STEALTH AIRCRAFT TECHNOLOGY

USAMAH ABD LATIF 1118597

HABIBAH HANIM MOHMED @ SALLEH1118968

NIK MUHAMMAD SYAFIQ NIK MAT DAUD1119409

ADVISOR : DR SANY IZAN IHSAN

COORDINATOR : DR ASIF HODA

What is Stealth Aircraft?• Stealth aircraft are designed to avoid detection

using a variety of advanced technologies that reduce reflection/emission of radar, infrared,[1] visible light, radio-frequency (RF) spectrum, and audio, collectively known as stealth technology.

• While no aircraft is totally invisible to radar, stealth aircraft make it difficult for conventional radar to detect or track the aircraft effectively, increasing the odds of a successful attack.

Main Discussion

•What is radar system and how it works?• Various design of stealth aircraft and its effect.• Improvement in future stealth aircraft.

What is radar system?

•Radar system is a system that help pilot in navigating while fly in space• It uses a continuous wave and frequency to keep in touch with• This system is widely used around the world

How it works?

• There are 2 main components for this system to work• There are sender and receiver that have been installed on ground and aircraft as well•By radar system we could know how far the object is and it velocity

System mechanism

Sender (on

ground/aircraft)

Hit aircraft body /

antennas on ground

Receiver (on ground/ aircraft)

It sends out radar probe( Frequency

Modulated Continuos Wave)

Bounce back to antennas on

ground / aircraft

1. Information received is fed in into computer system

2. Signal processing system converts analog information to digital format

3. Then performs Fast Fourier Transformation on data

4. It calculate the position& velocity of the nearby object or aircraft

 

How stealth technology avoid radar detection?

Aircraft design

• Two major factors:

Materials been used

Aircraft design

Sharp edge and flat surface

Engine

Makes wave not be able to bounce back

efficiently

Extreme aerodynamics :- Minimize air turbulence- cut down flying noise

Hot fumes is mixed with cool air before

leaving aircraft

Uses a low noise engine

Radar absorbing materials -RAM

Radar absorbing structures- RAS

Materials used

in designi

ng stealth aircraft

“wesch”

• Has been used by German in WW II• it comprises rubber substrate loaded with iron

carbonyl powder• The powder dissipate radar energy into

substrate materials

Halpern anti-radiation paint

• Used by US, it carries within rubber matrix aluminum fakes & carbon black particles

Salisbury screen

• It is a sheet of resistive material overlays a conductive backplane

• Separated by dielectric materials( quarter of subject’s radar wavelength in thick)

• Incident radar waves penetrate outer layer, then reflected from inner and backplane layer

• For internal reflection, waves that 180° shifted meets other waves and cancel out each other

RAS

• Low weigh RAS can be made from glass & carbon fibre composites lattice which voids are occupied by microwave absorbent foam• This absorption effectiveness is related to volume fraction of grid cell structure & distance between elements

•Carbon composites can be used to absorb radio/radar frequency• It can metallize fabrics & conductive polymer

Goal of Stealth Technology

O To make aircraft invisible by reducing radar, IR, visual, and acoustic signature.

Principle of Stealth Technology

Infrared detection.Visual detection.Acoustic detection.Radar detection. Reduction in these detection is the

principle of stealth technology.

O Method to decrease the IR signature of the engines is to use exhaust masking.

O This is accomplished by placing the engines on top of the body and the wings, by which exhausts cannot be seen from below.

Infra-red stealthO Infra-red radiation are emitted by all

matter above absolute temperature zeroO Hot zones such as engine exhaust , wing

surface [ friction due to air ] get heated which rather increases the visibility

O These part should be kept cool as possible it can be ,

O Option would be mixing of cool air with the hot engine exhaust

Infra-red stealth

Reduction of Infrared Emission

O IF emission is occur due to heat.O All substances with a temperature above

absolute zero (0° K, or -273.15° C, or - 459.67° F), emit electromagnetic waves. The heat content of a material produces molecular vibrations which cause electron oscillations. These oscillations provide electromagnetic coupling that produces an emission of energy.

Visual stealth

O Low visibility is desirable for all military applications

O Earlier stealth aircraft were painted black and thus could be used during nights

O Now days an electro chromic polymer is being developed for daytime stealth

O These polymer sheets sense nature of the surrounding and change there color accordingly

Visual stealth

Reduction in Acoustic Detection

O In this we reduce mechanical noise.O For reduction of mechanical noise we use

different muffler, slow turning propeller.O Acoustic cells involves the sound waves to

detect the targetO Knowing the fact that’s sound waves

moves too slowly as compared to radio wave so it functionality should be directed towards low altitude flying aircraft.

Reduction in Radar Detection

Radar mainly work on electromagnetic wave reflection.

If we avoid these reflection towards the radar receiver than we can reduce radar cross section of object.

Radar cross section (RCS) is a measure of how detectable a object is with a radar.

RCS Reduction Technique(Reduction in Radar Detection)

Purpose shaping : The shape of the target’s reflecting surfaces is

designed such that they reflect energy away from the source.

Radar absorbent material : As an addition to highly reflective surfaces.

Active Cancellation : Target generates a radar signal equal in

intensity but opposite in phase to the predicted reflection of an incident radar signal

SHAPE DESIGN

O Conventional aircraft

- Use round shape cone as it support principle of aerodynamics.

O Stealth aircraft

- Made up of flat surface and very sharp edges

Radar signal heating the stealth plane are scattered in all directions by this.

ShapingO Normal design O Curved design

F117 A NIGHTHAWK

Radar Absorbing MaterialO RAM material absorb EM wave and convert this

energy into heat.O Metallic surfaces generally reflect the radar

signals.O There stealth aircraft should be coated with

radar absorbent materials.O Which deflect , absorbed incoming radar

waves and reduce the detection range.O Radar absorbent layer is present below the

surface coating of aircraft using corner reflector.

Active CancellationO In this method we have some RF

source on object(plane, ship) which modify radar signal but in opposite phase that generate destructive interference.

- Thus by the use of these three method we can reduce RCS of our plane and can make them low observable.

Deceiving of EyeO In this method we make the object

visually invisible. O In this we use different color and

different lightning system, by which system generate illusion.

B-2 Bomber

F-22 Raptor

Improvement in Design of Future Stealth Aircraft

O The main objective is to design an aircraft that can penetrate and reflect the radar waves very well.

O From the research, South Korea has come out with a new design of stealth aircraft called stealthy next-gen fighter.

O 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.

Example of Future Stealth Aircraft

Sukhoi T-50 PAK FA (2016)O Similar to Western stealth fighters like the

F-22, the airframe incorporates planform alignment in its leading and trailing edges and saw tooth edges for its skin panels.

O Incorporate radar blockers to hide the compressor face from all angles.

O The production T-50 is estimated to have reduced the radar cross-section to that of a tennis ball from optimal angles.

Chengdu J20 (2017)O Analysts noted that J-20 uses similar

stealth shaping design as the F-22 and F-35, providing good stealth capability at the front.

O It uses canard and low observable design for radar deflection.

O McDonnell Douglas and NASA's X-36 featured the use of canards and was shown to be extremely stealthy.

O The Eurofighter managed to reduce its Radar Cross Section (RCS) by controlling the deflection of its canards through the flight control software

ConclusionO Well to conclude the current scenario

appears some things similar to the cold war both sides are accumulating weapons to counter each other and each side can be termed as ‘stealth technology’ and the other as ‘anti-stealth technology’.

O Its an arm race except it isn’t between specific countries .