This is a photograph of a reconstructed mangonel or onager built, once again, in Middelaldercentret (The Medieval Center of Denmark). It is shown just before releasing it's shot froma sling. Mangonels or Onagers use slings instead of cups like catapults do. They also use the power of torsion or twisted ropes like a catapult. So it's kind of like a cross between trebuchet and a catapult.
