Rocket Propellant Technology

By Jawaharlal "Ram" Ramnarace

Rocket Propulsion has come of age. Although its potentialities and capabilities in many areas have been recognized for centuries, it is only in recent years that scientists have had the materials and the manufacturing techniques at their command so they could control and direct the tremendous forces available. Space exploration and manned flights by astronauts have brought the science of rocketry to the attention of the general public. It has also stimulated the interest of students at all levels of advancement in the technical details of space flight. Rocket Propellant Technologies is written for serious students of astronautics. This volume reviews briefly the history of rocketry and the fundamental principles connected with rocket propulsion. Types of propellants, the chemical reactions involved, and the techniques used in manufacturing are explained. The merits of solid and liquid fuels are enumerated. Exotic propellants of the future are discussed, with reasons why their development is essential. Finally, the safety aspects of manufacturing and testing rocket propellants are given in detail. The Amateur Rocket Association under whose guidance this series has been prepared, serves as a focal point for many related activities, bringing new ideas to the attention of its members and offering suggestions for future lines of research.

• Language: English
• Publisher: Page Publishing, Inc.
• Release date: Jan 11, 2016
• ISBN: 9781682134986

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Rocket Propellant Technology

By Jawaharlal Ramnarace

FIRST EDITION

FIRST PRINTING - 2015

Copyright © 2015 Jawaharlal Ramnarace

All rights reserved

First Edition

PAGE PUBLISHING, INC.

New York, NY

First originally published by Page Publishing, Inc. 2015

ISBN 978-1-68213-497-9 (pbk)

ISBN 978-1-68213-498-6 (digital)

ISBN 978-1-68213-499-3 (hardcover)

Printed in the United States of America

Table of Contents

Preface

Chapter 1 - History of Rockets

Tsiolkovsky—Father Of Interplanetary Travel

Goddard—Father Of Modern Rocketry

The Future

Apollo Spacecraft

Early Development

Developments in the Nineteenth Century

World War I

The Decades Between the Two World Wars

World War II

Modern Era

Chapter 2 - Introduction to Chemical Rockets

Solid-Propellant Rockets

Combustion Chambers

Nozzles

Liquid-Propellant Rockets

Pressure-Feed Sytems

Pump-Feed Systems

Combustion Chambers

Nozzles

Injectors

Igniters

Hybrid Rockets

Desirable Propellant Properties

Chapter 3 - Classification of energentic materials

Military Energetic Materials

Classification of Explosives

Low Explosives, Pyrotechnics, Propellants, and Practice Ordnance

High Explosives

Primary or initiating explosives

Booster or auxiliary explosives

Bursting explosives, main charge, or fillers

Incendiaries

Hazards Associated With Common Types Of Munitions

Chapter 4 - Propellant Componenets

Introduction

Background Of Propellant Development

Propellant Types

Ingredients

Properties

Liquid Propellants

Double-Base Propellants

Composite Propellants

Comparison Of Propellant Potential

Chapter 5 - Propellant Research And Developement

Introduction

Propellant Ingredients

Nitroglycerin

Nitrocellulose

Plastisol Nitrocellulose

Ammonium Perchlorate

Aluminum

New Ingredients

Fluorine Compounds

Cyclotetramethylenetetranitramine

Cyclotrimethylenetrinitramme

Composite Propellant Ingredients

Oxidizers

Fuels

Metals

Metal Hydrides

Binders

Thermoplastic Resins

Plastisols

Thermosetting Resins

Crosslinked Resins

Propellant Types And Properties

Homogeneous Propellants

Single-Base Propellants

Double-Base Propellants

Extruded Double-Base Propellants (EDB)

Cast Double-Base Propellants (CDB)

Nonhomogeneous (Composite) Propellants

Propellant Properties

Mechanical Properties

Physical Properties

Chemical Properties

Ballistic Performance

Safety Characteristics

Chapter 6 - Propellant grain manufacturing process

Cast Double-Base Process

Cast Propellant Grain Manufacture

Solventless Extrusion Process

Slurry-Cast Process

Thixotropic Slurry

Pourable Slurry

Composite Process

Inert-Diluent Process

Pneumatic-Mix Process

Chapter 7 - Internal ballistics and thermochemistry

General Function of a Rocket

Nozzle Flow Theory

The Theory

Energy Conversion

Derivation Of Thrust Equation

Isentropic Expansion In Converging- Diverging Nozzles (Ideal Nozzle)

