Rocket is an engine that burns stored fuel into a high-speed, high-temperature gas that moves out of a vehicle through a limited outlet. Since the gas moves downward at high speed, the carrier vehicle reacts by moving upward at the same high speeds. On the other hand, we can also describe a rocket as a cylindrical vehicle with a sharply pointed nozzle used to travel into space. The vehicles include missiles or spacecraft that uses a rocket as an engine. 

Rockets are an important invention, and they play various roles in shaping our world as we live it today. Rockets are the reason why scientists can monitor space to keep our planet safe. Here are various uses of rockets: 

Military Uses

Rockets are used as transporters of various warheads to various enemy destinations. When rockets are combined with warheads, their name changes to what is commonly referred to as missiles. Transporting warheads using rockets is safe for the military since they can be remotely controlled. The military function is a controversial use given the destructive nature of rocket transported warheads. 

Space Research

Astronauts use rockets to transport instruments to areas beyond the earth’s surface to record various research elements that scientists plan to study. 

Rockets Help Put Spacecraft into the Orbit

Rockets are preferred explicitly for this function because of their high speeds that march the orbit’s high velocity, as we shall discuss later. 

Rockets work using a simple scientific principle called the third law of motion. Isaac Newton came up with the laws of motion, and the third and final of these laws state that there must be an equal reaction in the opposite direction for every action. This principle means that if you push something forward, you also move backward at the same speed.

How is this related to rockets, you ask? Let’s get into it.

Rocket engines burn a special kind of fuel that we shall talk about in a little while. When the fuel burns, it produces a hot gas from the rocket’s rear at a very high speed. As the gas comes out at high speeds going downward, which is the most likely direction that the rocket will take? Of course, you guessed right; it will move upward at a rate equal to the gas’s speed going upward.

The force that causes the rocket engine to move up in the opposite direction from the hot gas is called a thrust, and the rocket keeps burning more fuel to produce the same effect over and over, giving the rocket the forward thrust over and over until it gets to its destination. The repeated thrusts also help the rocket to overcome the gravitational pull and resistance from air.

But how does a rocket know where it is going? Does it have a pilot? Before rockets are released from the earth, rocket scientists calculate a predetermined route that the rocket will take. The course is calculated in relation to the position of the sun and the moon. Other planets may also have a little effect, but it is very minimal. Before we look at how rockets are launched, let us understand how far rockets have come.

Today, the concepts used in rocketry go back to the 1st Century AD. A mathematical engineer, Heron of Alexandria, created a device that made a ball rotate using steam emitting nozzles. After this fete by Heron, things in rocketry history went silent until the 13 Century AD when people started making gun-powder rockets used in weapons like arrows.

Perhaps the most significant part of rocketing history was the publication of Investigating Space With Reaction Devices by Konstantin Tsiolkovsky. This publication detailed the dynamics of how rockets worked. Later in 1942, Germany makes another milestone when it successfully launches its rocket-based missile and lands it on target at the speed of over 4000mph.

Germany’s success in launching their missile made the U.S.A and U.S.S.R start their space programs, and in 1957, Russia was able to use a rocket to carry and launch Sputnik 1, which was the world’s first satellite into space, and in 1969, America launched Apollo 11, the rocket that graced the moon for the first time.

We have learned what a rocket is, the science behind how rockets work, and have gone through a brief history of rocketry. You must now be curious to know how a rocket launches, right? But before we go into how rockets are launched, let us first learn the energy that propels rockets, shall we?

To discuss rocket fuels, we shall discuss the types of rockets that we have today since rockets are categorized based on the type of fuel they use. Today, there are four types of rockets: 

• Solid fuel rockets 
• Liquid fuel rockets 
• Ion rockets 
• Plasma rockets 

Here is an analysis of each of the rockets to help you understand the energy used by rockets. 

Solid Fuel Rockets

Solid rocket fuels use solid propellants and are among the first fuels to be discovered. They were first used mainly for making small weapons, although after later research, scientists found that they could use them to power big rockets and for a more extended period.

Solid fuel rockets are monopropellant, which means that they do not require an external oxidant to burn the fuel. The basic science of combustion states that for anything to burn, there must be an oxidizing agent. For example, jets have air intakes, which provide the oxygen for the engines to ignite the fuel and propel the jet. Monopropellant rockets, however, do not require air intakes to burn the fuels.

Instead, solid fuels are a combination of many chemicals into one mixture. Among these chemicals are oxidants that burn the fuel to produce hot gas that propels the rockets. Some of the chemicals used to make solid rocket fuels include ammonium dinitramide, potassium nitrate, and ammonium perchlorate. For the solid fuels to work, they must be placed into the rocket’s combustions chamber, where it is ignited.

