This is a very simple and affordable project. It was my first mortar to be constructed and it has worked very well. It delivers one of the most satisfying firings of all my launching devices with an almighty boom!

This tennis ball mortar will fire a tennis ball about 100 meters when positioned at 45°. It does suffer from frequent repairs of the lower cans however.

• 5 baked bean tins with stacking ridges on base of tins and standard top
• 1 baked bean tin with a standard top and base (no stacking ridges)
• Tennis ball
• 5mm Ø drill bit and drill
• Duck tape
• Stanley knife
• Tin opener
• BBQ Lighter
• A few bricks and/or something to hold the mortar in firing position

The first problem was to find some stackable baked bean tins and some that did not stack.

The first photo on the right is the base of a ridged based tin (one that stacks) and the second photo is of a standard tin (one that does not stack).




I made baffles/holes in four out of the five ridge based tins by cutting out a circle in the bases using a Stanley knife. The hole in each of the bases is about 25mm in diameter. The baffles help to keep the mortar rigid and can improve the overall combustion of the propellant.






I then cut the top and bottom off the standard baked bean tin using a tin opener. This tin is then used for extending the 'barrel' part of the mortar.






With the remaining ridge based tin I drilled a 5mm Ø hole on its side about 25mm away from the base of the tin. See photo left.






This is a diagram on how the tins should be constructed. In turn, I joined each tin together using a couple of layers of duck tape (see photo).





Last of all I modified the tennis ball using duck tape. To keep the ball spherical, I wrapped the duck tape round in an "X" shape first, and then in a "+" shape. I kept adding layers until the ball fitted smoothly yet snuggly down the top section of the mortar.

This is just a small guideline to operating the mortar - to get best results you will need to practice and develop you own methods of operation.



• Place tennis ball down the mortar.
• Spray a very small amount of propellant through firing hole - about a teaspoon of lighter fluid or a quick squirt from a deodorant can.
• Cover the firing hole with your finger and give the mortar a quick shake if a liquid propellant was used to allow it to vaporise.
• Crouch beside the cannon and face away, whilst pointing the end of a BBQ lighter next to the firing hole.
• Light the lighter (still holding next to firing hole) and the flame produced should ignite the propellant inside the mortar - BOOM!

To improve the design of this mortar, more non-ridge based tins can be added to the barrel part of the mortar. Adding around three extra tins has shown a good improvement on the performance of the device.