"Chen Gui, author of the Shoucheng Lu or “Defense of Towns” who was an active participant and therefore a direct eyewitness of the earlier siege of De An in A.D. 1127-1132, recorded that the largest type of catapult had a pulling crew of 250 with two men to a pulling rope and had levers of 2.8 chang long (somewhat between 6 to 9 metres during the Song) while the smallest single levered catapults required a crew of 40 men pulling on 20 pulling ropes. The ranges obtained from these catapults were also recorded where he gave the ranges for Song era large and small catapults. Large first class catapults had a range of 270 bu, second class catapults 260 bu and third class catapults 250 bu, while the small single-levered catapults could hurl 1 kg stones up to a distance of 50 bu (where a bu at the time of the Song was approximately 60 centimetres)."
His maximum of 270bu only equates to 162m.
I need to clear some basic assumptions on Chinese traction catapults.
1. There were 2 pullers per traction rope.
2. What is a reasonable assumption of downward pulling force per puller expressed as a fraction of the puller's weight? (1/2? 1/3? 1/1?)
3. Throwarm ratio taken as 5:1
4. He doesn't give the projectile weights for the 1st, 2nd and 3rd class catapults although he does give a projectile weight of 1kg for small single-levered catapults. We assume a more decent projectile weight taken at 10kg?
5. Typical weight of a Song-era soldier (puller probably not wearing armour or weapons)? 65kg? 75kg?
6. Release angle for Chinese catapults are usually straight-up (ie. 180 degrees measured from throwarm)?
7. Height of catapult assumed to be 1.5 times a person's height (1.63m?), which would equal approximately 2.45m?
8. Weight of throwarm assumed at 150kg (for bamboo bundle)?
9. Length of sling taken at a reasonably long 2.45m?
I'll load all these figures into a catapult calculator written by LTC Stephen J. Ressler, Dept of Civil and Mech Engineering, West Point, and work out the maximum ranges and post them here as a graph later.
Edited by Liang Jieming, 24 April 2006 - 11:32 PM.