30-11-2012, 11:23 AM
Stealth Technology in Aircrafts
1Stealth Technology.pptx (Size: 3.5 MB / Downloads: 46)
WHAT IS STEALTH TECHNOLOGY ?
Concept of stealth - Operate or hide without giving enemy forces any indications as to the presence of friendly forces.
Also called Low Observable Technology.
HISTORY OF STEALTH
Development in the United States occurred in 1958,where earlier attempts in preventing radar tracking of its U-2 spy planes during the Cold War by the Soviet Union had been unsuccessful. Designers turned to develop a particular shape for planes that tended to reduce detection, by redirecting electromagnetic waves from radars. Radar-absorbent material was also tested and made to reduce or block radar signals that reflect off from the surface of planes. Such changes to shape and surface composition form stealth technology as currently used on the Northrop Grumman B-2 Spirit "Stealth Bomber". This concept was first explored through camouflage by blending into the background visual clutter
RADAR
Turns on its transmitter.
Shoots out a short, high-intensity burst of high-frequency radio waves.
Turns on its receiver and listens for an echo.
The radar set measures the time it takes for the echo to arrive, as well as the Doppler shift of the echo.
Vehicle Shape
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
NON METALLIC AIRFRAME
Dielectric composites are more transparent to radar, whereas electrically conductive materials such as metals and carbon fibers reflect electromagnetic energy incident on the material's surface.
Composites may also contain ferrites to optimize the dielectric and magnetic properties of the material for its application.
INFRARED
An exhaust plume contributes a significant infrared signature.
One means of reducing the IR signature is to have a noncircular
tail pipe order to minimize the exhaust cross-sectional
volume and maximize the mixing of the hot exhaust with cool
ambient air.
● Often, cool air is deliberately injected into the exhaust flow to
boost this process.
● Sometimes, the jet exhaust is vented above the wing surface
in order to shield it from observers below.
● To achieve infrared stealth, the exhaust gas is cooled to the
temperatures where the brightest wavelengths it radiates on
are absorbed by atmospheric carbon dioxide and water vapor,
dramatically reducing the infrared visibility of the exhaust
plume.
● Another way to reduce the exhaust temperature is to circulate
coolant fluids such as fuel inside the exhaust pipe, where the
fuel tanks serve as heat sinks cooled by the flow of air along
the wings.