ROCKET N.TAMILSELVAM, Assistant Professor, Department of Aeronautical Engineering, Adhiyamaan college of Engineering (Autonomous), Hosur,tamilnadu-635109.
INTRODUCTION
Rocket, self-propelled device that carries its own fuel. Rocket engine is the most powerful engine for its weight. Rockets can operate in space, because they carry their own oxygen. Rockets are presently the only vehicles that can launch into and move around in space.
How Rocket works….? Action and Reaction
Thrust and Efficiency Staging
Action and Reaction Rockets
produces the force that moves them forward by burning their fuel inside a chamber. Rocket, like the balloon, has an opening called a nozzle from which the exhaust gases exit.
Thrust and Efficiency
Thrust is a measurement of the force of a rocket, or the amount of “push” exerted backward to move a rocket forward.
Specific impulse measures the efficiency and power of rocket engines and propellants.
Staging In some rockets that use stages, the first stage has additional rockets attached to the outside, acting as boosters to further increase the thrust. The first and most powerful stage lifts the launch vehicle into the upper atmosphere. The second stage carries less weight than the first stage, because the first stage has dropped off of the rocket.
Thrusters Many spacecraft use small rockets called thrusters to move around in space. Thrusters can change the speed and direction of a spacecraft.
Rocket Propulsion
Classification of Rocket Based on gas acceleration mechanism Thermal
Electrostatic
Electromagnetic
• Chemical • Nuclear
• Ion • Hall Thruster
• MPD ( Magneto-plasma Dynamics) • PPT (Pulsed-plasma thrusters)
Chemical Propellants Solid Propellants
Black powder or gun powder
Liquid Propellants
Monopropellant
Homogeneous Bipropellant Single Base Double Base Petroleum Cryogenic Triple Base Heterogeneous (composite) Composite/double base
Hypergolic
Hybrid
Solid Propellants: Black powder or gun powder is a low explosive, composed essentially of a mixture of potassium nitrate or sodium nitrate, charcoal, and sulphur. It is hygroscopic and subject to rapid deterioration when exposed to moisture. It is also one of the most dangerous explosives to handle because of the ease with which it is ignited by heat, friction, or spark. The use of black powder as a propellant has ceased except for fireworks. Homogeneous propellants are either simple base or double base. A simple base propellant consists of a single compound, usually nitrocellulose, which has both an oxidation capacity and a reduction capacity. Double base propellants usually consist of nitrocellulose and nitroglycerine, to which a plasticiser is added. Homogeneous propellants do not usually have specific impulses greater than about 210 seconds under normal conditions. Their main asset is that they do not produce traceable fumes and are, therefore, commonly used in tactical weapons. They are also often used to perform subsidiary functions such as jettisoning spent parts or separating one stage from another. Triple-base propellants: Same as double-base propellants, but with nitroguanidine added.
Heterogeneous (or composite) propellants which consist of a separate fuel and oxidizer. Ordinary composite propellants generally consist of an organic fuel that also serves as a binder and a solid oxidizer. High-energetic composite propellants also include combustible metal particles which on combustion increase the energy available for propulsive purposes. The organic fuel is usually a hydrocarbon polymer, which initially is in a liquid state. The oxidizer and metallic fuel are then added in the form of small particles which are a few to a couple of hundred microns in diameter. After mixing with the liquid organic fuel, the mixture is cured to allow the binder to solidify. Modern composite propellants are heterogeneous powders (mixtures) that use a crystallized or finely ground mineral salt as an oxidizer, often ammonium perchlorate, which constitutes between 60% and 90% of the mass of the propellant. The fuel itself is generally aluminium. The propellant is held together by a polymeric binder, usually polyurethane or polybutadienes, which is also consumed as fuel. Additional compounds are sometimes included, such as a catalyst to help increase the burning rate, or other agents to make the powder easier to manufacture. Composite propellants are often identified by the type of polymeric binder used. The two most common binders are polybutadiene acrylic acid acrylonitrile (PBAN) and hydroxylterminator polybutadiene (HTPB). PBAN formulations give a slightly higher specific impulse, density, and burn rate than equivalent formulations using HTPB.
Composite/double propellants.
base:
Combinations
of
composite
and
double-base
Liquid Propellant: Petroleum fuels are those refined from crude oil and are a mixture of complex hydrocarbons, i.e. organic compounds containing only carbon and hydrogen. The petroleum used as rocket fuel is a type of highly refined kerosene, called RP-1 in the United States. Petroleum fuels are usually used in combination with liquid oxygen as the oxidizer. Kerosene delivers a specific impulse considerably less than cryogenic fuels, but it is generally better than hypergolic propellants. Liquid oxygen and RP-1 are used as the propellant in the first-stage boosters of the Atlas and Delta II launch vehicles. It also powered the first-stages of the Saturn 1B and Saturn V rockets. Cryogenic propellants are liquefied gases stored at very low temperatures, most frequently liquid hydrogen (LH2) as the fuel and liquid oxygen (LO2 or LOX) as the oxidizer. Hydrogen remains liquid at temperatures of -253 o C (423 o F) and oxygen remains in a liquid state at temperatures of -183 o C (297 o F). Because of the low temperatures of cryogenic propellants, they are difficult to store over long periods of time. For this reason, they are less desirable for use in military rockets that must be kept launch ready for months at a time. Furthermore, liquid hydrogen has a very low density (0.071 g/ml) and, therefore, requires a storage volume many times greater than other fuels. Despite these drawbacks, the high efficiency of liquid oxygen/liquid hydrogen makes these problems worth coping with when reaction time and storability are not too critical. Liquid hydrogen delivers a specific impulse about 30%-40% higher than most other rocket fuels.
