This document provides an overview of stealth technology, including its history, types of signatures that stealth aims to reduce, and methods used. It discusses radar absorbent materials and structures, as well as techniques to decrease infrared, acoustic, visual and other signatures. Examples of stealth aircraft like the F-117 and ships are given. Advantages like reduced detection and disadvantages like high costs are outlined. India's developments of stealth helicopters and aircraft are summarized. The future potential of stealth, including South Korea's KF-X fighter, is also examined.

1. BY
MANISH KUMAR RAJPOOT
(EC-1)

2. CONTENT
 Introduction to Stealth Technology
 History of Stealth Technology
 What is Signature ?
 Types of Signature
 Adaptive Water Curtain Technology
 Advantages and Disadvantages
 India’s Step Towards Stealth
 Future Scope
 Conclusion
 Refrences

3. What Is Stealth Technology?
 Scientifically known as
low observatory.
 Used in Military
aviation.
 Reduces detection
range of an aircraft.
 Similar to camouflage
tactics used by soldiers.
 Partial invisibility to
radar and other
detection.
http://www.airforce-technology.com/projects/f117/images/nhawk11.jpg

4. History
 The first “STEALTH” aircraft have been developed in
Germany during the last years of WWII.
 Later Americans worked on stealth technology and
succeeded by developing U-2 and F-117A Stealth
aircraft.
 F-117A has the ability to evade enemy radar so , it
was given a nick name “NIGHTHAWK”.
 This technique has also been used in ships and
Americans developed a ship named “SEA SHADOW”
which was first unveiled on April 9 ,1993.

5. What is Signature ?
 Signature can be defined as any activity or
radiation or the characteristic of the body that
helps to revile its presence at a particular point.
 All the detection methods used that be in military
and civil systems are by detecting the signature of
the body.
 signature can be rightly called as observability of
an object and stealth vehicles can be called as low-
observable vehicles or low-signature vehicles.

6. Types of Signatures
 RADAR Cross Section (RCS)
 LIDAR (Light Detection And Ranging)
 Acoustic Signature
 Visible Signature
 Infrared Signature
 Plasma Stealth

7. Radar Cross Section
 Radar cross section is the measure of a target's
ability to reflect radar signals in the direction of
the radar receiver
 It is a measure of the ratio of backscatter power per
steradian (unit solid angle) in the direction of the
radar (from the target) to the power density that is
intercepted by the target.

8. Reduction of RCS
 RCS minimization techniques involves two
methods:
Radar Absorbent Material (RAM)
Radar Absorbent Structures (RAS)

9. Radar Absorbent Materials
 Radar-absorbing materials (RAMs) are used to
dissipate the energy of the radar wave so to prevent
the reception of a reflected signal by an antenna.
 The dissipation process converts the radio
frequency (RF) energy to a negligible quantity of
heat.
 Other ways of reducing RCS include passive
cancellation, incorporating an echo source which
by design cancels another echo source for a certain
frequency and angle, active cancellation etc.

10. Types of RAM’s
 IRON BALL PAINT
 FOAM ABSORBER
 JAUMANN ABSORBER

11. Limitations of RAM
 Absorbs only a portion of the incident radiation.
 Effective only at certain frequencies and angle of
incidence.
 Thickness and weight increases with effectiveness
of RAM.
 Sensitive to adverse weather (rain)

12. Radar Absorbent Structures
 RAS uses the most efficient way to reflect radar waves
back to the transmitting radar is with orthogonal
metal plates, forming a corner reflector consisting of
either a dihedral or a trihedral.

13. RAS (continued)
 Behind the skin of some aircraft are structures
known as re-entrant triangles. Radar waves
penetrating the skin of the aircraft get trapped in
these structures, bouncing off the internal faces
and losing energy.
 Stealth aircraft such as the F-117 use a different
arrangement, tilting the tail surfaces to reduce
corner reflections formed between them.

14. LIDAR
 Laser radar can detect stealth targets effectively
because it has short wavelength, high beam
quality, strong directionality, high measuring
accuracy and it has functions of target identifying,
posture displaying and orbit recording.
 Target and background optical properties on
different wavelengths and atmospheric effects of
different wavelength need to be considered in lidar
detection.

15. Image captured using LIDAR

16. Acoustics Signature
 Acoustics means Sound and Acoustic signature is
used to describe a combination of acoustic
emissions of ships and submarines. Although
Acoustic Signature are found in for land and ariel
units acoustic signature turns out to be the key
method of detection for Naval field rather than the
other two.
 It includes SONAR( SOund Navigation And
Ranging) Detectors.

17. SONAR Detectors
 Sonar detectors are simply devices that detect the
presence of Sonar beams.
 They can be classified as :
 Passive: In this operator listens to sounds emitted by
the object one is trying to locate.
 Active: Active sonar creates a pulse of sound, often
called a "ping", and then listens for reflections of the
pulse.

