Blog – Daire Doyle O`Brien  

An addendum to stealth  

Stealth, particularly when discussing it with regards to a military jet, is one of the most important aspects of warfare since the invention of guided missiles. Using several phenomena present in the interactions with dielectric media, it can absorb/deflect incident waves, preventing them from returning to an antenna. This is important of course as it prevents a military radio antenna from absorbing said waves and using a complex system that replicates said phenomena to locate the fighter jet. This is quantified by something known as the Radar Cross-Section or the “RCS” colloquially. This gives you an idea of how “stealthy” the jet is. The most used version of the RCS is the bi-static RCS, which essentially means how big the RCS would appear if a wide profile of emitters (things that emit the electromagnetic waves) and antennas. The exact relationship is the squared ratio of the incident wave and the detected wave, multiplied by some constant.  For comparisons’ sake, the RCS of an F-35 is roughly 0.0015m^2, or roughly the size of a golf ball! The reduction of RCS primarily has to do with the geometry of the plane with regards to diffracting and reflecting the waves away (think of shooting a basketball at a backboard for reflecting, then with for diffraction visualize how a pro baseball pitcher would throw a curveball around the bat of an opposing player). It also has a lot to do with RDAs or Radar Absorbent Material. These are materials with the help of an oscillating current, possess a net negative energy flow. This helps absorb the power of a wave to some extent and helps reduce the number of relevant waves that make it back to the antenna.  

Stealth is not some uncompromisable technology, however. Adverse weather effects, particularly heavy rain and lightning help “scatter” rain and photons across the shape of the fighter. This happened in 1999 when a nighthawk went for a routine air raid in Serbia during the Yugoslav wars. These adverse weather conditions, on top of prior knowledge obtained through espionage helped an anti-aircraft operator manually track and shoot down the nighthawk with a laser-guided missile.  

Stealth also applies to other aspects of the military as well. For example, there exists such things as “Stealth missiles”. This is essentially the ideas of the fighter but taken to the maximum; a lot of these missiles feature complex, smooth twining geometry that makes them look like some alien prism rather than something with the capability to take out multiple apartment complexes upon impact. Also, if you’ve ever seen a modern naval vessel (particularly with light cruisers and destroyers) will have noticed that they are incredibly grey, dull with flat models, looking rather drab and more like a depressed VFX model from 2005 rather than their bombastic WWII counterparts. Well, thank stealth for that! 

Recent developments in stealth mainly pertains to maximizing firearms capacity whilst trying to maintain a reasonable amount of stealth. This has led to jets which are not quite as stealthy, mainly the Sukhoi 57 and the Jhonghdu 20. However it is hard to know if this is in the right direction, as if a jet on a modern airspace is targeted before their target, statistical odds quite simply suggest that nine times out of ten the pilot of said jet will have to pull the escape cord.  

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