Another cryogenic fuel with desirable properties for space propulsion systems is liquid methane (-162 o C). When burned with liquid oxygen, methane is higher performing than state-ofthe-art storable propellants but without the volume increase common with LOX/LH2 systems, which results in an overall lower vehicle mass as compared to common hypergolic propellants. LOX/methane is also clean burning and non-toxic. Future missions to Mars will likely use methane fuel because it can be manufactured partly from Martian in-situ resources. Liquid fluorine (-188 o C) burning engines have also been developed and fired successfully. Fluorine is not only extremely toxic; it is a super-oxidizer that reacts, usually violently, with almost everything except nitrogen, the lighter noble gases, and substances that have already been fluorinated. Despite these drawbacks, fluorine produces very impressive engine performance. It can also be mixed with liquid oxygen to improve the performance of LOX-burning engines; the resulting mixture is called FLOX. Because of fluorine's high toxicity, it has been largely abandoned by most space-faring nations. Some fluorine containing compounds, such as chlorine pentafluoride, have also been considered for use as an 'oxidizer' in deep-space applications.
Hypergolic propellants are fuels and oxidizers that ignite spontaneously on contact with each other and require no ignition source. The easy start and restart capability of hypergols make them ideal for spacecraft maneuvering systems. Also, since hypergols remain liquid at normal temperatures, they do not pose the storage problems of cryogenic propellants. Hypergols are highly toxic and must be handled with extreme care. Hypergolic fuels commonly include hydrazine, monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH). Hydrazine gives the best performance as a rocket fuel, but it has a high freezing point and is too unstable for use as a coolant. MMH is more stable and gives the best performance when freezing point is an issue, such as spacecraft propulsion applications. UDMH has the lowest freezing point and has enough thermal stability to be used in large regeneratively cooled engines. Consequently, UDMH is often used in launch vehicle applications even though it is the least efficient of the hydrazine derivatives. Also commonly used are blended fuels, such as Aerozine 50, which is a mixture of 50% UDMH and 50% hydrazine. Aerozine 50 is almost as stable as UDMH and provides better performance. Hydrazine is also frequently used as a monopropellant in catalytic decomposition engines. In these engines, a liquid fuel decomposes into hot gas in the presence of a catalyst. The decomposition of hydrazine produces temperatures up to about 1,100 o C (2,000 o F) and a specific impulse of about 230 or 240 seconds. Hydrazine decomposes to either hydrogen and nitrogen, or ammonia and nitrogen. The oxidizer is usually nitrogen tetroxide (NTO) or nitric acid. In the United States, the nitric acid formulation most commonly used is type III-A, called inhibited red-fuming nitric acid (IRFNA), which consists of HNO3 + 14% N2O4 + 1.5-2.5% H2O + 0.6% HF (added as a corrosion inhibitor). Nitrogen tetroxide is less corrosive than nitric acid and provides better performance, but it has a higher freezing point.
Hybrid Propellant: Hybrid propellant engines represent an intermediate group between solid and liquid propellant engines. One of the substances is solid, usually the fuel, while the other, usually the oxidizer, is liquid. The liquid is injected into the solid, whose fuel reservoir also serves as the combustion chamber. The main advantage of such engines is that they have high performance, similar to that of solid propellants, but the combustion can be moderated, stopped, or even restarted. It is difficult to make use of this concept for vary large thrusts, and thus, hybrid propellant engines are rarely built.
A hybrid engine burning nitrous oxide as the liquid oxidizer and HTPB rubber as the solid fuel powered the vehicle.
A flying weapon that has its own engine so that it can travel a long distance before exploding at the place that it has been aimed at … Missiles have four system components: targeting and/or guidance, flight system, propulsion system and warhead.
17
The word missile comes from the Latin verb mittere, literally meaning "to send". They are basically rockets which are meant for destructive purposes only.
Missiles differ from rockets by virtue of a guidance system that steers them towards a pre-selected target. Missiles are often used in warfare as a means of delivering destructive force (usually in the form of an explosive warhead) upon a target. Aside from explosives, other possible types of destructive missile payloads are various forms of chemical or biological agents, nuclear warheads, or simple kinetic energy (where the missile destroys the target by the force of striking it at high speed). 18
HISTORY OF MISSILES Rockets were invented in medieval China (1044 AD) but its first practical use for serious purpose took place in 1232 AD by the Chinese against the Mongols. There after Haider Ali and Tipu Sultan (Sultan of Mysore in south India) perfected the rocket's use for military purposes, very effectively using it in war against British colonial armies. At the Battle of Seringapatanam in 1792, Indian soldiers launched a huge barrage of rockets against British troops, followed by a huge massacre of British forces.
19
Portrait of Tipu Sultan Sultan of Mysore, present day Karnataka, India Unlike contemporary rockets whose combustion chamber was made of wood (bamboo), Tipu's rockets (weighing between 2.2 to 5.5 kg) used iron cylinder casings that allowed greater pressure, thrust and range (1.5 to 2.5 Km). The British were greatly impressed by the Mysorean rockets using iron tubes.
