Kayden Clapp, left, and Adee Smith carefully glued strands of spaghetti together for the sides of their truss bridge.
Liberty Bell students use their noodles to meet engineering challenge
Spaghetti may be known for its ability to stick to the wall, but not necessarily for its utility as a construction material.
But last week a group of Liberty Bell High School seventh- and eighth-graders succeeded in building a bridge — from less than 1.6 pounds of spaghetti and lasagna — that supported a 1-kilogram (2.2-pound) weight for three minutes.
For the final bridge test, Kyler Mitchell gingerly positioned a support to hold the 1-kilogram weight.
Four teams in the engineering class at Liberty Bell High School designed and built bridges from raw spaghetti, lasagna and other pasta in a contest to see which could support a 1-kilogram weight for three minutes. Three of the four bridges collapsed almost instantly as the students attached the weight, but the winning bridge held in there for the full three minutes.
“Think about your force diagrams from your concept models,” engineering teacher Matt Hinckley told the students as they gingerly set the bridges on two tables, 1 meter apart, and prepared to hang the weight from the bridge deck of lasagna noodles. “Envision the compression and tension forces.”
Teams typically follow different strategies, some creating bridges that will be super-light, but others opting for super-strong, said Hinckley. “If you use a pound of hot glue, it’s not going to break,” he said. If more than one bridge holds the weight, the lightest bridge wins, according to the contest rules.
The competition was off to a strong start as the first bridge supported the weight without apparent sagging. Although the three other bridges collapsed almost instantly, the students had a good laugh as their bridges splintered into shards of spaghetti and lasagna on the floor.
A 25- or 50-percent success rate is typical, said Hinckley. “I thought most would hold up — I was surprised they broke,” he said. “But most groups took the risk of making their bridges really lightweight.”
Strict rules
There are strict rules governing the spaghetti-bridge contest, which specify the use of lasagna for the deck but allow other pasta shapes for the main structure. The fundamental idea is to replicate real bridge structures using pasta, rather than relying on glue, said Hinckley.
After the budding engineers researched bridge designs and construction, most opted for a truss design because of its inherent strength. Truss bridges rely on connecting triangles to support the load and stress forces across the entire structure.
“There are lots of real-life examples of truss bridges,” said Mackenzie Scott, pointing to bridges in Winthrop and Omak and the Beebe bridge near Chelan.
Addison Stratman (left) and Melody Langan worked together to carefully construct their bridge’s supports.
Students did enough research that most arrived at a similar design, said Hinckley. Some wanted to create a suspension bridge until they realized how difficult that would be to build from spaghetti, he said.
The students built and tested bridge prototypes from popsicle sticks, then graphed those results to come up with the sturdiest designs for their pasta bridges. The popsicle-stick construction didn’t always translate into pasta. Although one group built a popsicle-stick bridge so durable it held 52 pounds, their spaghetti version buckled right away.
Most groups combined several strands of spaghetti for each side member. One team decided it was important for both sides of the bridge to be identical, but that was difficult with just a glue gun and spaghetti. “We had to break it and redo it because it was really wonky,” said Addison Stratman. They laid spaghetti diagonally to support the lasagna deck for added strength.
Hinckley furnished students with spaghetti and lasagna, but they were free to use any shape of pasta for the main structure. “We wanted to use bucatini, but the grocery store didn’t have it,” said Lucy Tobiska-Doran. Bucatini is like spaghetti, but the long strands are hollow, which the students thought would increase the strength. The team placed small tubes of rigatoni over the spaghetti joints for extra stability.
Leki Albright carefully applies what she hopes will be just the right amount of glue.
“It needs to be light, so we’re trying to minimize the use of spaghetti and glue,” said one member of that team.
Engineering feats
The first heavyweight bridge contest was held 30 years ago at Okanagan College in Kelowna, British Columbia.
The record was set in 2009, when a team of engineering students from Hungary fabricated a bridge that held 443.58 kilograms — almost 978 pounds — in the heavyweight division. The bridge itself weighed just 982 grams (a little over 2 pounds), according to Michelle Lowry, coordinator of the spaghetti-bridge contest at Okanagan College.
The rules for bridges in the heavyweight contests are similar to the secondary-school division — the bridges must weigh less than 1 kilogram and span a 1-meter gap — but weights are added as long as the bridge remains intact, said Lowry. Contestants in the heavyweight competition are allowed to cook the pasta first and then harden it, which can change the properties and make it stronger, said Lowry.
Nobody’s ever come close to the 443-kilogram record, although they often see bridges that support 200 or 300 kilograms, she said.
Next projects
Other projects on the agenda for the junior-high engineers include testing thermal enclosures such as a cooler, coffee mug and solar oven to learn about heat transfer, said Hinckley.
The students will also develop an electromagnet that can pick up 50 paper clips, and build miniature microscopes to understand light and lenses.
All the engineering lessons teach the engineering-design cycle of investigation, planning and designing, creating and evaluating, said Hinckley.
The next contest involving foodstuffs will test different containers to see which will protect a raw egg from breaking when the students slam them into one another.
