The Air Cannon OK, here's a couple of room ideas and a prototype design for the air cannon. These notes were taken from an halloween-l contest entry from a few years ago.
Guests enter a long hallway.
They immediately hear ghostly sounds all around. Then, as they proceed a bit into the hallway, a loud ghost scream is heard from behind. A second later, the guests feel and hear the ghosts flying through the hallway. An extension is where the ghost disappears, then the guests hear and feel them moving back down the hallway. The air ram is triggered by a momentary foot switch connected to a washing machine valve.