What goes up must come down . . . unless the
object achieves escape velocity.
anonymous rocket scientist
A Short History
A trebuchet is a medieval siege weapon with origins in China. The original implementation followed step-wise refinement as the idea traveled west, and design matured in the Middle East and Europe in the 1100's. The trebuchet is powered by a large counterweight rather than by twisted ropes as a catapult is, and if built large enough with a heavy enough counterweight (say several tons), it can hurl a 250 pound rock a hundred yards. Typically the trebuchet was aimed at a castle under siege with the purpose of battering a breach in one of the walls. About five years ago NOVA (see NOVA Trebuchet Program) funded a group of timber-framers to make two full-sized trebuchets of different design in Scotland and test them against a masonry wall; both were successfully constructed and fired (see Timber Framers in Scotland).
Trebuchet as Spectacle
In modern times people have built trebuchets and used them to launch a
variety of objects. Hugh Kennedy, a landed gentleman in England, has used
his substantial machine to fling defunct flaming pianos and even a compact
car. However, someone with minimal carpentry skills can construct
a much smaller one
consisting of a throwing arm made from a standard eight-foot long two by
four and a ninety pound dumbbell; a machine of these dimensions is capable
of throwing water balloons in excess of one hundred sixty feet and is
enormously popular at birthday parties (not just with the kids, either).
Even smaller devices
made from copper tubing are capable of throwing a hacky-sack fifty
feet - these are a hit too.