The Science of Behind Chucking Pumpkins

Pumpkins play an important role in our fall holidays. A member of the gourd family, pumpkins are carved up to create Jack-o-lanterns for Halloween and play a starring role in the delicious pies we all love to eat at Thanksgiving feasts. These versatile members of the gourd family come in a variety of colors and sizes and are native to Central America and Mexico but now grown on six continents.

As much as people enjoy carving and eating them, they also love to throw, or “chuck,” them. In fact, launching pumpkins into the air has evolved into a sport of sorts. Every year thousands of people gather in Delaware to participate in Punkin Chunkin, an intense national competition to determine who can hurl or “chuck” a pumpkin the farthest using solely mechanical means.

Might sound pretty simple, but there’s some serious science and engineering behind the sport of chucking pumpkins, and Punkin Chunkin covers every angle from growing special, aerodynamic pumpkins and determining the perfect pumpkin’s mass to the mechanics of the air cannon and the physics of catapults.

The World Championship Punkin Chunkin, an annual three-day event sponsored by the World Championship Punkin Chukin Association (WCPCA), is the oldest and largest of the competitions and has been held since 1986. Each year 115 teams from across the country and abroad compete in this action-packed, squash-slinging event.

The machines used to launch the pumpkins in Punkin Chunkin include slingshots, catapults, centrifuges, medieval-style Trebuchets, and pneumatic cannons. The range achieved by these devices depends upon multiple factors including: mass, shapes, size, yield limits, stiffness, pitch, elevation of hurler, and weather conditions.

The Guinness world record shot is held by team that used a pneumatic cannon, dubbed the “Big 10 Inch”, to launch a pumpkin 5,545.43 feet (1,690.25 M) on September 9^th, 2010. To accomplish this feat, the team placed the pumpkin in a tube with a valve separating it from a large tank of high-pressure air. The second farthest chuck on record (3,636.39 feet) was accomplished using a torsion device that uses twisted rope as its primary source of power.

At the Punkin Chukin competition, pumpkins that burst upon leaving the barrel or sling of the launch machine—dubbed “pie” shots (short for “pumpkin pie in the sky”—result in the “shot” being disqualified by WCPC rules. Though no pumpkin has yet to be launched a mile, in order for one to do so it would need to be chucked faster than the speed of sound—770 mph.

Tips to “chuck” like a pro

It all starts with choosing the right pumpkin. Here are a few rules for picking the perfect “chuckable” pumpkin. First off, don’t make the rookie mistake of picking an orange pumpkin. The most common varieties of pumpkins used are Caspers, Luminas and La Estrellas, but nearly all of the competitors of Punkin Chunkin throw dense, white Luminas. Next determine the optimal weight that works best with your machine.

Improve your aerodynamics by choosing a pumpkin with a spherical, smooth surface with no blemishes and wait to pick it until right before launch since pumpkins start loosing weight through evaporation as soon as they are plucked from the patch. Also, take your pumpkin’s temperature since any rise indicates active rot and pick only the densest ones since they are about 90 to 95% water.

Punkin Chukin Champion uses SOLIDWORKS to design winning air cannon

The current world champions for the Air Cannon Division of Punkin Chunkin is the American Chunker team. The team relies on SOLIDWORKS Simulation software to conduct CAD-embedded testing of its winning pneumatic cannon design. The American Chunker cannon is a wonder of science; a huge fire-engine-red tank with a 60-foot aluminum barrel that resembles a humungous, six-ton screwdriver.

American Chunker uses SOLIDWORKS Solutions to simulate the pumpkin shooting out of the cannon before physical testing; predict the pumpkins’ flight path; analyze how in-flight pumpkins will react to breaking the sound barrier; identify potential problems; retain engineering knowledge in designs; and minimize engineering rework.

Learn more about the all the science and engineering that goes into being a pumpkin-chucking master by checking out our “How Far Could You Chuck a Pumpkin” infographic on the SOLIDWORKS web site.