Gas Propelled Rocket Launcher

Build your own gas powered rocket launcher with a few off the shelf parts. Some time ago I built a Remote Control Rocket Launcher which used butane fuel as the propellant. It worked really well so I decided to make a hand held version.

I’ve use Butane again as the propellant. The gas reservoir and piping are pulled from a BBQ lighter which are very cheap and easy to get your hands on. The spark to light the gas is generated from a battery operated Piezo Electric generator. If you wanted to you could use the piezo electric spark generator from the BBQ lighter. However, I find that using an electric one maintains a steady spark and makes the job of ignition a hell of a lot easier to do. Plus kids can easily push the button and set off the rocket.

The rest of the launcher is made from PVC pipe which you can get at any hardware store. The barrel section I used some opal pipe with is translucent. I had a piece of this pipe lying around and thought it would look pretty cool being able to see the flame in the barrel.

Parts:

1. Spark Generator – eBay. You could also probably use one of these as well, although you would have to solder it together. You could also try an arc lighter like this one as well

2. BBQ Lighter – eBay

Bunnings is a hardware store in Australia but nearly any hardware store will stock these parts. It's probably going to be cheaper buying these parts from your local hardware store then eBay

3. 25mm PVC Tee – eBay, Bunnings

4. 25mm Coupling with male screw end – eBay, Bunnings

5. 25mm Coupling with female screw end – eBay, Bunnings

6. 2 X 25mm Caps - eBay, Bunnings

7. 25mm PVC Tube – eBay, Bunnings

8. Momentary on/off button – eBay

9. 2 x AAA battery holder – eBay

10. Wire. I used sold core wire

11. Small piece of wood (to block-up one of the couplings

To build the rockets

1. Cardboard or stiff paper to make the rockets

2. Masking tape

3. Hot glue

Tools

1. Pipe cutter (you can also use a grinder)

2. Drill

3. Soldering iron

4. PVC glue

5. Epoxy glue

6. Hot glue

7. Dremel (always handy)

Steps:

1. Take off the plastic part that is around the neck of the lighter

2. Un-screw any screws holding the plastic body together

3. Remove the cap from the end of the lighter and make sure that the tube is loose before you remove the gas tank. You will need the tank, tubing and the metal end inside the tubing

4. You can also remove the piezo electric spark generator and use this to annoy your friends with. If can also substitute this if you wanted to for the electric spark generator.

5. Put aside the tank and tube and move onto the spark generator

Steps:

1. Remove the top section of the generator.

2. Un-screw any screws holding it together

3. Remove the circuit board and wires from the generator. You only need this part so the rest can go into the bin

4. Next, de-solder the 2 wires that were in the neck section of the generator and add a couple of new ones. Use solid core wire as this is stiffer and will help when generating the spark

5. You may have noticed that there is only 1 wire soldered to the circuit board for the battery. This is the negative wire. A positive wire can be soldered to one of the solder points on the part in the middle of the board. I have highlighted this in the image below

6. Test by adding 3v to the battery wires and holding the spark wires next to each other.

Put this aside and start work on the launcher

Steps:

1. Attach a piece of the 25mm PVC pipe to the male coupling. I used about a 250mm length of PVC pipe. As mentioned earlier, I used a piece of translucent pipe which was slightly too big for the coupling. To make the opening larger, I used a dremel with a sanding drum attached and removed some of the material

2. To attach the PVC, you will need PVC glue. Make sure the areas are clean, add some glue to the inside of the coupling and push together.

3. Next you need to add a small piece of PVC tubing to one of the ends of the Tee. Cut and glue into place. The pipe should be long enough to fit the 25mm cap to the end

When adding the gas tank it’s important that you can easily refill the tank and also use the trigger on the top of the tank to fill-up the chamber. To do this I added the tank to the end of the cap. This allows we to easily reach the trigger and I can just pull of the cap and fill the tank when I need to. The important thing here is to make sure the tube is long enough. You don’t want to take the cap of and have the tube too short to be able to re-fill the tank.