The major disadvantage of solid fuels is that once the fuel starts burning, it cannot go off, which means the fuel will continually burn without control until it is over. This lack of control leads to the need to use massive amounts of solid fuel, which is both expensive and can use up a lot of the limited space afforded by the rocket. Another disadvantage of solid fuels is the risk of el running out before the rocket reaches its desired destination. Also, nitroglycerin, one of the compounds used to make solid fuels, evaporates quickly.

On the other hand, solid propellants are relatively easy to store and handle than their liquid counterparts. They are also cheaper and are preferred whenever large thrusts are needed. Some of the famous rockets that used solid fuel include the Russian Proton series (Proton 8K82K and Proton-M), European Ariane 5, Space Shuttle, US Atlas V and Japan’s H-I.

Liquid-Fuel Rocket

Liquid fuel rockets use liquid propellants. Liquid propellants are, as the word states, liquid. Liquid fuels are widely used and can be either monopropellant (remember monopropellant from solid fuels?), or Bipropellant, or even more rarely, tripropellant. Some of the chemicals used to make liquid propellants include Dinitrogen tetroxide combined with hydrazine, liquid oxygen, and liquid hydrogen. These chemicals are light and easy to carry, and therefore reduce the weight of the rocket.

Rocketry engineers trust liquid Fuels because they have high density and have a high specific impulse. Engineers love the high density and high specific impulse because they make it easy for them to use lighter centrifugal turbopumps to move the fuel from the rocket’s fuel tanks to the combustion chambers. Turbopumps increase the pressure of the fuel into the combustion chamber.

In addition to their high density and specific impulse, liquid propellants are useful because they are easy to control. Unlike solid propellants that you cannot control when they start burning, liquid propellants are easy to control and only burn when required to burn. This controlling ability makes it easy for astronauts to control the rocket speed and turn the rocket on and off to control fuel usage.

One major undoing for the liquid propellants is that engineers have to design a separate piping system from the liquid’s storage chambers to reach the combustion chambers. Perfecting this design is particularly hard since the goal of creating a rocket is to make it as light as possible.
Some of the rockets that use liquid propellants include the German V-2, Space X Falcon 9, and the Atlas ICBM

Ion Rocket
Ion rockets have been functional since 1998, and they use electron energy from solar cells. Solar cells convert sunlight into electric energy and are ten times faster than traditional rockets that use chemical fuels. However, the thrust produced by ion rockets is weak and cannot lift the rocket from the ground. Rocketing engineers must, consequently, find an alternative way to raise the rocket off the ground.

Plasma Rockets
Plasma rockets are known in scientific conversations as Variable Specific Impulse Magnetoplasma Rocket (VASIMR). These rockets work by accelerating plasma produced by stripping negative electrons from hydrogen atoms inside a magnetic field and expelling them out of the engine. These rockets are touted to be faster and can reach Mars faster than other types of rockets. Their sustainability is still being tested, and more information about them will be available soon.

Scientists consider many things before launching a rocket. Some of the considerations they make include: 

• The rocket’s payload
• The cargo’s destination
• The Weather
• Proximity to the equator
• The proximity of the launch site to social amenities and residences 
• Time of the day

The list above is only a highlight and is meant to direct you to some of the considerations that scientists make before launching a rocket. 

The Multi-stages of a Successful Rocket Launch :

Before we discuss the various stages, let us answer this frequently asked question: What is staging?

Rocket staging is the process through which engineers arrange different parts of a rocket. The arrangement of rocket engines determines how they will come off the ship at various stages.

Effective staging also ensures that as the rocket sheds parts that are no longer useful, it becomes lighter, and the subsequent engines give the rocket the required thrust to make it through the atmosphere and travel at the right speed to match the orbit’s speed requirements. Depending on the rocket’s function, scientists put as many detachable parts as the number of stages they expect the vehicle to undergo before reaching its final destination. However, the more the number of stages a rocket has, the more complicated it is, and the more the probability of its failure.

As scientists make rockets, the rockets’ fuel carries around 90-94% of the rocket’s total weight, and the other 6-10% is shared between the rocket’s building materials and payload (we shall discuss what payload in a few paragraphs). This means that the material used to make rockets must be extremely light, and astronauts must ensure that the load they transport using a rocket is equally light.

There are four different ways of staging, as we discuss below:

Serial Staging

Serial staging occurs when scientists stack stages on top of each other. In this kind of staging, the stage that will burn first is placed as the most bottom, while the final stage is nearest to the top. Saturn V moon rockets were good examples of rockets that used serial staging.

