Went down a rabbit hole one day and couldn’t be satisfied until I saw it through.
The Rabbit Hole:
So saw a potato gun made up to look like a civil war canon, looked similar to an M18 recoilless so started looking at that. Then figured potatoes were a little dangerous so switched to something softer. turns out that tennis balls and 2-1/2″ schedule 40 PVC are good match and the tennis balls is roughly the diameter of a 2.36 rocket. Then the idea went from using combustion as I worried it would weaken the PVC over time to compressed air. Added benefit is that compressed air is fine legal wise. Apparently the old hairspray (or whatever combustible you’re using) and piezo can be considered a destructive device.
The mechanism is based off a sprinkler valve and a air blower with a lot of JB weld.
hardest part was the external details. a lot of forming with a heat gun and sander went into the sights, grip/stock and tail cage. Wish I had taken photos to document the process. Pretty happy with the end result.
For the air went out in the field I use a battery powered tire pump. in the photos here I have a Black & Decker one but have also used those AirHawg things. Actually like those better.
I got a lot of the details and ideas from this thread I found (although sadly it looks like a lot of the photos have been lost) https://ww2aa.proboards.com/thread/11214/bazooka-m1a1 and combined it with tennis ball cannon info I found around the web.
Here’s the dimensions I found and used.
Here’s some of my sketches while planning the layout. Unfortunately I lost my written notes from the actual build.
Top is the mechanical portion, second level is the aesthetic parts and bottom is a close up of the valve.
Here’s a site with some good pictures of the me mechanism construction. http://www.k4icy.com/launcher.html
Whatever you do, DO NOT USE ABS. or DWV PVC. Those are not meant for pressure and WILL burst.
If I were to redo it I think I would use schedule 80 for the pressure tank for the added safety.