The three most common types of propellants are compressed powder, usually black powder, sugar propellant (most commonly sucrose, dextrose and most recently, sorbitol) and composite propellant using ammonium nitrate or ammonium perchlorate as the oxidizer and a powdered metal (usually aluminum or magnesium) as the fuel).
Compressed propellant is prepared dry but may be wet at some stage of the preparation. It is loaded into the motor casing by compressing with constant mechanical or hydraulic pressure or by impact such as by blows of a mallet or hammer. The burn rate depends on how fine the components are ground, how intimately it is mixed, and the density which is determined by how much it is compressed.
Black powder is made from Potassium Nitrate (KNO3), Charcoal and Sulfur. The common ratio is 75:15:10. Like zinc-sulfur, the burn rate depends on the particle size and how much it is compressed. Black powder can be used used as a propellant with more consistency than zinc-sulfur and is the propellant used in small commercial model rocket engines.
End burner VS Core burner:
End burners are used because they are reliable and easy to manufacture. While core burners can be a little less reliable and if something on your rocket is off, it can cause the rocket to CATO. Core burners usually have the ability to lift more payload, giving a stronger thrust, although it doesn't last as long. An end burner will last longer, but not giving as much thrust, thus it won't be able to lift as big of a payload.
Compressed propellant is prepared dry but may be wet at some stage of the preparation. It is loaded into the motor casing by compressing with constant mechanical or hydraulic pressure or by impact such as by blows of a mallet or hammer. The burn rate depends on how fine the components are ground, how intimately it is mixed, and the density which is determined by how much it is compressed.
Black powder is made from Potassium Nitrate (KNO3), Charcoal and Sulfur. The common ratio is 75:15:10. Like zinc-sulfur, the burn rate depends on the particle size and how much it is compressed. Black powder can be used used as a propellant with more consistency than zinc-sulfur and is the propellant used in small commercial model rocket engines.
End burner VS Core burner:
End burners are used because they are reliable and easy to manufacture. While core burners can be a little less reliable and if something on your rocket is off, it can cause the rocket to CATO. Core burners usually have the ability to lift more payload, giving a stronger thrust, although it doesn't last as long. An end burner will last longer, but not giving as much thrust, thus it won't be able to lift as big of a payload.
A cored rocket motor is the traditional motor, typically with a clay nozzle, and a hollow core going up through the nozzle and into the fuel grain for some distance. Ignition starts at the core’s forward end. and instantly spreads to the rear, lighting the length of the core as it goes. From that point on the flame spreads outward in the shape of an expanding cylinder, consuming the last of the propellant as it reaches the inside of the casing wall. In motors with small nozzles and short cores, the chamber pressure and thrust start out low and reach their maximums at burnout. In motors with larger nozzles and longer cores the initial values are higher. In motors with very large nozzles and very long cores the starting pressure and starting thrust can exceed 50% of their maximums.
A motor’s core length is critical because it directly controls the amount of propellant burning at any given moment. If the core is too short, the motor performs poorly. If the core is too long, the maximum chamber pressure can exceed the motor’s design limits, and cause the motor to explode.
Because the burning surface in a core burner is larger than the burning surface in an end burner, a core burner requires a slower burning propellant. Because the distance that the flame travels is short (from the edge of the core to the inside of the casing wall), small core burners have comparatively short burn times. All core burners have the advantage that the layer of unburned propellant between the flame and the casing wall insulates the casing from the heat of the flame until the final moments of the burn.
A motor’s core length is critical because it directly controls the amount of propellant burning at any given moment. If the core is too short, the motor performs poorly. If the core is too long, the maximum chamber pressure can exceed the motor’s design limits, and cause the motor to explode.
Because the burning surface in a core burner is larger than the burning surface in an end burner, a core burner requires a slower burning propellant. Because the distance that the flame travels is short (from the edge of the core to the inside of the casing wall), small core burners have comparatively short burn times. All core burners have the advantage that the layer of unburned propellant between the flame and the casing wall insulates the casing from the heat of the flame until the final moments of the burn.