Updated: Fri, 2006-08-25 11:23
This page contains some Sketchup models of hwacha. They are free to use for any purpose. There's a less detailed model available here, which might be more useful for some purposes.
This is the most accurate and detailed model. It's based on a number of sources, including the reconstructed hwacha at the Seoul War Memorial. Generally I'd say it's a lot more accurate than, say, the hwacha that every dreadful historical film seems to put in the background these days.
In particular, I resisted the temptation to put spikes on it. The Chinese weapon from which the hwacha is descended did indeed have spikes, but that's because it was used at point-blank range, more like an exploding pushcart than a ranged weapon. The point of the hwacha was that it could be used like artillery -- very, very inaccurate artillery, perhaps.
Anyway, I hope someone finds this model useful.
Download here 
I'm not really sure how useful this is; it's the same hwacha model but with a stream of singijeon rockets coming from it. The rocket model isn't very interesting and doesn't really look like any particular type of singijeon; it's supposed to vaguely be the medium-size type, but the head is too big and there's no fuse or explosive charge. The white cylinders represent the propellant charge in its paper tube.
Download here
This page contains some Sketchup models of hwacha. They are free to use for any purpose. There's a less detailed model available here, which might be more useful for some purposes.
3D Hwacha Model
This is the most accurate and detailed model. It's based on a number of sources, including the reconstructed hwacha at the Seoul War Memorial. Generally I'd say it's a lot more accurate than, say, the hwacha that every dreadful historical film seems to put in the background these days.
In particular, I resisted the temptation to put spikes on it. The Chinese weapon from which the hwacha is descended did indeed have spikes, but that's because it was used at point-blank range, more like an exploding pushcart than a ranged weapon. The point of the hwacha was that it could be used like artillery -- very, very inaccurate artillery, perhaps.
Anyway, I hope someone finds this model useful.
Download here
Points to Improve
Despite my best efforts there are some glaring flaws in this model. There's a major inaccuracy in that the number of tubes should really be 60 (since these are large tubes for firing large projectiles; if they were small tubes there'd apparently be 100). The mechanism by which the support pole at the back is fixed to the hwacha isn't shown clearly in any contemporary manuscript that I happen to know of, or in any modern reconstruction. So I just put a blob there, sorry. In reality, the 'wheelbarrow' part of the hwacha and the rocket box were separate bits, joined with pegs. I haven't tried to show this because life is too short.Hwacha Firing
I'm not really sure how useful this is; it's the same hwacha model but with a stream of singijeon rockets coming from it. The rocket model isn't very interesting and doesn't really look like any particular type of singijeon; it's supposed to vaguely be the medium-size type, but the head is too big and there's no fuse or explosive charge. The white cylinders represent the propellant charge in its paper tube.
Download here