Unlike the cannons or mortars used in Western warfare during Middle Ages and the 16th century, which required heavy iron balls, hwachas fired arrows which were thin and light, making it an easy-to-maneuver siege weapon [REF].
The holes in the hwacha's launching array ranged in diameter from 2.5 to 4 cm, which allowed thin Gungdo bow-like arrows to be fired and also admitted sajeonchongtong class igniters placed in the back side of the shooting board [REF].