Methods Of Comparing Propellant Performance

Glossary

Chapter 8 - Grain And Motor Design

Propellant Geometry

End-Burning Or Cigarette Burning Design

Regressive Burn Design

Progressive Burning Design

Neutral Burning Designs

Corners And Angularity Design

Summary Of Geometrical Considerations

Burning Rate-Pressure-Temperature Relationships

Measurement Of Burning Rates

Determination Of Equilibrium Pressure As A Function Of Burning Surface

Calculation Required For Nominal Performance Level

Alternate Method To Find Equilibrium Pressure With The K Ratio

Port Area And Effects On Internal Ballistics

Other Factors For Propellant Design Considerations

Types Of Thrust-Time Programs And Applications

Boost Velocity And Specific Impulse Reviewed

Loading Density And Scaling

Internal Ballistic Parameters And Scaling

Grain Design Calculations

Example Of Exact Profile Calculation Of A Propellant Grain Burning On Inside And Ends (Outside Surface Inhibited)

Propellant Selection

Grain Length And Internal Perforation Diameter

Hardware Technology

chamber design

Nozzle Design

Problems

Rocket Motor Design

Glossary

Chapter 9 - Modern Composite Propellants

Propellant Requirements

Major Binder Systems

Polysulfides

Polyurethanes

Polybutadiene Acrylic Acid

Carboxy-Terminated Polybutadiene

Rheology Of Uncured Propellant Suspensions

Distribution Effects Of Particle Size

Chapter 10 - Liquid Propellants

Liquid Propellants And Their Properties

Monopropellants

Bipfopelants

Liquid-Propellant Rocket System

Propellant Feed System

Liquid-Propellant Injectors

Combustion

Thrust Chamber Cooling

Torpedo Application

Auxiliary Uses

Chapter 11 - Motor Evaluation Systems

Testing Techniques

Nondestructive Tests

Destructive Tests

Test System Components

Instrumentation

Automatic Data Acquistion System

Chapter 12 - Gun Propulsion

Terminology And Operation

Terminology

Description Of Operation

Projectiles

Interior Ballistics Of Guns

Grain Configuration

Glossary

Chapter 13 - Safety Testing

Explosive Safety Development

Explosive Safety Research

Sensitivity Tests

Initiation and Propagation Tests

Stability Tests

Compatibility Tests

Chapter 14 - Safety Considerations

General Considerations

Composite Propellants

Homhogenous Propellants

General Safety Rules For All Propellants

Solvent Safety

Potential Hazards

Safety-Control Methods

Safety Aspects Of Explosives

Hazards of Explosives

Igniters

Exotic Ingredients

Oxidizers

Fuels

Binders

Preface

This book is a more comprehensive volume of my previous book, PROPELLANTS which was published by HOWARD W. SAMS publishing company under contract with Dr. Bruce Ketcham of the University of Oklahoma in 1967. In that book, I was advised by Dr. Ketcham to provide general information on modern composite (solid) rocket propellants which should be in textbook format for use by his students, but to leave out all of the advanced internal ballistics and thermochemistry. This book is being published to cover the material omitted from the previous book. It also includes chapters on manufacturing processes for other types of propellants, and ballistic and safety testing for a safe operation. Also included are chapters on gun propellants and other energetic materials.

Some of the material on modern composite rocket propellants was provided by Dr. Russell Reed, and the safety testing was provided by Mr. Bennett Kelley. I also wish to thank Amreik Vaid for editing the manuscript and putting it into textbook format.

Jawaharlal Ramnarace

Chapter 1 - History of Rockets

It was in the early thirteenth century that man turned toy fireworks into weapons of war. The first recorded use of rock­ets as military weapons was in defense of Kai Fung Fu, China, in 1232.

Fig 1-1. The Chinese arrows of flying fire

The Chinese arrows of flying fire were fired from some sort of crude rack-type launcher- and were pro­pelled by gunpowder. The gunpowder was packed in a tube (probably bamboo) that had a hole in one end for the escap­ing hot gases, a closed end for the push to be exerted against, and a long stick as an elementary guidance system.

About 1280 A.D., Arab military men, referring to the pro­pulsive ability of gunpowder, suggested improvements over the simple Chinese skyrocket. One interesting innovation was what might be best described as an air squid or traveling land mine; it could scurry across land in the manner of a squid through water.

It was about 1400 when rocketry became of commercial importance throughout Europe and especially in Italy—where perhaps the greatest designers of pyrotechnics were found. The use of fireworks for all sorts of celebrations created a major market for the manufacture of large quantities of rockets. This spread throughout Europe and reached its zenith during the middle of the eighteenth century.

