CRUISE MISSILE TECHNOLOGY

A Seminar Report submitted in partial fulfilment

of the requirements for the degree of

Bachelor of Technology (Mechanical Engineering)

By

RAMAN

(110604)

Department of Mechanical Engineering

National Institute of Technology, Kurukshetra

January 2014

ACKNOWLEDGEMENT

I deemed it a great pleasure and opportunity to express my gratitude to some persons who

enabled me to complete the seminar. I am thankful to Professor Dinesh Khanduja,

Department of Mechanical Engineering, N.I.T KURUKSHETRA for providing Permission

and resources to conduct the seminar. I am thankful to all the faculty members in the

Department of Mechanical Engineering, N.I.T KURUKSHETRA for their constant support.

Last but not the least I am very much thankful to my parents who guided me in every step I

took.

RAMAN

ABSTRACT

The reason behind the study of cruise missile technology is to examine, that how the

proliferation of technology has remedied the shortcomings of artillery and to investigate the

extent and limitations of engaging a distant target. Intuitively a better and cheap technology

can be developed only when we have some basic and historical knowledge about it. The

second theme of study is that India must develop its defence manufacturing sector, which is

potential market for foreign players roughly accounting for 10% of all defence trade around

the world.

LIST OF ABBREVIATIONS

TERCOM Terrain Contour Matching DSMAC Digital Scene Mapping Area Co-relator

SATNAV Satellite Navigation

INDEX

Contents Page no

AKNOWLEDGEMENT

ABSTRACT

LIST OF ABBREVIATIONS

1 Introduction

2 Historical Development

3 General Design

4 Guidance Systems

5 Types of Guidance systems

5.1 Inertial navigation system

5.2 TERCOM (Terrain Contour Matching)

5.3 DSMAC (Digital Scene-Mapping Area Correlator)

6Advantages and Disadvantages of cruise missiles

7Satellite Navigation

8Advantages & Disadvantages

9Conclusion

References

1. Introduction

A cruise missile is basically a small, pilotless airplane. Cruise missiles have an 8.5-foot

(2.61-meter) wingspan, are powered by turbofan engines and can fly 500 to 1,000 miles (805

to 1,610 km) depending on the configuration. A cruise missile's job in life is to deliver a

1,000-pound (450-kg) high-explosive bomb to a precise location -- the target. The missile is

destroyed when the bomb explodes. Cruise missiles come in a number of variations and can

be launched from submarines, destroyers or aircraft.

Figure1: Tomahawk Cruise missile

Definition

An unmanned self-propelled guided vehicle that sustains flight through aerodynamic lift

for most of its flight path and whose primary mission is to place an ordnance or special

payload on a target. This definition can include unmanned air vehicles (UAVs) and unmanned

control-guided helicopters or aircraft.

2. History

In 1916, Lawrence Sperry patented and built an "aerial torpedo", a small biplane carrying

a TNT charge, a Sperry autopilot and a barometric altitude control. Inspired by these

experiments, the US Army developed a similar flying bomb called the Kettering Bug. In the

period between the World Wars the United Kingdom developed the Larynx (Long Range

Gun with Lynx Engine) which underwent a few flight tests in the 1920s. In the Soviet Union,

Sergey Korolev headed the GIRD-06 cruise missile project from 1932–1939, which used a

rocket-powered boost-glide design. The 06/III (RP-216) and 06/IV (RP-212) contained

gyroscopic guidance systems.

Germany first deployed cruise style missiles, during World War II. The V-1(Ref. fig. 2)

contained a gyroscopic guidance system and was propelled by a simple pulse-jet engine, the

sound of which gave it the nickname of "buzz bomb". Accuracy was sufficient only for use

against very large targets (the general area of a city). The V-1 and similar early weapons are

often referred to as flying bombs.

Immediately after the war the United States Air Force had 21 different guided missile

projects including would-be cruise missiles. All were cancelled by 1948 except four: the Air

Material Command BANSHEE, the SM-62 Snark, the SM-64 Navaho, and the MGM-1

Matador. The BANSHEE design was similar to Operation Aphrodite; like Aphrodite it failed,

and was canceled in April 1949.

