Huge Roman Ballista Catapulta - Tod’s Workshop TV job

In 2012 I headed the engineering on a TV show where we made a catapulta in 3 days. This machine looks like a ballista and people call it that, but in fact the Romans would have called it a Catapulta (NOT catapult). A ballista shoots stones or round shot. A catapult shoots stones or round shot in medieval Europe. This is a CATAPULTA and shoots arrows. It needed to be big for TV but also work well, so we followed the sizes laid down in Vitruvius and had advice from Alan Wilkins and Tom Feely and of cou