History Of Stealth Aircraft
With the increasing use of early warning detection devices such as radar by militaries around the world in the 1930's the United States began to research and develop aircraft that would be undetectable to radar detection systems. The first documented stealth prototype was built out of two layers of plywood glued together with a core of glue and sawdust. This prototype's surface was coated with charcoal to absorb radar signals from being reflected back to the source, which is how radar detection systems detect items in the air.
Introduction
Stealth means now observable. The very basic idea of Stealth Technology in the military is to 'blend' in with the background. The quest for a stealthy plane actually began more than 50 years ago during World War II when RADAR was first used as an early warning system against fleets of bombers. As a result of that quest, the Stealth Technology evolved. Stealth Technology is used in the construction of mobile military systems such as aircrafts and ships to significantly reduce their detection by enemy, primarily by an enemy RADAR. The way most airplane identification works is by constantly bombarding airspace with a RADAR signal.
Design
The surfaces and edge profiles are optimized to reflect hostile radar into narrow beam signals, directed away from the enemy radar detector. All the doors and opening panels on the aircraft have saw-toothed forward and trailing edges to reflect radar. The aircraft is mainly constructed of aluminum, with titanium for areas of the engine and exhaust systems. The outer surface of the aircraft is coated with a radar-absorbent material (RAM). The radar cross-section of the F-117 has been estimated at between 10-100cm2. The entire stealth fleet will be stripped of the sheet-coated, radar-absorbing materials on the wings, rudders and fuselage.
Radar Absorbent Material (Ram)
As its name implies, RAM is intended to reduce the scattered signal by absorbing some part of the incident radiation. Microwave energy is converted into heat energy with hardly any noticeable temperature rise because the energies involved are extremely small. Various kinds of materials can be made to absorb microwave energy by impregnating them with conducting materials such as carbon and iron.
Heat Radiation Reduction
Infrared radiation (heat) should be minimized by a combination of temperature reduction and masking. The main body of the airplane has its own radiation, heavily dependent on speed and altitude, and the jet plume can be a most significant factor, particularly in after burning operation. The engines are buried deep in the fuselage These have got shallow 'platypus' exhausts, which cool and deflect the exhaust gases upward to minimize heat emissions.
Radar
Currently the way to detect and even identify an aircraft is the use of RADAR (radio detection and ranging). This system invented during World War II, simply works by constantly sending bursts of radio waves of certain frequencies and measures the echoes of each burst. Objects are reflecting parts of the energy of radio waves.
Abstract
Stealth or low observability (as it is scientifically known) is one of the most misunderstood and misinterpreted concepts in military aviation by the common man. Stealth aircraft are considered as invisible aircraft, which dominate the skies. With an additional boost from Hollywood action movies, stealth is today termed as the concept invincibility rather than invisibility.
Conclusion
Imagine you can electronically change the color of a given surface in such a way it can match the terrain below it. Looking from above, the surface appears to match the terrain. Fly over forest, and the surface takes on a green like hue. A cloudy day adds clouds to match what sensors see underneath and the aircraft becomes a chameleon and disappears. This may sound like science fiction, but then think of the LCD display of notebooks and it may not seem so far fetched all of a sudden.
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