Engineering at Nebraska Fall09


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Andrew Kocarnik, a senior mechanical engineering student from Lincoln, has his pilot’s license—so what could be challenging about flying a remote-control airplane?

Quite a bit of challenge, actually—but nothing that Nebraska Engineering students couldn’t handle.

Kocarnik volunteered to lead a UNL team in the 2010 American Institute of Aeronautics and Astronautics (AIAA) Design-Build-Fly competition. UNL sent a successful team to AIAA’s Spring 2009 CANSAT international rocket-payload competition, and its DBF team was "next on the tarmac" for an international collegiate competition of radio-controlled aircraft in Kansas.

The team was nicknamed "Red Horizon" after a suggestion from senior Joe Bartels, AIAA chapter president. Preparations took off in fall 2009 with eight students on board including: seniors Chris Benner, Earle Mock and Tim Prost; juniors Caleb Gronewald, Charles Nichols and Taylor Young; and freshman Derek Stevens. Kocarnik navigated leadership as well as technical aspects.

"People on a team may think on the same lines, but each person has different ideas," he explained, "and they need to be motivated by the same goal." Fortunately, the Red Horizon group all shared a similar "aviation bias," and actively took on helpful roles, Kocarnik recalled.

Since UNL does not have an aeronautical engineering program, the project gave the whole team a hands-on experience, he added. Team members enhanced their engineering skills with real understanding of how and why flight equipment functions.

Adviser Kevin Cole, professor of mechanical engineering, praised the team as "completely self-inspired and very driven to get themselves together and make this happen." Throughout the winter, the team worked in the first-floor machine shop of Scott Engineering Center, sharing a tight space with another team at work on the college’s Baja SAE competition vehicle. After Spring Break, with the DBF competition just days away, the Red Horizon team’s hours of involvement soared. Would they be ready?

To answer that question, an engineering angel arrived in the form of Leonard Akert. He manages Othmer Hall facilities for UNL’s Department of Chemical and Biomolecular Engineering, and has 40 years of evenings and weekends devoted to radio-control aircraft racing. Akert said he was "amazed" when he discovered what the student team had accomplished on their own in the workshop, and connected them with his hobbyist network: the Lincoln Sky Knights. Soon the Red Horizon aircraft became the focus of the group’s expert advice.

Feeling well-prepared, the Red Horizon team traveled to Wichita in April for the weekend competition. Kocarnik logged the rest of the story in an e-mail message to Akert:

Design Build

Flight Prep Plane must be assembled on-site by three team members in five minutes or less.

Plane must carry payload of 10 softballs and up to five bats.

Plane must take off in less than 100 feet.

Disassembled plane must fit in 2’ x 2’ x 4’ box.

Motors must not draw more than 40 amps each.

Plane must use fewer than four pounds of propulsion batteries.

Plane must survive wingtip test simulating a 2.5-g load.

All controls must be programmed to enter failsafe mode upon loss of radio signal.

Team must submit a written technical report.

View Red Horizon footage from the 2010 AIAA DBF competition at and on YouTube.

We had three mission attempts … Before flying, we had to get our loss-of-signal procedure to work. We found out our receiver would not allow us to program the correct failsafe specified by the DBF rules. A new receiver and $180 later, we were back in business. We passed tech inspection Saturday morning, but we missed the first flight attempt due to speed controller adjustments ([we] found out we could program the speed controllers with the transmitter and pull more speed out of the motors).

On the second attempt (there were 69 teams, so we had to wait awhile between flights), we built our plane within the five-minute limit. However, at take-off, it just kept nosing over, and the front gear would bend; a strong crosswind didn't help matters. On the last run up, the plane flipped and the rudder tops broke. Discouraged, we weighed our options and decided to rebuild and try again Sunday.

We brought the main wheels forward by switching the main strut around, took the nose gear further into the fuselage (allowing the whole aircraft to sit lower to the ground), and removed the spring connecting the two main wheels. ‘Rigorous’ taxi tests revealed we had fixed the problem. On Sunday, we passed our second tech inspection (required when any plane takes damage) and awaited our flight attempt. We once again completed assembly in under five minutes and prepared for take-off, throttled up, stabilized, and then gave it full power. The results of our third and final attempt placed us 46th of 69 teams. Considering it was our first year and many teams had no successful flights, we are pleased. The experience as a whole was good, and I must admit we enjoyed seeing many good crashes. We learned a lot for next year, and I am eager to see the underclassmen do it all again for 2011.

Also, the whole team owes you (LSK) guys each a debt of gratitude. We would not have been successful without you and the time and help you offered us.

Kocarnik graduated a few weeks later and plans to be in commercial flight school during the next DBF competition in 2011, but he’ll likely never forget this experience with the smallest powered plane in his command.

UNLUNL© 2010 University of Nebraska-Lincoln | College of Engineering

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