Shulou(Shulou.com)11/24 Report--

Rockets and missiles have the same wonderful, are a gas propulsion device, but carry different things. Similar to cars, the power to move rockets at high speeds is provided by rocket engines, which rely on propellant or reaction forces generated by high-speed ejection from the tail of the rocket after combustion to push the rocket at high speeds, so that its maximum speed reaches the first cosmic speed, and finally overcomes the gravity of the earth and flies into space.

Rockets can be divided into launch vehicles and sounding rockets according to their uses. Launch vehicles are used to launch satellites, and they are usually multi-stage launch vehicles. The various stages are connected in series and parallel. Rockets currently use chemical energy and can be divided into solid fuel rockets and liquid fuel rockets according to the type of fuel used. For multi-stage rockets, solid and liquid propellant rocket motors can also be used separately at different stages of the rocket.

Solid fuels can be stored for long periods of time and have high thrust, the most powerful solid fuel rocket engines of their type ever used in space shuttles. However, solid fuel is difficult to stop before fuel is exhausted after ignition, which poses safety risks, while liquid fuel can cut off propellant supply to emergency stop when necessary, which has a higher safety factor and is more suitable for manned space flight.

Pexels liquid propellants are divided into oxidizer and combustion agent according to their functions. These two substances need to be stored separately and then transported to the combustion chamber of rocket engine by delivery system when the rocket starts flying.

At present, the fuel used in liquid rocket engines is mainly liquid oxygen kerosene, liquid oxygen liquid hydrogen and other types, such as that toxic and seriously polluting fuel has been gradually eliminated. For example, the Saturn 5 launch vehicle developed by the United States in the last century for the Apollo manned moon landing program is one of the most powerful rockets in human history. Its first stage uses liquid oxygen kerosene, and its second and third stages use liquid oxygen liquid hydrogen.

The propulsion efficiency of Unsplash rocket engines is usually measured in terms of specific impulse, which can be simply understood as the duration of one kilogram of thrust per kilogram of fuel, in seconds. The higher the specific impulse, the more efficient the engine or fuel is.

Liquid oxygen liquid hydrogen is a rocket propellant with extremely high impulse ratio and extremely strong performance. At present, this type of rocket engine is widely used in all major main rockets in the world, usually used in the final stage, but the cost performance is not high.

Liquid oxygen kerosene is a cost-effective rocket propellant, but its specific impulse is still much worse than liquid oxygen liquid hydrogen.

But humans aren't satisfied. Musk's SpaceX space exploration technology company uses liquid oxygen kerosene for its Merlin rocket engine on Falcon 9, while its Raptor engine for Starship uses methane fuel. SpaceX's competitor, Bezos 'Blue Origin BE-4, is also a methane rocket engine. China's private space company Blue Arrow Aerospace previously developed the world's first methane rocket "Rosefinch 2" although the first flight failed, failed to enter the scheduled orbit, but not far from success.

Why is everyone racing to develop methane rockets? What are the advantages of rockets fueled by liquid oxygen methane?

1. Although the specific impulse of liquid oxygen methane is not as strong as liquid oxygen hydrogen, it is slightly higher than liquid oxygen kerosene.

2, kerosene combustion is easy to produce carbon coking, and methane will not, if methane is used, it will improve the efficiency of rocket recovery and reuse, saving cleaning work.

3. Compared with hydrogen-oxygen rocket engine, the rocket engine using methane fuel is less difficult to design. Basically, it can follow the mature engine system of liquid oxygen kerosene without too much modification.

4, the boiling point of liquid methane is much higher than hydrogen, and the boiling point of liquid oxygen is relatively close, so it is less difficult to preserve. Liquid methane is also denser than liquid hydrogen and can store more fuel in limited space.

5, kerosene molecular structure is complex, very difficult to find on other planets, but methane is easy to find or synthesize on other planets, such as Titan has liquid methane formed lakes. At the same time, its preparation difficulty is also relatively low, natural gas purification and liquefaction directly on the line.

In short, considering various advantages and disadvantages and cost performance, liquid oxygen methane is the perfect choice between liquid oxygen kerosene and liquid oxygen liquid hydrogen.

Because of its many advantages, China and the United States and other space powers are currently developing methane rockets. Reuse of rockets can greatly reduce launch costs. Although the performance of rocket engines using liquid oxygen methane propellant is not much better than that of liquid oxygen kerosene, it is a better choice for rocket recycling.

This article comes from Weixin Official Accounts: Scientific Exploration Bacteria (ID: kxtsj9405), Author: Nansha Jingmeng

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