This was a contribution to a section of a Rube Goldberg machine for a college science building grand opening. The request was to build a rocket launch device that when triggered by a rolling golf ball would pull a cord as a finally to the show.
Borrowed a tire bead seater to store a large amount of pressurized air. Modified the outlet port of the bead seater for a PVC pipe that a projectile could launch from. Installed an air dump valve activated by a solenoid in place of the original mechanical valve.
The solenoid valve was wired in with a 9 volt battery and a micro contact switch from a convertible top that was inserted inside the tube where the golf ball would fall through.
Once the ball dropped through a funnel it would pass through a hollow tube triggering the embedded micro switch. When the micro switch closed the circuit it activated the air dump valve to completely release to contents of the air tank through the modified outlet port.
This was planned for an outdoor event and pressurized at around 500 psi to launch any projectile from the outlet to few hundred feet. Unfortunately the event was later moved indoors and had to be changed to a measly 20 psi in order not to damage the ceiling of the new science building.