PHYSICS PROJECT

TOPIC- BALLISTIC MISSILES

SUBMITTED TO –

MR. B.K.PUTI

SUBMITTED BY-

SHUBHAM SHARMA

XI (NON-MEDICAL)

ROLL NO.-14

ST.KABIR’S RESI. AND DAY SCHOOL

CONTENTS-

• HISTORY

• FLIGHT

• PROPULSION, CONTROL AND GUIDANCE

• MISSILE TYPES

• INTERCONTINENTAL BALLISTIC MISSILES

• FLIGHT PHASES

• MODERN ICBMs

• REFERENCES

Ballistic missile
A ballistic missile is a missile that follows a sub-orbital ballistic flight path with the objective of delivering one or more warheads to a predetermined target. To date, ballistic missiles have been propelled during powered flight by chemical rocket engines of various types.

History

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Diagram of V-2, the first ballistic missile.

The first ballistic missile was the A-4, commonly known as the V-2 rocket, developed by Nazi Germany in the 1930s and 1940s under direction of Wernher von Braun. The first successful launch of a V-2 was on October 3, 1942 and began operation on September 6, 1944 against Paris, followed by an attack on London two days later. By the end of World War II, May 1945, over 3,000 V-2s had been launched.

A total of 30 nations have deployed operational ballistic missiles. Development continues, with around 100 ballistic missile flight tests (not including those of the US) in 2007, mostly by China, Iran and the Russian Federation. In 2010 the US and Russian governments signed a treaty to reduce their inventory of intercontinental ballistic missiles (ICBMs) over a seven-year period (to 2017) to 1550 units each

Flight

A ballistic missile trajectory consists of three parts: the powered flight portion, the free-flight portion which constitutes most of the flight time, and the re-entry phase where the Ballistic missiles can be launched from fixed sites or mobile launchers, including vehicles (transporter erector launchers, TELs), aircraft, ships and submarines. The powered flight portion can last from a few tens of seconds to several minutes and can consist of multiple rocket stages.

When in space and no more thrust is provided, the missile enters free-flight. In order to cover large distances, ballistic missiles are usually launched into a high sub-orbital spaceflight; for intercontinental missiles the highest altitude (apogee) reached during free-flight is about 1200 km.

The re-entry stage begins at an altitude where atmospheric drag plays a significant part in missile trajectory, and lasts until missile impact.

Missile re-enters the Earth's atmosphere.

Propulsion, control, and guidance

Although missiles can be propelled by either liquid-fueled or solid-fueled rocket engines, solid fuel is preferred for military uses because it is less likely to explode and can be kept ready-loaded for quick launch. Such engines commonly propel tactical guided missiles—i.e., missiles intended for use within the immediate battle area—toward their targets at twice the speed of sound. Strategic missiles (weapons designed to strike targets far beyond the battle area) are either of the cruise or ballistic type. Cruise missiles are jet-propelled at subsonic speeds throughout their flights, while ballistic missiles are rocket-powered only in the initial (boost) phase of flight, after which they follow an arcing trajectory to the target. As gravity pulls the ballistic warhead back to Earth, speeds of several times the speed of sound are reached.

Almost all missiles are steadied in flight by stabilizing fins. In addition, guided missiles contain control systems to adjust their flight paths. The simplest control systems are aerodynamic, making use of movable vanes or flaps that alter the flow of air past the stabilizing fins. A more complicated system—used especially in ballistic missiles, which often travel beyond the Earth’s atmosphere—is thrust vectoring. In this system the stream of gases from the rocket engine is deflected by placing vanes within the exhaust nozzle or by swiveling the entire engine.

The guidance system is the most important and sophisticated part of the missile. In tactical missiles, electronic sensors locate the target by detecting energy emitted or reflected from it. For example, heat-seeking missiles carry infrared sensors that allow them to “home” onto the hot exhaust of jet engines. Anti radiation missiles home onto radar emissions, while one type of optically homing missile may “lock” onto an image of the target that is captured by a television camera. Upon receiving information through its sensor, the guidance system relays instructions for course correction to the control mechanism through some type of autopilot contained within the missile or through commands transmitted from the launch platform.

Ballistic missiles contain some type of inertial guidance system, which compares the missile’s actual speed and position to the positions that it must assume in order to hit the target. The guidance system then generates correcting commands to the control system. Inertial guidance has become so accurate that the United States’ MX Peacekeeper ballistic missile, with a range of more than 6,000 miles (more than 9,650 km), has a 50-percent chance of delivering its 10 nuclear warheads within 400 feet (120 m) of their target

Missile types

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Trident II SLBM launched by ballistic missile submarine.