One of the earliest technical publications on rocketry, the Treatise Upon Several Kinds of War-Fireworks, appeared in France in 1561. The treatise made a critical analysis of the rockets used in earlier military campaigns. A recommendation was made to substitute varnished leather cases for the com­monly accepted paper and bamboo ones. There is no evidence that this suggestion was followed by later rocketeers.

Comparatively, refinements in rocket design came faster in the next few hundred years, at least on paper. In 1591, some three hundred years before Dr. Robert Goddard thought of it, a Belgian, Jean Beavie, described and sketched the important idea of multi-staged rockets. Multi-staging, placing two or more rockets in line and firing them in step fashion, is today’s prac­tical answer to the problem of escaping earth’s gravitational attraction.

By 1600, rockets were being used in various parts of Europe against cavalry, foreshadowing the modern antitank hand weapon, and the bazooka of World War II and Korean fame. Later, in 1630, a paper was written describing exploding aerial rockets which created an effect similar to that of the twentieth- century shrapnel shell. By 1688, rockets weighing over 120 pounds had been built and fired with success in Germany. These German rockets, carrying 16-pound warheads, used wooden powder cases reinforced with linen.

Toward the end of the eighteenth century, a London lawyer, Sir Walter Congreve, became fascinated by the challenge to improve rockets. He made extensive experimentation on pro­pellants and case design. His systematic approach to the problem resulted in improved range, guidance, and incendiary capabilities. The British armed forces used Congreve’s new rockets to great advantage during the Napoleonic Wars.

When Congreve died in 1828, his applied engineering and dedication had already resulted in several technological ad­vances. In addition to fortified cases, new propellants, and incendiaries, Congreve developed stabilizing fins that provided rocketeers with effective guided missiles.

The latter half of the nineteenth century saw the demise of rockets as weapons, but man’s ingenuity, fortified with rapidly expanding technology, was directed towards the chal­lenge of human transportation by rockets. This period of time and the first quarter of the twentieth century saw the significant growth of reasoning and mathematics applied to rocket development. For the most part, military applications were forgotten. The founders of modern rocketry made their appearance at the threshold of the exciting events of our time.

A Russian assassin, Nikolai Kibaltchitch, while in prison awaiting trial in 1881, proposed a rocket ship powered by controlled firing of explosive pellets. His ship consisted of a firing chamber centered above a hole in a manned platform. The firing chamber could be rotated 90 degrees to move the ship in a horizontal direction. To avoid any influence of pub­lic opinion in favor of the prisoner, Russian officials withheld his plans. It wasn’t until after the Russian Revolution that Kibaltchitch’s writings were finally revealed.

In 1891, a German inventor, Hermann Ganswindt, designed a spaceship for travel to Mars. He also described a propulsion system similar to that of Kibaltchitch, except that he suggested a series of dynamite explosions that would shoot out steel balls with the hot exhaust. He reasoned that controlled explosions would eventually allow the ship to escape the earth’s gravita­tional attraction. Ganswindt also proposed the idea of rotating the ship while in space to produce an artificial gravity for the passengers, thereby recognizing the weightlessness phenom­enon. He never succeeded in obtaining support for his imprac­tical propulsion scheme.

Tsiolkovsky—

Father Of Interplanetary Travel

The first person to spell out the theory of space travel as based on serious mathematical study was a deaf and poor Russian school teacher. For many years he was barely noticed in his own country and drew even less attention elsewhere. Now recognized as the father of astronautical theory and of Russian rocketry, Konstantin Tsiolkovsky was one of the first, if not the first, to suggest the use of liquid propellants. For centuries, solids like gunpowder were considered to be the only possible fuels. There was, however, a Peruvian, Pedro Paulet, who claimed in 1925 that he had built and successfully fired in 1895 a 5-pound rocket engine which used gasoline and nitrogen peroxide. It is doubtful that this event took place, at least as early as claimed; otherwise it would have received widespread publicity, even with the poor communications of the day. Spanish publications had a much wider readership than those in Russian. This lack of communications and the chaotic conditions in Russia did prevent Tsiolkovsky’s writ­ings from being circulated outside of Russia.

Very little actual rocket experimentation took place any­where prior to World War I. Most of this work was largely concerned with solid propellants, as almost all liquid propellant studies met with failure. In 1915, the U.S. Navy and a private contractor worked out a rocket missile that could be easily guided, and the expectation arose at the time that it was now no longer a matter of aim, fire, and hope. These weapons, as well as succeeding ones used during World War I, were still primitive as compared with today’s missiles; they never had destructive capability.

