Xaxk's TNT Cannon is an fully-operation Siege Engine that can either be used for defense or destruction. It can also be used for research.
How To Build
Dimensions: 5x3x2(minimal design) 5x3x3(double layer charge holder)
Materials: Stone or anything that's not effected by gravity
Upgrades: A good smaller cannon, although charges in many layers tend to fall out and blow the cannon up without a charge holder. Many upgrades possible.
Stone/Cobblestone: 11 needed for the cannon itself, 14 (in total) for double layer charge holder (more for good looking redstone circuit, can be replaced by any other material)
Redstone (For firing mechanism): 8+
Any activator (Pressure plate/switch)
TNT used per launch: 2-3 or 2-5 (double layer charge)
Charge: up to 3 layers of charge tested (total of 6 blocks per launch)
Automated warhead trigger: Activator for the warhead, a seperate redstone wire that leads to the projectile TNT. (Makes it much more safe as well)
An ordinary cannon. Using 1-4 booster charges and firing 1 TNT, Different rages from 20-30, further measuring needed.