18. SONAR Stealth
 Its aim is to reduce sound from a Submarine or
Ship thus remain undetected.
 There are many ways of reducing Acoustic
Signature like reduction of vibration of the
Submarine, reduce sounds due to cavitations etc.

19. Bathythermograph
 A thermo cline is a layer of water where the
temperature gradient is greater than that of the
warmer layer above and the colder layer below.
 When the temperature gradient is greater, a sound
wave rapidly bends towards the sea bottom. The sound
wave goes to the sea bottom and "stay there". The
sound wave is useless.

20. Towed vs Hull Mounted SONAR
Towed SONAR Hull Mounted SONAR

21. Visual Signature
 Low visibility is desirable for all military
applications.
 Earlier stealth aircraft were painted black and thus
could be used during nights.
 Now days an electro chromic polymer is being
developed for daytime stealth.
 These polymer sheets sense nature of the
surrounding and change there color accordingly.

22. Aircraft Camouflage

23. Infrared Signature
 Infra-red radiation are emitted by all matter above
absolute temperature zero.
 Hot zones such as engine exhaust , wing surface
[friction due to air ] get heated which rather
increases the visibility.
 These part should be kept cool as possible it can
be.
 Option would be mixing of cool air with the hot
engine exhaust .

24. Infra-red Stealth

25. Plasma Stealth
 Aircraft using Plasma Stealth Inject Stream of
Plasma(Ionized gas).
Plasma is generated by “Plasmatron”.
 Plasma Covers entire body of aircraft.
 Absorbs most electromagnetic energy of radar.
 First developed by Russians.

26. Plasma ejecting Aircraft

27. Adaptive Water Curtain
Technology
 The Adaptive Water Curtain Technology (AWCT)
is intended to deflect and scatter enemy radar
waves thus reducing the ship's radar cross section
(RCS).
 It consists of (highly conductive) sea water sprayed
in a fashion that effectively creates an angled radar
reflective curtain around the ship.

28. Ship using AWCT

29. Advantages of Stealth
Reduces the causality rates during war.
Saving military budget.
Develop the military secretes.
Bluff the anti-detective device.
Stealth aircraft are invisible to radar.
We can perform the Spy Missions.
Can be used in civil aviation.

30. Disadvantages of Stealth
.
 High cost-B2 Bomber 2 billion USD
-F117-A 70 million USD
-F22 100 million USD

31. India’s Step towards Stealth
 HAL LIGHT COMBAT HELICOPTER (LCH)

32. General characteristics
• Crew: 2
• Length: 15.8 m
• Rotor diameter: 13.3 m
• Height: 4.7 m
• Disc area: 138.9 m²
• Max. take off weight: 5,800 kg
• Power plant : 2 × HAL/Turbo meca Shakti
turbo shaft, 1,067 kw each
performance HAL Light Combat Helicopter
• Never exceed speed: 330 km/h (178 knots,
207 mph)
• Maximum speed: 268 km/h (145 knots,
167 mph)
• Range: 700 km (297 nmi, 342 mi)
• Service ceiling: 6,500 m (21,300 ft)

33. DRDO AURA (Autonomous Unmanned Research
Aircraft)
Role -Unmanned Stealth Bomber
Manufacturer- DRDO
Designer- DRDO
First flight- 2015
Introduction -2019-2020
Status -Under Development
Primary user-Indian Air Force
Indian Navy
Number built -0
Program cost -tbd
Unit cost -tbd

34. Future Scope of Stealth Technology
 The main objective is to design an aircraft that can
penetrate and reflect the radar waves very well.
 From the research, South Korea has come out with
a new design of stealth aircraft called stealthy
next-gen fighter.
 The KF-X is a twin-engine stealth fighter with a
design goal of achieving maneuverability, speed
and range performance between a Lockheed
Martin F-16 and a Boeing F-15.

35. Conclusion
 Stealth technology developed a lot.
 Investment needed is very high.
 High chance of low cost gain.
 A lot learned about signature reduction and
absorption.
 Success yet to be proved extensively.
 Useful for other projects.
 Its an arm race except it isn’t between specific
countries .

36. Refrences
 http://www.totalairdominance.50megs.com/articles/stealt
h.htm
 http://en.wikipedia.org/wiki/Stealth_technology
 http://en.wikipedia.org/wiki/Radar
 http://en.wikipedia.org/wiki/Stealth_ship
 http://www.resonancepub.com/images/stealth_ship.gif
 http://images.google.co.in/images
 http://science.howstuffworks.com/question69.htm
 http://www.espionageinfo.com/Sp-Te/Stealth-
Technology.html
 http://www.airplanedesign.info/51.htm

37. THANK YOU