20
MISSILES IN MODERN INDIA After regaining independence in 1947, India focused all its energy in nation building, primarily on economic and industrial development fully understanding the key role of science and technology. Indian rocketry was reborn, thanks to the farsighted technological vision of Prime Minister Pundit Jawaharlal Nehru. Professor Vikram Sarabhai took the challenge of realizing this dream. 21
Hon. President of India Dr A.P.J. Abdul Kalam played a key engineering role in realizing both the Indian SLV-3 space launcher as well as the Prithvi and Agni missiles. Initial missile programs like Project Devil (a theatre ballistic missile) and Project Valiant (an intercontinental ballistic missile) were scattered and stymied by many issues. But the success of all our missile programs including BRAHMOS makes up for the shelved old projects.
Agni missile.
Dr A.P.J. Abdul Kalam
22
MISSILE COMPONENTS Guided missiles are made up of a series of subassemblies. The major sections are carefully joined and connected to each other. They form the complete missile assembly.
The major components of a missile are: WARHEAD FUSING GUIDANCE SYSTEM PROPULSION SYSTEM FINS 23
24
WARHEAD A warhead is an explosive device used in military conflicts, used to destroy enemy vehicles or buildings. Typically, a warhead is delivered by a missile or rocket . It consists of the explosive material, and a detonator.
Types of warhead :Explosive: An explosive charge is used to disintegrate the target, and damage surrounding areas with a shockwave. Chemical: A toxic chemical, such as nerve gas is dispersed, which is designed to injure or kill human beings.
Biological: An infectious agent, such as anthrax is dispersed, which is designed to sicken and kill humans. Nuclear: A runaway nuclear fission or fusion reaction causes immense energy release. 25
Fragmentation: Metal fragments are projected at high velocity to cause damage or injury. Shaped Charge: The effect of the explosive charge is focused onto a specially shaped metal liner to project a hypervelocity jet of metal, to perforate heavy armour.
Fig.- A NUCLEAR WARHEAD
26
FUSING It includes those devices and arrangements that cause the missile's payload to function in proper relation to the target. There are two general types of fuzes used in guided missiles • proximity fuzes and contact fuzes.
Some common methods of fusing are:-
Radio frequency sensing The shell contains a micro transmitter which uses the shell body as an antenna and emits a continuous wave of roughly 180–220 MHz .
As the shell approaches a reflecting object, an interference pattern is created. This causes a small oscillation of the radiated power and consequently the oscillator supply current of about 200–800 Hz, the Doppler frequency. This signal is sent through a band pass filter , amplified, and triggers the detonation when it exceeds a given amplitude. 27
Optical sensing Based on the use of petoscope which is an optoelectronic device for detecting small, distant objects such as flying aircraft. modern air-to-air missiles use lasers. They project narrow beams of laser light perpendicular to the flight of the missile.
Magnetic sensing can only be applied to detect huge masses of iron such as ships. It is used in mines and torpedoes. Fuzes of this type can be defeated by degaussing, using non-metal hulls for ships (especially minesweepers) or by magnetic induction loops fitted to aircraft or towed buoys. 28
Acoustic sensing used a microphone in a missile. The characteristic frequency of an aircraft engine is filtered and triggers the detonation. Naval mines can also use acoustic sensing, with modern versions able to be programmed to "listen" for the signature of a specific ship.
Pressure wave sensing Some naval mines are able to detect the pressure wave of a ship passing overhead.
29
GUIDANCE SYSTEM Missiles may be targeted in a number of ways. The most common method is to use some form of radiation , such as infrared , lasers or radio waves , to guide the missile onto its target. There are two types of guidance system i. fire-and-forget ii. Another method is to use a TV camera—using either visible light or infra-red—in order to see the target.
30
Some methods of target detection are:-
Laser Guidance - A laser designator device calculates relative position to a highlighted target. Most are familiar with the military uses of the technology on Laser-guided bomb. The space shuttle crew leverages a hand held device to feed information into rendezvous planning. The primary limitation on this device is that it requires a line of sight between the target and the designator.
31
Terrain contour matching (TERCOM)- This method uses a ground scanning radar to "match" topography against digital map data to fix current position. Used by cruise missiles such as the BGM-109 Tomahawk.
Infrared homing : This form of guidance is used exclusively for military munitions, specifically air-toair and surface-to-air missiles. The missile’s seeker head homes in on the infrared (heat) signature from the target’s engines (hence the term “heat-seeking missile”).
32
Long-range Navigation (LORAN) : This was the predecessor of GPS and was (and to an extent still is) used primarily in commercial sea transportation. The system works by triangulating the ship's position based on directional reference to known transmitters.
Wire-Guidance -A wire-guided missile is a missile guided by signals sent to it via thin wires reeled out during flight. 33
Global Positioning System (GPS) GPS was designed by the US military. GPS transmits 2 signal types: military and a commercial. GPS is a system of 24 satellites orbiting in unique planes 10.9-14.4 Nautical miles above the earth. The Satellites are in well defined orbits and transmit highly accurate time information which can be used to triangulate position.
34
PROPULSION SYSTEM Guided missiles use some form of jet power for propulsion.
35
ATMOSPHERIC JET PROPULSION SYSTEM.—There are three types of atmospheric jet propulsion systems—the turbojet, pulsejet, and ramjet engines. Of these three systems, only the turbojet engine is currently being used in Navy air-launched missiles. The various methods are as follows:-
TURBOJET – The turbojet is the oldest kind of general-purpose air breathing jet engine. Compared to turbofans, turbojets are quite inefficient if flown below about Mach 2 and are very noisy.
