Fundamentals of Rocket Propulsion

DP Mishra

• Publisher: CRC Press
• Year: 2017
• ISBN:
  9781351708418
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

The book follows a unified approach to present the basic principles of rocket propulsion in concise and lucid form. This textbook comprises of ten chapters ranging from brief introduction and elements of rocket propulsion, aerothermodynamics to solid, liquid and hybrid propellant rocket engines with chapter on electrical propulsion. Worked out examples are also provided at the end of chapter for understanding uncertainty analysis. This book is designed and developed as an introductory text on the fundamental aspects of rocket propulsion for both undergraduate and graduate students. It is also aimed towards practicing engineers in the field of space engineering. This comprehensive guide also provides adequate problems for audience to understand intricate aspects of rocket propulsion enabling them to design and develop rocket engines for peaceful purposes.

CHAPTER 1

Introduction

The rockets can be built so powerful that they would be capable of carrying a man aloft.

Herman Oberth, 1923

1.1Introduction

I enjoy looking at the star-studded sky particularly at night. Sometimes, I hum the childhood rhyme “twinkle twinkle little star, how I wonder what you are.” I am sure most of you must feel happy gazing at a dark clear sky. Besides, when you relax in the moonlight away from the din and bustle of a hectic life in a remote village during your vacation, you may look at the sky and feel like going to the moon in your imagination. You may wonder how to travel to outer space. It is not that you are attracted by the beauty of the moon or stars. Rather the charisma of celestial objects like the sun, stars, planets, and moon has impressed several poets and writers to create volumes of literary work since ages. Humans from time immemorial have been baffled by the exotic beauty of the celestial bodies in space. The desire of modern humans to know more about these bodies in space has led to the invention of the telescope, which has been instrumental in unraveling a plethora of knowledge about space. Today, humans are able to send spacecraft even to distant celestial bodies like the moon and mars. If one wants to travel above 25 km into space, one cannot use an air-breathing turbojet because of the nonavailability of sufficient oxygen. One must consider using a non-air-breathing propulsive device, which can carry both fuel and an oxidizer. Such a device is known as a rocket engine. Thus, a rocket engine is a non-air-breathing jet propulsive device that produces the required thrust by expanding high-temperature and pressured gas in a convergent–divergent (CD) nozzle. This book is devoted to the rocket engine, particularly one that uses chemical fuel and an oxidizer. However, a brief account of a nonchemical rocket engine is provided in Chapter 11. Interested readers can refer to other advanced books on rocket engines [1,2,3,6,7]. Let us now look at the basic principle of propulsion.

1.2Basic Principle of Propulsion

Recall that propulsion is a method by which an object is propelled in a particular direction. The word “propulsion” stems from the Latin word propellere, where pro means forward or backward and pellere means drive or push. In addition, we know that the verb “propel” means to drive or cause to move an object in a specified direction. Hence, for the study of propulsion we will have to concern ourselves with this propelling force, the motion thereby caused, and the bodies involved. The study of propulsion is not only concerned with rocket engines but also with vehicles such as aircraft, automobiles, trains, and ships. We may recall that the principle of Newton’s laws of motion is the basis for the theory of jet propulsion. Jet propulsion can be expounded mainly by the second and third laws of motion. For example, a spacecraft is flying vertically at uniform speed. The resultant force in the vertical direction must be zero to satisfy Newton’s second law of motion, according to which an unbalanced force acting on the body tends to produce an acceleration in the direction of the force which is proportional to the product of mass and acceleration. In other words, the spacecraft must produce thrust which must be equal to the drag force caused due to the fluid motion over the body of this spacecraft and the gravitational force. For accelerating the spacecraft, one needs to supply higher thrust than that of drag forces and gravitational force acting on it. According to Newton’s third law of motion, we know that for every acting force, there is an equal and opposite reacting force. The acting force is the force exerted by one body on another, while the reacting force is exerted by the second body on the first. Although these forces have equal magnitude and occur in opposite directions, they never cancel each other because these forces always act on two different objects.

1.3Brief History of Rocket Engines

Interestingly, the Chinese Han Dynasty that prevailed around 200 BC had developed rockets which were used, of course, for fireworks at that time. But the early invention of the basic principle for a jet engine goes back to the Hero of Alexandria (around AD 67), an Egyptian mathematician and inventor who had invented several machines utilizing water, air, and steam. Figure 1.1 shows a schematic of the aeropile of Hero, which is considered to be the first device in the world to illustrate the reactive thrust principle much before Newton, who established the third law of motion. The name of this device derives from the two Greek words aeolos and pila, which mean the ball (pila) of Aeolus, the Greek god of the wind. This device consists of a metal boiler, a connecting pipe, and rotating joints that carry two opposing jets. It may be noted in Figure 1.1 that the heat from the burning fuel is utilized to convert water into steam. Two tubular pipes attached to the head of the boiler carry the steam to two nozzles. The steam that issues from the two nozzles forms two opposing jets, which can make the system rotate. It is really an interesting device for demonstrating the principle of reactive thrust, which is the basis of rocket propulsion. It is also believed that around the same period the Chinese had developed windmills based on the principle of reactive thrust.

FIGURE 1.1 Schematic of the aeropile by Hero. (From Treager, I.E., Aircraft Gas Turbine Engine Technology, 3rd edn., McGraw-Hill Inc., New York, 1995.)

However, the real rocket was invented by the Chinese around the tenth century AD while experimenting with gunpowder and bamboo. The gunpowder was discovered in the ninth century AD by a Taoist alchemist. Subsequently, Feng Jishen managed to fire a rocket using gunpowder and bamboo, and this is considered to be the first rocket engine to leave the ground. In the beginning, a bamboo tube closed on one side is filled with gunpowder with a small opening in the tail end as shown in Figure 1.2a. On igniting the gunpowder, high-pressure hot gas, which had moved around in an erratic manner, is ejected from the small opening. Later, a bamboo stick was attached to the gunpowder-loaded bamboo rocket (see Figure 1.2b) to give stability to the rocket, which is similar to our present-day fireworks rocket. All these developments were used to make beautiful displays of color and light in the dark sky. It is also believed that around this time, a Chinese scholar, Wan Hu, had developed a rocket sled (see Figure 1.3), which comprised of a series of rockets attached to the seat. Unfortunately, he died while operating this device due to an explosion of the rockets. But later on, the concept behind these toy rockets was developed further for use as a de...

Table of contents

• Cover
• Halftitle Page
• Title Page
• Copyright Page
• Dedication Page
• Contents
• Preface
• Author
• CHAPTER 1 Introduction
• CHAPTER 2 Aerothermochemistry of Rocket Engines
• CHAPTER 3 Elements of Rocket Propulsion
• CHAPTER 4 Rocket Nozzle
• CHAPTER 5 Spacecraft Flight Performance
• CHAPTER 6 Chemical Rocket Propellants
• CHAPTER 7 Solid-Propellant Rocket Engines
• CHAPTER 8 Liquid-Propellant Rocket Engines
• CHAPTER 9 Hybrid Propellant Rocket Engine
• CHAPTER 10 Liquid-Propellant Injection System
• CHAPTER 11 Nonchemical Rocket Engine
• APPENDICES
• INDEX