WRIGHT-PATTERSON AIR FORCE BASE, Ohio -- What do ancient Greek artillery, materials engineering and pumpkin chucking have in common? How about a senior Air Force Research Laboratory materials engineer who is inspiring future scientists—and having fun in the process.
David Mollenhauer is a Senior Materials Engineer in the AFRL Materials and Manufacturing Directorate. His days are spent in the laboratory exploring composite mechanics, carbon fiber and other cutting-edge materials to advance research for Air Force technology of the future.
However, when evenings and weekends roll around, Mollenhauer discards his lab coat, grabs his trademark cowboy hat, and heads to the shed to contemplate new ways to toss pumpkins as far as he can--a hobby that lets him use his science for fun.
“I’ve always been interested in learning how what I do in the lab can work in a larger scale application,” said Mollenhauer. “In the lab I develop and test materials on a small scale; my hobby is an opportunity to educate myself on how a theory really works in application.”
Mollenhauer is the captain of Team ETHOS, a nationally-ranked ‘Punkin Chunkin’ team that uses cutting edge, modern materials and technology combined with advanced scientific analysis and classical Greek engineering to fling pumpkins thousands of feet through the sky. Since 2007 the team has competed in events across the country, launching autumn’s most notable squash distances exceeding 3,450 feet, squashing competitors in the process.
ETHOS, which stands for “Experimental Torsion Hybrid Onager System” is not only an acronym-based team name (true to military style), but a moniker that describes their chucking machine- the Phoenix-and its basic design.
“Greek and Roman artillery has always interested me, and what the Greeks did as engineers without modern mathematics, computers and materials is astonishing,” said Mollenhauer. “The ancient Greeks had a type of catapult called an Onager, and our machine is based on this. We stayed close to traditional design, but we modified our Onager by using modern materials and engineering to bring it into the future.”
Team ETHOS’s pumpkin chucking machine operates using the ancient Greek concept of torsion. Torsion machines, which originated more than 2,300 years ago, generate power through the twisting of a rope at the root of throwing arm. This “torque” on the rope builds up a force, or power. Team ETHOS uses the Phoenix’s built up torsion power to catapult pumpkins thousands of feet through the sky.
“It’s similar to twisting a pencil in a rubber band stretched across your hand,” said Mollenhauer, in describing the torsion process, “Eventually the potential energy stored in the twisted rubber band will need to be released. Our machine works similarly, using the energy in the twisted ropes to launch a pumpkin.”
Though the Phoenix does not diverge much from the traditional Greek and Roman Onager in concept and design, it’s the modern scientific touches that set it apart from all others. Perhaps most interesting is the integration of a sensor network in the machine itself that allows the team to generate real-time data assessment of their performance and anticipated performance in any condition.
“Our built-in sensors measure strain, loads and acceleration. We process this data just like we would in the lab to make sure we understand best conditions and optimal weights for our machine so we can have the best performance on any given day,” said Mollenhauer. “We are constantly looking for ways to refine our models and adjust our machine to achieve the best results.”
Designing the Phoenix was not an easy feat, and it took a team of engineers, scientists and students to evolve the machine to where it is today. Mollenhauer likens the process to a major military acquisitions program approached through a systems engineering process.
“It wasn’t nearly as formal (as a military acquisition), but we had a schedule, held design reviews, raised money and needed to get donated materials. We had to work through the constraints, all while keeping the contest date in mind to ensure our project would complete,” he said.
Team ETHOS competes annually in contests across the U.S., and the team most recently earned a first-place finish at the Air Force Lifecycle Management Center’s Annual Combined Federal Campaign competition Oct. 21 with a 3,391 foot pumpkin toss. The team will compete in the 2016 World Championship ‘Punkin Chunkin’ competition in Bridgeville, Delaware, Nov. 4-6.
Though the prizes for these competitions is never more than a trophy, Mollenhauer said that the real reward is the excitement and interest in science that his hobby brings to the students he meets.
“To see the inspiration this causes in kids, even college age kids, is so rewarding,” Mollenhauer said. “We are inspiring our future scientists in a way that is fun. It’s different, it’s interesting, and it’s a great motivational tool.”
Who would’ve thought that ancient Greek technology would be used in such a way today?
To learn more about Team ETHOS and its mission, visit their website at http://ethoscatapult.com Also, to see how Team ETHOS fairs in this year’s 2016 World Championship event, check your local television listings to find out when the competition recording will be shown in your area.