All You Need To Know About The Stealth Fighter Aircraft

Hello Defence Lovers, The term “stealth” is commonly applied to aircraft or missile systems that have been designed to produce as small a radar signature as is practicable. In fact, stealth technology goes beyond this to include reducing as many “observables” of an aircraft or missile system as possible—for example, its visual, noise, and heat signatures, as well as its electromagnetic ones. Stealth technology is applicable to other systems as well, particularly to ship design. Overall, while the term “stealth” is convenient shorthand, a more precise and all‐encompassing term used in the military community is “low observables.”

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What Is Stealth Aircraft & Stealth Technology ?
  • Stealth aircraft are designed to avoid detection using a variety of technologies that reduce reflection/emission of radar, infrared, visible light, radio-frequency (RF) spectrum, and audio, collectively known as stealth technology.
  • Development of stealth technology likely began in Germany during World War II, the prototyped Horten Ho 229 was designed for twin BMW 003 jet engines but finally powered by twin Junkers Jumo 004 jet engines being described as the first stealth aircraft.
  • Well-known modern examples of stealth of U.S. aircraft include the United States’ F-117 Nighthawk (1981–2008), the B-2 Spirit, the F-22 Raptor,and the F-35 Lightning II.
  • While no aircraft is totally invisible to radar, stealth aircraft make it more difficult for conventional radar to detect or track the aircraft effectively, increasing the odds of an aircraft successfully avoiding detection by enemy radar and/or avoiding being successfully targeted by radar guided weapons.
  • Stealth is the combination of passive low observable (LO) features and active emitters such as Low Probability of Intercept Radars, radios and laser designators.
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  • These are usually combined with active measures such as carefully planning all mission maneuvers in order to minimize the aircraft’s radar cross section, since common actions such as hard turns or opening bomb bay doors can more than double an otherwise stealthy aircraft’s radar return.
  • It is accomplished by using a complex design philosophy to reduce the ability of an opponent’s sensors to detect, track, or attack the stealth aircraft.
  • This philosophy also takes into account the heat, sound, and other emissions of the aircraft as these can also be used to locate it.
  • Full-size stealth combat aircraft demonstrators have been flown by the United States (in 1977), Russia (in 2010) and China (in 2011).
  •  The U.S. military has adopted three stealth designs, and just recently adopted the Lockheed Martin F-35 Lightning II.

  • Interest in reducing the observable characteristics of aircraft dates to World War I, when various of the warring powers experimented with both camouflage paint schemes and even see‐through fabric coatings applied to airplanes.
  • Theoretical studies in World War II indicated that it might be possible to reduce the radar signature of an airplane; in related work, the Germans developed radar‐absorbent materials to shield radar return from submarines’ Schnorkels when these retractable air pipes were raised above the surface of the water.
  • The first aircraft designed to have a greatly reduced radar signature was the Lockheed A‐12, the predecessor of the SR‐71 Blackbird strategic reconnaissance airplane.
  • The first true “stealth” airplane—an aircraft designed primarily to defeat radar–was the Lockheed Have Blue technology demonstrator.
  • Two of these aircraft, first flown in 1977, demonstrated that an aircraft company could design and build a potentially militarily useful airplane incorporating low observable principles.
  • Development of the first stealth aircraft encouraged the development of the Northrop B‐2 stealth bomber (which entered Air Force service in December 1993), and an advanced stealthy cruise missile, the General Dynamics AGM‐129.
  • Stealth is an important development in military aerospace, for it renders an aircraft or missile difficult to detect, and virtually impossible to track, engage, and destroy.
  • Stealth technology also termed LO technology (low observable technology) is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, missiles and satellites to make them less visible (ideally invisible) to radar, infrared, sonar and other detection methods.
  • It corresponds to military camouflage for these parts of the electromagnetic spectrum (Multi-spectral camouflage).
  • The concept of stealth is to operate or hide without giving enemy forces any indications as to the presence of friendly forces.
  • This concept was first explored through camouflage by blending into the background visual clutter.
General Design :

The general design of a stealth aircraft is always aimed at reducing radar and thermal detection. It is the designer’s top priority to satisfy the following conditions, which ultimately decide the success of the aircraft:-

