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Knowledge in Rocket propulsion
Gas turbine and jet and Rocket propulsion Reference book
containing introduction to gas turbine, analysis of gas turbine cycle, dynamic compressor, gas turbine combustion chamber, jet propulsion , rocket propulsion and many more
Harshit kumar
Rocket Staging: Steps to Achieve(UNIT -I)
Hello Reader!! Welcome to another article on Rocket Science, one of the most interesting topics I have ever come across. In this article, I will discuss a very interesting part named ‘Rocket Staging’. If you are new to Space Science and Rocket Technology, I would like to suggest you to go through the previous article for a better understanding.In the last article, I discussed Orbit and its different types. The basic objective of a rocket is to take a payload to a certain height and insert it into the desired orbit. To insert the payload into the desired orbit, the payload needs to be provided the Orbital Velocity (The velocity required to remain in a particular orbit, is termed as orbital velocity). Do you remember Konstantin Eduardovich Tsiolkovsky??.... He gave us the basic equation of rocketry, which is known as Tsiolkovsky’s Equation. In this equation, there are two terms Initial Mass and Final Mass. Initial mass is the mass of the rocket before the ignition of the rocket engine and the final mass is the mass when the rocket engine shuts down. The mass of the whole rocket at the time of lift-off is termed as Lift-Off Mass.You may arise one or two questions here about Fuels, Oxidizers, Rocket Engine(s), Motors, etc. Don’t worry, we will look into this in another article where we discuss the propulsion system. For now, let’s consider these as some masses only.What is Staging?The launch vehicles are designed in multiple stages. (Why??.. We will discuss it after some time in this article.) Each stage has its own propellants and engine. The major part of the mass of a stage is the mass of propellants. A large amount of propellant is needed to take a relatively very small payload into an orbit. The mass of propellent decreases as the rocket moves upward. When all the propellent are burnt out, the major part of rocket mass is the mass of empty tanks and other parts. So, to lighten the vehicle these parts are separated from the vehicle. This process is termed as Staging.Why Staging is Important?You can arise with some questions. Why staging is important??... Why Launch Vehicles are designed in stages??... What if I design a single-stage launch vehicle??CONTINUE WITH UNIT -II
KRISHNENDU GHOSH
Rocket Staging: Steps to Achieve(UNIT-II)
CONTINUE WITH I Why Staging is Important?Let’s find out the answers in a different way. Suppose you have designed a Launch Vehicle that has only one stage and you want to insert a small payload into Low Earth Orbit using the Launch Vehicle. You need a large amount of propellant. For now, consider your propellants are in liquid form. So, you need large-sized tanks for the propellants. After some time of lifting off, when half of the propellants are already used, the propellant tanks are half empty. But your vehicle has to carry the half-empty tank with the payload.Now imagine, if you design the Launch Vehicle in two stages for the same mission, you can separate the burnt stage to make the vehicle lighter. And we all know that it is easy to move a lighter object. So, here less amount of fuel is required to get the same velocity and the Launch Vehicle becomes more efficient.There is another reason behind staging. A launch vehicle has to cross different layers of the atmosphere where the pressures are different. The same rocket engine cannot be appropriately used in different atmospheric layers and outer space. So, different types of engines are to be used. This requirement is solved by staging.Types of Staging1.Serial Staging In serial staging, the stages are connected in series. The payload is on the top of the Launch Vehicle and followed by uppers stages. The lowest stage is also called Ground Stage or Booster Stage. When the booster stage is burnt out, it is separated and the engine of upper stage fires. This process continues until the required velocity is acquired.2. Parallel StagingIn parallel staging, multiple first-stage rockets are attached to the main body of Launch Vehicle. Here the main body is termed Sustainer and the small rockets are called Strap-on Boosters. At the time of lift-off all the rockets fire. When the propellants of Strap-on Boosters are extinguished, they are separated and the Sustainer keeps firing to move in the upward direction.The separated stages come down to earth and fall in oceans. Sometimes they are lost and sometimes they are recovered and used in another mission.Some space research organizations are working to design Reusable Launch Vehicles that are capable of landing on the earth's surface. This type of Launch Vehicle will make spaceflight more economic.ow, when you hear,"First Stage Separation Complete""Second Stage Ignited""Second Stage Separation Complete"You can easily understand the meaning of these phases. Right? Isn't it interesting?
