British Columbia, marked the first of two steps towards flying the first joined wing UAV with bendable wings.

The 3-meter-span vehicle looked like a diamond-shaped picture frame with a rod connecting what would be the “front” and “back” corners. The purpose of this flight was to confirm that the UAV could be controlled remotely from the ground. Would this unusual craft take to the skies?

When the countdown hit zero, the UAV zipped into the air. Like a bird learning to fly, the vehicle needed a second to stabilize in midair but soon hurtled smoothly into the sky. Engelsen, a Boeing engineer, and his research colleagues from the University of Victoria in Canada let out yells of excitement as they watched the vehicle gracefully soar.

Almost 30 minutes later, after a smooth yet exhilarating flight, the UAV landed in a patch of tall grass. The team retrieved the vehicle and deemed the flight a success that marked a big step forward in testing this concept for a surveillance vehicle with improved capabilities. The next step, scheduled for 2016: a test flight of a flexible-wing version of this vehicle.

“It’s revolutionary,” said Engelsen, principal investigator with the Aeromechanics department of Boeing Research & Technology, Boeing’s advanced R&D organization, about the vehicle and its shape. “No one else in the world has tested it either.”

A typical aircraft has one set of forward wings, which are somewhat flexible. The joined-wing UAV that Boeing and the university are slated to test next year has not just a set of flexible forward wings – but also aft wings that are very flexible and are meant to buckle. The wings on each side of the UAV are joined in the middle, giving the vehicle its diamond-frame shape, and the UAV also has a vertical stabilizer to help stiffen the wings.

Though private remote-control airplane enthusiasts have flown joined-wing configurations before, the model flown by Engelsen and his research colleagues is larger than existing versions and features more advanced manufacturing and systems.

Since the bending of the wing can cause large twists and deformations, the purpose of the project is to determine whether a vehicle can be flown as it goes in and out of a buckling state.

Because the flexible wings will be very hard to fly, having an advanced autopilot was crucial. This test proved that next year’s vehicle could be controlled.

A UAV of this shape could enable surveillance missions that are longer-lasting and provide richer data than vehicles today can offer. The flexible wings would reduce the aircraft’s mass, which would allow the UAV to stay aloft longer without refueling, while the joined-wing configuration could enable 360-degree surveillance.

“The front wing is stiffened by the back wing so it can be made more flexible and lighter,” said Raj Talwar, Boeing’s program manager of the project with Boeing’s Global Technology Organization. “If the aft wing wasn’t there, you couldn’t fly the plane with the front wing alone.”

The University of Victoria’s Center for Aerospace Research has been a critical partner throughout development of the project, which began in 2014. They created the vehicle design based on Boeing’s design configuration of the Joined Wing Aircraft concept. About 10 students from the university participated.

Jenner Richards, project lead at the University of Victoria, has been involved with the project for five years and completed his Ph.D. on it. He said Boeing’s engagement is critical: “It’s a really great way to expose students and professors here at the center to such a diverse range of engineering. You really get a global view of the vehicle.”

The project is also challenging because aircraft today are designed with linear aeroelastic tools. Because of the new wing configuration, non-linear aeroelastic tools were required to design this vehicle.

“This project is a good test of our capability to analyze and design these kind of non-linear aircraft. We are really trusting our analysis tools ahead of time to do this and do it correctly,” said Engelsen. “It’s a great technology challenge and we are really in the forefont.”

Virginia Tech, along with the Air Force Research Laboratory, also provided consultation support.

http://www.boeing.com/features/2015/10/corp-joined-wing-body-test-10-15.page

Who can forget the Chinese joined wing hobby project, the Soaring Dragon. Ed