Stealth Aircrafts – How system works?
Purpose of Stealth
The purpose of stealth in simple words means shielding your fighter jet from radar, so that when you are in enemy's territory, the enemy cannot find you on their radar system.
Read more about how stealth works?
Indian Sukhoi SU-30 MKI's wears a coat of RAM (radar absorbent material), which is why we see a coarse matt finish on the body, a common technique used in order to achieve stealthy characteristics. Designers would have to for go many things. The trade off is too much (lose speed, aerodynamic design, etc.)
A B2 stealth bomber has to make 3 million calculations a second just to stay airborne. Stealth aircrafts are not easily detected because of their shapes and the waves are deflected upwards. RAM and using composites is not the only way to avoid radar. The Russians have developed the plasma screening technique, an electron generator, which ionizes the air around the aircraft and thus a plasma cloud is generated and the plane becomes invisible on radar. This is most likely to be incorporated into the SU-47 or the PAK-FA.
How radar systems can detect a stealth aircraft?
If we use our radio networks with low frequency like radio or mobile and we do not have plasma technology as this is developed by Russians, low frequency would not help much.
Lower wavelengths are preferable. Reduction of radar cross section is the common technique used by Indians, whereas Russians use an ion jacket (Pak-Fa's plasma) signal jamming, nap of the earth flight, creating false clutter are used by the comanche. There is not one sure shot system, which can do all the work, but a combination of systems can do it.
Certain new high tech satellites are experts at plasma residue detection, for example., those used in Mars Express, Venus Express (ESA); MGS (NASA) type of probes in space, so if employed in earth orbit using latest microsatellites a hoard of these will make PAK-FA detection child's play for the US. The bottom line is there can never be perfect stealth.
What's stealthy to one wavelength may be visible on other wavelength. There is no perfect stealth, unless the Pak-Fa plasma shield begins series production. A combination of multiple radars can help. Chinese radar systems have detected F-117 in the past. Australian wake turbulence detectors have also detected stealth. For every weapon, there is a counter weapon. All planes show up on radar, some just have a smaller signature.
When an airplane loses its stealth
All airplanes lose their stealth, the moment they switch their radar on. Stealth just does not mean shielding your aircraft from radar. You have to do IR shielding (which includes ducting your engine exhausts). Also the stealthy bombers (B-2) use acoustic shielding to eliminate any jet noise. The B2 Spirit is so quiet that it will fly over your head at 500 feet and you would not hear a thing.
There is also a thing called visual stealth, which is achieved by performing night missions only. Besides, even a stealth plane like the raptor or JSF will not be stealthy when you are at its tail. Also, it will lose its stealth when it fires a missile for two reasons, one its own radar is on, second as soon as it opens its weapon bay doors, the stealth is compromised and the aircraft is visible to the radar. For this reason, the bay doors of raptor only open for less than a second. The first point of compromising stealth because of your own radar can be taken care of in BVR mode where the targets are assigned to you by a nearby AWACS (airborne warning and control system) like the hawkeye.
However, in close air combat, the only aircraft that will be stealthy will be the one, which is smaller in size, and for then, the only thing that matters will be the visual stealth. For this reason, the best plane is India's very own old Folland Gnat.