Goddard—

Father Of Modern Rocketry

One of the most famous of rocket heroes, but acclaimed only after his death, was the American scientist, Dr. Robert H. Goddard. Unlike Tsiolkovsky and others, Goddard was a trained mathematician in addition to being a physicist. In­trigued by the challenge of rocketry, he began his studies in this field while still an undergraduate at Massachusetts’ Clark University (1904-08).

In 1907, a year before receiving his B.S. degree, Goddard wrote an article on nuclear rockets which was never published as the idea was considered much too advanced or ridiculous for his time. After receiving his doctor’s degree in 1911, God­dard combined a successful teaching career along with his lifelong interest in rockets.

Until he received a naval commission in 1917, Dr. Goddard carried out basic rocket propulsion studies using primarily his own resources. Initially the Navy assigned him the problem of improving their signal rockets. Although Goddard became more involved in rocket theory, he did take time out to develop a solid-propellant antitank rocket for the Army. However, World War I ended before the rocket design left the experimental stage.

In 1916 the Smithsonian Institution gave Goddard some financial support which enabled him to begin his intensive studies in liquid propellants. He had reasoned earlier that only high-energy propellants, such as liquid oxygen and hy­drogen, could provide the great velocities required for space travel. The Smithsonian published, in 1919, the summation of his years of work in the scholarly A Method of Reaching Ex­treme Altitudes.

Dr. Goddard, a retiring individual, essentially dropped from the public eye after the dubious reception of his book. How­ever, he actually increased the intensity of his studies. With continued support from the Smithsonian, he made a successful static test firing of a liquid-propellant—type rocket in 1923. On March 16, 1926, he successfully launched the world’s first liquid-fuel rocket near Auburn, Massachusetts (Fig. 1-2). The Guggenheim and Carnegie Foundations gave Goddard addi­tional financial backing, enabling him to move to a more suita­ble rocket-launching territory in New Mexico. Some twenty years later, New Mexico was to be the proving grounds for America’s first all-out effort in modem rocketry.

It was in New Mexico that Goddard accomplished his great­est development work with liquid-fuel rockets. By 1935 one of his rockets reached the height of 7500 feet. A year later he published Liquid-Propellant Rocket Development which detailed his progress to that time.

Fig. 1-2. Goddard’s liquid-propelled rocket

During World War II Goddard worked for the Navy again, this time developing rockets to assist airplane take-off (JATO), in addition to furthering his liquid-propellant studies. His JATO rockets, however, were not as successful as those devel­oped by scientists and engineers at California Institute of Technology (Cal Tech). Although these later became oper­ational, there was so little confidence in their success that no production facilities were set up to manufacture the JATO units. In fact, all the rockets used by the United States during the war were produced in makeshift facilities located near Cal Tech in Pasadena, California.

Dr. Goddard continued his studies until his death in 1945, still not completely recognized for his great and original con­tributions to rocketry. Among his achievements were flying a liquid-propelled rocket faster than sound and inventing a gyroscopic stabilization system for rockets. He eventually had in his name 214 patents, covering such concepts as pro­pellant pumps, variable-thrust engines, retrorockets, and mul­tistage rockets.

Table 1-1. Fuel Used in Space Vehicles

While Goddard was the leading exponent of rocketry in the United States, there were others doing some work in this field. The American Interplanetary Society (AIS) experimented with liquid rockets in the early 1930’s. In addition to having farsighted nontechnical members, the AIS included many competent scientists as participants. Among these was James H. Wyld who developed a solution to one of the liquid rocket’s most troublesome problems—hot walls. Wyld’s method to cool the walls of the rocket was to provide the engine with double walls and have the fuel move rapidly through the space be­tween them, keeping the inner wall from melting from the intense heat of combustion. The fuel was moved too fast to reach the boiling point, and it arrived at the fuel injectors hot and easily vaporized.

In the 1930’s the Germans, like Goddard, began to con­centrate on the use of liquid propellants, recognizing that the primary advantage of a liquid is that it can be readily controlled. This concentration on liquid propellants has lasted until the present, but the inherent advantage of handling ease has generated increased attention to the use of solid propel­lants for the future.

An incident in the early days of German experiments dra­matically pointed out the dangers of liquid fuels. An attempt was made to put an alcohol fuel and liquid oxygen in the same vessel and connect it with a single pipe to the engine— similar to supplying gasoline to a car engine. When the engine was ignited, the flame traveled back through the pipe and the tank exploded. The test stand was completely destroyed, and three scientists were killed.