As a result, most modern aircraft use turbofans instead for economic reasons, although turbojets are still common in medium range cruise missiles, due to their high exhaust speed, low frontal area, and relative simplicity. 36
Fig.-TURBOJET
Fig.-RAMJET
37
RAMJET – A ramjet uses the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed, thus they cannot move an aircraft from a standstill .
Ramjets work most efficiently at supersonic speeds around Mach 3. This type of engine can operate up to speeds of Mach 6. Ramjets can be particularly useful in applications requiring a small and simple mechanism for high-speed use, such as missiles or artillery shells. They have also been used successfully, though not efficiently, as tip jets on the end of helicopter rotors.
Ramjets employ a continuous combustion process. 38
PULSEJET - A pulse jet engine (or pulsejet) is a type of jet engine in which combustion occurs in pulses. Pulsejet engines can be made with few or no moving parts , and are capable of running statically. Pulse jet engines are a lightweight form of jet propulsion, but usually have a poor compression ratio , and hence give a low specific impulse. One notable line of research of pulsejet engines includes the pulse detonation engine which involves repeated detonations in the engine, and which can potentially give high compression and good efficiency.
39
ROCKET— Thermal jets include solid propellant, liquid propellant, and combined propellant systems.
Liquid Propellant - Liquid fuel is used in space vehicles and satellites and that this fuel is put into the tanks of the space vehicles immediately before launching. A missile cannot wait to be fueled when it is needed for defense or offense-it must be ready. That is one of the reasons why solid propellants have replaced liquid propellants in most of our missiles.
40
Solid Propellant Engines- The combustion chamber of a solid propellant rocket contains the charge of solid propellant. Solid propellant charges are of two basic types: restricted burning and unrestricted burning.
41
HYBRID PROPULSION – A hybrid engine combines the use of liquid and solid propellants. The liquid is the oxidizer and the solid is the propellant. Ignition is usually hypergolic, that is, spontaneous ignition takes place upon contact of the oxidizer with the propellant. The combustion chamber is within the solid grain, as in a solid-fuel rocket; the liquid portion is in a tank with pumping equipment as in a liquid-fuel rocket. Combustion takes place on the inside surface of the solid fuel, after the liquid fuel is injected, and the combustion products are exhausted through the nozzle to produce the thrust as in other rockets
Liquid Propellant + Solid Propellant Engines = HYBRID PROPULSION
42
PRINCIPLE OF WORKING TRACKING : To target the missile by knowing the location of the target, and using a guidance system such as inertial navigation system (INS), TERCOM or GPS. This job can also be performed somewhat crudely by a human operator who can see the target and the missile, and guides it using either cable or radio based remote-control, or by an automatic system that can simultaneously track the target and the missile.
GUIDANCE – It involves guiding the missile to the target 43
FLIGHT The working of a missile is based on the Newton’s Third Law i.e. Action and reaction are equal and opposite The propulsion of a missile is achieved with the help of a rocket engine. It produces thrust by ejecting very hot gaseous matter, called propellant. The hot gases are produced in the combustion chamber of the rocket engine by chemical reactions. The propellant is exhausted through a nozzle at a high speed. This exhaust causes the rocket to move in the opposite direction (Newton's third law). MISSILE AERODYNAMICS - Guided missiles launched from surface ships have their flight paths within the earth's atmosphere, so it is important that you understand some basic aerodynamic principles. Aerodynamics may be defined as the science that deals with the motion of air and other gases, and with the forces acting on bodies moving through these gases.
44
45
MISSILE CLASSIFICATION Guided missiles are classified according to their range, speed, and launch environment, mission, and vehicle type.
Range:Long-range guided missiles are usually capable of traveling a distance of at least 100 miles. Short-range guided missiles often do not exceed the range capabilities of long-range guns.
Speed:The speed capability of guided missiles is expressed in Mach numbers. A Mach number is the ratio of the speed of an object to the speed of sound in the medium through which the object is moving. Under standard atmospheric conditions, sonic speed is about 766 miles per hour (Mach 1.0). Guided missiles are classified according to their speed as shown below: • Subsonic—Up to Mach 0.8 • Transonic—Mach 0.8 to Mach 1.2 • Supersonic—Mach 1.2 to Mach 5.0 • Hypersonic—Above Mach 5.0
46
MISSILE DESIGNATION The Department of Defense established a missile and rocket designation sequence. The basic designation of every guided missile are letters, which are in sequence. The sequence indicates the following: 1. The environment from which the vehicle is launched 2. The primary mission of the missile 3. The type of vehicle Examples of guided missile designators common to the Aviation Ordnance man are as follows: Designator Meaning AGM Air-launched, surface-attack, guided missile AIM
Air-launched, intercept-aerial, guided missile
ATM
Air-launched, training guided missile
RIM
Ship-launched, intercept-aerial, guided missile 47
48
49
50
A design number follows the basic designator. In turn, the number may be followed by consecutive letters, which show a modification. For example, the designation of AGM-88C means the missile is an air-launched (A), surface-attack (G), missile (M),eighty-eighty missile design (88), third modification (C). In addition, most guided missiles are given popular names, such as Sparrow, Sidewinder, and Harpoon. These names are retained regardless of subsequent modifications to the original missile.
MISSILE IDENTIFICATION The external surfaces of all Navy guided missiles , except random and antenna surfaces, are painted white. The color white has no identification color-coding significance when used on guided missiles. There are three significant color codes used on guided missiles and their components— yellow, brown, and blue. These color codes indicate the explosive hazard in the missile component. If components are painted blue on a practice missile and have a yellow or brown band painted on them, the component has an explosive component that doesn't have a comparable part in a service missile. 51
TYPES OF MISSILES ON THE BASIS OF MODE OF FIRE An air-to-air missile (AAM) is a missile fired from an aircraft for the purpose of destroying another aircraft.
