Lt Gen (Dr) V K Saxena (Retd)
The stealth muscle in the air threat vehicles of today is one dimension of survivability that is fast becoming a nightmare to the air defence warriors. Why so? Because, survivability directly translates into lethality.
The relationship is fairly simple. Stealthy machines, by managing to become near invisible to the sensors of the adversary, not only survive by avoiding the onslaught of the defender’s air defence arsenal, but also with all smart and intelligent arsenal at their disposal, cause disproportionate damage by getting to attack defender’s vulnerabilities nearly undetected and unchallenged.
A shadow boxing of sorts, detection of stealthy air threat vehicles is therefore an operational compulsion. Stealth Threat we Face Today
Has the Stealth threat arrived at our doors? Yes, for a one word answer, if we were to examine some features of the frontline aircrafts with our northern neighbour which are fast approaching operationalisation and are making waves all over in the professional circles.
The case in point is Chengdu J-20 (Black Eagle), a stealthy fifth generation fighter aircraft (FGFA) with the Peoples Liberation Army Air Force (PLAAF), optimised for long range strikes. Starting its first flight on 11 Jan 2011, J-20 was planned for induction in Jan 18. In Mar 2017, Chinese media reported that the aircraft has entered initial operational capability phase with the Air Force1,2. In Sep 17 it was reported that J-20 officially entered military Service with the PLAAF3. In Oct 17, Chinese media reported that Chengdu Airspace Corporation (CAC) has initiated series production for J-20 and is on a path towards achieving full operational capability4. Though very few details are available about the said FGFA, it is assessed that the aircraft is likely to have a very strong stealth muscle.
For instance, the alignment of the outer surfaces of the aircraft is are so configured as to have all surfaces at the same angle. Such an arrangement (called Planform Alignment) reflects defender’s radar signal in a definite direction away from the mother radar, making the aircraft invisible to the radar. In addition, the aircraft is likely to be painted with the state-of-the-art Radar Absorbing Material based on nano-substances and active carbon coats. This is likely to enable the aircraft to absorb most of the defender’s radar energy and reflect back so little as to prohibit the defender’s radars to detect the craft.
The avionics of the aircraft are so designed that it rarely offers its underbelly or its heat emitting points ( engine nozzles etc) to a full and sustained view making it difficult for the defender’s missiles (especially heat seeking missiles) to lay on the aircraft and track it consistently (a precondition for missile launch).
Another stealthy feature of the aircraft relates to its weapon bays. Unlike the conventional types which always exposed to full view and hence provide strong signals for detection, weapon bays of this aircraft are fully concealed inside the body, only opening for a brief moment of firing. This reduces the aircraft’s electronic signatures a great deal.
Subject Matter Experts are comparing the stealthy muscle of J-20 with the likes of F 22 Raptor, F 35 Fighting Falcon, Su- PAK FA, the Japanese ATX, or Korean KAI KF-X (last two still under development). The question is not which aircraft tips the other or otherwise, the grave fact is that the stealth threat in a tangible measure has arrived at our doors. An expert analysis has opined that J-20 has the potential of a high performance stealth aircraft. With the ever strengthening military bond between our neighbours on the North and West, the likelihood of seeing these machines on our West is only a matter of time.
Shenyang J-31 Gyrfalcon or Falcon Hawk is also maturing alongside as a fifth generation twin engine, mid-size, stealthy, multi-purpose medium fighter. Starting with its first flight in Oct 12, the aircraft is due for induction in 2018-19. The aircraft is likely to have comparable stealthy features as quoted above5. If that is the shape of things firming up, where is the doubt that the stealth threat has indeed arrived at our doors. In the years to come, it is also likely to make its unwelcome appearance on our Western border.
Dealing with the Stealth Threat
If we have to counter the deadly threat from such multi-role stealth fighters like J-20, J-31 and others, we need to have sensors that can detect them in the first place. Thanks to many a state-of-the-art stealth technologies on board stealth aircrafts remain undetectable by the old conventional radars. Also, since most of such class of aircrafts have long standoff capabilities, these are likely to strike while remaining in the Beyond Visual Range (BVR) domain. It follows, that if these machines have to be countered, they must be detected electronically by our sensors at long ranges. How do we do it?
