Engineering
How a counterweight trebuchet works
A trebuchet is a lever with a very heavy short end and a very long light end. Drop the weight, and the long end whips a sling around faster than any arm could swing on its own. The release angle, the sling length and the mass ratio decide where the pumpkin lands.
- 01The counterweight drops and the arm rotates about the axle.
- 02The sling trails the arm tip, then swings out past vertical.
- 03The release pin slips off its hook and the pouch opens at the launch angle.
Fig. 1 Side elevation, not to scale
counterweight
sling and pouch
axle
Fig. 1 Side elevation, not to scale
counterweight
sling and pouch
axle
What the numbers mean
Every value in a spec table or a results table on this site carries one of three labels.
- measured
Taken with a tape, scale or stopwatch on this machine.
- estimated
A best figure, not weighed or measured. Always written with "about".
- unmeasured
Never recorded. Shown as a gap on purpose, not guessed.
The 2026 build is being measured as it goes, so every row on its page should read measured.