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Originating in China, fireworks have been around since before the 16th Century and have been making people look to the night sky with delight. Firework formulas are closely guarded secrets handed down from generation to generation and the overall concept has not changed much over the centuries. Mix chemicals compounds, place them in a delivery device, light a fuse, and watch the fun. That was until now of course. At Soldering Sunday we wondered if we could use LEDs to create a firework display? The answer is a resounding yes, we can!

While there are thousands of forms fireworks, we focused on the aerial fireworks that make the big displays in the sky. Aerial fireworks have several components: a lifting charge to send it in the air, a container which holds the stars, charges, and fuses. The stars are what paint the sky with light and are made of various chemical compositions, shapes, and sizes. After some thought we settled on soda bottle rockets, like those found in Make Volume 05, to be our delivery device. The rockets have everything we need to deliver the LED stars into the night sky.

The container is the 2-liter soda bottle.  The lifting charge is the compressed air and water. The LEDs are the stars and fuses. The charge that disperses the stars is usually black powder – it is what makes the big boom before the stars light. We are not using black powder so our charge is going to be gravity and the wind. What about the boom? If you have launched soda bottle rockets before you know that when they release they make a big boom on launch.  We have all the elements of a successful firework: loud noise, pretty lights, and the element of surprise.

LED Soda Bottle Rocket

Big Bertha Bottle Rocket Firework loaded and ready for action

 

During our experiments we created the LED Chutie, which we brought with us to the 2013 World Maker Faire in New York City. The LED Chutie is an aerial version of the LED Throwie. The Chutie uses a plastic bag for a parachute, a LED, and a 3-volt coin-cell battery. If you can not get outside for fireworks, the Chutie is perfect for indoor fun too.

The Chutie is the basis for the stars in our firework. By combing the Chuties with ping pong balls, plastic practice golf balls, balloons, and straws we can make a wide array of effects in the sky. Just remember that everything that goes up must come down which means that your stars should be light and not a threat if it were to fall on someone or something.  The stars with parachutes fall the slowest and spread out the widest from the rocket. The ping pong balls and the plastic golf balls travel higher and fall faster.  If you are over asphalt or concrete the ping pong balls make fun sounds when they hit the ground.

LED_Stars

LED Stars

We need to use a launcher for our rockets. The one I use is a combination of the one from the MAKE Soda Bottle Project and the release mechanism from this launcher on Instructables. Before you try all this at night, I suggest you test during the day to be sure you are comfortable how everything works and how your rockets behave. Besides, its another excuse to do more launches. Keep safety always and first in mind. These fireworks may be filled with water instead of fire but they still pack a lot of energy.  During tests our launch crew decided to put on helmets for safety (but mostly for fun).

Fireworks Always Bring Smiles!

Fireworks Always Bring Smiles!

We  hope you have a lot of fun with your Soda Bottle LED Fireworks. We are hooked. We already have plans for other forms of LED Fireworks. Keep in touch and check us out at SolderingSunday.com.  If Make let’s us and we are ready maybe we will have a “Firework” display at the 2014 World Maker Faire in New York. We just need to build that Raspberry Pi launch controller we have been thinking about.

LED Fireworks - Big Bertha day time Launch

Big Bertha’s Daytime launch showed us we needed more air pressure.

 

 

Steps

Step #1: Prepare the soda bottles.

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  • You will need two bottles for each rocket, one for the main body of the rocket and the other for the nose cone which holds the LED stars.
  • Despite the obvious shape difference, most 2-liter bottles have similar dimensions.
  • While you work you can keep bottles from rolling around by making a rack out of bamboo skewers and a piece of foam.
  • Clean the bottles and remove any labels.

Step #2: Cut the nose cone.

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  • If you want to make a traditional rocket shape, then use a 2-liter from that particular cola company. if you want more payload area, use the longer 2-liter shape.
  • The nose cone and the body are not attached with a cord like a model rocket. We want the two to separate so the payload, the stars, can fall out.
  • Cut the bottom of the bottle off using one the ridges as a guide.

