AE students design UAVs with special missions in mind

Aerospace Engineering Professor Greg Elliott’s new course this spring gave groups of students a choice of building one of three unmanned aerial vehicles (UAVs), with designs reflecting the vehicles’ intended uses.

In addition to educating students in designing small UAVs, the purpose of the course – AE 498 Uninhabited Aerial Vehicles – is to teach them about various manufacturing techniques including carbon fiber construction, basic and CNC machining, and rapid prototyping techniques. Students also learn about instrumentation, sensors, and electronics associated with UAVs.

Students in the course this past spring were divided into three teams: one building a flying wing (low aspect ratio wing); another, an indoor flyer; and the third, a powered sailplane.

“The concept requirements came from the mission,” said graduate student Zachary Herman.

The teams spent about two-thirds of the semester conducting analysis to come up with the design concept, then another two to three weeks building their UAVs.

Herman teamed with Sahithi Kalidiandi, Steven Cummins and Izan Peris in building the flying wing. The vehicle’s Delta design and 40-inch wing span were intended to promote the UAV’s maneuverability and allow it to reach speeds of at least 60 miles per hour.

The wing performed well in climbs, drops, and rolls, and hit a top speed of 71 miles per hour when tested early in May at the Champaign County Radio Control Club.The plane was then instrumented with a camera, GPS, system monitoring, and telemetry, completing the dash search and rescue mission for which it was designed.

The mission for Lucas Buwick’s group was to build a light, slow-flying plane that could fly indoors and take photos of entertainment events: sports, concerts, or even large theater productions. It needed to be safe enough so that the aircraft would not cause serious injury if it accidentally hit a person. Buwick’s group members were Fabio Fernandes de Castro Santos, Micah Fehr, David Sherman, and Ernest Company Vallet.

Buwick indicated that the plane was designed based on a small R/C model called a Vapor. It used ribs and a fuselage made out of carbon fiber with light plastic film glued on the wings and control surfaces. It also used a pusher propeller located behind the wing. “That way the prop was not on the front of the plane, which could injure someone if it crashed, “ Buwick said.

The plane had to weigh less than 12 ounces, and have a wingspan of less than 38 inches. The plane’s top speed had to be less than 15 miles per hour, with a sustained stable flight speed as low as possible for safety purposes and to allow suitable in-flight photography at arena or theater-sized events. The plane met all of its specific criteria, Buwick said. “The wingspan is 32 inches and it weighs about 4.5 oz.”

Buwick’s team faced a challenge in balancing the plane’s weight versus strength. The team needed to make the plane light but structurally strong enough to support the forces generated in acquiring lift. Problems arose in identifying materials that were light but offered necessary support.

“One last issue we faced was with having a motor in the back,” Buwick said. “It threw off the center of gravity of the plane, making it difficult to make the plane stable.”  The plane flew successfully and was able to take in-flight videos around the engineering quad.

The sailplane was designed to fly over one or more areas for long periods of time for search and rescue and agricultural observation purposes; for example, emergency situation first response, crop assessment or aerial photography, said team member Cameron Breedlove.

With team members Alfred Yeo, Daniel McDermott and Henry Yan, Breedlove designed the vehicle according to known principals for sailplanes: high aspect ratio wings, a small fuselage, and small control surfaces. But, wanting to beef up the traditional design, the team used an embedded ducted fan to power the plane.

“Essentially, we made a traditionally slow, elegant plane go really fast,” Breedlove said.

The sailplane’s requirements were that it have a wingspan of less than 90 inches, be compact enough to be carried by one person, and be able to fly above 40 miles per hour for more than 20 minutes. The team’s design had a 72 inch wingspan, weighed about 2.5 pounds, and could reach speeds of 65 miles per hour.

“The first time we flew our aircraft it was flown in 12 to 15 mile per hour winds at almost full throttle for about 25 minutes,” Breedlove said.

He said the team had to overcome two challenges.

The first was the wings. “We needed a long wingspan on a fairly thin airfoil. This meant that our wings needed to be very strong but also very light.” To do this, the wings were made of foam and covered with carbon fiber composites.

“First we tried fiberglass but that proved to be too weak. Then we switched to carbon fiber and made the current wings.”  The wings apparently were strong enough, having survived all the flight tests, extreme maneuvers (not usually part of a sailplane’s design) and a hard landing.

“The second major problem came from the ducted fan,” Breedlove continued. “It was a challenge to fit the ducted fan in and still keep a solid structure throughout the aircraft. We ended up making a skeleton out of carbon fiber plates that held all of the components and actually used the ducted fan housing for additional structural support.”

Additional photos from the class and test flights can be seen on the Aerospace Engineering at Illinois Facebook Page.
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Contact: Gregory Elliott, Department of Aerospace Engineering, 217/265-9211.

Writer: Susan Mumm, editor, Department of Aerospace Engineering, 217/244-5382.

If you have any questions about the College of Engineering, or other story ideas, contact Rick Kubetz,editor, Engineering Communications Office, University of Illinois at Urbana-Champaign, 217/244-7716.