Whistle Mix Rocket Propellant

Whistle propellant, also known as whistle mix, is a very fast burning propellant compared to many others.  Do to this characteristic; it is always used as an end burner.  Because of its notorious instability, it is not suitable for large rockets, and has not found its way into amateur rocketry.  However, whistle mix is used extensively in fireworks, and these devices are generally small to medium in size.  Bottle-rockets and Saturn missiles are two common examples.

A common simple mix:

Potassium Chlorate..................70%

Sodium Benzoate....................30%

(In this formula, potassium perchlorate can be used for the oxidizer; and Potassium Benzoate for the fuel)

The following formula is better for larger motors or devices:

Potassium Perchlorate..................70%

Sodium Benzoate........................30%

Red Iron Oxide...........................1%

Petroleum Jelly...........................4%

Advantages:

• Very fast burn rate
• End burner
• Dry-press

Disadvantages:

• Almost too fast burn rate
• Hard to make very large reliable motors
• Somewhat unstable

Cautions:

Mixes not pressed correctly have a tendency to burst motor casings easily in a very explosive manner.

Un-pressed, loose whistle mix will burn with a speed comparable to good flash powder, and will self contain at moderate to low masses depending on particle size.

Interesting Facts:

The deflagration properties of the propellant are what cause the mix to whistle, not the gas passing by the tube end that it is pressed into.