Step #3: Install the fuse.

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  • Using an LED inside the body of the rocket we can create the effect of seeing the fuse as the firework flies through the air.
  • In the bottom of the soda bottle (the top of the rocket body) drill a 1/4" hole. Conveniently the molding process of the bottle leaves a nice mark where that center is. Use a hobby knife or a small file and clean up any burs in the plastic.
  • Using a long straw (or two taped together) insert the LED into the hole from inside the bottle. The leads should fit in the hole and the LED lens should sit flush against the inside of the bottle.
  • Bend the LED leads over to hold it in place while you add the 5-minute epoxy.

Step #4: Epoxy the LED FUSE and chute ring.

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  • Epoxy the LED in place and seal up the hole. Bend the LED leads over to hold it in place while you add the 5-minute epoxy.
  • Stand the Bottle on edge. Using the bamboo skewer rack you made earlier helps.
  • Mix your epoxy and apply to the hole. I use a bamboo skewer to do this. The epoxy should flow into the hole and onto the back of the LED.
  • The chute ring is where we attach the main chute for the body of the rocket. Make this from a zip-tie and epoxy in place.
  • TIP: 5-minutes sounds like a lot of time, it really is not. If you are building more than one rocket build all the rockets first, install the LEDs and then epoxy them all at once. Once the epoxy is gooey it is no good. Keep the container you used to mix the epoxy. If you want to know if your epoxy is cured, you do not need to poke your project - just check the mixing container.
  • Insert a straw to cover the LED. The straw diffuses the light. Add a 3-volt coin cell battery and tape in place.

Step #5: Cut and attach the fins.

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  • Fins add stability in flight. You can go without them but your flight results will be less predictable. Fins with a slight angle will make the rocket spin and make it more stable. Think of how a quarterback throws a football. By adding spin to the ball it makes it stable in the air.
  • Use 1/8" to 1/4" cardboard, foam board, or fan fold foam insulation. We had plenty of 1/4" blue fan fold insulation on hand so that is what we used.
  • Cut your fins 1" x 9" inches and on each end cut a 45-degree angle. You can make them bigger, as we did for our "Big Bertha" rocket. Try different shapes and sizes.
  • An easy way to mark where to attach the fins is to use a long piece of paper, wrap it around the center of the bottle and mark the paper where it meets. Then place the paper flat on your workbench and measure your marks. That is the circumference of the bottle. Divide by four and mark the paper accordingly. These marks will become the marks of where to put the fins. Wrap the paper once again around the bottle and transfer your marks to the bottle.
  • TIP: An old school method for marking the fin locations is to use a door jam or a folding door. Place the bottle along the jam and rotate to each mark, use the molding to help you draw a straight line. Just be sure not to mark the wall, or there will be a different type of fireworks.
  • Glue the fins with hot glue.
  • If you want to add an angle, just angle them slightly off of your lines. A small angle goes a long way here.

Step #6: Make some Chuties.

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  • The Chuties will be for the stars. We can use the same process for the parachutes for the nose cone, the body.
  • Attach the string to each conner of the plastic bag. We demonstrate with round paper savers, but you can use masking tape.
  • For the parachute for the nose cone and the body, do not add the LED.
  • The LED cathode is negative lead and is the short leg. The LED anode is the positive side and is long leg. Attach to the battery and tape. We have seen these LEDs last over two weeks on a single coin-cell, so do not worry about it losing power before tonights firework display.

Step #7: Attach the parachutes.

