THE MODERN STEALTH FIGHTER TECHNOLOGY
ABSTRACT

There have been countless innovations in the field of aerospace military application as nations battle in the air and undoubtedly stealth technology has been the most compelling of all of them making fighter jets “invisible” and hence invincible. This article presents an overview into the implementation of the scientific knowledge of it including the history, basics of the radar technology and how the materials work and are made from. Not to mention, unorthodox detection methods of stealth jets are also explored in addition to investigate the other end of the spectrum and how it can be overcomed.

INTRODUCTION

Ever since the inception of wars and fighting, military personnel and people have wanted to hide themselves from their enemies to stay away from danger. An excellent way of doing so would be camouflaging oneself by evading predation. War planes, though fast and agile in the 1940s, were still detected by the nemesis through simple radar technology, making their moves predictable and therefore ineffective. With the advancement of stealth technology, fighters became more agile and untraceable to even the latest radar detection posing a huge threat to the camp on the other side.

The history of stealth technology could be traced back to 1958 where the Cold War was taking place. The United States researched stealth technology for its U-2 spy plane over the Soviet Union, but it was unsuccessful, but it was a good first step in the right direction.

Various kinds of shapes, sizes and materials are utilized to operate in stealth mode and give no notification to the adversaries [1]. To become invincible, there is not one but multiple technology that comes together allowing commanders to move with impunity. The exponential rise in stealth innovation could be thought to have culminated in the manufacture of the modern F-35 and other similar aircraft making it a huge threat in its time.

Figure 1: Stealth jet, Lockheed Martin F-35 Lightning II

RADAR TECHNOLOGY

To understand how stealth fighters were masked from the radar systems, it is essential to know the nuts and bolts of them to have a deeper comprehension of them. Radar simply uses electromagnetic sensors which recognizes things at substantial distances. As it is an active sensing apparatus, it sends out its own radiance when pinpointing desired objects, by sending out EM waves and analyzing the echoes of the reflected energy imaging it on the display. Incidentally, it was also the time of the World Wars when radar technology picked up its speed and a lot of countries experimented with it to take advantage of it knowing where their enemies are aerially and even on the sea.

As time went by, many countries had gained enough knowledge to operate radar technologies, the enemies moves and projectiles became well-known and could easily be dodged using straightforward predictions. Thus, this required the use of stealth technology that could make the jets not completely invincible but make it hard for an enemy to track the jet.

RADAR CROSS-SECTION

The physics of radar technology became more apparent as when the concept of the Radar Cross-Section (RCS) was discovered which was essentially an EM signature of the traced object on the radar. This made stealth more accessible as it was a quantifiable measure of how detectable an object is. The goal for stealth aircrafts was to keep the RCS as low as possible, giving the operators impunity to attack others. There are numerous factors that affect the RCS of an object, some of which are the material, absolute size, directivity, and the incident angle of the transmitted beam [2]. It is noteworthy that as stealth aircraft tend for lower RCS values, commercial aircraft need to have a higher value as they need to be always on the radar.

Figure 2: Typical Radar Cross-Section

In terms of shape, the aircraft should be fabricated in a way to reduce its RCS. Taking for instance Lockheed’s F-117 Nighthawk has a smooth surface which is very angled and flat. The purpose of it being angled is such that when an EM wave is hit on the surface of the aircraft, the sharp angled surface bounces back the wave into a forward scattered direction not letting the signal to be transmitted back [3]. The bottom line is that the incident radar angle would hit the skin of the aircraft and reflect at a higher angle than to the normal angle away from the source. In contrast, commercial airplanes have curvy surfaces ensuring that at least some of the signal will be returned through the normal direction.

MATERIALS SCIENCE

No matter the use of a vehicle, the material it is made up of has significant implications on its application and operation and it is no exception to stealth technology. Apart from directing the EM signal from radar sources, the Radiation-Absorbent Material (RAM) as the name suggests absorbs the wave energy preventing reflection of it in any way. It is an innovative material that soaks up the radio frequency radiation as much effectively as possible, lowering the power of the reflected radiation and hence lowering the RCS. The performance of the material is subject to its composition as the absorbency level of different frequencies vary for distinct materials [4]. It is significant that the coating of materials on the surface of the aircraft would not make it completely invisible for any frequency but does lessen the RCS.

