The Science of Rockets

What are the most important technologies in the history of human space exploration? If we make a list to answer this question, there will be rockets at the very beginning. Through this, people have crossed the borders of the world. Whether it’s a novotelescope or an artificial satellite or a spacecraft, if we want to send anything out of Earth, we have to go to this rocket first. But how does a rocket work? What exactly happens when it launches? Before we get into that story, let’s take a brief look at the history of rockets.

Rockets were invented mainly by the Chinese. At that time they used to call the explosive bamboo tube Ti Lao Shu (Small-Rat). Because, in the beginning, these bamboo tubes were not blown. Instead, when it exploded, they would run around the ground. Then, in the thirteenth century, a strange thing happened in China.

The royal festival is going on. The festival is organized by the Chinese emperor Li Chung. Suddenly his wife screamed. A ‘mete-rat’ flew up and pushed under his chair. That’s where the festival ends. And, Lee Chung arrested and imprisoned those who were in charge of these ‘Small-Rats’.

Bamboo rockets made by the Chinese. Collected


Scientists speculate that some of the explosive tubes may not have exploded. Maybe he jumped out of the fire. At that time gas and gunpowder came out from inside. These gunpowder pushes the tubes upwards while burning. There was a push of gas. As a result, this bamboo tube-rocket flew.

The accident opened a new horizon for the Chinese. They began research on gunpowder-filled bamboo tubes. At first, the explosives were poured into a tube, tied to the tip of an arrow, and thrown away. A few days later they discovered that these tubes could leak on their own. The back of the tube is open.

If the inner explosion is set on fire, the gas and gunpowder powder that comes out from the back of the tube as a result of the explosion can fill the tube and release it quickly. The first true rocket was born.

Rockets have long been used as weapons. Much later, in the 19th century, people thought of using the first rocket for space travel. Among the pioneers of this idea are Konstantin Jalkovsky, Robert Goddard, Hermann Oberth and Warner von Brown. The first rocket to cross the Earth’s border during the Cold War with their hands. As I said before, rockets are no longer used as weapons. It is now used in science.

You don’t need to know many complex things to know the basic story of this rocket science. (To be honest, there is a need. The story of rocket science that we will tell here is more basic than basic!)

Newton introduced rocket science by discovering the law of gravitation. We know that the gravitational force or gravity of the earth is called gravity. With this force, the world pulls everything towards itself. The formula can be written as follows:

g = GM/R2

This formula is supposed to be very familiar to the students of ninth-tenth class. According to the formula, g is gravity. G is the universal gravitational constant, M is the mass of the earth and R is the radius of the earth. Let us say that the value of the gravitational constant, G = 6.67 × 10-11 Nkg-2m2, mass of the earth, M = 5.9722 × 1024 kg and radius, R = 6.38 x 106 m (from 6,357 km to 6,378 km) . Calculating these, the value of gravity is g = 9.81 ms-2.

Another important aspect of the law of gravitation is that the release velocity of the planets (actually, for all objects) can be calculated from this. The speed of release means how fast a thing (read, rocket) can be thrown and it can break the attraction of another object (read, earth) and go out. The formula is also quite simple. Release velocity, V = √ (2GM / R). Here M is the mass of the object, and R is the radius of that object. As I said before, G is the famous universal gravitational constant.

Universal means that the value is the same inside and outside the earth, in space or anywhere in the universe. According to this formula, the Earth’s release velocity, VE = 11.2 kms-1. In other words, if a rocket is traveling at a speed of about 11.2 kilometers per second, it will be able to break the gravity of the earth and go out. Now the question is, how does the rocket do that?

Rockets that are sent into space usually have 4 main parts.
One, the structural system or infrastructure. The frame or structure of a rocket that holds different parts, so its infrastructure. Its main parts are cylindrical rocket-body, pointed nose and fin or wings. The body of the rocket is mainly made of aluminum and titanium. It has a thermal insulation system on it. The reason is obvious. This protects the rocket from the intense heat generated by friction with the air during launch.

Two, the propulsion system. It occupies the most space on the rocket. It also holds a large part of the weight or mass of the rocket. Its main components are rocket engines, fuels and oxidizers.
Then there is the pay-load system. The rockets that carry it can be humans or spacecraft, spacecraft or anything. It is at the very head of the rocket. Fourth, the rocket’s guidance system. Its job is to make sure that the rocket can reach its target and to direct the rocket in the right direction. It contains radar, computers and other auxiliary components.