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  • Use rubber bands as shock cords, it keeps the parachute from ripping when it is deployed.
  • Attache one parachute to the chute ring you epoxied to the rocket.
  • Attach a parachute to the nose cone.
  • Put a LITTLE amount of clay in the nose. The clay increases the mass of the nose cone. Newtons law of inertia tells us that it's greater mass means it will have greater inertia then the main rocket body. In other words, the nose cone will continue further along the trajectory, while the body of the rocket will be more susceptible to the wind and gravity changing its path.
  • Fold and roll the parachutes neatly and lightly. If you do it tight it will not unfurl in the air. If you do it too loose then it will become wadding in the nose and keep the stars from falling out. You can test if you are doing it right by gently throwing it up in the air. It should unfurl and float to the ground.

Step #8: Make the stars.

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  • Stars are what are at the center of an aerial firework. It is what you see in the sky making all the colors and twinkles that we love. They come in all sorts of chemical compositions, shapes, and sizes.
  • Our stars are made from LEDs, 3-volt coin-cell batteries, and common household items.
  • Placing the LEDs inside a ping pong ball, a plastic golf ball, a balloon, or a straw diffuses the light and enhances it to the eye.
  • Cut the ping pong balls halfway and you can insert the LED and battery into them. A hobby knife works fine for this.
  • The golf balls require a saw and a little more effort.
  • For balloons, stretch them and blow them up first before inserting the LEDs and batteries.
  • For added effect you can use slow blinking LEDs that cycle through red, green and blue.
  • Not every star needs a parachute. The ones without parachutes will fly higher and fall faster. Use common sense, what goes up must come down and should not be dangerous if it hits someone.

Step #9: Prep for Launch

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  • Pack the nose cone by placing the nose cone chute first, the golf balls second, the ping pong balls next, then the Chuties. Try variations of this to see what works best for your rockets.
  • Place the nose cone on the rocket. With the nose cone on, the stars in place, you should be able to shake the rocket and have some movement in the nose. If it is packed too tight the stars wont release.
  • The nose cone should sit on the rocket, but not be pushed down or too tight. If you think it is not on tight enough, its probably just fine. As long as it is straight you should be good. Again, this is what daytime testing is for.
  • Fill your rockets with about two-thirds of water.
  • A bicycle pump is fine. We wanted to to launch a lot of rockets and used a portable air compressor and a 12-volt battery.

Step #10: Practice.

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  • Test everything in the daytime to avoid the fun of fumbling around in the dark.
  • Be safe. 2-liter soda bottles SHOULD be able to hold up to 120lbs of air pressure. However that is a good case scenario and anything can go wrong.
  • The same energy that makes the rockets go up can make the rocket explode. Stay 15 to 20 feet away while the rocket is pressurized.
  • Try different pressures, angles of launch, and payloads.
  • We found that 70 to 75lbs of pressure worked well with our rockets.
  • Too much pressure in your bottle, say 90+ lbs of air and the rocket will take off so fast it embeds itself into the nose cone and becomes a missile instead of a firework. Don't ask how we know that one.
  • If you put too much weight in the nose, the nose cone falls to earth fast and make a thunderous boom when it hits your car. Also, don't ask how we know. Just know that It made a spectacularly loud sound.

Step #11: Launch Your Fireworks.

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  • You are ready for some fun.
  • Prep several rockets ahead of time so you can have fun launching and not loading.
  • Embellished your launcher with LED lights. It makes loading easier and looks cool.
  • Just as with regular fireworks it is best to keep the crowd back. The closer you are to the rocket, the less you will see.
  • Switch off between being a launcher and a spectator so you can enjoy too.
  • Let out the OOOOHs and AAAAHs...

Paul Gentile (The Hobby Guy)

I have been making stuff my whole life, from model trains to multicopters. It is why friends call me The Hobby Guy. More than making I enjoy sharing and teaching others how to make. In 2013 along with two fellow makers, Lee Siegel and Jean Consorti, we founded Soldering Sunday. Our mission is to help Makers of all ages and skill levels explore new ideas, connect with fellow makers, and create what they are passionate about. Come Explore, Connect, and Create with us at SolderingSunday.com.


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