Rocket engines, their diversity, capabilities and prospects
Mankind has always sought to the stars, but only in the XX century, with the development of science and technology, was able to achieve a vacuum. Overcoming gravity is difficult, and to achieve the goal it was necessary to invent something special. As such a vehicle made rocket engines. And if we consider what is now and what may appear in the near future, what are the prospects for deep space for humanity?
What is a rocket engine, and what types of it exist?
Under the rocket engine understand the mechanism in which the working fluid and the source of energy for work are located in the vehicle itself. It is the only means of launching payloads into Earth orbit, and can also work in airless space. The main bet is made on the conversion of the potential energy of fuel into kinetic energy, which is used in the form of a jet.Based on the type of energy source, chemical, nuclear and electric rocket engines are distinguished.
The concept of specific impulse (or thrust) is used as a characteristic of efficiency: the ratio of the amount of movement to the mass flow of the working fluid. Calculated in m / s. But even if rocket engines have significant momentum, this does not mean that they are used. Why this happens, you will learn by reading about the nuclear and electrical mechanisms.
Chemical rocket engine
They are based on a chemical reaction into which fuel and oxidant enter. During the reaction, the combustion products are heated to significant temperatures, while they expand and accelerate in the nozzles, then to leave the engine. The heat generated by this engine is used to expand the working fluid having a gaseous appearance. There are two types of mechanisms of this type.
Solid propellant engines have a simple construction, they are cheap to manufacture and do not require significant costs for storage and preparation for operation. This determines their reliability and desire to use.But at the same time this type has a significant drawback - a very high fuel consumption. It also consists here of a mixture of fuel and oxidant. More efficient, but also challenging, is a liquid-propellant rocket engine. In it, the fuel and oxidizer are in different tanks and are metered into the nozzle. An important advantage is that you can adjust the level of supply and, accordingly, the speed of the spacecraft. Despite the fact that such rocket engines have a low specific impulse, they develop strong thrust. Such their property led to the fact that now they are used exclusively in practice.
Nuclear rocket engine
This is one of the likely analogues for modern systems of motion. In a nuclear rocket engine, the working fluid is heated due to the energy that is released during radioactive decay or thermonuclear fusion. Such mechanisms make it possible to achieve a significant specific impulse. And their total traction is comparable to that of chemical engines. But how many types of mechanisms based on nuclear energy are distinguished? Total 3:
The use of nuclear rocket engines in the Earth’s atmosphere is quite problematic due to radiation contamination. A possible solution to this problem will be a gas phase type.
Electric rocket engine
This type has the greatest potential for development and use in the future. Electric rocket engines offer great promise. Thus, their specific impulse can reach values of 210 km / s. There are 3 types of engines:
- Electrostatic (ionic rocket engine, for example).
A feature (about which it can be said that it is both an advantage and a disadvantage) is that with an increase in the specific impulse, less fuel is needed, but more energy. From this point of view, the ion rocket engine that runs on gas has good chances. At the moment, it is used in practice to adjust the trajectory of orbital stations and satellites. The limited sources of electricity in outer space, as well as problems with working capacity at altitudes above 100 kilometers, still hinder their widespread use.Plasma rocket engines, in which the working body has a plasma state, but which are only at the experimental stage, have great potential for use.