Hajtóanyagúak

Hajtóanyagúak, commonly referred to as propellants, are substances or mixtures that produce thrust through the rapid expulsion of mass. This expulsion is typically achieved by a controlled combustion or decomposition process, generating high-temperature, high-pressure gases. The principle behind propellant action is Newton's third law of motion: for every action, there is an equal and opposite reaction. The energetic expulsion of mass in one direction creates a force, or thrust, in the opposite direction.

Propellants are broadly categorized into two main types: chemical propellants and non-chemical propellants. Chemical propellants undergo a chemical reaction to produce hot gases. These are further divided into solid propellants, where all reactants are in a solid state, and liquid propellants, which consist of a liquid fuel and a liquid oxidizer that are mixed and ignited in a combustion chamber. Hybrid propellants combine a solid fuel with a liquid or gaseous oxidizer. Examples of chemical propellants are widely used in rockets, firearms, and pyrotechnics.

Non-chemical propellants, on the other hand, do not rely on combustion. They typically involve the expulsion of a working mass through physical means, such as electrical or thermal energy. Examples include electric propulsion systems like ion thrusters, which use electric fields to accelerate ions, and thermal propulsion systems that heat a propellant like hydrogen to high temperatures before expulsion. These systems are often employed for spacecraft propulsion where efficiency and long-duration burns are crucial. The selection of a propellant depends on the specific application, considering factors like required thrust, duration, efficiency, cost, and safety.