19-12-2012, 06:07 PM
Stealth technology
[attachment=44487]
INTRODUCTION
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. Though, the debate still continues on whether stealth technology can make an aircraft invincible it was found that stealth aircraft are detectable by radar.
The motive behind incorporating stealth technology in an aircraft is not just to avoid missiles being fired at is but also to give total deniability to covert operations. This is very much useful to strike targets where it is impossible to reach. Thus we can clearly say that the job of a stealth aircraft pilot is not to let others know that he was ever there.
In simple terms, stealth technology allows an aircraft to be partially invisible to Radar or any other means of detection. This doesn't allow the aircraft to be fully invisible on radar. Stealth technology cannot make the aircraft invisible to enemy or friendly radar. All it can do is to reduce the detection range or an aircraft. This is similar to the camouflage tactics used by soldiers in jungle warfare. Unless the soldier comes near you, you can't see him. Though this gives a clear and safe striking distance for the aircraft, there is still a threat from radar systems, which can detect stealth aircraft.
The Russian radar system is very much capable of detecting the "Night Hawk" stealth fighter. There are also some other radar systems made in other countries, which are capable of detecting the Night Hawk stealth fighter. During the Gulf war the Iraqis were able to detect the stealth fighter but failed to eliminate its threat because of stealth aircraft was during the NATO (North Atlantic Treaty Organisation) air-war over Yugoslavia. This was done by a Russian built "not so advanced" SAM(Surface to Air Missile) . The SAM(Surface to Air Missile) system presumably used optical detection for target acquisition in the case. Development of stealth technology likely began in Germany during World War-2.
Radar Absorbent Surfaces
RAS or Radar absorbent surfaces are the surfaces on the aircraft, which can deflect the incoming radar waves and reduce the detection range. RAS (Radar absorbent surfaces) 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 refuelling boom on the aircraft. The extensive use of RAS (Radar absorbent surfaces) is clearly visible in the "Night Hawk". Due to the facets (as they are called) on the fuselage, most of the incoming radar waves are reflected to another direction. Due to these facets on the fuselage, the Night Hawk is a very unstable aircraft. Stealth bomber with the Radar Absorbent Material on its surface is shown in the Fig.1.2.
The concept behind the RAS (Radar absorbent surfaces) 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 Night Hawk stealthy.
Radar Absorbent Material
Radar absorbent surfaces absorb the incoming radar waves rather than deflecting it in another direction. Radar absorbent surfaces totally depend on the material with which the surface of the aircraft is made. Though the composition of this material is a top secret. The Night Hawk extensively uses RAM (Radar Absorbent Material) to reduce its radar signature or its radar cross section. The Radar absorbent surface is believed to be silicon based inorganic compound. This is assumed by the information that the RAM coating on the Stealth bomber is not water. This is just a supposition and may not be true. What we know is that the RAM (Radar Absorbent Material) coating over the Stealth bomber is placed like wrapping a cloth over the plane. When radar sends a beam in the direction of the Stealth bomber, the radar waves are absorbed by the plane’s surface and are redirected to another direction after it is absorbed. This reduces the radar signature of the aircraft.
Infrared
Another important factor that influences the stealth capability of an aircraft is the IR (Infrared) signature given out by the plane. Usually planes are visible in thermal imaging systems because of the high temperature exhaust they give out. This is a great disadvantage to stealth aircraft as missiles also have IR(Infrared) guidance system. The IR(Infrared) signatures of stealth aircraft are minute when compared to the signature of a conventional fighter or any other military aircraft. If reducing the radar signature of an aircraft is tough, then reducing the IR(Infrared) signature of the aircraft is tougher. It will be like flying a plane with no engines. The reduced IR(Infrared) signature totally depends on the engine and where the engine is placed in an aircraft. Engines for stealth aircraft are specifically built to have a very low IR(Infrared) signature. The technology behind this is top secret like others in stealth aircraft.
[attachment=44487]
INTRODUCTION
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. Though, the debate still continues on whether stealth technology can make an aircraft invincible it was found that stealth aircraft are detectable by radar.
The motive behind incorporating stealth technology in an aircraft is not just to avoid missiles being fired at is but also to give total deniability to covert operations. This is very much useful to strike targets where it is impossible to reach. Thus we can clearly say that the job of a stealth aircraft pilot is not to let others know that he was ever there.
In simple terms, stealth technology allows an aircraft to be partially invisible to Radar or any other means of detection. This doesn't allow the aircraft to be fully invisible on radar. Stealth technology cannot make the aircraft invisible to enemy or friendly radar. All it can do is to reduce the detection range or an aircraft. This is similar to the camouflage tactics used by soldiers in jungle warfare. Unless the soldier comes near you, you can't see him. Though this gives a clear and safe striking distance for the aircraft, there is still a threat from radar systems, which can detect stealth aircraft.
The Russian radar system is very much capable of detecting the "Night Hawk" stealth fighter. There are also some other radar systems made in other countries, which are capable of detecting the Night Hawk stealth fighter. During the Gulf war the Iraqis were able to detect the stealth fighter but failed to eliminate its threat because of stealth aircraft was during the NATO (North Atlantic Treaty Organisation) air-war over Yugoslavia. This was done by a Russian built "not so advanced" SAM(Surface to Air Missile) . The SAM(Surface to Air Missile) system presumably used optical detection for target acquisition in the case. Development of stealth technology likely began in Germany during World War-2.
Radar Absorbent Surfaces
RAS or Radar absorbent surfaces are the surfaces on the aircraft, which can deflect the incoming radar waves and reduce the detection range. RAS (Radar absorbent surfaces) 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 refuelling boom on the aircraft. The extensive use of RAS (Radar absorbent surfaces) is clearly visible in the "Night Hawk". Due to the facets (as they are called) on the fuselage, most of the incoming radar waves are reflected to another direction. Due to these facets on the fuselage, the Night Hawk is a very unstable aircraft. Stealth bomber with the Radar Absorbent Material on its surface is shown in the Fig.1.2.
The concept behind the RAS (Radar absorbent surfaces) 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 Night Hawk stealthy.
Radar Absorbent Material
Radar absorbent surfaces absorb the incoming radar waves rather than deflecting it in another direction. Radar absorbent surfaces totally depend on the material with which the surface of the aircraft is made. Though the composition of this material is a top secret. The Night Hawk extensively uses RAM (Radar Absorbent Material) to reduce its radar signature or its radar cross section. The Radar absorbent surface is believed to be silicon based inorganic compound. This is assumed by the information that the RAM coating on the Stealth bomber is not water. This is just a supposition and may not be true. What we know is that the RAM (Radar Absorbent Material) coating over the Stealth bomber is placed like wrapping a cloth over the plane. When radar sends a beam in the direction of the Stealth bomber, the radar waves are absorbed by the plane’s surface and are redirected to another direction after it is absorbed. This reduces the radar signature of the aircraft.
Infrared
Another important factor that influences the stealth capability of an aircraft is the IR (Infrared) signature given out by the plane. Usually planes are visible in thermal imaging systems because of the high temperature exhaust they give out. This is a great disadvantage to stealth aircraft as missiles also have IR(Infrared) guidance system. The IR(Infrared) signatures of stealth aircraft are minute when compared to the signature of a conventional fighter or any other military aircraft. If reducing the radar signature of an aircraft is tough, then reducing the IR(Infrared) signature of the aircraft is tougher. It will be like flying a plane with no engines. The reduced IR(Infrared) signature totally depends on the engine and where the engine is placed in an aircraft. Engines for stealth aircraft are specifically built to have a very low IR(Infrared) signature. The technology behind this is top secret like others in stealth aircraft.