UK-based aerospace engineer Tom Stanton has successfully designed and tested a medieval-style trebuchet capable of launching a four-gram projectile at supersonic speeds, reaching 776 mph according to video documentation of the build. While modern industry has no practical demand for siege weapons, Stanton’s custom engineering projects draw an audience of over 1.5 million subscribers on his YouTube channel, where he previously constructed builds like an air-powered plane and a bicycle powered by a Stirling engine.
How Medieval Trebuchets Operate and Defy Constant Acceleration
Historically, military engineers designed trebuchets to hurl massive stones to breach heavy stone castle walls through sheer momentum. According to historical mechanics, the device relies on a heavy counterweight dropped by manual force, which pulls a lever and sling mechanism to fling a lighter payload over long distances. However, any object in freefall on Earth accelerates at a maximum of 9.81 meters per second squared due to constant surface gravity. This physical limitation means standard trebuchet projectile speeds remain largely identical regardless of how much extra counterweight operators add, setting a formidable ceiling for anyone attempting to break the sound barrier.
Engineering a Supersonic Siege Weapon at Home
To overcome physical acceleration limits, Stanton built his trebuchet with a counterweight suspended from a 3:1 ratio pulley system to alter the relationship between the dropping weight and the projectile velocity. For the arm, Stanton used a carbon fiber material on a home-built CNC mill to keep the structure both rigid and light. Stress tests exposed initial weaknesses in the build, prompting complete redesigns before field testing began. Stanton tested the apparatus in 22-pound (10 kg) increments to gradually scale up the system’s velocity.
| Counterweight Mass | Projectile Velocity |
|---|---|
| 22 pounds (10 kg) | 394 mph |
| 88 pounds (40 kg) | 716 mph |
| 110 pounds (50 kg) | Structural failure |
| 88 pounds (40 kg) (4-gram payload) | 776 mph (1,248 kph) |
Breaking the Sound Barrier with a 4-Gram Payload
Initial testing with a 22-pound (10 kg) counterweight sent payloads to 394 miles per hour, while an 88-pound (40 kg) counterweight pushed projectile speeds to 716 mph, falling just 51 mph short of the speed of sound. When Stanton scaled up to a 110-pound (50 kg) counterweight, the wooden and carbon fiber apparatus suffered structural failure under the extreme load. Returning to the 88-pound counterweight configuration, Stanton reduced the projectile mass down to just four grams. This final adjustment allowed the payload to reach 776 mph (1,248 kph)—exceeding the speed of sound by nine miles per hour—confirmed visually by data and audibly by a sharp sonic boom crack.
Did You Know?
Tom Stanton’s YouTube catalog includes mechanical builds powered by pendulums and Stirling engines, showcasing amateur aerospace and physics experiments outside of his supersonic trebuchet project.
Frequently Asked Questions
How fast did Tom Stanton’s trebuchet projectile travel?
The four-gram projectile reached a top speed of 776 mph (1,248 kph), surpassing the speed of sound by nine miles per hour.
What materials were used to build the supersonic trebuchet?
Stanton used carbon fiber for a rigid yet lightweight arm, carved using a home-built CNC mill.
Why do standard trebuchets have a speed limit?
Objects in freefall on Earth are limited by constant surface gravity accelerating objects at 9.81 meters per second squared, restricting standard velocity gains.
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