Astra missile of Indian army
F-22A Raptor ,.
52
An air-to-surface missile (ASM) or air-to-ground missile (AGM or ATGM) is a missile designed to be launched from military aircraft (bombers , attack aircraft, fighter aircraft or other kinds) and strike ground targets on land, at sea, or both.
Silkworm , US .
Storm Shadow by France
53
An anti-ballistic missile (ABM) is a missile designed to counter ballistic missiles. Ballistic missiles are used to deliver nuclear, chemical, biological or conventional warheads in a ballistic flight trajectory. The term "anti-ballistic missile" describes any antimissile system designed to counter ballistic missiles. However, the term is used more commonly for systems designed to counter intercontinental ballistic missiles (ICBMs).
A Standard Missile Three (SM-3) ,U.S. Navy ballistic missile flight test.
54
the Prithvi Air Defence(PAD) 55
Anti-satellite weapons (ASAT) are designed to incapacitate or destroy satellites for strategic military purposes. Currently, only the United States, the former Soviet Union, and the People's Republic of China are known to have developed these weapons.
Standard Missile - 3 (SM-3)
56
Anti-ship missiles are guided missiles that are designed for use against ships and large boats. Most anti-ship missiles are of the sea skimming variety, and many use a combination of inertial guidance and radar homing.
RGM-84 surface -to-surface Harpoon missile.
57
An anti-submarine missile is a standoff weapon including a rocket designed to rapidly deliver an explosive warhead or homing torpedo from the launch platform to the vicinity of a submarine.
Ikara dummy missile onboard HMAS Stuart(DE-48) off the New South Wales coast. The ship in the distance is a Japanese Guided Missile Destroyer, visiting for Australia's Bicentennial Naval Salute/Bicentennial Naval Review in September/October 1988.
58
An anti-tank missile (ATM), anti-tank guided missile (ATGM), anti-tank guided weapon (ATGW) or anti-armor guided weapon, is a guided missile primarily designed to hit and destroy heavilyarmored military vehicles.
Nag missile and the Nag missile Carrier Vehicle (NAMICA),Antitank Guided missile developed by DRDO.
59
A land-attack missile is a naval surface-to-surface missile that is capable of effectively attacking targets ashore, unlike specialized anti-ship missiles, which are optimized for striking other ships. Some dual-role missiles are suitable for both missions.
Cruise missile BrahMos shown on IMDS-2007, owned By India
60
A surface-to-air missile (SAM), or ground-to-air missile (GTAM), is a missile designed to be launched from the ground to destroy aircraft or other missiles. It is one type of anti-aircraft system; in modern armed forces missiles have replaced most other forms of dedicated anti-aircraft weaponry, with the anti-aircraft cannon pushed into niche roles.
Two SA-2 Guideline (S-75 Dvina) missiles in the National Museum of Military History in Sofia
61
A surface-to-surface missile (SSM) or ground-to-ground missile (GGM) is a missile designed to be launched from the ground or the sea and strike targets on land or at sea. They may be fired from hand-held or vehicle mounted devices, from fixed installations, or from a ship.
RPG-7 with warhead detached
BGM-71 TOW , variant M220, SABER. U.S. Army 62
A wire-guided missile is a missile that is guided by signals sent to it via thin wires connected between the missile and its guidance mechanism, which is located somewhere near the launch site.
A Stryker vehicle crew belonging to the 4th Brigade, 2nd Infantry Division, fires a TOW missile during the brigade's rotation through Fort Polk's, Joint Readiness Training Center
63
A ballistic missile is a missile that follows a ballistic flight path with the objective of delivering one or more warheads to a predetermined target. Shorter range ballistic missiles stay within the Earth's atmosphere, while longer range ones are designed to spend some of their flight time above the atmosphere and are thus considered sub-orbital.
United States Trident II (D-5) missile underwater launch.
64
A cruise missile is a guided missile, the major portion of whose flight path to its target (a land-based or sea-based target) is conducted at approximately constant velocity; that relies on the dynamic reaction of air for lift, and upon propulsion forces to balance drag.
Shaurya missile (left) and BrahmosII(model) (top) by Government of India.
65
Reference : www.google.com
ANY QUESTIONS ?
