Whistle mix
Encyclopedia
Whistle mix is a general term to refer to any pyrotechnic composition that emits a whistling sound when pressed into a tube and ignited. It is used as a rocket propellant
, particularly in small bottle rocket
s. Whistle mix tends to be fast burning and brisant
; therefore it is also used as burst charge
in shells.
A typical whistle mix is made from 70% potassium perchlorate
and 30% sodium benzoate
, measured by weight. The fuel in most whistle compositions is a salt of an aromatic hydrocarbon
. Compositions with chlorate
s and gallates were used historically, but have now been abandoned as prone to accidental ignition.
Whistle compositions tend to be particularly sensitive. To achieve the whistling behavior, the composition must be formed into a solid grain; it otherwise burns too rapidly and just explodes
. The composition is typically compressed using an arbor or hydraulic press
. Ramming with a mallet
(which is acceptable for many other compositions) may result in an explosion.
Rocket propellant
Rocket propellant is mass that is stored in some form of propellant tank, prior to being used as the propulsive mass that is ejected from a rocket engine in the form of a fluid jet to produce thrust. A fuel propellant is often burned with an oxidizer propellant to produce large volumes of very hot...
, particularly in small bottle rocket
Bottle rocket
A bottle rocket is a very small skyrocket. A typical bottle rocket consists of a rocket engine attached to a stabilizing stick. The user can place the stick in an empty bottle , and ignite the rocket engine; the mouth of the bottle guides the stick, stabilizing the rocket in its first moments of...
s. Whistle mix tends to be fast burning and brisant
Brisance
Brisance is the shattering capability of an explosive. It is a measure of the rapidity with which an explosive develops its maximum pressure. The term originates from the French verb "briser", which means to break or shatter...
; therefore it is also used as burst charge
Burst charge
In fireworks, a burst charge is an energetic pyrotechnic mixture placed in a shell which is ignited when the shell reaches the desired height in order to pass fire to and spread the stars. Burst charge compositions are usually coated onto rice hulls or other low-density fillers, which increases...
in shells.
A typical whistle mix is made from 70% potassium perchlorate
Potassium perchlorate
Potassium perchlorate is the inorganic salt with the chemical formula KClO4. Like other perchlorates, this salt is a strong oxidizer and potentially reacts with many organic substances...
and 30% sodium benzoate
Sodium benzoate
Sodium benzoate has the chemical formula NaC6H5CO2; it is a widely used food preservative, with E number E211. It is the sodium salt of benzoic acid and exists in this form when dissolved in water. It can be produced by reacting sodium hydroxide with benzoic acid.-Uses:Sodium benzoate is a...
, measured by weight. The fuel in most whistle compositions is a salt of an aromatic hydrocarbon
Aromatic hydrocarbon
An aromatic hydrocarbon or arene is a hydrocarbon with alternating double and single bonds between carbon atoms. The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent...
. Compositions with chlorate
Chlorate
The chlorate anion has the formula ClO. In this case, the chlorine atom is in the +5 oxidation state. "Chlorate" can also refer to chemical compounds containing this anion; chlorates are the salts of chloric acid. "Chlorate", when followed by a roman numeral in parentheses, e.g...
s and gallates were used historically, but have now been abandoned as prone to accidental ignition.
Whistle compositions tend to be particularly sensitive. To achieve the whistling behavior, the composition must be formed into a solid grain; it otherwise burns too rapidly and just explodes
Explosion
An explosion is a rapid increase in volume and release of energy in an extreme manner, usually with the generation of high temperatures and the release of gases. An explosion creates a shock wave. If the shock wave is a supersonic detonation, then the source of the blast is called a "high explosive"...
. The composition is typically compressed using an arbor or hydraulic press
Hydraulic press
A hydraulic is a machine using a hydraulic cylinder to generate a compressive force. It uses the hydraulic equivalenta mechanical lever, and was also known as a Bramah press after the inventor, Joseph Bramah, of England. He invented and was issued a patent on this press in 1795...
. Ramming with a mallet
Mallet
A mallet is a kind of hammer, usually of rubber,or sometimes wood smaller than a maul or beetle and usually with a relatively large head.-Tools:Tool mallets come in different types, the most common of which are:...
(which is acceptable for many other compositions) may result in an explosion.