During the Cold War period both the United States and the Soviet Union experimented

further with the concept, deploying early cruise missiles from land, submarines and aircraft.

The main outcome of the U.S. Navy submarine missile project was the SSM-N-8 Regulus

missile (Ref. fig. 3), based upon the V-1.

The U.S. Air Force's first operational surface-to-surface missile was the winged, mobile,

nuclear-capable MGM-1 Matador, also similar in concept to the V-1. Deployment overseas

began in 1954, first to West Germany and later to the Republic of China (Taiwan) and South

Korea. On November 7, 1956 U. S. Air Force Matador units in West Germany, whose

missiles were capable of striking targets in the Warsaw Pact, deployed from their fixed day-

to-day sites to unannounced dispersed launch locations. This alert was in response to the

crisis posed by the Soviet attack on Hungary which suppressed the 1956 Hungarian

Revolution.

Between 1957 and 1961 the United States followed an ambitious and well-funded

program to develop a nuclear-powered cruise missile, Project Pluto. It was designed to fly

below the enemy's radar at speeds above Mach 3 and carry a number of hydrogen bombs that

it would drop on its path over enemy territory. Although the concept was proven sound and

the 500 megawatt engine finished a successful test run in 1961, no airworthy device was ever

completed. The project was finally abandoned in favor of ICBM development.

While ballistic missiles were the preferred weapons for land targets, heavy nuclear and

conventional tipped cruise missiles were seen by the USSR as a primary weapon to destroy

U.S. naval carrier battle groups. Large submarines (for example, Echo and Oscar classes)

were developed to carry these weapons and shadow U.S. battle groups at sea, and large

bombers (for example, Backfire, Bear, and Blackjack models) were equipped with the

weapons in their air-launched cruise missile (ALCM) configuration.

Figure1: The German V1 rocket

Figure2: SSM-N-8 Regulus missile

3. General design

Cruise missiles generally consist of a guidance system, payload, and propulsion

system, housed in an airframe with small wings and empennage for flight control(Ref. fig. 4

& 5). Payloads usually consist of a conventional warhead or a nuclear warhead. Cruise

missiles tend to be propelled by a jet engine, turbofan engines being preferred due to their

greater efficiency at low altitude and sub-sonic speed.

Figure 3

Figure 4

4. Guidance systems

The purpose of a guidance subsystem is to direct the missile to target intercept

regardless of whether or not the target takes deliberate evasive action. The guidance

function may be based on information provided by a signal from the target, information

sent from the launching ship, or both. Every missile guidance system consists of two

separate systems-an attitude control system and a flight path control system. The attitude

control system maintains the missile in the desired attitude on the ordered flight path by

controlling it in pitch, roll, and yaw. This action, along with the thrust of the rocket

motor, keeps the missile in stabilized flight. The flight path control system guides the

missile to its designated target. This is done by determining the flight path errors,

generating the necessary orders needed to correct these errors, and sending these orders to

the missile's control subsystem. The control subsystem exercises control in such a way

that a suitable flight path is achieved and maintained. The operation of the guidance and

control subsystems is based on the closed-loop or servo principle. The control units make

corrective adjustments to the missile control surfaces when a guidance error is present.

The control units also adjust the wings or fins to stabilize the missile in roll, pitch, and

yaw. Guidance and stabilization are two separate processes, although they occur

simultaneously.

Guidance systems also vary greatly. Low-cost systems use a radar altimeter,

barometric altimeter and clock to navigate a digital strip map. More advanced systems use

inertial guidance, satellite navigation and terrain contour matching (TERCOM). Use of an

automatic target recognition (ATR) algorithm/device in the guidance system increases

accuracy of the missile. The Standoff Land Attack Missile features an ATR unit from

General Electric.

