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ASeminar Report

On

In partial fulfillment of requirements for the degree ofBachelor of Technology

InElectrical Engineering

Under the guidance of: Submitted By:

Mr. Sanjay Rawat Abhishek Singh

Assistant Lecturer 0913220007 [3rd yr]

DEPARTMENT OF ELECTRICAL ENGINEERING

GREATER NOIDA INSTITUTE OF TECHNOLOGYGr. Noida – 201306

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CONTENTS

S.No. Details Page No.

1. Certificate 3.2. Acknowledgement 4.3. Abstract 5.4. Introduction 6.5. How does stealth technology works? 8.

5.1 RAS 9. 5.2 RAM 10.

6. Characteristics of stealth technology 11.7. Methods to avoid detection 12.

7.1 Stealthy Shapes 13. 7.2 AWCT 14. 7.3 Radar Absorbing Material 15.

8. Detection methods 16.9. Advantages 17.

10. Disadvantages 18.11. Future of Stealth Technology 19.12. Bibliography 20.

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CERTIFICATE

ELECTRICAL ENGINEERING DEPARTMENTGNIT, UPTU UNIVERSITY

TO WHOMSOEVER IT MAY CONCERN

This is to certify that Mr. Abhishek Singh, student B.Tech pre-final year, of Electrical Engineering Department at this institute, has successfully delivered a seminar on the topic “STEALTH TECHNOLOGY” under the guidance of Er. Sanjay Rawat, Department of Electrical Engineering.

I appreciate his hard work & wish him success in his future endeavour.

Er. Sanjay RawatSeminar in charge/ lecturerElectrical Engineering Department

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GNIT, Gr. Noida

ACKNOWLEDGEMENT

It is matter of great pleasure for me to submit this seminar report on STEATH TECHNOLOGY, as a part of curriculum for award of Bachelor in Technology (Electrical Engineering) degree of Greater Noida Institute of Technology, Gr. Noida.

I am thankful to my seminar guide Mr. Sanjay Rawat, Assistant Lecturer in Electrical Engg. Department for his constant encouragement and able guidance.

I take this opportunity to express my deep sense of gratitude towards those, who have helped me in various ways, for preparing my seminar.

At the last but not least, I am thankful to my parents, who had encouraged & inspired me with their blessings.

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ABHISHEK SINGH

ABSTRACTStealth aircraft are aircraft that use stealth technology to make it harder to be detected by radar and other means than conventional aircraft by employing a combination of features to reduce visibility in the visual, audio, infrared and radio frequency (RF) spectrum. Well known examples include the United States' F-117 Nighthawk (1980s-2008), the B-2 Spirit "Stealth Bomber," and the F-22 Raptor. While no aircraft is totally invisible to radar, stealth aircraft limit current conventional radar's abilities to detect or track them effectively enough to prevent an attack. Stealth is accomplished by using a complex design philosophy to reduce the ability of an opponent's sensors to detect, track and attack an aircraft. Modern stealth aircraft first became possible when a mathematician working for Lockheed Aircraft during the 1970s adopted a mathematical model developed by Petr Ufimtsev, a Russian scientist, to develop a computer program called Echo 1. Echo made it possible to predict the radar signature an aircraft made with flat panels, called facets. In 1975, engineers at Lockheed Skunk Works found that an airplane made with faceted surfaces could have a very low radar signature because the surfaces would radiate almost all of the radar energy away from the receiver.

The first combat use of stealth aircraft was in December 1989 during Operation Just Cause in Panama. On December 20, 1989 two USAF F-117s bombed a Panamanian defence Force Barracks in Rio Hato, Panama.

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INTRODUCTION“Stealth”, a buzzword common in defence circles since the early 80s, only became a mainstream reference in the nineties, after the second Persian Gulf War in 1991.Night-enhanced images of the otherworldly-shapedF-117s taking off in the night and striking high-value targets with scarcely believable precision and seeming invulnerability to thick air defences were widely televised and etched in the memories of TV viewers worldwide. The subsequent exposure of stealth aircraft and their participation in numerous air operations in the 90s, in combination with the loss of at least one F-117 in Kosovo, has peeled off some of the mythical cloak surrounding stealth. However, a lot of misconceptions about the abilities and limitations of this technology still remain, even amongst people in posts of high professional responsibility. It is therefore useful to take a broad look at how stealth works, what it can and what it cannot do. This article will examine strictly the application of stealth in air assets. Different technologies and strategies for stealth are the province of land, naval and underwater forces. First of all, although it is common to discuss the principles of stealth technology (also referred to as VLO or Very Low Observables technology) only as relevant to a narrow band of the electromagnetic spectrum (radar emissions), stealth as a design practice applies a wide range of signatures. Ben Rich, the leader of the Lockheed team that designed the F-117, has stated: "A stealth aircraft has to be stealthy in six disciplines: radar, infrared,visual, acoustic, smoke and contrail. If you don't do that, you flunk the course." That said, not all

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disciplines are equally important when discussing any given platform category. Underwater warfare will naturally hand dominance to the acoustic spectrum (though onacoustic sensors can and do exist). Land combat will emphasize visual, infra-red and acoustic signatures. Radar and (to a lesser extent) infrared bands dominate the scene of airspace surveillance, and so they have to be given higher priority when thinking the applications in air warfare. Before discussing the various techniques of reducing the radar and infrared signature, it is useful to understand the principles of radar reflectivity and how they can be exploited when one starts thinking about aiming for stealth in earnest.

