Working Cannon Completed

[Darren Stoddart]

Hello Everyone,
I just completed a working cannon for a performance of The Nutcracker. BY working I mean that it shoots low-density foam balls.

This is the firing mechanism. A piston slides back in forth and is "sprung" with the bungee cord you can see at the bottom of the photo. There is a drawcord that attached to the eyelet that gets pulled back to set the firing piston, it is heald the ready position by a bead on the cord that fits through a hole and slot. This triggering area can be seen in the second photo.

I am very well pleased with the mechanism and have all sorts of ideas for how to use it in other special effects that require launching doo dads into the air.

Photo 3 are the foam balls. These balls do not fly well or far but they are very safe which is a top priority. I used similar balls in an air cannon for a big finale scene in High School Musical. In this configuration they fly 8 - 10 feet, if I compressed the ball in a smaller tube the piston strike would be able to launch it further.

Photo 4 is the completed cannon.

I look forward to your thoughts and any suggestions for improvements!

 

[BillConnerFASTC]

Fun!

Reminds me a of field artillery "cannon" for Brecht's Puntilla. They machined a block of aluminum to hold 5 shotgun shells with wadding, and 5 firing pins, and the actor struck them with a hammer (actor was upstage and cannon straight to audience so hammer not seen.) Only Tom Skelton and I were at rehearsal desk for tech,and we both slowly ducked down behind rehearsal desk. Bang! - and about 2-3 seconds later a styrofoam cup and some other debris blew off the rehearsal desk. Fun times.

 

[Darren Stoddart]

That's a funny story Bill. I have also been working on some piston valve vortex cannons (think high powered airzooka) to do exactly what you describe. Safely shoot a tight torus (smoke ring) into the audience.

 

[Amiers]

If you find the center of your sphere and plunge a ball bearing in there and seal it up it should shoot a bit farther without injuring someone.

A giant golf ball comes to mind as far as design. If you were looking to shoot the moon.

 

[Van]

Very cool!

 

[Silicon_Knight]

It looks like your current ammunition is of polystyrene balls. Maybe something like open or closed cell polyeurathane foam might be slightly heavier and lest resistant to drag forces (e.g. it might fly further), but still safe as a projectile. I'm not certain of your bore diameter, but here a maybe some possibilities:
https://www.amazon.com/dp/B0044D5RRA/?tag=controlbooth-20
https://www.amazon.com/dp/B017YVV4KM/?tag=controlbooth-20
https://www.amazon.com/dp/B01M6WSOBM/?tag=controlbooth-20

 

[Silicon_Knight]

That's a funny story Bill. I have also been working on some piston valve vortex cannons (think high powered airzooka) to do exactly what you describe. Safely shoot a tight torus (smoke ring) into the audience.

Several years ago, I was working on a marching band show that was circus-themed. We built a vortex air cannon out of a 10' piece of 24" diameter Sonotube. If the wind was co-operating, we could shoot a smoke ring from the end zone to the 50yd line!

 

[kicknargel]

Here's one I PMed for an immersive Peter Pan in Beijing. Cool think was, audience kids could do it, and when you released the pull cord it also midi triggered a sound effect.