Basically, when the Electro Magnetic (EM) waves from the surveillance and other radars of the defender fall on the stealthy (also called Low Observable) aircrafts, these either get absorbed, diluted or deflected in one or multiple directions away from the mother radar. This results in the mother radar getting very weak to nil reflected signal from the aircraft, thus remaining unable to detect the stealth aircraft and paint it on its screen.
Air Defence warriors the world over are working to break the above trick one way or the other. The anti-stealth technologies are referred to as Counter Very Low Observable or CVLO technologies. Some emerging trends in the CVLO domain are briefly summarised below:-
oExperiments have shown that in contrast to the latest ultra high frequency compact radars, lower frequency radars are better suited to detect stealthy targets. Hence countries around the world engaged in the business of anti-stealth radars are producing radars in the lower frequency bands.
oAlso, since the stealthy targets reflect back the defender’s radar signals away from the mother radar, the trend is to produce radars so that transmitter of radar and its receiver are paced at different location (called Bi-static Radars). Also, for one transmitter, more than one receiver is placed at different locations thus increasing the probability of detection. Experts world over are also exploiting the lasers for detection of stealth targets. Laser waves, because of their short wave length, high beam quality, strong direction-ability, and high measuring accuracy, can successfully detect stealth targets. Radars using Laser waves are also called LIDARS (Light Detection and Ranging) 6.
oAnother prevalent concept is Passive Detection, or more precisely, Passive Coherent Location (PCL). In this, the radars do not transmit any radar energy but achieve detection of targets based on receiving electromagnetic waves (EM) waves that hit the stealthy targets from multiple domains, such as Digital Audio Broadcast etc..
While much is happening all round the world, what does it mean in our scenario? A possible way forward is suggested as under:-
oSince the stealth threat is very much alive at our doors, it is imperative that all new radars being procured for target detection and fire control must be stealth capable.
oIt is fortunate that several legacy missile system held with the forces actually had the sensors in the low frequency bands, and hence capable of detecting stealthy aircrafts. These must be kept alive.
oEfforts must be made by our R&D to provide stealth capable radars to the forces. In this, head start is available along multiple routes of Joint Ventures/Memorandum of Understanding/Transfer of Technology (JV/MoU/ToT) etc. with foreign Original Equipment Manufacturers (OEMs) under the “Make in India” initiative.
oIn the context of producing anti stealth equipment, what applies to the defence public sector is also equally applicable to private industry. Since the stealth muscle in our scenario is just about maturing, it is only going to become a more and more prominent feature of the futuristic air threat. Opportunities to develop stealth detectable radars for indigenous consumption, as well as for the export market either on the ‘go alone’ mode, or through technological tie ups, is thus an emerging business opportunity.
oIn the Def Expo 2016, some radars were stated to be able to detect birds and unmanned aerial vehicles, sense-n-avoid situations, foliage penetration and portable ground surveillance. There is a need to build further on these capabilities and grow into the anti-stealth domain.
With what has been stated under the head ‘Focus India’ above, the net Indian position as of date and actions required in the foreseeable future can be summarised as under:-
oThere is a need to start factoring the stealth threat in all qualitative and quantitative analyses of air threat from our potential adversaries and develop strategies to counter the same through multiple mediums. These may include optimising the existing inventory of radars, developing and procuring new anti-stealth equipment and putting out the cyber counter capability.
oTowards optimising, the vintage low frequency radars capable of CVLO must be retained and keep alive. As to new inductions, there is a need to insist that the future indigenous development of sensors is stealth capable (capability already stands demonstrated). Besides this, the Indian R&D establishment must venture into niche CVLO technologies by catching on the world trends and getting a head-start through joint ventures etc. And finally, the cyber warriors must train their soft arsenal towards debilitating the electronics and electromagnetics on board the stealthy machines of fifth generation warfare.
Such is the exciting and dynamic field of stealth and anti-stealth. The eternal cause-effect duel between the prosecutors of air threat and defenders there from, is only going to become more intense and interesting in so far as it pertains to the ‘magic of invisibility’ on one end and the resolve to ‘find the invisible’ at the other. And with stealth already at our door, we need to equip ourselves to deal with the same adequately.
Lt Gen (Dr) V K Saxena (Retd)