  • Reducing thermal emission from thrust.
  • Reducing radar detection by altering some general configuration (like introducing the split rudder).
  • Reducing radar detection when the aircraft opens its weapons bay.
  • Reducing infra-red and radar detection during adverse weather conditions.
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Operational Usage Of Stealth Aircraft :
  • The U.S. is the only country to have used stealth aircraft in combat. These deployments include the United States invasion of Panama, the first Gulf War, the Kosovo Conflict, the War in Afghanistan the War in Iraq and the 2011 military intervention in Libya.
  • The first use of stealth aircraft was in the U.S. invasion of Panama, where F-117 Nighthawk stealth attack aircraft were used to drop bombs on enemy airfields and positions while evading enemy radar.
  • During the May 2011 operation to kill Osama bin Laden, one of the helicopters used to clandestinely insert US troops into Pakistan crashed in the bin Laden compound.
  • From the wreckage it was revealed this helicopter had stealth characteristics, making this the first publicly known operational use of a stealth helicopter.
  • Stealth aircraft will continue to play a valuable role in air combat with the United States using the F-22 Raptor, B-2 Spirit, and the F-35 Lightning II to perform a variety of operations. The F-22 made its combat debut over Syria in September 2014 as part of the US-led coalition to defeat ISIS.
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Limitations Of Stealth Aircraft :

(1.) Instability Of Design 
  • Early stealth aircraft were designed with a focus on minimal radar cross section (RCS) rather than aerodynamic performance.
  • Highly-stealth aircraft like the F-117 Nighthawk are aerodynamically unstable in all three axes and require constant flight corrections from a fly-by-wire (FBW) flight system to maintain controlled flight.
  • As for the B-2 Spirit, which was based on the development of the flying wing aircraft by Jack Northrop in 1940, this design allowed for a stable aircraft with sufficient yaw control, even without vertical surfaces such as rudders.
(2.) Aerodynamic Limitations
  • Earlier stealth aircraft (such as the F-117 and B-2) lack afterburners, because the hot exhaust would increase their infrared footprint, and flying faster than the speed of sound would produce an obvious sonic boom, as well as surface heating of the aircraft skin which also increases the infrared footprint.
  • As a result, their performance in air combat maneuvering required in a dogfight would never match that of a dedicated fighter aircraft.
  • This was unimportant in the case of these two aircraft since both were designed to be bombers.
  • More recent design techniques allow for stealthy designs such as the F-22 without compromising aerodynamic performance.
  • Newer stealth aircraft, like the F-22, F-35 and the Sukhoi T-50, have performance characteristics that meet or exceed those of current front-line jet fighters due to advances in other technologies such as flight control systems, engines, airframe construction and materials.
(3.) Electromagnetic Emissions
  • The high level of computerization and large amount of electronic equipment found inside stealth aircraft are often claimed to make them vulnerable to passive detection.
  • This is highly unlikely and certainly systems such as Tamara and Kolchuga, which are often described as counter-stealth radars, are not designed to detect stray electromagnetic fields of this type.
  • Such systems are designed to detect intentional, higher power emissions such as radar and communication signals. Stealth aircraft are deliberately operated to avoid or reduce such emissions.
  • Current Radar Warning Receivers look for the regular pings of energy from mechanically swept radars while fifth generation jet fighters use Low Probability of Intercept Radars with no regular repeat pattern.
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(4.) Vulnerable modes of flight
  • Stealth aircraft are still vulnerable to detection during, and immediately after using their weaponry.
  • Since stealth payload (reduced RCS bombs and cruise missiles) are not yet generally available, and ordnance mount points create a significant radar return, stealth aircraft carry all armaments internally.
  • As soon as weapons bay doors are opened, the plane’s RCS will be multiplied and even older generation radar systems will be able to locate the stealth aircraft.
  • While the aircraft will reacquire its stealth as soon as the bay doors are closed, a fast response defensive weapons system has a short opportunity to engage the aircraft.
(5.) Reduced Payload 
  • Fully stealth aircraft carry all fuel and armament internally, which limits the payload. By way of comparison, the F-117 carries only two laser- or GPS-guided bombs, while a non-stealth attack aircraft can carry several times more.
  • This requires the deployment of additional aircraft to engage targets that would normally require a single non-stealth attack aircraft.
  • This apparent disadvantage however is offset by the reduction in fewer supporting aircraft that are required to provide air cover, air-defense suppression and electronic counter measures, making stealth aircraft “force multipliers”.
(6.) Sensitive Skin
  • Stealth aircraft often have skins made with Radar-absorbent materials or RAMs. Some of these contain Carbon black particles, some contain tiny iron spheres.
  • There are many materials used in RAMs, and some are classified, particularly the materials that specific aircraft use.
(7.) Cost Of Operations
  • Stealth aircraft are typically more expensive to develop and manufacture. An example is the B-2 Spirit that is many times more expensive to manufacture and support than conventional bomber aircraft.
  • The B-2 program cost the U.S. Air Force almost $105 billion.
Jai Hind