One of the most common RAM in the stealth technology sphere is Iron ball paint. It is well-known that energy cannot be created or destroyed and thus is the case with the principles of the Iron ball paint. The Iron ball coated will convert the radar energy received from various sources to heat energy which is then dissipated from the aircraft. It is possible because of the paint which contains carbonyl iron. The radar waves bring about molecular oscillations because of the inherent alternating magnetic field in the iron paint. There have been multiple variations of this type although the core principles of it remain the same.

For instance, the infamous F-117 Nighthawk employs a similar technique. It is important to say the least to understand the electrochemical fabrication process that enables this radar evasion. The carbonyl iron balls are individually suspended in commonly used epoxy paint [5]. A layer of silicon dioxide is coated and its purpose is to act as an insulator to negate any electrical reactions given out. While the paint is still liquid, a magnetic field is applied such that it penetrates the liquid balls and thus creating a magnetic field pattern inside the balls. As the paint hardens and solidifies, the magnetic field is held in its place and locks them in the magnetic pattern. Once the paint is made as it needs to be coated, it says without going the application of it on the aircraft is as crucial. Remarkably the paint job is done by industrial robots which layers the paint on the F-117 with known and particular thickness and liquid properties.

Figure 3: Iron ball paint coating on the F-35

The iron ball paint method as a RAM has been used by several air forces such as Taiwan and the Mainland. Noticeably, the Taiwanese RAM stealth aircrafts is in response to their opponent China who were the first to employ stealth fighters [6]. This shows how keen countries are striving to take a stance on becoming military heavyweights by using state-of-the-art technology. There are various other materials that are embedded in the fighter aircrafts such as the foam absorber, split-ring absorber, etc. Most of which use the physical and chemical properties of the materials with nuances that differentiates the efficiency of evading the radar.

DETECTING STEALTH AIRCRAFTS

The realm of stealth technology is certainly vast and rapidly improving with improving sciences but on the other end of the spectrum, what could be done to detect these “invisible” aircrafts that could be literally fatal for some states.

There are also a number of spotting stealth aircrafts tricks but one the most promising technology is that of the usage of quantum radar [7]. Though there have been sizable organizations and regions in the field of it, Canada’s University of Waterloo has invested millions to their design of the quantum radar. The radar is expected to pinpoint aircrafts with higher accuracy than conventional ones and nevertheless perceive sly aircrafts. It is well known that the quantum world has given a large boost to existing technology in many fields such as computing and telecommunications and it is certainly the case for radar applications.

Quantum illumination works by the principle of quantum entanglement which is a physical feature of quantum particles. The entanglement entails that when the photon particles are connected, no matter the displacement, the state of each of one of them is known to the other photon and continues to affect it. This phenomenon of decoherence is the basis of detecting stealth aircrafts.

Under traditional circumstances, the photons emitted by the radar will get bounced off the surface of the stealth aircraft due to its sharp angles as aforementioned making it difficult to see on radars. However, using the quantum radar

would yield a different result when in contact with the object [8]. As it bounces off the surface of the aircraft, as the photons are entangled, the detecting source could trace back where the photons were fired at and keep shooting more of them until a picture of it is built up making it known to the radar.

Figure 4: Diagram depiction of photon entanglement

CHALLENGES IN STEALTH TECHNOLOGY

Although as seen there are rapid innovations in the domain of stealth innovations, there are several setbacks that have to be dealt with in order to bring about fully-fledged stealth mode. In terms of the Radio Absorbent Materials mentioned, it is critical to note that not all of the types of materials used work at all radio frequencies but are designed for specific radar frequency. With regards to the application of it on the aircrafts, it is not easy to be coated on moving or intricate surfaces which are usually the case in stealth aircrafts.

Moreover, the quantum radar used to detect these aircrafts are very much in their preliminary works and would need substantial design work to implement it. Primarily, the engineering challenge in the quantum radar would be the miniaturization of the electrical components in the system. Without saying, this would require more toil to integrate these complex photon detectors into smaller conglomerates which can make the detection more effective.

CONCLUSION

The advent of special materials and quantum technology has fostered the development of stealth technology. Even though there might be several drawbacks on either side of the spectrum the benefits most definitely outweigh them and with reassuring research and development, it is only going to get better with time.

All in all, in this brief article, stealth innovation has been looked at and how it operates from the contemporary radar technology and the radar cross-section to the fascinating stealth materials used and not to mention the revitalized modern quantum radar. The huge potential in stealth has provoked many countries to take part in it and it is bringing about a mini-arms race within the military forces making the future prospects of it truly riveting.

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