John C. Aldrin, PhD
    Engineering Consultant




Engineering Educational Tools - Trebuchet Project
What is a Trebuchet?

A trebuchet is a historical ballistic mechanism used during the middle ages.  From a dynamics perspective, the trebuchet is a triple pendulum mechanism.  A diagram of the mechanism is shown below.  The mass m3 is the projectile located at the end of a sling of length c.  The main arm of length L and mass m1 drives the projectile through the lowering of a counterweight of mass m2.  Unlike a catapult, this counterweight was often designed in the form of a pendulum as shown below, thus optimizing the transmission of potential energy of the counterweight to the kinetic energy of the projectile..

Figure 1.  Diagram of a triple pendulum mechanism.

Undergraduate Research Project:   Dynamic Analysis of a Historical Ballistic Mechanism

  • Objective: to solve the equations of motion for a triple pendulum ballistic mechanism, a trebuchet (Prof. W. Soedel - Project Sponsor)

Current Project Work:
  • Write code to solve for equations of motions, given dynamic parameters and initial conditions. (completed)
  • Develop user interface to simulate equations of motion (completed - to be offered as Shareware in near future)
  • Develop 3-D animation of simulation response (in progress)
  • Develop educational package for science / engineering students (to do)
  • Develop educational game using the trebuchet simulation (to do)


If you are interested in obtaining a copy of the trebuchet simulation program, 
please contact me via email:

This page was last updated on May 6, 2001 by John C. Aldrin ( )