Medieval device will help teach STEM at STARBASE Academy

Published Aug. 17, 2016
By Dave Smith
21st Space Wing Public Affairs

PETERSON AIR FORCE BASE, Colo. -- In 1304, during the siege of Stirling Castle, King Edward I of England had created a war machine so powerful the mention of it brought about the surrender of the castle garrison. The machine was a trebuchet, believed to be taller than 300 feet and able to launch stones that would knock down entire sections of castle wall in one hit.

More than 700 years later, STARBASE Academy at Peterson Air Force Base has received a trebuchet of its own. Though the scaled-down war machine is no threat to knock down any buildings on the base, it will help teach science, technology, engineering and mathematics.

“We teach a lesson on trebuchets when we teach Newton's Second Law of Motion,” said Patty Smathers, Peterson STARBASE director. “So, we are thinking we will demo it for the students prior to them doing their hands-on activities using our mini-trebuchets.”

Ian Porter, 12, son of Staff Sgt. Adam Porter, concert band operations manager for the U.S. Air Force Academy band, is heading to Germany. Since he cannot take the trebuchet along, he offered it to STARBASE. Smathers saw the potential to use the device as a teaching aid and readily accepted the offer.

Porter built the trebuchet, which has a one meter tall base and a four-foot long launching arm, initially as a project for his Cub Scout Supernova award. He also built a torsion catapult to compare performance against the trebuchet.

During the building of the siege engines, Porter used STEM skills. Engineering played the major role in building them, but math, science and technology came into play during the design and adjustment phases. Scientific method was used in comparing the device’s performance.

“The design is what struck me as most useful,” Porter said. “It was simple and sometimes simple things work better. This basic design was one of the most advanced things until the cannon, basically.”

The original design was obtained on the Internet and Porter expanded it from there. In the process of the science project, Porter said he got into a lot of research. The project advanced and he ended up getting deeper into the science of how war machines work. He said he was exited to experiment with what was probably the largest weapon if its time.

The biggest discoveries came where weight was concerned. Trebuchets rely on weight to drop, causing the arm to swing up, whipping the projectile from the sling and toward the target. For his project he used weights varying from as low as five pounds up to a maximum of 90 pounds. He found that only about 50 pounds could be used on a PVC plastic pivot bar, while a metal bar could handle up to 90 pounds easily. Higher weight typically led to longer range for launched projectiles.

“We were happy with the results of the first shot,” Porter said. “As we progressed we adjusted the design a little and it got good, then better, then worse, then better.”

Eventually the trebuchet launched baseballs about 210 feet and the torsion catapult could cover a distance of about 100 feet.

“The best part was the launching,” he said. “Or the impact.”

Both the trebuchet and torsion catapult were donated to STARBASE. Smathers is happy to have them, and not just to use as teaching aids.

“They will be great conversation pieces on display in our lobby.”