This cannon work on falling TNT,when you had a TNT face to a wall,the TNT will hit the wall and rebound to other direction.
Using that effect,you can use different hight,let the TNT fall on different place.
When you shoot 3 TNT(2 is booster),1 of the TNT is a little bit higher,so it will get a longer range.
The boost will get a lower range,but also the boost will explode in midair.That force will put the longer TNT to much longer...
Currently is a concept,i am finding a way to shoot it lower angle,so that will realy make TNT cannon more compact and also longer range.
I have made one of these before but reversed, it was used to fire through a very small opening in a obby wall. Reverse the cannon, have the tnt dropped down from above and then fired and it is VERY effective. One of the most accurate cannons ive ever used aswell, can get very specific with its angle and speed using this design.