Propulsion System : The Introduction(UNIT-I)
Hello Reader!! Welcome to another article on Rocket Science. In this article, I will discuss a very important topic, or you may consider as the most important topic, named Propulsion System. This is one of the most complicated topics of rocket science. Don't worry, I will keep it simple for you. If you are new to space science, please go through the previous articles for a better understanding.We discussed a little about the propulsion of a rocket in the first article and we found that to propel a rocket in the desired direction we need to exhaust mass in the opposite direction. So, the primary objective of the propulsion system is to exhaust mass in the opposite direction of the motion of the rocket. The exhaust of mass generates thrust which tends to move the rocket in the desired direction. The generated thrust depends upon the exhaust velocity. The higher velocity of exhaust mass generates higher thrust.In a rocket, fuels are combusted in a Chamber in presence of oxidizers. Hot gases are generated in this combustion and these gases are exhausted through a Nozzle with a high velocity which creates the thrust to propel the rocket. Studies reveal that the velocity is directly proportional to the temperature of the combustion chamber. A higher temperature of the combustion chamber leads to a higher exhaust velocity of product gases and a higher thrust. So, fuels to be used are chosen such that they produce a higher temperature when combusted.
Propulsion System(UNIT -II)
CONTINUE WITH UNIT -INow, we got a new term, Nozzle. Here we will discuss only those nozzles which are generally used in the rocket. These nozzles have a converging part followed by a small uniform section (termed as Throat) and a diverging part. In the converging part, the flow is Subsonic (Velocity of the hot gasses is less than the velocity of sound). In the diverging part, the flow is Supersonic (Velocity of the hot gasses is greater than the velocity of sound) and in the throat, the flow is Sonic (Velocity of the hot gasses is equal to the velocity of sound). Hot gasses enter the nozzle with low velocity and high pressure and leaves the nozzle with high velocity and low pressure. So, Nozzles play a very important role in the exhaust of hot gases and the efficiency of the rocket.The most important element of the propulsion system is the Propellant. The fuel and oxidizer are collectively called propellants as they propel the rocket.Depending upon the state of the propellant used in a propulsion system, it can be classified in different types, like the Liquid Propulsion System, Solid Propulsive System, Hybrid Propulsive System. Apart from this, more advanced propulsion systems have also been developed, like the Electric Propulsion System.In Liquid, Hybrid, and Solid propulsion systems, the basic principle is the same for all three. Fuels are combusted and hot product gases are exhausted through the nozzle with high velocity. But all of them have their unique characteristics and applications. We will discuss them in different articles and we will try to understand their importance in different applications. (THE END)
Solid Propulsion System
Hello Reader!! Welcome to another article on Rocket Science. In this article, I will discuss the Solid Propulsion System. In the previous article, I discussed some basics of Rocket Propulsion. If you are new to Rocket Propulsion, please go through the previous article for better understanding.What is Solid Propulsion System?A solid propulsion system is a rocket propulsion system that uses propellants in solid form.In the first article, we discussed the similarity between a firework rocket and a rocket that is used for space exploration. A firework rocket can be considered as the simplest form of solid propulsion rocket. Here, Black Powder is used as a propellent. A paste of black powder and binder is inserted into the frame and it becomes solid after drying. This is ignited with the help of Magnesium Wire. Burning of black powder generates hot gas which is exhausted through a small vent in the downward direction and propels the rocket in the upward direction.In the case of a heavy rocket, different propellants are used and they are ignited with the help of an Ignitor. The generated hot gases are exhausted through the rocket nozzle with a high velocity generating upward thurst.Parts of Solid Rocket Motors:A Solid rocket motor consists of 3 basic parts: 1.Casing 2.Propellant Grain 3. Igniter 4.Nozzle Casing The casing is the cylindrical outer shell of a Solid Rocket Motor. It contains the propellant grain. The burning of propellant grain takes place inside the Casing. So, the casing can be considered as a Combustion Chamber.Propellant Grain Fuels and Oxidizers are mixed with some additional components (catalysts and binders) to make a paste and then the paste is given a particular shape and heated. Heat sets the paste and makes solid propellant grain.If the paste is set in the casing of the rocket, the grain is termed as Case Bounded Propellant Grain.If the grain is prepared in a different case and then inserted to the Casing of Rocket, the grain is termed Free Standing Propellant Grain.The geometric shape of the propellant grain is very vital for the performance of the rocket motor. We will discuss the Geometry of propellant grain after some time. Ignitor: Ignitor is used to ignite the propellant grain. There are different types of ignitors used in Solid Rocket Motors. The most popular type of ignitor is Pyrotechnic Ignitor. In this type of ignitor, pyrotechnic powder (materials that are easy to ignite) is used to generate a flame. Electricity is passed through a Nichrome wire to heat it and ignite the pyrotechnic powder. The pyrotechnic powder creates flame and ignites the propellant grain. Nozzle: The generated hot gasses are exhausted through a Convergent-Divergent Nozzle with a high velocity. Geometry of Propellant Grain:The generated upward thrust produced by a Solid Rocket Motor depends on the exhaust velocity of the exhaust gases. The exhaust velocity depends upon the pressure inside the chamber. Chamber pressure depends upon the area of the burning surface.Usually, the outer surface of the propellant grain is cylindrical. The inner surface varies according to the requirement. For different types of inner surfaces, the areas of the burning surfaces are different. So the generated thrusts are also different for different grains.So, the shape and geometry of propellant grain are designed according to the thrust requirements. But after the ignition, the thurst can not be regulated.Solid rocket motors are usually used in the Booster Stages of different Launch Vehicles. In the 1st stages (Booster Stages) of PSLV and GSLV, solid rocket motors are used.In some versions of PSLV, 6 Solid Rocket Strap-On Motors are augmented with the 1st stage.In GSLV, 4 Liquid Propulsion Strap-Ons are augmented with the 1st stage.