5Types of Guidance Systems

There are basically three types of Navigation systems, these are :

5.1Inertial navigation system

An inertial guidance system is one that is designed to fly a predetermined path. The missile is

controlled by self-contained automatic devices called accelerometers .Accelerometers are

inertial devices that measure accelerations. In missile control, they measure the vertical,

lateral, and longitudinal accelerations of the controlled missile (Ref. fig. 6) .Although there

may not be contact between the launching site and the missile after launch, the missile is able

to make corrections to its flight path with amazing precision. During flight, unpredictable

outside forces, such as wind, work on the missile, causing changes in speed commands.

These commands are transmitted to the missile by varying the characteristics of the missile

tracking or guidance beam, or by the use of a separate radio uplink transmitter. This data is

taken by onboard computers and converted onto precise position of the missile .Lately,

however, inertial systems have been combined with GPS (Global Positioning System) to

navigate missiles more accurately. However, even with the best inertial systems available,

missiles suffer from a phenomenon called drift. This is measured in distance (meters) per

hour. For example, during the making of the Tomahawk Cruise missiles it was determined

that even with the inertial navigation system, it would have a drift of 900 meters per hour.

This essentially means that if the missile flew for one hour, it could miss the target by as

much as 900 meters! Further, while ICBMs travel at sonic and supersonic speeds, smaller

Cruise’s speed was subsonic. So, the chances of missing the target are higher.

Figure5: Inertial navigation system

5.2. TERCOM (Terrain Contour Matching)

Terrain Contour Matching, or TERCOM, is a navigation system used primarily by

cruise missiles. It uses a pre-recorded contour map of the terrain that is compared to

measurements made during flight by an on-board radar altimeter. A TERCOM system

considerably increases the accuracy of a missile compared to inertial navigation systems

(INS). The increased accuracy allows a TERCOM-equipped missile to fly closer to obstacles

and generally lower altitudes, making it harder to detect by ground radar.

Figure 6

TERCOM navigation "maps" consist of a series of strips of land that the missile is

expected to fly over, encoded as a series of altitudes (Ref.fig8). Since a radar altimeter

measures distances, height over the ground, and not an absolute altitude, the maps generally

encode a series of changes in altitude, not the absolute altitude itself. Additionally, the strips

of land on either side of the expected path are also stored. A series of such maps are

produced, typically from data from radar mapping satellites. When flying over water, contour

maps are replaced by magnetic field maps.

The missile's radar altimeter feeds measurements into a smaller buffer, which

periodically "gates" the measurements over a period of time and averages them out to

produce a single measurement. The series of such numbers held in the buffer produce a strip

of measurements similar to those held in the maps. The two are compared to overlay the

buffer's strip on the known map, and the positioning of the strip within the map produces a

location and direction. The guidance system can then use this information to correct the flight

path of the missile.

During the flight to the target the accuracy of the system has to be high enough only

to avoid terrain features. This allows the maps to be relatively low resolution in these areas.

Only the portion of the map for the terminal approach has to be higher resolution, and would

normally be encoded at the highest resolutions available to the satellite mapping system.

TERCOM systems have the advantage of offering accuracy that is not based on the length

of the flight; an inertial system slowly drifts after a "fix", and its accuracy is lower for longer

distances. TERCOM systems receive constant fixes during the flight, and thus do not have

any drift. Their absolute accuracy, however, is based on the accuracy of the radar mapping

information, which is typically in the range of meters, and the ability of the processor to

compare the altimeter data to the map quickly enough as the resolution increases. This

generally limits first generation TERCOM systems to targets on the order of hundreds of

meters, limiting them to the use of nuclear warheads. Use of conventional warheads requires

further accuracy, which in turn demands additional terminal guidance systems.

One disadvantage of TERCOM systems is that the entire route has to be pre-planned,

including its launch point. If the missile is launched from an unexpected location or flies too

far off-course, it will never fly over the features included in the maps, and become lost. The

INS system can help in this regard, allowing it to fly to the general area of the first patch, but

gross errors simply cannot be corrected. This makes TERCOM based systems much less

flexible than more modern systems like GPS, which can be set to attack any location from

any location, and does not require any sort of pre-recorded information which means they can

be targeted immediately prior to launch.