Germany, by using the men of the Society for Space Travel (Dr. Walter Domberger and Dr. Werhner von Braun), was able to provide many of the answers to the problems posed by modern rocketry. The German government poured hundreds of millions of dollars into the rocket effort; the size of this project was exceeded only by America’s Manhattan Project.

Dornberger and von Braun’s real developmental work began in 1937 after their original research center at Kummersdorf-West was transferred to a new and bigger operation near the Baltic fishing village of Peenemunde, a name now famous in rocket annals. It was here the V-2 was produced and tested extensively before being launched as a missile against England. At one time during World War II there were more than 20,000 people working at Peenemunde.

One of von Braun’s advanced liquid-fuel rockets, the A-3 (A represents prototype), reached an altitude of 40,000 feet. When fired at an angle it had a range of 11 miles. After the A-3 came the A-4 or V-2 (Vengeance Weapon No. 2), as it became known later. The V-2 weighed approximately 15 tons when fully loaded with its liquid oxygen and alcohol propellant. It had a maximum range of about 200 miles, an altitude of 60 miles, and reached a velocity of close to 2000 miles per hour. The V-2 did not require a launching pad; once launched, it was kept on its ballistic path by an auto­matic pilot and steering vanes. When the American forces captured the V-2 launching sites, they found the plans for a transatlantic version of the V-2.

After the war, 300 carloads of V-2 parts were shipped to the newly established White Sands Proving Grounds in New Mexico and assembled into operational rockets there. While scientists and engineers began studying and firing the V-2’s, another group, under the direction of the late, great aerodynamicist von Karman, perfected a small but efficient solid-propellant rocket named the Private. They later produced an improved version that used a liquid propellant; it was called the Wac Corporal. Weighing less than 1000 pounds and only 16 feet long, the Corporal reached an altitude of 43 1/2 miles in 1945.

It soon became apparent that the size of White Sands was too small for the testing of large rockets. In 1949, plans were completed for the tremendous rocket launching facilities at Cape Canaveral, Florida (now Cape Kennedy). America’s first scientific satellite, Explorer 1, was launched from here on January 31, 1958. In addition to White Sands and Cape Kennedy, a large test center called the George C. Marshall Space Flight Center was built near Huntsville, Alabama. Dr. von Braun; headed by a large group of space scientists at this center. Other testing facilities include the Atlantic Mis­sile Range and Vandenberg Air Force Base in California.

This brief look at the history and development of rocketry illustrates two interesting facts of modem times. One is that nothing is really new in rocketry, as we have

Fig. 1-3. U.S. Rockets

had chemical rocket propulsion for hundreds of years. In this connection note the fact that the use of solid propellants is once again assuming a place of paramount importance in rocketry. Only techniques and developments have changed, not the funda­mentals. The other contemporary aspect is that the greatest development of chemical rockets has come about in a relative­ly short period. This has been the case in many scientific and engineering fields.

The majority of the small rockets used by the military are fueled with solid propellants: The larger (ICBM) missiles are divided between liquids and solids: vehicles such as the Minuteman, Polaris, Poseidon, and others use a solid propellant, and the Atlas uses liquid fuels and oxidizers. Fig. 1-3 pictures several of the rockets in the National Aeronautics and Space Agency’s program for space exploration. The type of fuel used is shown in Table 1-1. Because of the progress being made in propellant development it is difficult to say with certainty what chemical propellants will be used in tomorrow’s rockets.

Description: http://history.nasa.gov/MHR-5/Images/fig086.jpg

Fig. 1.4. Test launch of Saturn 1B rocket

The Future

One of the outstanding chemical rockets of the late 1960’s is the Saturn, which was designed to launch the Apollo space­craft with its three astronauts on their journey to the moon. The George C. Marshall Space Flight Center at Huntsville, one of many NASA centers, had the prime responsibility for developing the Saturn rockets. A family of Saturn rockets is projected for this space-exploration program. Present planning calls for a Saturn I, a Saturn IB, and a Saturn V (the Apollo booster). The Saturn I can place in orbit a weight seven times that of the capsule first used by John Glenn, while the Saturn V, the largest launch vehicle under development, was designed to lift a payload 80 times the weight of the Mercury spacecraft.

The Saturn I first stage has eight engines which develop a total thrust of 1.5 million pounds while burning liquid oxygen and kerosene. A more powerful propellant (liquid oxygen and liquid hydrogen) was used in the second stage, giving about 40 percent more thrust per pound of propellant than the first stage.

The Saturn IB is a combination—the third stage of the Saturn V on top of the first stage of the Saturn