Capital Idea, Tim! Very inexpensive, but extremely effective against a variety of targets. Just about anything you can think of will be crushed by 60 or 70 pounds of concrete coming back to earth from 300 or 400 feet aloft!! Mike and I agree about this suggestion. Why not build a modified version of our concrete-filled, 137 lb., Water Jug projectiles we made for our 2/5 Scale, 11", Paixhans Monster Mortar we built last year? It required a little work to get them prepared and filled, but one full weekend would see it done. Building on our experience of sending over half a ton of concrete downrange in that 4" mortar (old cardboard oil cans), we built the Monster Mortar projos with rabbit fence rebar and a low carbon steel lifting loop, knowing that some reinforcement is necessary to hold your sackrete together.
Here are a few photos to jog your memory. Use or discard any part of this design as you wish. It's just a friendly suggestion to get you started.
Tracy and Mike
Bending rabbit fence to form an internal concrete reinforcing mesh.
The mesh and lifting loop installed.
Gary and My son helped out quite a bit with mixing and filling, much appreciated help. Not one of these projos ever failed, not even a little crack, but some lost their plastic jug covering, leaving a perfectly smooth concrete shot with a water jug shape! We sent a few out to 400 yards. At a set, 60 degrees tube elevation, we calculated conservatively that they reached 1,000 feet elevation. You must check for low flying aircraft BEFORE you fire the 1.5 lb. charge that gets you out to 400 yards. We are NOT kidding!
