A More Practical HPV

Ragnarök, the human-powered vehicle built by students at Rose-Hulman Institute of Technology, proved to be both fast and useful.

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The bicycles entered in ASME’s 2010 Human Powered Vehicle Challenge don’t look like your ordinary ten-speed. The student-built designs are low-slung contraptions, with brightly colored cowlings that wrap around the riders.

For the third year running, the engineering students from Rose-Hulman Institute of Technology in Terre Haute, Ind., have placed first in both the East Coast and West Coast competitions. But unlike in years past, when the Rose-Hulman team concentrated on building the fastest possible vehicle, the students this year strove for something different: utility.

The Human Powered Vehicle Challenge pits student teams from across North and South America to build and race unmotorized machines. The most successful entries have drawn from a few simple design features, the most important of which is very low aerodynamic drag. The riders are in a recumbent position—sitting with their legs straight ahead—to cut down on the profile, and many have fairings to create a more streamlined shape.

While the results can be impressively fast, with a team from Missouri University of Science and Technology in Rolla clocking in at more than 45 miles per hour in 2009, the vehicles themselves can be difficult to ride.

Even though the Rose-Hulman team brought home two titles in a row, the impracticality of their creations in past years began to weigh on the members.

"During a question-and-answer session with the judges of the competition, one asked a thought-provoking question: ‘Is your vehicle practical?’" said Chris Wlezien, a recent graduate who was the vice president on this year’s team. "There was almost no way for us to answer ‘yes.’ The vehicle was only designed to go fast. It needed a team of people to launch it and retrieve it; it needed constant maintenance; it was very difficult to ride, and it was uncomfortable."

Taking that critique to heart, the team members building this year’s machine aimed for something more practical. The contest had a new category—the unrestricted class—and the team members worked to build a machine that could do more than just go fast.

Teams in the unrestricted class competition must compete not only in speed-oriented races but also in a utility endurance event that requires putting the vehicle through an obstacle course. The bikes have to climb a ramp, go over a speed bump, pass through a simulated rain shower, and stop so that the driver can pick up a parcel. While this might not seem like much of a challenge to your typical motorist, many of the vehicles built for the speed contest can’t perform such simple tasks.

"The unrestricted class appealed to our team because it nurtures the development of an ideal human-powered vehicle," said Andrew Bomar, a mechanical engineering major from Big Rapids, Mich. "A vehicle that is fast but uncomfortable, unsafe to ride on roads, or cannot carry cargo is not a viable means of transportation.  Neither is a slow vehicle no matter how convenient it is to use."

Although the utility endurance event accounted for only 20 percent of the total available points, it completely changed the design philosophy. For instance, in years past, the riders fit into their machines with scarcely a cubic inch to spare; this year’s vehicle, known as Ragnarök, had enough cargo space for groceries.

The robust design, which aimed for building less of a thoroughbred and more of a workhorse, also wound up saving the team from certain defeat. "We suffered a huge mechanical failure and were almost out for the count, but with some skill, a machine shop, and some luck we managed to put together a fix and come out in first overall," Wlezien said. "If we did not design the bike durably enough, we would have never been able to implement the fix we came up with."

Michael Moorhead, an assistant professor of mechanical engineering and the faculty advisor for the team, said the vehicle, while by no means a replacement for an SUV, points toward a design that could one day supplement automobiles.

"This is the type of device that someone—today, not ten or twenty years from now—could use as a daily commuter vehicle," Moorhead said.

Even so, Moorhead added, the biggest boost to the practicality of human powered vehicles isn’t in design or technology, but in infrastructure and acceptance. Building dedicated bike lanes and parking areas would make the most difference.

In addition to its first place finishes, the Rose-Hulman HPV dynasty is getting another reward as well. The east division of the 2011 ASME Human Powered Vehicle Challenge will be hosted by Rose-Hulman and held at the historic Indianapolis Motor Speedway.

Jeffrey Winters, Associate Editor, Mechanical Engineering.  

The Human Powered Vehicle Challenge pits student teams from across North and South America to build and race unmotorized machines.

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