Onager -- (Catapult) Locked and Loaded

Onager (Catapult)
The Onager was used to throw rocks against a castle or fortification wall.   The
orange arm  is propelled by two loops of twisted skiens which when twisted
 tightly will eturn the arm and its ball rapidly against the upright and its
cushion.   This model which is about 9" long will catapult the wooden ball
about 25-30 feet