Steps:

1. Drill a couple of holes into the top of the cap.

2. File and make the hole the same size as the tank

3. Push the tank into place. If the tank is loose, add some glue to hold into place

4. Drill a small hole next to the tank and push the tube through it

5. Lastly, add some hot glue to the inside where the tube comes through to hold it in place.

You need to block the end of the tee that the barrel is attached to. To do this I just used a small piece of wood and glued it into place

Steps:

1. With a hole cutter bit on your drill, cut out a piece of wood that will fit snuggly into the female coupling.

2. Glue the wood into place

3. Next, attached the female PVC coupling to the tee with some PVC glue

4. Place the cap with the tank onto the end of the tee. Thread the gas tube through the hole in the middle of the wood and hot glue into place. Make sure that you can pull the cap off and get to the bottom of the tank in order to fill it up with gas

5. Lastly, drill a couple small holes to the side. These will be used to house the spark wires

Steps:

1. Grab the spark generator and push the 2 wires that make the spark through the holes in the wood.

2. Glue these down with some hot glue once they are in place.

3. Make sure that the tips of the wires are slightly facing towards each other. This will help with directing the spark

4. Test by adding some power to the battery wires and make sure that the wires produce a spark. If they don’t push the wires closer together

Steps:

1. Cut a piece of the 25mm PVC pipe for the handle.

2. Push the handle into the tee and work out the best stop to add the switch

3. Drill the hole and attached the switch

4. Next solder the positive wire from the spark generator to one of the solder points on the switch and then solder another wire to the other solder point. Thread this wire along with the negative wire from the generator through the handle and glue the handle into place.

Steps:

1. Solder the positive and negative wires to the battery terminals

2. Test by pushing the button and seeing if a spark appears at the end of thr wires

3. Push the battery into the handle and decide whether you want to trim the handle down or not.

4. Next, place a 25mm cap to the bottom of the handle. If the battery moves around inside the handle, stuff some paper or cloth inside to hold it in place.

Steps:

1. Now you’re ready to put the launcher together. First, screw in the barrel section to the tee

2. Make sure the batteries are in place and that you can make a spark

3. Next, release a small amount of gas into the chamber. Point the launcher away from yourself and push the button. You should see some flames come out the top of the gun.

How to Adjust the Flame

If you saw a clue flame come out the end then your launcher is pretty well dialled in. If you saw a yellow flame come out the end then you have have to put less gas into the chamber. The more gas you add, the less the air will be available to help combustion. You only need to release a second or two worth of gas usually.

4. Once you have ignited the gas you will need to un-screw the barrel and wave it a couple of times. This will remove any stale air and old gas. It’s important that you do this each time otherwise the gas won’t ignite in the barrel

When making the paper rocket there are a few things you need to keep in mind. Make sure that the rocket isn’t too big or heavy, don’t have it too tight around the barrel and make sure you make it last (at least for a few launches!)

Steps:

1. First you need to get either some A4 paper. It should be stiff paper for best results. Cut the paper through the middle and trim about 50mm off the side.

2. Wrap the paper around the barrel of the launcher so you have a tube

3. Add some masking tape around the paper tube to make it stronger and also keep it all together. Remember, don't make the tube too tight, you want it to slide up and down the tube easily.

Steps:

1. Cut 3 fins from some stiff paper.

2. Next bend the sides of the fins as shown in the image below. This is where it will attach to the body of the rocket.

4. Add some masking tape to the bent section of the fin and tape it to the body of the rocket. Add a few more pieces to ensure that the fins are secure

5. Add as much tape as you think necessary.

Steps:

1. Make a cone shape out of a piece of stiff paper.

2. Add some masking tape to hold it together

3. Next, place the cone inside the top of the body of the rocket and mark where the cone and top of the body meet.

4. Cut the cone flush with the rocket top

5. Next , push the nose cone right through the rocket tube so it is sticking out the top

6. Add some hot glue to the sides of the cone and tube. This will secure the nose to the body of the rocket and will also add some weight to the top of the rocket.

Now that you have finished your rocket, it’s time to give it a test run.

Steps:

1. In order for the gas inside the barrel to propel the rocket, you
will need to add some tape around the barrel. When pushing on the rocket, the bottom section should slipe over the tape. The connection between the tape and the rocket should be quite tight. This will ensure you get some good height when launching.

2. Add some fuel into the barrel. How you add depends on how much comes up the nozzle of the gas tank and also how long the barrel is. You will need to probably experiment a couple of time before you work out the right mix of butane and air. If there is too much butane then you won’t get the height, and if there is too little then it won’t ignite

3. Point the rocket launcher up into the air and hit the fire button. Your rocket should get propelled high into the air.

4. Remove the barrel after firing and give it a couple shakes and try it again. It’s important to remove the stale gas and air in the barrel before each flight of the rocket.