One of my favorite things to do with my granddaughters is to use pneumatics to lob things around the yard. This is a great build that is very affordable and can be made by anyone. All you need is a pair of adjustable pliers, a pipe wrench, teflon tape and ideally a bench-mounted vise grip. You will need a small pancake compressor capable of producing 90 psi.
The general idea is to launch a Stomp Rocket several feet into the air by sliding the rocket over the barrel. The slide valve is the trigger mechanism. You move it forward to charge the chamber with air and slide it backward to dump the air very quickly. The result is a sudden burst of air.
I do not recommend operating this component at any greater than 40-60 psi when children are present. Yes, it is a foam rocket but all it takes is one careless move or leave it unattended to do serious injury to the eyes or throat. We primarily use these projects to "lob" these rockets at baskets. At times we shoot them just to see how far they go and the girls chase after them...we do not let them try and catch them in the air. Not safe.
This same configuration can be used to do a multitude of things by swapping out the barrel. I have installed 4" barrels and launched foam torpedo footballs about 150 yards. I have swapped it out with another barrel to shoot nerf darts and they quite seriously disappear from sight. That is really a BLAST!
Step 1: Assembling the Slide Valve to the Reducer
Connect the 1/2" to 1/4" reducer galvanized pipe fitting with the slide valve. The slide valve needs to have the 1/4" NPT plug installed on the inlet side. One end of the slide valve has a 1/4" female NPT and the other end has a 1/4" NPT male fitting.
List of Tools Needed:
List of Components:
(1) 1/4" MNPT plug
(1) Slide Valve
(1) 1/2" to 1/4" bell reducer
(3) 1/2" x 2" galvanized nipple
(1) Quick Exhaust Valve 1/2" inlet/Outlet
(1) 1/2" galvanized end cap
(1) 3/8" to 1/2" bell reducer
(1) 1/2" x 12" galvanized pipe (threaded)
weaverzinger is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com
Step 2: Install One of the 1/2" X 2" Nipples Into Slide Valve Assembly
Step 3: Install Quick Exhaust Valve
Thread the slide valve assembly into the Quick Exhaust Valve. Be careful not to crack the body of the valve.
Step 4: Install Air Chamber
The Quick Exhaust Valve has 3 ports. The bottom port is where you will install the second 1/2" x 2" nipple and the end cap. You are creating an air chamber to store the compressed air, the volume of air that is trapped here is what will be exhausted through the barrel to propel the rocket. You can change the size of the chamber by adding a longer section of pipe. I replaced the 2" long nipple with a 4" nipple and the results are amazing.
Step 5: Install 3/8" to 1/2" Bell Reducer
Now thread the the last 1/2" x 2" nipple into the Quick Exhaust Valve and thread the 1/2" to 3/8" bell reducer as shown above.
Step 6: Thread the Barrel Into the Assembled Piece
The last step is to thread the 3/8" x 12" galvanized pipe into the reducer as shown. The completed component should look like the picture above.
Step 7: Operation
Set the output pressure on your air compressor to about 60 psi. Connect your air source to the 1/4 NPT plug on the slide valve side of the assembly.
Place a Stomp Rocket over the 12" barrel, grasp the air chamber with your non-dominant hand and push the slide valve forward to charge the air chamber.
Set the desired angle and pull the slide valve back down and toward you.
NOTE: Stomp Rockets are not very aerodynamic and they can easily be effected by the wind. Wait for a relatively calm day to launch these rockets.
Never point this at anyone.
Never shoot an object harder than foam.
Serious injury can occur if hard, or sharp objects are used with this device.
Please use this device responsibly, just because it can be used as a toy it can also produce lethal results if misused.