Whistle rocket

Whistle rockets as the name describes are rockets which emit a very loud whistling sound as it shoots into the air. It contains a pressed pyrotechnic composition called whistle rocket mix. In comparison, the whistle rocket tube is usually about half the length of a similar diameter black powder rocket. No nozzle material is used in the construction of this rocket and it has a very short core making this device an end burner. When the rocket is lit, the composition around the core burns extremely fast, propelling the rocket into the air very quickly. The rocket then changes characteristics, and the material oscillates and the remaining half of the tube acts as a resonating cavity, essentially amplifying the whistle sound. During this process the burning composition still generates enough thrust to continue propelling the whistling rocket through the sky.

[edit] Materials

Casing
A paper tube is used as a casing. Under no circumstances be tempted to use materials other than paper. It is dangerous and unnecessary. Find, roll or buy thick walled cardboard tubes, preferably parallel wound as they are much stronger than spiral wound tubes. The tubes should be sufficiently strong to allow pressing without wrinkling and to withstand the internal pressure during flight.

Tools
DO NOT use a rammer and hammer when making a whistle rocket. Whistle mix is very sensitive to shock, and using a rammer will definitely cause the composition to prematurely ignite. For optimum safety, professional tooling should be used. A typical whistle kit comes with a stainless steel nipple mounted on a square aluminum base with two aluminum rammers (one with a hole in the base which fits over the spindle) and can be purchased online from pyrotechnic online suppliers of tools.

Propellant
Whistle rocket mix, which is a slightly modified version of whistle mix is used. The difference being whistle rocket mix contains red iron oxide and vaseline.

Other
You will also need visco fuse or black match, a suitable hydraulic press, paper end plug, white glue and a rocket stick.

[edit] Construction

It is very important to remember that whistle rockets must be pressed. Whistle mix is very energetic and will react to static and shock so please exercise great care when handling it. Due to the large amount of pressure generated by the hydraulic press, a reinforcing sleeve must be used otherwise your casing will most likely split. Try not to use a metal reinforcing sleeve because if the an accident occurs then you will have metal shrapnel everywhere. As mentioned previously whistle rockets do not require a nozzle. If you were to add a nozzle the rocket would not be whistle and the it would explode due the burning speed of the composition.

Place your tube inside the reinforcing sleeve and fit the tube on to the whistle spindle base. Next you need to add the whistle rocket mix in small increments (as always, no more at a time than will give a layer after pressing as thick as the casings inner diameter). Using a powder scoop for adding the meal powder can help produce consistent results at this point. If you add too much composition, you can create small air pockets in the composition and this will affect the performance of your rocket.

Insert the rammer with the hole into the tube and press the mix. Repeat this process until the rammer has cleared the spindle.

Using the solid rammer continue pressing the whistle rocket mix into the tube until it is about 1 to 1 1/2 inches above the spindle. Now remove the reinforcing sleeve and carefully remove the spindle from the whistle rocket. It will appear that the rocket has a nozzle, but this is actually the mix that has been pressed hard against the spindle.

Using white glue, attach the paper end plug inside the top of the tube of the whistle rocket, this step is mainly for cosmetic effect.

When fusing your whistle rocket do not insert the fuse into the cavity hole in the composition as this will cause the rocket to CATO at take off. Attach a fuse to the side inner wall of the rocket so the fuse touches the composition. You can use hot glue to hold it in place, but apply the glue directly to the fuse and not inside the tube opening and only apply a very small amount.

[edit] Rocket Stabilization

Now that you have built your rocket, it needs to be stabilized during it's flight time (in other words it needs to fly vertically). This control of your rocket is essential, not only for the safety of you or your audience but for your satisfaction. Especially if you have a payload attached, this needs to explode high in the sky and not on or near ground level. At all times we want to avoid injury or possibly starting a fire.

Stabilizing your rocket is relatively a simple process as long as you follow these rules. Your stick needs to be straight and it needs to be long and heavy enough to pass the balance test. This test is simple, attach a stick to the side of your finished rocket and try and balance your rocket on your finger. Do this by placing your finger just behind the exhaust nozzle. If the rocket topples forward, then your stick is not long or heavy enough and may cause it to fly in unpredictable directions. If it topples backwards then your stick is too long or heavy and will make your rocket sluggish and reduce it's apogee. If it's too long simply trim a small amount off and do the test again. If it's not long or heavy enough replace the stick with a larger one. Also, if you have for example 2 sticks, which both pass through the balance test, but one is longer and lighter and the other one is shorter and heavier, it's the best to pick the longer lighter stick, so that you rocket will fly better.

Basically the end result you are after is a rocket and stick that balance nicely on your finger when it is placed behind the nozzle. It's a simple process that will ensure your rocket will fly straight into the night sky and join the stars.