History of Cryogenic Engine
Hello readers!! Welcome to another article on rocket technology. In the last article, I discussed the Liquid Propulsion System. In this article, I will focus on a special type of liquid propulsion engine, Cryogenic Engine.You may have heard of this term before. If not, don’t worry, we will keep our discussion very simple and knowledgeable as well. But, if you are new to this topic, please go through the previous article for a better understanding.What does the term Cryogenic mean?The term “Cryogenics” is associated with the branch of physics that deals with the effects and behavior of materials in very low temperatures.Here a question may be raised, is there any bordering temperature for Cryogenics??..... No, there is no specific bordering temperature for cryogenics.Scientists assume a gas to be cryogenic if it can be liquified at or below -150°C.IAs an example, Hydrogen is a cryogenic fluid and it can be liquified at -253°C.What is a cryogenic rocket engine?A Cryogenic Rocket Engine is an engine that uses cryogenic fluid as fuel and oxidizer. Both the fuel and oxidizer are liquified gases and they are stored and handled at very low temperatures in the cryogenic rocket engine.So, maintaining the temperature that is far less than 0°C and execute the operations at that temperature is a challenge for rocket engineering. This challenge leads to a much-complicated structure of a cryogenic rocket engine than the structure of a usual liquid propulsion engine or a solid propulsion motor. Importance of Cryogenic Rocket Engine:In the choice of fuel and oxidizer, Oxygen is the simplest oxidizer and Hydrogen is the simplest fuel. So, we can consider hydrogen-oxygen combination is one of the most preferable propellants for rocket engines as they release a high amount of energy when combusted and generate high thrust to propel a rocket.But the problem with the hydrogen-oxygen combination is both of them are gas at normal temperature. It is possible to store them as pressurized gas, but this would require large and heavy storage tanks, which would make spaceflight almost impossible.So, these gasses are cooled to sufficiently low temperature and liquified and then stored in tanks. They are handled at that temperature and used as the propellant in the Cryogenic engine.Various fuel-oxidizer combination has been used as propellent of the cryogenic engine. But generally, the hydrogen-oxygen combination is used as they are easily and cheaply available.History of Cryogenic Engine:he world's first cryogenic engine, RL10, was developed in 1962 in the United States of America by Marshall Space Flight Centre (NASA) and its first successful flight took place on 27th November 1963. It was mainly developed for Lunex Lunar Lander. On the first flight, it was used in the upper stage of Atlas Launch Vehicle.This RL-10 engine was one of the most important weapons of NASA’s space exploration.On 26th February 1966, another cryogenic engine, J-2, developed by NASA, completed its first flight successfully. This engine is considered as one of the main factors of the success of SATURN-V Launch Vehicle in many different missions including the Appolo-11 mission ...IMPORTANT NOTE:-(A) In GSLV Mk-I, Russian cryogenic engine, KVD-1 was used in the third stage of the launch vehicle. In GSLV Mk-II, KVD-1 was replaced by India’s CE-7.5 engine. In GSLV MK-III, it is further replaced by India’s CE-20 engine.(B) In India, Liquid Propulsion Systems Centre (ISRO) developed the first Indian Cryogenic Engine, CE-7.5 under Cryogenic Upper Stage Project (CUSP).(C) Unfortunately, the first flight of the CE-7.5 engine ended with a failure in 2010. Later in 2014, this engine completed its first flight successfully.(D) In 2017, Liquid Propulsion Systems Centre (ISRO) developed another cryogenic engine, CE-20. It completed the first successful flight on 5th June 2017. (THE END )