|J-20 Stealth Fighter|
When China displayed the prototype of its first ever stealth aircraft , the J 20 in 2010 it sent alarm bells ringing not just in the US but more importantly in countries across East and South East Asia. China has now joined the foremost ranks of fighter-building nations, setting off a debate in the West and among China’s immediate neighbors over if and when the J-20 might begin entering service in great numbers and how that may shape the Asia Pacific balance of power. Suddenly countries ranging from Japan to South Korea to Indonesia decided to jump into the stealth bandwagon and co develop Low Observable fighters with foreign partners. Since the mid nineties backers of F 22 and F 35 fighters which rely on stealth have utilized simulators and conferences to uphold the idea that stealth will be an overpowering advantage in air combat.
We can probably take a deep dive and understand stealth fighter programs of other Asian countries sometime in the future, however for the time being I will focus on something that is more close to our heart - When will India get it’s stealth fighter aircraft ? As we know, India has started work in right earnest with it’s “strategic partner” Russia to develop a Low Observable or stealth fighter aircraft. In this regard it’s worth asking an important question. Is it worth having a stealth aircraft ?
Isn’t it true that the F 22 has never been tested and the Serbs shot down a F 117 using similar X band radars. After Russia introduced the low band radars, especially operating in the VHF band isn’t it now possible to detect and shoot down any stealth fighter before they can do any damage. Most stealth design features are intended to scatter incoming illumination in a controlled fashion. The prerequisite for this to work is that the wavelength be much smaller than the basic dimensions of the shaping feature of relevance. Therefore, for stealth aircrafts to counter VHF band radar the wavelengths must be of the order of a metre or more, which today only the B 2 has (however it is not a fighter aircraft). A fighter sized aircraft such as the F 22 or F 35 will see most of its cautiously designed shaping features fall into the resonance where shaping is of little or no import, and skin depth penetration of the induced electrical surface currents defeats most absorbent coatings or laminates. To answer this question let us take a close look at the PAK FA program. The PAK FA already comes with a forward looking large nose mounted X band AESA, side looking smaller X band AESA radars, and wing mounted L band AESA radars, multi spectral IRST, front and back looking IRSTs. Going by the prototype it seems that extreme maneuverability has been given precedence over all aspects of stealth so the PAK FA may not carry out the deep penetration role of the F 22. My understanding is that the PAK FA has been designed from the onset to detect the F 22 or similar stealth aircrafts from a long distance using it’s IRST and then destroy these aircrafts in a Within Visual Range conflict.
Obviously, designing the avionic suite of the PAK FA is not going to be easy for Sukhoi. The provision of high capacity avionic cooling, which does not produce infrared hotspots, and in the design of wideband, yet very low RCS radio-frequency apertures for both passive and active sensors (similar to the F 22s Agile Beam), and aircraft datalink/network terminal transceivers. Unlike the F-22, which uses stealth technology, 85 percent of the surface of PAK FA is covered with unique nano technological materials that decrease both the visibility of the plane and air drag.
Proper stealth needs to be a factor from the very start of the design stage because every aspect of the design will influence the final radar cross section.There are two aspects that are important with stealth and they are shaping and materials absorption. Shaping means designing the reflecting surface to redirect radar waves coming from any direction in any direction other than the direction the energy came from. Materials absorption means materials that absorb radio waves. Having a composite radar invisible skin is pointless. They currently use dielectric nose radomes that cover the nose. Mounted radar are invisible to radar otherwise the radar inside them would not work through them. Making the outer skin of a plane out of that material would just make the insides of the plane visible to the radar and all that external shaping to redirect radar so that it doesn’t return to the radar antenna would be completely wasted.There is no reason why the PAK FA needs to use all the same methods to reduce RCS that the F-22 or any other aircraft uses.
The PAK FA will not be some miracle plane, but it renders obsolete all Euro canards in a single step and renders Meteor pretty useless because with its IR sensors the PAK FA will be able to spot Meteor from quite a distance and will be able to fly “around” it. Even when it turns on its radar scanner its reduced detection range means the PAK FA pilot need never let it get close enough to see him and that is assuming the Rafale or Typhoon even sees him in the first place to launch. The stealth aircrafts of adversaries (like the J 20) on the other hand will be up against an aircraft using L band radar in wing mounted AESA antenna arrays, plus the latest in IIR sensors. A simple data link connection between a flight of 4 Su-30MKIs and they could synthesize an L band antenna thousands of metres in length which should be able to spot J 20’s or even B2’s at extended distances. Stealth is worth it as long as it doesn’t completely compromise everything else. Otherwise one breakthrough and you are a sitting duck with your very expensive white elephant.
Therefore, we shouldn’t think of stealth as a be all and end all. Rather we should think of stealth as a type of ECM. It means that even if they have long wave radars that will tell them roughly where you are they no longer have the option of a long range shot with a BVR missile because the stealth effect has reduced its detection range enough to make it near useless as a fire and forget weapon. Being able to see a target is only half the problem, you have to be able to hit it with something.