2 Inch Aerial Shell
An aerial shell is the usual firework you see at a comercial display. Aerial shell's are all about the colors and the patterns. Use your imagination on these once you get the hang of building a few. I have seperated this pictorial into 2 parts just so you know when you can take a nice long breather.
|Plastic easter egg||Hot glue gun & hot glue|
|Visco or other types of fuse||Razor Blade|
|granulated blackpowder||An organic solvent such as acetone, MEK, or Methylene Chloride|
|Stars of your choice (this tut uses rolled stars)|
|Small ammount of flashpowder (optional but recomended)|
Kleenex or other tissue paper
|plastic drinking straw|
|Dental floss or small thread|
|3/4" Masking tape|
|1 1/2" Masking tape|
PART 1: THE SHELL
What you must do first is take your easter egg apart. Drill a hole in the exact center of the longest of the two halves. Then cut a 3cm peice of fuse.
Next insert the fuse so that 75% of it sticks outside of the egg and hotglue it in place on the outside. Your hotglue job does not have to be pretty because I don't think anyone is going to see, let alone comment on how poor or how good the hotglue looks when the shell is 300ft in the air.
The next step is to get the ignition insurance tube set up. Thats not really what its called, but thats its job so I will call it that. Take your drinking straw and push it over the fuse on the inside so you can get an idea of how much you need. Cut the straw so that it ends just before the rim of the egg. Hotglue this into place but be sure not to cover the fuse with hot glue otherwise it will fail to light.
Now you have to fill this little tube with some granulated blackpowder. Fill it until there is about 0.5cm space left at the top. Remeber to tap the egg once in a while to make sure you fill it full with the blackpowder. After that is done, wad up a peice of tissue paper (I used kleenex) so that it fits in the end of that tube snugly, but can come out fairly easily. This should not fall out if the shell is turned upside down.
It is now time to make our break charge mix. The secret to this is to add a tiny bit of flash to make an even break and also to give it a better sound when it explodes. To do this, scoup a little cup full of granulated blackpowder (Picture 1) and sprinkle in a pinch of your favorite flashpowder. Shake it and swirl it around (by moving the cup, not using a untensil) until all the granules are lightly coated with the flashpowder (Picture 2). There, I blew that secret out of the water.
Take the half of the eggshell with the fuse in it, and stand it up on a toilet paper tube cut in half. Place the first couple of stars in; just enough to surround the bottom. These stars should be relatively big to give the other stars a stable base. This is not neccesary (but it avoids making your life a living hell later on) as its not the size that matters, its how you use it (or them in this case). I used a red star formula for this particular aerial shell, just for your information.
Continue filling up the aerial shell by strategically placing the stars. It is recomended that you go bigest to smallest from bottom to top and always place them with future star placement in mind (that means make room for the next layer of stars). The following picture is an example of what I like to refer to as a "Darnit". After a few "Darnit", you are permitted to call them "Oh S**t's" and after a few "Oh s**t's", you are allowed to verbally abuse your aerial shell and its contents assuming that this will prevent future "Darnit's" or "Oh s**t's". When the following occurs, use a pliers or tweezers to remove the stars. This is a very small aerial shell and if you attempt to grab the star with your hands, the ammount of "Darnit's" will increase drastically.
When it gets about halfway to the top of the egg shell, you should fill the space in the center with a bit of the break charge, just to help keep the stars up against the wall of the egg. In the picture below you can see actual flashpowder. This should not happen because if there is too much flashpowder in there, the shell will explode too fast and the stars wont have a chance to ignite. (The visable flashpowder is the smooth surface seen in a couple patches between the granules)
Continue this star-lining and filling routine until you get to the rim of the egg. There should be atleast .5cm between the top of the stars and the top of the rim otherwise you'll have a hard time fitting this shell together.
Set this half off to the side. It is now time to fill the other half of the egg. Repeat all the steps above on filling the egg with stars for the other half and then grab the first half. You should now have two halves that look about the same
This part is the part that drives people crazy. You must hold both halves so that the rims are touching and that the eggs make a 90degree angle with eachother. Then in one quick motion you must swing them together and press them tightly. You might not get it on the first try. I know its frustrating to have the contents of the aerial shell now all over your work area, but just try again. You are either going to have to catch on, or just don't build aerial shells. Its that simple. Unfortunately, I don't have a picture of this motion. I should be getting one shortly just as soon as I build another shell.
Now its time to make sure this thing isn't going to fly apart when its fired. Open the shell just slightly so that there is a 1mm gap between the outside of the two rims and put about 8-9 drops of your solvent into there quickly. You only have to drip it into one area as capilary action will draw it around the whole shell. After all the solvent is added, hastily press the two shell halves together and hold it for about 60 seconds or more. If when you release this death grip the shell moves apart, then you didn't hold it long enough. After this you must wrap the shell in a couple layers of scotch tape. This helps the burst pattern, sound, and helps it stay together during launch.
The final step on preparation of this shell is to crossmatch the fuse. This isn't always neccesary but I find it reduces the ammount of shells that fly back to the earth. Read my pictorial on how to crossmatch in the pure pyro section to find out how to do this. Congratulations. You are done with part one. Sit down and relax for a few minutes or just admire your work until you are ready to start part two.
PART TWO: THE LIFT-CHARGE
Now that you've gotten your well-earned rest, its time to make this thing tube ready. Take your egg and stick it in a toilet paper tube (a whole one) so that the fuse points down into the tube. Take two strips of the 3/4" masking tape and make a plus sign on top of the egg and down onto the tube to secure the egg.
Take 2 more strips of this masking tape and go over the exposed spots forming another plus sign (but not on top of the other one). The two plus signs should not be on top of eachother.
Repeat the last 2 steps. What you should have now is 4 plus signs of tape on the egg which all extend halfway down the toilet paper tube. Take a strip of your 1 1/2" masking tape and wrap it around the toilet paper tube at the end that the egg is on. Make sure there are about 3 layers of this wrapped around.
Take a peice of aluminum foil and a 4 1/2" length of fuse and wrap the foil around the fuse as shown. This is for a light and drop type mortar (where you light it, and then drop it in the tube and duck for cover)
Cut slits in the bottom end of the toilet paper tube that are about 1 to 1 1/2" long. Cut a notch at the base of one of these and insert the bent part of the new fuse shown above.
Tape this fuse into place and open up the flaps that were created with the slits from the previous step as shown.
Fill this new cavity up with either granulated blackpowder or rice hulls. I chose rice hulls this time mainly because I was running out of blackpowder. A little trick to give this an extra kick for going up is to add 5% by weight (of the lift charge medium) of your favorite flashpowder and shake into the lift charge.
Now fold the flaps this hole to cover it as shown
Place a strip of the 1 1/2" masking tape over this to secure, and then another, forming a plus sign on the bottom. Repeat this step one more time to make sure there are 4 layers of tape covering the bottom of this shell.
The last step is to wrap the lift charge area (toilet paper tube) with multiple strips of masking tape forming multiple layers. After you are done waisting your masking tape, the finished product should look like this:
These work well in 2 Inch mortar tubes and the 4 inch fuse provides a long enough delay to duck for cover incase this thing decides to go off in the tube.