5.3. DSMAC (Digital Scene-Mapping Area Correlator)

Figure 7

Early cruise missiles did not have the mapping satellites to draw information from,

and there were plans to use a TERCOM-like system based on photographs rather than

elevations. A series of photographs taken from surveillance aircraft were put into a carousel

in the missile, which were selected at timed intervals and imaged using a television camera(

Ref. fig 9). Another camera took pictures out of the bottom of the missile, imaged onto a

similar display. A computer compared the two displays and attempted to line up areas of high

contrast, similar to the contrast seekers used in the Maverick missile, and the offsets needed

to align the two images could be decoded into a location and heading. However, this system

proved to be very slow, and no such system was ever employed operationally, its role being

taken up by TERCOM.

The massive improvements in memory and processing power from the 1950s when these

scene comparison systems were first invented to the 1980s when TERCOM was widely

deployed changed the nature of the problem considerably. Modern systems can store

numerous images of a target as seen from different directions, and often the imagery can be

calculated using image synthesis techniques. Likewise, the complexity of the live imaging

systems has been greatly reduced through the introduction of solid-state technologies like

CCDs. The combination of these technologies produced the Digital Scene-Mapping Area

Correlator (DSMAC). DSMAC systems are often combined with TERCOM as a terminal

guidance system, allowing point attack with conventional warheads.

5.4. Satellite navigation

Another way to navigate a cruise missile is by using a satellite positioning system, such as

GPS (Ref. fig 10) . Satellite navigation systems are precise and cheap. Unfortunately, they

rely on satellites. If the satellites are interfered with (e.g. destroyed) or if the satellite signal is

interfered with (e.g. jammed), the satellite navigation system becomes inoperable. Therefore,

the GPS-based navigation is useful in a conflict with a technologically unsophisticated

adversary. On the other hand, to be ready for a conflict with a technologically advanced

adversary, one needs missiles equipped with TAINS and DSMAC.

Figure 8

6. Advantages and Disadvantages of cruise missiles

Advantages:

1. The big advantage of the cruise missile is its smallness and cost. The missile's small

size and weight of less than 3000 pounds enables an aircraft to carry a great number

of them: a projected 18 by a B-52 (in comparison with only two Hound Dogs) or as

many as 50 by a Boeing 747 or similar wide-bodied transport converted into a missile

carrier.

2. Its small size also improved the weapon’s chances of penetration, especially when

combined with its ability to fly along the contour of the earth, as low as 20 meters

above a level surface or within 100 meters of mountainous terrain, according to some

published reports.

3. The map matching system (TERCOM) is combined with an inertial navigational

system in a system called TAINS. This not only gets the cruise to its target but also

with an accuracy heretofore unheard of for an intercontinental weapon: less than 100

meters, an accuracy that brings the cruise missile full circle by making nonnuclear

warheads feasible.

Disadvantages :

1. The missiles aren't always accurate, they're expensive, and they're becoming scarce.

2. The lack of a human pilot means you can't re-use the thing, whereas you can get

multiple missions out of a piloted aircraft.

3. While they'e cheaper than ballistic missiles, they're more expensive than the gravity

bombs you'd drop from a manned aircraft.

4. Finally, their low and slow flight means they can be engaged by a much wider variety

of systems, including MANPADS and SAMs, with consequently less chance of

reaching target.

7. Conclusions

Currently cruise missiles are among the most expensive of single-use

weapons, up to several million dollars apiece. However, they are cheaper than human

pilots when total training and infrastructure costs are taken into account. cruise

missiles are much more difficult to detect and intercept than other aerial assets,

making them particularly suited to attacks against static air defense systems.

Guidance System used in cruise missile is a complex system which involves

several systems working in tandem. Development of missile involve huge

expenditures it is essential that guidance system is properly designed for accurate

interception of targets.

8. References

1. www.airpower.maxwell.af.mil/airchronicles

2. www.foreignaffairs.com/.../cruise-missiles-technology-strategy-politics

3. everything2.com/title/Cruise+Missile

4. www.ausairpower.net/DT-CM-Guidance

5. www.howstuffworks.com

6. www.aerospaceweb.org/.../ missiles

7. www.wa3key.com