GUIDED MISSILES , by - T V Karthikeyan & A K Kapoor , Scientists Defense Research &- Development Laboratory, Hyderabad , Defense Scientific Information & Documentation Centre (DESIDOC) , Ministry of Defense, DRDO PRINCIPLES OF MISSILE FLIGHT AND JET PROPULSION PRINCIPLES OF GUIDED MISSILES AND NUCLEAR WEAPONS, by BUREAU OF NAVAL PERSONNEL OF U.S NAVY ,Prepared and produced by the U. S. Navy Training Publications Center under direction of the Bureau of Naval Personnel
66
Solid Rocket Propulsion Basics
Solid Rocket Motors A solid rocket motor is a system that uses solid propellants to produce thrust Advantages High thrust Simple Storability High density
Disadvantages Low Isp (compared to liquids) Complex throttling Difficult to stop and restart Safety
Solid Rocket Motors Solid rocket motors are used for Launch vehicles High thrust (high F/W ratio) High storage density
Ballistic Missiles Propellant storability Excellent aging Quick response storability high F/W ratio)
Solid Rocket Motor Components
Thermal Insulation Design involves: Analysis of combustion chamber environment Stagnation temperature Stagnation pressure Propellant gases (material compatibility)
Selection of insulation material Material thickness determination for various areas of the motor case For the cylindrical part of the case, the walls are only exposed to hot combustion gases at the end of the burn
The Nozzle The design of the nozzle follows similar steps as for other thermodynamic rockets Throat area determined by desired stagnation pressure and thrust level Expansion ratio determined by ambient pressure or pressure range to allow maximum efficiency
Major difference for solid propellant nozzles is the technique used for cooling Ablation Fiber reinforced material used in and near the nozzle throat (carbon, graphite, silica, phenolic)
Ablation Meteorite Re-entry speed of 10 - 20 km/sec Extreme heating in the atmosphere Ablation and internal energy modes cooled the meteorite through its fall Ablation gas cloud Dissociation Internal energy deposition
Stony-Iron Classification (95% of all meteorites)
Ignition System Large solid motors typically use a three-stage ignition system Initiator: Pyrotechnic element that converts electrical impulse into a chemical reaction (primer) Booster charge Main charge: A charge (usually a small solid motor) that ignites the propellant grain. Burns for tenths of a second with a mass flow about 1/10 of the initial propellant grain mass flow.
Propellant Grain Two main catagories Double Base: A homogeneous propellant grain, usually nitrocellulose dissolved in nitroglycerin. Both ingredients are explosive and act as a combined fuel, oxidizer and binder Composite: A heterogeneous propellant grain with oxidizer crystals and powdered fuel held together in a matrix of synthetic rubber binder. Less hazardous to manufacture and handle
Conventional Composite Fuel 5-22% Powdered Aluminum
Oxidizer 65-70% Ammonium Perchlorate (NH4ClO4 or AP)
Binder 8-14% HydroxylTerminated Polybutadiene (HTPB)
Fuels Aluminum (Al) Molecular Weight: 26.98 kg/kmol Density: 2700 kg/m3 Most commonly used
Magnesium (Mg) Molecular Weight: 24.32 kg/kmol Density: 1750 kg/m3 Clean burning (green)
Beryllium (Be) Molecular Weight: 9.01 kg/kmol Density: 2300 kg/m3 Most energetic, but extremely toxic exhaust products
Oxidizers Ammonium Perchlorate (AP) Most commonly used Cl combining with H can form HCl Toxic Depletion of ozone
Ammonium Nitrate (AN) Next most commonly used Less expensive than AP Less energetic No hazardous exhaust products
Binders Hydroxyl Terminated Polybutadiene (HTPB) Most commonly used Consistency of tire rubber
Polybutadiene Acrylonitrile (PBAN) Nitrocellulose (PNC) Double base agent
Additives Used to promote Curing Enhanced burn rate (HMX) Bonding Reduced radiation through the grain (darkening) Satisfactory aging Reduced cracking
Igniters TYPES OF IGNITER: The types of igniters which are commonly used are, Gaseous Igniter Liquid igniter Solid igniter
GASEOUS IGNITER It is the old and primitive type of igniter which is not used now. In this type of igniter the reactive gaseous mixtures are held in a very thin tube with high pressure. It is hazardous in nature and reliable. Directional control can be done by using burst dampers. Example for gaseous igniters is shock tube.
LIQUID IGNITER: Liquid igniter is of two types. Theyare, Liquid- Liquid type , which is known as hypergolic igniter Liquid – Solid type, which is known as hybrid igniter
CHARACTERISTICSOF HYPERGOLIC LIQUIDS: Hypergolic liquids have a very high bulk density. Ignition delay for these types of liquids should be less than 50 milliseconds. These liquids are chemically instable. They must be work well together with some of selected polymers and resins. Their viscosity should be less than 10 centistokes. They should have a very low vapour pressure. They should have a very good heat transfer characteristics.
FACTORS AFFECTING IGNITION DELAY: The factors which affect the ignition delay are, Purity of materials Initial temperature and pressure.
t = A𝒆𝑬/𝑹𝑻 t = Time A= Minimum possible ignition delay
E = Temperature coefficient R = Universal Gas constant T=Temperature
IGNITER DESIGNCONSIDERATION : The data to be considered while designing an igniterare, The pyrotechnic material data Propellant ignitability data Rocket motor data Back up data (previous test firing data).
IGNITABILITY BOMB: The ignitability bomb is a device used to determine the relative ignitability of the propellants at various pressures under the direct fire of ignition materials.
INJECTORS : An injector or ejector is a system of admitting the fuel into the combustion engine. Its function issimilar to a carburettor. PRIMARY DIFFERENCE BETWEEN A CARBURATOR AND AN INJECTOR: In an injector the fuel injection atomizes the fuel by forcibly pumping it through a small nozzle under high pressure while a carburetor relies on suction created by intake air rushing through a venture to draw the fuel into the airstream.
FUNCTION OF AN INJECTOR: The injectors are mainly used to meter the flow of the liquid propellant to the combustion chamber which causes the liquids to be broken into small droplets. This process is known as atomization. It also helps to distribute and mix the propellant in a correctly proportionate mixture of fuel and oxidizer, which results in uniform propellant mass flow.
