Who said pumpkins can’t fly?
For the second straight year, Orcutt’s McLean family is prepared to prove the feat is possible, hauling a homemade trebuchet—a medieval device used for castle assaults—to Arroyo Grande High School’s Pumpkin Catapult competition on Nov. 13.
There, they’ll attempt to defend their long-distance launching title against the AGHS Eagle Robotics Team 1388, a school club that hosts the annual contest.
Scott McLean, an Air Force Reserve lieutenant colonel and aerospace engineer based at Vandenberg Air Force Base, conceived of the produce-slinging weapon to ignite interest in an engineering club at Orcutt Academy. The group has since evolved into the school’s robotics team.
Scott and son Peter, a sophomore at the Academy and member of the team, found plans for small-scale trebuchets on the Internet and expanded the design into an 8-foot-tall version made of wood. Scott called their first try a “rather serious challenge.”
“There’s not a lot of plans for a larger machine like that,” he said. “There were plans for a Popsicle-stick-sized one about 8 inches tall. We made it 12 times bigger.”
Building the machine took the family “a lot of trips” to the hardware store, cost about $400 in materials, and took about a month to complete. Calling themselves the “Pumpkinators,” three generations of family members helped operate the machine in the 2009 event, including Peter’s grandfather, grandmother, sister Erica, and brother Mark.
The McLeans’ trebuchet works with a counterweight, and ropes are used to hold the lever weight down. Using the same type of release mechanism as a parachute, a pin is pulled, the weight drops, and the machine’s arm pivots around the uprights, launching the pumpkin from a sling.
“As it whips around, its release point is probably a good 20 feet up in the air,” Scott explained. “The velocity is very fast, given the length of its arm. It’s a pretty efficient process of actually releasing it.”
Arroyo Grande High’s event is just one of dozens of “Pumpkin Chunkin’” competitions held across the country around harvest time, where “chunkers” use cannons, slingshots catapults, and pneumatic devices to propel pumpkins great distances.
The Pumpkin Chunkin’ World Championships take place in Sussex County, Delaware, on the first weekend after Halloween, drawing in more than 20,000 spectators. There’s even a World Championship “Punkin Chunkin” Association. The group lists the current world record for a trebuchet toss as 2,034 feet for adults, and 1,232 feet for youths.
The McLeans won last year’s Eagle Robotics contest—held at the Talley Vineyard in Arroyo Grande—with a launch of 140 feet. This time around, they expect to reach between 160 and 180 feet.
“I’m very confident that we can do better than that,” Scott said of last year’s marks. “There are some definite tweaks that we need to make on our machine.”
In the weeks before the competition, the McLeans will practice launching soccer balls from the trebuchet. It’s the same machine they used last year, with some minor modifications and a replacement for a strut broken during the competition.
“We learned a lot at the contest about the size of the pumpkins that work better,” Scott said. “We didn’t want to throw rocks because these can be lethal. These things were war machines at one time.”
Eagle Robotics Team 1388 will be hosting the event again, and though Orcutt Academy’s robotics team won’t be competing this year, Scott said he hopes to bring a few team members along to give them a sense of what to expect. With more time and money, Scott said the club would likely build their own machine next year.
Scott added he hopes the event will serve as an inspiration for the science, technology, and business aspects of the club.
“It’s a great chance to talk about science and technology,” he said. “This stuff’s really cool, and we go through a lot of that with the math behind building the machine.”
Staff Writer Jeremy Thomas knows jack about o’ lanterns. Send comments to jthomas@santamariasun.com.
This article appears in Oct 28 – Nov 4, 2010.