Ballistic missiles can vary widely in range and use, and are often divided into categories based on range. Various schemes are used by different countries to categorize the ranges of ballistic missiles:

• Tactical ballistic missile: Range between about 150 km and 300 km • Battlefield range ballistic missile (BRBM): Range less than 100 km • Theatre ballistic missile (TBM): Range between 300 km and 3,500 km • Short-range ballistic missile (SRBM): Range 1,000 km or less • Medium-range ballistic missile (MRBM): Range between 1,000 km and 3,500 km • Intermediate-range ballistic missile (IRBM) or long-range ballistic missile (LRBM): Range between 3,500 km and 5,500 km • Intercontinental ballistic missile (ICBM): Range greater than 5500 km • Submarine-launched ballistic missile (SLBM): Launched from ballistic missile submarines (SSBNs), all current designs have intercontinental range.
Short- and medium-range missiles are often collectively referred to as theater or tactical ballistic missiles (TBMs). Long and medium-range ballistic missiles are generally designed to deliver nuclear weapons because their payload is too limited for conventional explosives to be cost-effective (though the U.S. is evaluating the idea of a conventionally-armed ICBM for near-instant global air strike capability despite the high costs).

The flight phases are like those for ICBMs, except with no exo atmospheric phase for missiles with ranges less than about 350 km.

Intercontinental ballistic missile
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A Minuteman III ICBM test launch from Vandenberg Air Force Base, California, United States

An intercontinental ballistic missile (ICBM) is a ballistic missile with a range of more than 5,500 kilometers (3,400 mi) typically designed for nuclear weapons delivery (delivering one or more nuclear warheads). Most modern designs support multiple independently targetable reentry vehicles (MIRVs), allowing a single missile to carry several warheads, each of which can strike a different target.

Early ICBMs had limited accuracy that allowed them to be used only against the largest targets such as cities. They were seen as a "safe" basing option, one that would keep the deterrent force close to home where it would be difficult to attack. Attacks against military targets, if desired, still demanded the use of a manned bomber. Second and third generation designs dramatically improved accuracy to the point where even the smallest point targets can be successfully attacked. Similar evolution in size has allowed similar missiles to be placed on submarines, where they are known as submarine launched ballistic missiles, or SLBMs. Submarines are an even safer basing option than land-based missiles, able to move about the ocean at will. This evolution in capability has pushed the manned bomber from the front-line deterrent forces, and land-based ICBMs have similarly given way largely to SLBMs.

ICBMs are differentiated by having greater range and speed than other ballistic missiles: intermediate-range ballistic missiles (IRBMs),medium-range ballistic missiles (MRBMs), short-range ballistic missiles (SRBMs)—these shorter range ballistic missiles are known collectively as theatre ballistic missiles. There is no single, standardized definition of what ranges would be categorized as intercontinental, intermediate, medium, or short. Additionally, ICBMs are generally considered to be nuclear only; although several conceptual designs of conventionally armed missiles have been considered, the launch of such a weapon would be such a threat that it would demand a nuclear response, eliminating any military value of such a weapon.

Flight phases

The following flight phases can be distinguished:

• boost phase: 3 to 5 minutes (shorter for a solid rocket than for a liquid-propellant rocket); altitude at the end of this phase is typically 150 to 400 km (93 to 250 mi) depending on the trajectory chosen, typical burnout speed is 7 km/s (4.3 mi/s), up to the speed of Low Earth Orbit. • midcourse phase: approx. 25 minutes—sub-orbital spaceflight in an elliptic flight path; the flight path is part of an ellipse with a vertical major axis; the apogee (halfway through the midcourse phase) is at an altitude of approximately 1,200 km (750 mi); the semi-major axis is between 3,186 and 6,372 km (1,980 and 3,959 mi); the projection of the flight path on the Earth's surface is close to a great circle, slightly displaced due to earth rotation during the time of flight; the missile may release several independent warheads, and penetration aids such as metallic-coated balloons, aluminum chaff, and full-scale warhead decoys. • Re entry phase (starting at an altitude of 100 km (62 mi)): 2 minutes – impact is at a speed of up to 4 km/s (2.5 mi/s) (for early ICBMs less than 1 km/s (0.62 mi/s)); see also maneuverable reentry vehicle.