These four parts have to work properly to launch and cross the Earth’s borders. Only then can the rocket sever the attraction of gravity.

It all started with the rocket fuel system. There is a lot to be said about rocket fuel. Long discussion. In short, solid materials were once used as fuel. Robert Goddard first worked with liquid fuels. In 1928, he launched the first liquid-fueled rocket. At present, different types of rockets use the same fuel.

However, liquid fuel is used more. The most commonly used are liquid hydrogen, kerosene, ethanol (a type of alcohol), etc. Liquid oxygen is used for these as oxidizer. The job of the oxidizer is to help burn the fuel. We know that a fire does not ignite in a bottle or box without oxygen. That means it takes oxygen or some oxidizer to burn something. Here liquid oxygen does just that.

However, the fuel system burns the fuel and pushes it out through a narrow tube at high speed. As the pipe is narrow, it puts a lot of pressure on the fuel when it comes out. In addition, the air from all around exerts a strong pressure on it, so that the fuel cannot spread around. Comes out densely. Newton’s third law of motion states that every action has an equal and opposite reaction.

As a result, at the speed at which the rocket engine releases the fuel, the fuel pushes the rocket in the opposite direction at the same speed. Since the fuel cannot scatter around, the rocket feels its reaction or thrust in a very linear way, that is, strongly, over a small area. Prachanda pushed the rocket away.

Now, once you push like that, it won’t happen. Because, until the rocket crosses the Earth’s boundary, the wind will try to block it violently. The tension of the world is on him. This is why fuel continues to flow out of the rocket at a regular rate until it crosses the atmosphere, and at a regular rate it pushes the rocket upwards. Today’s boosters use about 5,000 kg of fuel per second, and at a speed of about 4 and a half kilometers (about 10,000 miles per hour) it pushes the rocket upwards! In this way, if the rocket achieves a speed greater than the speed of release, gravity can be surpassed.

Needless to say, Newton’s first and second laws of motion are also used here. When pushing, the fuel is basically applying force to the rocket, and as a result the momentum of the rocket is changing. And, this change is where the fuel is pushing. Without the use of force, the rocket would remain stationary, as it was before launch. After departure, where wind or gravity no longer interferes with the rocket, fuel is used only to change direction, or to increase speed in an emergency.

What I said about the booster is actually related to the stage or episode of the rocket. As I said before, the rocket’s fuel system is responsible for most of its mass. Now, for so much mass it would take a lot of speed to carry it all the way.

Again, it would be pointless to carry it. This is because the fuel tanks are slowly being emptied and the fuel burns out, so these tanks are no longer needed after the fuel runs out. That’s why rockets have a few episodes or steps. Usually rockets are of 3 stages or episodes.

structure of rockets
The general structure of a rocket. Engine type and stage number, booster number, etc. may vary by rocket.

Picture 3 shows three boosters on either side of the rocket, providing fuel for the first step of the rocket. When the fuel runs out, they become detached from the rocket. Then the lower part of the rocket becomes detached in the second step. This part of the work is usually completed after the rocket’s gravity barrier is broken. At the top of the rest is the payload of the rocket, then there is the direction control system, below it is the engine and the third phase fuel. This goes from fuel and engine. As mentioned above, these fuels and engines are used to change direction or increase speed only after gravity has passed (and the Earth’s boundaries). Moreover, it remains closed.

Let’s end with a funny thing this time. Notice we said, the rocket body has fins or wings? We know the wings of an airplane. But notice, have you ever heard of a rocket wing? Or do you know, the rocket has wings? But, why does it exist? What does it actually do?

Wings of Rocket

Notice, the fuel pushed the rocket straight up. And, the upper part of the rocket is a lot of needles or eyes. That’s why the wind can’t stop it by pushing it from above. But the wind from all around pushes or pushes on it. As a result, the rocket goes crazy. Simply put, this push is like a rocket jumping around a roundabout and falling off its own path. Its wings protect the rocket from this problem. A kind of balance is created by the mass of the wind on the wings on both sides. Through this balance the rocket floats, runs its own way.

Source: Wikipedia; Joseph A, Angelo, Jr., Frontiers in Space: Rockets; Brilliant.Org; National Geographic

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