How Does STEALTH TECHNOLOGY works?

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The concept behind the stealth technology is very simple. As a matter of fact it is totally the principle of reflection and absorption that makes aircrafts “stealthy”. Deflecting the incoming radar waves into another direction and thus reducing the number of waves does this, which returns ti the radar. Another concept that is followed is to absorb the incoming radar waves totally and to redirect the absorbed electromagnetic energy in another direction. What ever may be the method used, the level of stealth an aircraft can achieve depends totally on the design and the and the substance with which it is made of.

RASRAS or Radar Absorbent surfaces are the surfaces on the aircraft, which can deflect the incoming radar waves and reduce the detection range. RAS works due to the angles at which the structures on the aircraft’s fuselage or the fuselage itself are placed. These structures can be anything from wings to a refueling boom on the aircraft. The extensive use of RAS is clearly visible in the F-117 “Night Hawk”. Due to the facts (as they are called) on the fuselage, most of the incoming

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radar waves are reflected to another direction. Due to these factes on the fuselage, the F-117 is a very unstable aircraft.

The concept behind the RAS is that of reflecting a light beam from a torch with a mirror. The angle at which the reflection takes place is also more important. When we consider a mirror being rotated from 0o to 90o, the amount of light that is reflected in the direction of the light beam is more. At 90o, maximum amount of light that is reflected back to same direction as the light beam’s source. On the other hand when the mirror is tilted above 90o and as it proceeds to 180o, the amount of light reflected in the same direction decreases drastically. This makes the aircraft like F-117 stealthy.

RAMRadar absorbent surfaces absorb the incoming radar waves rather than deflecting it in another direction. RAS totally depends on the material with which the surface of the aircraft is made. Though the composition of this material is a top secret. The F-117 extensively uses RAM to reduce its radar signature or its radar cross section.

The RAS is believed to be silicon based inorganic compound. This is assumed by the information that the RAM coating on the B-2 is not waterproof. This is just a supposition and may not be true. What we know is that the RAM coating over B-2 is placed like a wrapping a cloth over the plane. When radar

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sends a beam in the direction of the B-2, the radar waves are absorbed by the plane’s surface and is redirected to another direction after it is absorbed. This reduces the radar signature of the aircraft. This can be done by:

By using media with appropriate refractive index.

By using suitable optical material.

CHARACTERISTICS OF STEALTH TECHNOLOGY

The object can be shaped so that any radar signals coming to it are reflected away from the object.

The object can be covered in materials that absorb radar signals.

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METHODS TO AVOID DETECTION

There are some methods by which planes can avoid detection. These methods do not need any hi-tech equipment to avoid detection. Some of the have been used for years together to avoid detection. Some of the most common ways are listed below:

Use of Stealthy Shapes Use of AWCT (Adoptive water curtain technology) Use of Radar absorbing material

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Stealthy Shape:

When we are using normal Shape

While we use Stealth Technology

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AWCT (Adoptive water curtain technology)

This technology is a part of stealth which is used in the ships for making low observable. The water curtain around the ship flowing out of water jets either absorb or re-direct the radr waves in some other direction.

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Radar absorbing material

1. Nanostructural composite material, absorbing without reflection radar wave.

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2. These materials are based on Nanotechnology.

DETECTION METHODS Whenever a technology is delivered for military purpose, another technology is also developed to counter that technology. There are strong efforts to develop a system that can counter the low observability of the fifth generation stealth aircraft. There are ways of detection and elimination of a low observable aircraft but this doesn’t give a 100% success rage at present.

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A proven method to detect and destroy stealth aircraft is to triangulate its location with a network of radar systems. This was done while the F-117 was shot down during the NATO offensive over Yugoslavia.

A new method of detecting low observable aircraft is just over the horizon. Scientists have found a method to detect stealth aircraft with the help of microwaves similar to the ones emitted by the cell phone towers. Nothing much is known about this technology, but the US military seems to be very keen about doing more research on this.

Advantages

• Reduce the causality rate during the war.• Saving military budget.• Develop the military secrets.

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• Bluff the anti-detective device.

DISADVANTAGES

• Instability of design• Electromagnetic emission• Cost of maintenance• Sensitive skin• Cost of operations

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FUTURE OF STEALTH TECHNOLOGY

Stealth technology is clearly the future of air combat. In the future, as air defence systems grow more accurate and deadly, stealth technology can be a factor for a decisive by a country over the other. In the future, stealth technology will not only be incorporated in fighters and bombers but also in ships, helicopters, tanks and transport planes. These are evident from the RAH-66 “Comanche” and the sea shadow stealth ship. Ever since the Wright Brothers flew the first powered flight, the advancements in this particular field of technology has seen staggering heights. Stealth technology is just one of the advancements that we have seen. In due course of time we can see many improvements in the field of military aviation which would one-day even make stealth technology obsolete.

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BIBLIOGRAPHY

Wikipedia – http://en.wikipedia.org/wiki/Stealthtecnology

HowStuffWorks-http://defence.howstuffworks.com/stealth.htm

Images from http://images.Google.co.in

www.totalairdominance.50megs. com /articles/ stealth .htm