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Modern ICBMs
Modern ICBMs typically carry multiple independently targetable reentry vehicles (MIRVs), each of which carries a separate nuclear warhead, allowing a single missile to hit multiple targets. MIRV was an outgrowth of the rapidly shrinking size and weight of modern warheads and the Strategic Arms Limitation Treaties which imposed limitations on the number of launch vehicles (SALT I and SALT II). It has also proved to be an "easy answer" to proposed deployments of ABM systems—it is far less expensive to add more warheads to an existing missile system than to build an ABM system capable of shooting down the additional warheads; hence, most ABM system proposals have been judged to be impractical. The first operational ABM systems were deployed in the U.S. during 1970s. Safeguard ABM facility was located in North Dakota and was operational from 1975–1976. The USSR deployed its Galosh ABM system around Moscow in the 1970s, which remains in service. Israel deployed a national ABM system based on the Arrow missile in 1998, but it is mainly designed to intercept shorter-ranged theater ballistic missiles, not ICBMs. The U.S. Alaska-based National missile defense system attained initial operational capability in 2004.

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External and cross sectional views of a Trident II D5 nuclear missile system. It is a submarine launched missile capable of carrying multiple nuclear warheads up to 8,000 km (5,000 mi). Trident missiles are carried by fourteen active US Navy Ohio-class and four Royal Navy Vanguard-class submarines.

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ICBMs can be deployed from TELs such as the Russian Topol.

ICBMs can be deployed from multiple platforms:

• in missile silos, which offer some protection from military attack (including, the designers hope, some protection from a nuclear first strike) • on submarines: submarine-launched ballistic missiles (SLBMs); most or all SLBMs have the long range of ICBMs (as opposed to IRBMs) • on heavy trucks; this applies to one version of the RT-2UTTH Topol M which may be deployed from a self-propelled mobile launcher, capable of moving through road less terrain, and launching a missile from any point along its route • mobile launchers on rails; this applies, for example, to РТ-23УТТХ "Молодец" (RT-23UTTH "Molodets"—SS-24 "Sсаlреl")
The last three kinds are mobile and therefore hard to find.

During storage, one of the most important features of the missile is its serviceability. One of the key features of the first computer-controlled ICBM, the Minuteman missile, was that it could quickly and easily use its computer to test itself.

In flight, a booster pushes the warhead and then falls away. Most modern boosters are solid-fueled rocket motors, which can be stored easily for long periods of time. Early missiles used liquid-fueled rocket motors. Many liquid-fueled ICBMs could not be kept fuelled all the time as the cryogenic liquid oxygen boiled off and caused ice formation, and therefore fueling the rocket was necessary before launch. This procedure was a source of significant operational delay, and might allow the missiles to be destroyed by enemy counterparts before they could be used. To resolve this problem the British invented the missile silo that protected the missile from a first strike and also hid fuelling operations underground.

Once the booster falls away, the warhead continues on an unpowered ballistic trajectory, much like an artillery shell or cannon ball. The warhead is encased in a cone-shaped reentry vehicle and is difficult to detect in this phase of flight as there is no rocket exhaust or other emissions to mark its position to defenders. The high speeds of the warheads make them difficult to intercept and allow for little warning striking targets many thousands of kilometers away from the launch site (and due to the possible locations of the submarines: anywhere in the world) within approximately 30 minutes.

Many authorities say that missiles also release aluminized balloons, electronic noisemakers, and other items intended to confuse interception devices and radars.

As the nuclear warhead reenters the Earth's atmosphere its high speed causes compression of the air, leading to a dramatic rise in temperature which would destroy it if it were not shielded in some way. As a result, warhead components are contained within an aluminum honeycomb substructure, sheathed in pyrolytic graphite-epoxy resin composite, with a heat-shield layer on top which is constructed out of 3-Dimensional Quartz Phenolic.

Accuracy is crucial, because doubling the accuracy decreases the needed warhead energy by a factor of four. Accuracy is limited by the accuracy of the navigation system and the available geophysical information.

Strategic missile systems are thought to use custom integrated circuits designed to calculate navigational differential equations thousands to millions of times per second in order to reduce navigational errors caused by calculation alone. These circuits are usually a network of binary addition circuits that continually recalculate the missile's position. The inputs to the navigation circuit are set by a general purpose computer according to a navigational input schedule loaded into the missile before launch.

One particular weapon developed by the Soviet Union (FOBS) had a partial orbital trajectory, and unlike most ICBMs its target could not be deduced from its orbital flight path. It was decommissioned in compliance with arms control agreements, which address the maximum range of ICBMs and prohibit orbital or fractional-orbital weapons.

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China. India is known to be working on a SLBM system called the K-4 although there is no hard evidence this will come into service in the near future.

References-

^ http://en.wikipedia.org/wiki/Ballistic_missile

^http://www.britannica.com/EBchecked/topic/385396/missile

^http:// world-military-army.blogspot.com

^http:// armyrecognition.com