With solid fuel, there must be both fuel and an oxidizer to make a solid fuel rocket go. An oxidizer is a chemical that is needed to make fuel burn. Since space has no atmosphere, rockets have to carry both their own fuel and their own oxidizers.
The most common fuel in solid fuel rockets is aluminum. In order to make the aluminum burn, these solid fuel rockets use ammonium perchlorate as the oxidizer, or to make the aluminum burn. In order to work together, the aluminum and the ammonium perchlorate are held together by another compound called a binder. When mixed all together, the fuel has a slightly rubbery consistency.
This rubbery substance is then packaged into a casing. As the fuel burns, the heat and energy cause the inside of the rocket to heat up. Top 5 Facts — Rocket fuels. Hybrid propellants — These are a combination of solid and liquid propellants, with a liquid oxidiser injected into a solid fuel.
Hybrids are a lot cleaner than solid rockets. Hydrazine — Commonly known as hypergolic rocket fuel, hydrazine simply needs nitric acid in order to ignite and is frequently used for propulsion when out in space.
Rocket-grade petroleum is called RP-1 and consists of a highly refined kerosene mixed with liquid oxygen. Hypergols are highly toxic and must be handled with extreme care. Hydrazine gives the best performance as a rocket fuel, but it has a high freezing point and is too unstable for use as a coolant. MMH is more stable and gives the best performance when freezing point is an issue, such as spacecraft propulsion applications.
UDMH has the lowest freezing point and has enough thermal stability to be used in large regeneratively cooled engines. Consequently, UDMH is often used in launch vehicle applications even though it is the least efficient of the hydrazine derivatives.
Aerozine 50 is almost as stable as UDMH and provides better performance. The oxidizer is usually nitrogen tetroxide NTO or nitric acid. Nitrogen tetroxide is less corrosive than nitric acid and provides better performance, but it has a higher freezing point. Consequently, nitrogen tetroxide is usually the oxidizer of choice when freezing point is not an issue, however, the freezing point can be lowered with the introduction nitric oxide.
The resulting oxidizer is called mixed oxides of nitrogen MON. The number included in the description, e. Hydrazine is also frequently used as a monopropellant in catalytic decomposition engines. In these engines, a liquid fuel decomposes into hot gas in the presence of a catalyst.
The decomposition of hydrazine produces temperatures up to about 1, o C 2, o F and a specific impulse of about or seconds. Hydrazine decomposes to either hydrogen and nitrogen, or ammonia and nitrogen.
Other propellants have also been used, a few of which deserve mentioning: Alcohols were commonly used as fuels during the early years of rocketry. However, as more efficient fuels where developed, alcohols fell into general disuse. Hydrogen peroxide once attracted considerable attention as an oxidizer and was used in Britain's Black Arrow rocket.
In high concentrations, hydrogen peroxide is called high-test peroxide HTP. The performance and density of HTP is close to that of nitric acid, and it is far less toxic and corrosive; however it has a poor freezing point and is unstable. Although HTP never made it as an oxidizer in large bi-propellant applications, it has found widespread use as a monopropellant.
In the presence of a catalyst, HTP decomposes into oxygen and superheated steam and produces a specific impulse of about s. Nitrous oxide has been used as both an oxidizer and as a monopropellant. It is the oxidizer of choice for many hybrid rocket designs and has been used frequently in amateur high-powered rocketry.
In the presence of a catalyst, nitrous oxide will decompose exothermically into nitrogen and oxygen and produce a specific impulse of about s. Solid Propellants. Solid propellant motors are the simplest of all rocket designs. In addition the energy density Joules per kilogram of propellant tends to be high and that, as a result of the high combustion temperature, the specific impulse impulse [in Newton seconds] per kilogram of propellant is very large.
A modern solid fuel rocket has a specific impulse of up to approximately N s kg -1 whilst a good liquid fuel rocket can produce up to N s kg It is common practice to take a shortcut in the units, at ground level one kg of propellant weighs a little under 10 N and these two figures are cancelled out.
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