1) Noise: The noise in the microphones needs to be mufled since the sounds involved are so loud. Place electrical tape over the crystal microphone cartridges and wrap the microphone up with paper or wrapping material.
2) Receiving Box: Before class, set the distance between the box and the projectile laucher so it will hit the back of the box each time. This way, you have a constant, set x-distance. Fill the box with wads of paper to keep the ball from bouncing out.
3) Launching: If the Apparatus is mounted on something that jerks slightly, tightening its mount or adding weight to make the mounting more stable will cause the projectile to fly farther. Set-up everything the same way everytime.
4) Alignment: Put tape marks where each foot of the cannon's tri-pod should be placed. These can be used to realign everything after each shot.
5) Safety: Be careful. If the measurements are off just a little, the student holding the ring for the projectile to be fired through could end up with an injured finger. Wear safety goggles and be alert.