The Science Behind Pumpkin Chucking

By Marisa Novobilski
Air Force Research Laboratory

Team ETHOS assembles their pumpkin chucking machine prior to a competition. The team is comprised of researchers, engineers and students from the Air Force Research Laboratory and competes annually in contests across the U.S. Air Force Photo by David Dixon

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.”

Less than 100 pounds of rope are twisted together to generate the force needed by Team ETHOS’ pumpkin chucking machine. U.S. Air Force Photo by David Dixon

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’ 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.

Team ETHOS’ pumpkin chucking machine, the Phoenix, launches a pumpkin through the sky during the annual Air Force Life Cycle Management Center’s Pumpkin Chucking competition, Oct. 21. U.S. Air Force Photo by David Dixon

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.

Who would’ve thought that ancient Greek technology would be used in such a way today?

Read more about Team ETHOS on DVIDS.

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