KNSU propellant is the traditional single-grain propellant used in amateur rocketry. It is popular because it is one of the easiest propellants to make, and the ingredients for it are readily available. Note that KNSU works best in larger motors (18mm ID or more). Motors with a ID smaller than 18mm should be loaded with BP propellant. KNSU consists of potassium nitrate and sucrose (sugar). The ratio at which you mix them depends on the consistency you want to achieve. The higher percentage of solids in the mixture (ie potassium nitrate), the thicker the propellant is going to be. A common ratio of 65% potassium nitrate to 35% sugar is the optimum level for viscosity and performance. However, if this is your first time, a ratio of 60% to 40% should be used to make the propellant more liquid.

INSTRUCTIONS:

MATERIALS:
65% or 60% Potassium Nitrate
35% or 40% Sugar (icing sugar works the best)
Water

EQUIPMENT:
Heat source (a oil bath is the best, but a portable gas stove will do)
Cast iron pot
Electronic scales
Mould (see below)
Coring tool (see below)
Rammer (see below)

METHOD:

PREPARING MOULD AND TOOLS

1. Before the mixture is melted you need to find a suitable mould, coring tool and rammer. Use the rocket motor casing as the mould. That way you don't have to remove the KNSU once it has set. Add a nozzle on one end of the tube, and plug up half the hole with some hot glue. Don't plug the whole thing up, as the hole can be used to centralize the coring tool. Place the mould on a flat surface.

2. Select an approiate coring tool. It should be a metal rod about 3mm in diametre. The end of a screwdriver works well.

3. You will need a rammer to compact the propellant once it has been loaded into the mould. It should be metal and have a head which is just smaller the the diametre of the mould. Before use it should be put in the freezer for a few hours to prevent the propellant sticking to it. A large bolt is ideal. I find a bolt and then file down the head untill it fits into the mould.