IMPINGING STREAM PATTERN : The types of impinging stream pattern are , Doublet impinging stream pattern Triplet impinging stream pattern Self impinging stream pattern
SHEET (or) SPRAY TYPE INJECTORS:
SHEET (or) SPRAY TYPE INJECTORS:
Sheet (or) spray type injectors give cylindrical, conical or other types of spray sheets , these sprays generally intersect and there by promote mixing and atomization . By varying the width of the sheet (through an axially movable sleeve) it is possible to throttle the flow over a wide range without excessive reduction in the pressure drop. This type of variable area concentric tube injector was used on the descent engine of the lunar excursion module.
THE COAXIAL HOLLOW POST INJECTOR:
The coaxial hollow post injector has been used for liquid oxygen and gaseous hydrogen injectors. It works well when the liquid hydrogen has absorbed heat from cooling jackets and has been gasified. This gasified hydrogen flows at a high speed of 330m/s. The liquid oxygen flows far slowly at a speed of 33m/s ,and the differential velocity cause a shear action which helps to break up the oxygen stream into small droplets The coaxial hollow post injector is not used with liquid storable bipropellants in part because the pressure drop to achieve high velocity would become too high.
DESIGN CONSIDERATION OF A LIQUID ROCKET COMBUSTION CHAMBER: Combustion chamber which is also known as thrust chamber, where the combustion or burning of propellants take place. The combustion temperature is much higher than the melting points of most chamber wall materials. Therefore it is necessary to cool these walls or to stop rocket operation before the critical wall areas become too hot. If the heat transfer is too high and thus the wall temperatures become locally too high, then the thrust chamber will fail.
VOLUME AND SHAPE CONSIDERATIONS: The volume and shape of a combustion chamber are selected after evaluating various parameters. Some of them are as follows, 1. The volume has to be large enough for adequate mixing, evaporation and complete combustion of propellants. 2. Chamber volume varies for different propellants with the time delay necessary to vaporize and activate the propellants and with the speed of the propellant combination. 3.
When the chamber volume is too small, combustion is incomplete and the performance is
4. With higher chamber pressure or with highly reactive propellants and with injectors that give improved mixing, a smaller chamber volume is usually permissible. 5. The chamber volume and diameter can influence the cooling requirements. If the chamber volume and diameter are large, the heat transfer rates to the wall will be reduced, the area exposed to heat will be large, and the walls are somewhat thicker. 6. All inert components should have a minimum mass. The thrust chamber mass is a function of the chamber dimensions, chamber pressure, and nozzle area ratio, and the method of
7.
Manufacturing consideration favor simple chamber geometry, such as a cylinder with a double cone bow tie shaped nozzle, low cost materials and simple fabrication process.
8. In some applications the length of the chamber and the nozzle relate directly to the overall length of the vehicle. A large diameter but short chamber can allow a somewhat shorter vehicle with a lower structural inert vehicle mass.
9.The gas pressure drop for accelerating the combustion products within the chamber should be a minimum; any pressure reduction at the nozzle inlet reduces the exhaust velocity and the performance of the vehicle. These losses become appreciable when the chamber volume less than three times the throat area. 10.For the same thrust the combustion volume and the nozzle throat area become smaller as the operating chamber pressure is increased. This means that the chamber length and the nozzle length also decrease with increasing chamber pressure, the performance will go up with chamber pressure
Problem Associated With Liquid Propulsion Thrust Chambers
PROPELLANT HAMMER Propellant hammer is nothing but a pressure surging present in the liquid propellant feed line. Basically the feed lines are very thin. On sudden closure of valve, a pressure pulse is generated at the neighborhood of the valve. It travels back to the tank at some velocity and keeps the liquid static pressure increasing.
TANK OUTLET DESIGN CONSIDERATION: Before designing the tank outlet the designer have to solve three main problems. They are, 1. Cavitation 2. Dropout 3. Vortexing
Cavitation Cavitation is the phenomenon which occurs when the static pressure drops below the vapour pressure of the propellant. This may be due to the increased flow velocity in the tank outlet. It can be also defined as the boiling of liquid at low pressures and the release of dissolved gas from the liquid. Small gas bubbles grow in the liquid and then collapse within a few milliseconds. This is accompanied by high temperature rises up to 10,000K and the pressure rises up to 400MPa.
Cavitation Cavitation is an undesirable phenomenon because there will be increased losses in the outlet. Cavitation occurs in the converging duct of the outlet where the fluid velocity increases and there is acorresponding decrease in static pressure.
SOLUTION FOR CAVITATION Cavitation problem can be avoided by contouring the outlet, so that the static pressure is constant throughout the outlet. Cavitation can also suppress by avoiding high flow velocities or by using high fluid pressures or by combination of both. The high fluid pressures in the turbo pumps are achieved by high tank pressures, possibly in combination with booster pumps.
LIQUID DROP OUT Liquid drop out is an undesirable phenomenon in case of liquid rocket engines. Liquid dropout is basically a depression in the liquid surface at center of the flow lines, which occurs in higher vertical velocity along the center line of the outlet than along the wall exit
How to avoid LIQUID DROP OUT Liquid dropout will not occur when the liquid surface remains stationary. This problem can be avoided by contouring the outlet so that the axial component of velocity along a stream line adjacent to the wall of outlet is equal to the average velocity which is obtained by dividing the flow rate by the cross sectional area.
VORTEXING Vortexing is a phenomenon which is similar to the coriolisforce effects in bath tubs being emptied and can be augmented if the vehicle spins or rotates during flight. Typically a series of internal baffles is often used to reduce the magnitude of vortexing in propellant tanks with modest side acceleration. vortexing can greatly increase the unavailable or residual propellant , and thus cause a reduction in vehicle performance .
