Missile fuel: species and composition
Solid rocket fuel is aa solid substance (a mixture of substances) that can burn without air and at the same time release many gaseous compounds heated to a high temperature. Such compounds are used to create reactive thrust in rocket engines.
Missile fuel is used as a sourceenergy for rocket engines. In addition to solid fuel, there are also gel-like, liquid and hybrid analogs. Each type of fuel has its advantages and disadvantages. Liquid fuels are one-component and two-component (fuel + oxidizer). Gel-like fuels are compositions thickened to the state of the gel with the help of organic acids. Hybrid fuels are systems that include a solid fuel and a liquid oxidant.
The first types of rocket fuel werenamely solid. As a working substance, gunpowder and its analogues were used, which were used in military affairs and for the creation of fireworks. Now these compounds are used only for manufacturing small model rockets, like rocket fuel. The composition allows launching small (up to 0.5 m) rockets for several hundred meters in height. The engine in them is a small cylinder. It is filled with a solid combustible mixture, which is ignited by a red-hot wire and burns only a few seconds.
Rocket fuel of solid type most often consists offrom an oxidizing agent, a fuel and a catalyst, which makes it possible to maintain a stable combustion after ignition of the composition. In the initial state, these materials are powdery. To make them rocket fuel, it is necessary to create a dense and homogeneous mixture that will burn for a long, smooth and continuous. Solid rocket propulsion engines use: potassium nitrate as an oxidant, charcoal (carbon), as fuel, and sulfur as a catalyst. This is the composition of black powder. The second combination of materials that are used as a rocket fuel are: Berthollet salt, aluminum or magnesium powder and sodium chlorate. This composition is also called white powder. Solid combustible fillers for military missiles are divided into ballistic (nitroglycerin compressed powders) and mixed, which are used in the form of channel gauges.
Solid-fuel rocket engine runningin the following way. After ignition, the fuel starts to burn at a specified rate, throwing a hot gaseous substance through the nozzle, which provides traction. The fuel in the engine burns until it runs out. Therefore, it is impossible to stop the process and turn off the engine, until the filler burns to the end. This is one of the serious disadvantages of solid fuel engines, compared to other analogues. However, in real space ballistic media, solid fuel materials are used only at the initial stage of the flight. In the following stages, other types of rocket fuel are used, so the shortcomings of solid-fuel compositions do not represent a significant problem.