Parallel Staging

In parallel staging, scientists place single or multiple booster stages connected to the main sustainer. All engines start combustion at the onset of the journey, and when the trapped engines fully spend their fuel, the main engine continues burning to transport the cargo into orbit. The detachable stages are used as boosters and fall away as soon as they run out of fuel. The parallel staging can be combined with the serial staging on the same vehicle.
Some of the rockets that use the parallel staging method include launchers like Titan III and Delta II

Stage and a Half

A stage and a half involve using the main sustainer engine and another that acts as the booster. As expected of all booster stages, the attached stage and a half system fall off after all its fuel is spent. Examples of rockets that used a stage and a half include the Atlas and Atlas Agena.

Single Staging

This staging method is still under research, and its main dream is to have rockets that do not require multiple stages to function. As we have said above, the more stages a vehicle has the more complicated it is, and the more the chances of its failure. As such, when scientists figure out a way to actualize the single staging method, they will avoid a considerable risk and have lesser stages to deal with when launching rockets.
Now that we understand the different staging methods, let us delve into the multiple stages of a rocket launch.

Stages of a Rocket Launch

Rockets launch in various stages, and each stage has its unique role to perform. The various engines that will burn to launch a rocket successfully are stacked above each other and detach when their usefulness ends. Therefore, this detachment means that as the rocket sheds used-up engines, it becomes lighter and consequently uses less fuel. It is also worthy of understanding that each engine is independent of the others. This independence provides rocketing engineers the opportunity to customize each engine for the purpose it serves. Optimization means making the engine more adapted to the prevailing atmospheric pressure or the gravitational pull at each stage.

Here are a few steps that rockets go through to launch successfully:

1)Primary Stage

The primary is the first and most important stage of a rocket launch and is also called the stage “0”. At this stage, the engine burns fuel to provide the first thrust. The thrust must be strong enough to propel the rocket into a high speed that takes it skyward. The thrust must also be strong since it must be enough to carry the rocket’s heavyweight, which includes the first engine. When the first engine runs out of fuel, it detaches from the rocket and triggers a small explosive attached to the second engine, which takes over and propels the spacecraft further. The first engine burns out and falls back to earth. The detachment of the first engine from the rest of the rocket is referred to as Main Engine Cut Off (MECO).

Simple as it may sound, the first stage has to overcome many obstacles before it successfully burns out.

The Drag Increases as the Rocket Gains Speed:

Drag in rocketry is the resistance that the rocket has to overcome as it goes skyward. To understand drag in a simple language, suppose that you are running on a track. If you are running on a calm day when the wind moves slowly, you will use less effort to run. On the other hand, if you are running against a strong wind, running becomes a tad harder. Also, the faster you run, the more resistance you get. If you at the low speed that you run can get friction from the air, imagine a vehicle that travels at speeds up to 16200 Km/h. The rocket must face a lot of resistance, mustn’t it?

The Launch is Roughest on the First Stage:

The gravitational force (commonly referred to as G-force) is higher at the lower atmosphere compared to higher atmospheres. There is also high-frequency vibration to consider and the huge weight the rocket carries.

The Primary Stage Determines the Success or Failure of a Rockets Launch:

For a rocket to penetrate through the drag caused by the atmosphere and successfully attain MAXQ, the initial thrust must be strong enough to carry the rocket through it all. If a small miscalculation happens in the primary stage, then the whole project is bound to fail.

2)The Upper Stages

The rocket is already moving in the sky at high speed and has already shed some weight in the form of the burnt-up first engine. Therefore, this means that the engine at this stage has a relatively easier task to perform compared to the first stage engine.
The sole purpose of this stage is to get the rocket into the orbital velocity. This is the speed required to align with the movement of other space objects like planets and others. The rocket must move at a high speed that successfully counter the gravitational pull.

Failure to achieve the high speeds required to overcome the gravitational pull will mean that the rocket is pulled back to the ground by gravity. The important thing to note here is that the closer the rocket is to the earth’s surface, the higher the gravitational pull effect and the higher the speed required to overcome it.

Before the secondary stage engine burns out, the following must happen:

• The Vehicle Must Achieve Weightlessness
• Achieve higher Specific Impulse Rating
• Move faster
• The vehicle’s movement becomes stable

The used-up engine on the secondary stage also detaches from the rocket in a process called Second Engine Cut Off (SECO). However, the engine’s remains cannot come back to earth (Unless the rocket is modeled to be reused as we shall discuss later) but stay in space, orbiting around other bodies to infinity. These used up rocket detachments form part of what is called space debris or space junk.

Rockets are mainly sent to space to deliver a payload. The payload is any cargo transported using a rocket, and it might include research instruments, satellites, weapons, and people, among other payloads. But what happens to rockets after they deliver their cargo?

Traditionally, used up rockets either fall to the earth’s surface and into an orbit and start oscillating along with the planet. Other times, the rocket disintegrates and evaporates when it encounters high temperatures. With the latest advancement, however, rockets do not have to be destroyed after a single-use. Recent rockets like the latest SpaceX’s Falcon can be partially re-used to transport future payloads.