Recoil Based Cannon

For my maker faire project I decided to work on a recoil based rocket engine model. The way a recoil based engine works is a cannon fires a round at the precise direction, and then, using Newton's Third Law, the rocket is pushed forward. I was inspired by a Kerbal Space Program video made by YouTuber Scott Manley about a joke rocket made out of four GAU-8s (the A-10 Thunderbolt II's gun) pointed downwards, that actually worked until the guns needed to cool down and the rocket came crashing back down. I expanded the idea to include a turret for pitch, yaw, and roll control. I realize that the objective of this prototype was for a more efficient rocket engine, and the discarding of stages efficiency due to each individual "stage" (bullet) being so small that the weight is discarded as thrust remains the same. I had a challenge where the "instance" command wasn't working in Blender and I had to switch to Tinkercad to fix the issue. If I were to do anything next it would be designing the firing mechanism and loading mechanism. The 3D model probably costed around $800 (including cost of 3D printer), but if you already have a printer, then around $2.

Scott Manley's video: https://www.youtube.com/watch?v=G1wgGRcmxIE (Go to 13:18 for the recoil rocket)