OUTAGE The amount of liquid oxidizer or propellant present in the tank at the time of completing the operation of vehicle is called as an outage.
GEYSERING EFFECT The term geysering is applied to the phenomenon which occurs in a liquid propellant system, a column of liquid in long vertical lines is expelled by the release of bubbles. If the bubbles will swarm causing the creation of slow moving mass or a single large bubbles travels at faster velocity causing more and more bubble formation and decrease the column static pressure rapidly.
The pressure surging produced due to geysering can be large and damage the fluid lines, wall supports and the line supports. Geysering can be also results from the action of the release of super heat and reduced pressure boiling in a saturated or superheated liquid column.
Propellant slosh
METHOD TO AVIOD PROPELLANT SLOSH ude rigid ring baffles (Of various geometries and orientation), cruciform baffles, deflectors, flexible flat ring baffle, floating can, positive expulsion bags and diaphragms. Gel, packed fibers, and foams have been employed in non space applications, but are not now being used for space vehicles.
PROPELLANT FEED SYSTEM
1. Gas pressure feed system 2. Turbo pump feed system
VALVES AND PIPE LINES
Classification of Valves Used in Liquid Propellant Rocket Engines 1. Fluid valve: For carrying fuel, oxidizer, cold pressurized gas, and hot turbine gas this type of valve is used. 2. Application or Use: The valves which are mainly used for propellant control are Thrust chamber valve (dual or single),bleed valve, drain valve, filling valves, by-pass valve, preliminary stage flow valve, pilot valve, safety valve; overboard dump valve, regulato valve, gas generator control valve, sequence control valve.
3. Mode of Actuation: The valves are operated by different means of actuation. The different modes are, Automatically operated (by solenoid, pilot valve, trip mechanism, pyrotechnic, etc.) Manually operated Pressure-operated by air, gas, propellant, or hydraulic fluid (e.g., check valve, tank vent valve, pressure regulator, relief valve) 4. The flow magnitude determines the size of the valve.
5. Valve Types Normally open, normally closed, normally partly open, two-way, threeway, with/without valve position feedback, ball valve, gate valve, butterfly type, spring loaded valve.
PIPES (or) LINES: The various fluids in a rocket engine are conveyed by pipes or lines, usually made of metal and are joined by fittings or welds. Their design must provide thermal expansion and provide support to minimize vibration effects. For gimballed thrust chambers it is necessary to provide flexibility in the piping to allow the thrust axis tube rotated through a small angle, typically +3 to 10 °.
COOLING OF THRUST CHAMBER
NEED FOR COOLING The primary objective of cooling is to prevent the chamber and nozzle walls from becoming too hot, so they will no longer able to withstand the imposed loads and stresses, thus causing the chamber or nozzle to fail. Most materials lose strength and become weaker as temperature is increased. Cooling thus reduces the wall temperatures to an acceptable limit.
Methods of Cooling of Thrust Chambers
AERODYNAMICS OF ROCKETS AND MISSILES
AIRFRAME COMPONENTS OF A MISSILE
AIRFRAME COMPONENTS OF A MISSILE Nose or Fore body Midsection or Main body The aft or Boat tail section Fins
NOSE (or) FORE BODY It is the first and foremost component of a missile which experiences air while travelling through the atmosphere. Several types of nose sections were used in various types of missiles. Some of the types are, Conical fore body Ogival fore body Hemispherical fore body
MID SECTION: cylindrical shape. The shape is advantageous from the stand points of drag, ease of manufacturing, and the load carrying capability. The zero-lift drag of a cylindrical body is caused by skin friction force only. At low angle of attack, a very small amount of normal force is developed on the body, this results from the “carryover “from the nose section. BOAT TAIL:
The tapered portion of the aft section of a body is called the boat tail. The purpose of boat tail is to decrease the drag of a body which has a squared off base. The mid section has relatively large base pressure and consequently high drag values because of large base area. By “boat tailing” the rear portion of the body, the base area is reduced and thus the base drag is reduced. However, the decrease in base drag may be partially nullified by the boat
Fins
Fins The purpose of putting fins on the rocket is to provide stability, provide lift and control the flight path of the missile. The plan form of fins of a rocket is of different types. They are of clipped tip delta, rectangular, triangular, trapezoidal etc.
AERODYNAMIC SURFACES OF MISSILES
SUPERSONIC WING CROSS SECTIONAL SHAPES The various supersonic wings cross sectional shapes are, 1. Double wedge 2. Modified double wedge and 3. Biconvex
SUPERSONIC WING PLAN FORMS (a) CLIPPED TIP DELTA (b) DELTA (or) TRIANGULAR (c) RECTANGULAR (d) RECTAGULAR WITH RAKE
(b) DELTA (or) TRIANGULAR (a) CLIPPED TIP DELTA
(c) RECTANGULAR
AERODYNAMIC CONTROLS OF A MISSILE: Aerodynamic control is the connecting link between the guidance system and the flight path of the missile. Effective control of flight path requires smooth and exact operation of the control surfaces of the missile. They must have the best possible design configuration for the intended speed of the missile.
The control surface must move with enough force to produce the necessary change of direction. The adjustments they make must maintain the balance and centre of gravity of the missile. The control surface must also be positioned to meet variations in lift and drag at different flight speeds. All these conditions contribute to the flight stability of the missile.
The types of aerodynamic controls of a missile are, 1. Canard control 2. Wing control 3. Tail control 4. Unconventional control
