Y and ies worksheets and ies

Boo
I have seen a lot of people both here on reddit and on discord with questions on stealth or misconceptions on it. As a Docent and historian at the worlds largest private aerospace museum which has a lot of documentation on the subject and a few actual stealth aircraft, which helps in understanding this topic at a deeper level than most. This is meant to be a basic overview of how reduced Radar Cross Section, (RCS) is achieved. I’m not gonna go into detail about other features that matter in stealth such as Infrared signature reduction, or electromagnetic signature reduction both of which are just as critical to a proper stealth design.
If anyone wants to do some light reading on the subject I recommend Stealth by Doug Richardson, or Stealth Aircraft by Bill Sweetman. Both can provide a basic overview of the technical aspects of RCS. If you have a Aviation Week subscription they did a couple of great primer articles on this a few years ago and are also worth reading. There are also numerous academic papers on this topic that can be found if you want something with a bit more meat on the bones. What will follow is even further simplified from those books but should at least be more accessible and easy to understand.
The first thing I want to point out is how Radar actually works as this is something that a lot of people get wrong, and it can lead to many mistaken beliefs about how stealth works. People often think of a radar return as light reflecting off a object, and while in layman's terms this explanation suffices the actual quantum mechanisms are a bit more complicated and while the description is fine for basic knowledge knowing how it works at the smallest of scales is critical for getting your RCS to actually work.
When Radar strikes a object it doesn't just bounce off, what actually happens is that the radar wave induces a current in the material it hits, this then creates waves of the same magnitude as the incoming waves. It is this re-emitted energy that is what the radar receiver actually pics up. The direction of emission is also related to the direction of the incoming energy. One important factor in this is that object with a length/diameter about one half the wavelength will create a much stronger return. This is why some objects are much more radar reflective than others. However this isn't the only thing the energy can do. Sometimes the energy is absorbed by the material struck, this is your standard Radar Absorbing Material (RAM). Another interesting feature of radar is scattering and wave travel. The energy does not have to be emitted right away, it can travel along the object it hits before being re-emitted. Sharp boundaries are more likely to emit this radiation than smooth rounded shapes. This is further compounded by scattering which is how the magnitude of the return varies by the relationship of the wavelength to the size of the object. When they are about the same size (note this means the area the wave can travel not the size of the whole plane) you get what is called resonance which greatly increases the return of the object. When the wavelength is smaller than the object then it starts to treat smaller and smaller sections independently of each other as the object. This is important and will be discussed later.
The goal of RCS takes all of these considerations and more into the equation as some objects are also transparent to radar waves and others translucent. Furthermore the ability of a material to conduct electricity is important because this can help the waves propagate further before emitting. While on the surface this may seem bad and in some cases it is, it also allows for better control of where the emissions come from. Move over the angle of the surface being emitted dictates the strength of the signal and how it changes with direction, think this like a funhouse mirror, the cone/dome of radar can be emitted in a very different direction than it came from. This is not a easy thing to calculate and is a reason that early stealth aircraft were faceted as with the sharp lines were easier to predict where and in what direction the return waves would propagate. This has ironically led to many people thinking that faceted shapes are better for RCS, when in truth the opposite is true, however as stated earlier it is easier to model. This is why flat surfaces such as single vertical tail fins, and turbine blades are such big reflectors. The goal of any RCS is to reduce the amount of stuff making its way back to the emitting aircraft and being able to know exactly how the waves will travel is paramount to a successful RCS design.
To complicate matters further as I mentioned earlier when a wavelength is smaller than the object you are trying to detect than it will treat different parts of the aircraft separately however this can be modified by increasing the distance the wave can travel in a object. This is where the most critical part of any proper RCS effort comes into play. This is one of tolerances. See gaps are the ultimate emitter of waves since they have sharp edges, and break the electrical current flowing through the material thus drastically increasing the chance of emission. This is by far the largest contributor to RCS. It has also proved the bane of countries trying to develop stealth since it is very hard to have manufacturers that can achieve such tight tolerances and it isn't something you can just steal like the shape or RAM materials. Since a plane needs to have at least some moving parts being able to make them close to one another is paramount, having seems be almost non existent on a moving part is very hard. Most stealth aircraft require special tape to bridge the gaps especially the ones between materials with different electrical properties like those around the cockpit. This tape had to be applied every mission perfectly and was (and to some degree still is) the part that added the most to the Maintenance of aircraft like the F-117 and B-2. You can see a good example of this on the photo below of the TACIT BLUE aircraft which was one of the first stealth aircraft.

those dark area's around any hatches is the tape
As you probably well know part what is important is how the aircraft is structured and shaped, What isn't talked about is that most shapes that direct radar waves in a specific direction aren't the most conducive to good aerodynamics, thankfully for early stealth pioneers there are many materials that are very transparent to radar (such as the dome over most maritime radars). These materials can be used to smooth out the airflow and create a shape conducive to good flying characteristics (or even the ability to fly at all). Below is a good example of a photo showing the intricate sub surfaces on a aircraft control surface. You will notice that the underlying sawtooth shape would probably not be very aerodynamic but with the radar transparent leading edge the surface smooths out into the familiar shape you can recognize.

A great example of how the edges are smoothed over to create a clean wing
Another part that needs to be considered is that there are a wide range of radar wavelengths that can be used. What is a good RCS shape to one wavelength might matter a lot less to another frequency. This is why most broadband stealth designs are created and coated with materials the work to harmonize as many different wavelengths of radar as possible into a more cohesive waveform. This is mostly seen in third and fourth generation designs like the F-22 and F-35. You will often note the metallic sheen their paint tends to have and this is indicative of attempts to do this.

Stealthy paint
Not stealthy paint
There is one last effect that is worth noting and that is that if a wavelength is larger than the object then a effect know as Reyleigh Scattering happens and the radar treats the aircraft as one homogeneous aircraft and shape and angles no longer really mater to the return just the size and composition of the object. This is why many countries looking to develop counter stealth technologies often look at low frequency radar as it can get around the shaping of the aircraft as well as issues with things like gaps, though the effectiveness of RAM isn't changed. Ok so you are probably asking why people don't just use long wave radar, well there are two problems while long wave radar has great range due to the energy required for a given distance is proportional to the wavelength it also comes at the price of accuracy and also needing a large antenna to pick up any receiving signals since the reception of radar signals generally requires a receiver proportional to the wavelength. Also effected is resolution which means that knowing that something is out there is easier but knowing where it is, is much harder. The lower resolution can have other unhelpful effects such as combining many small objects (like a flock of birds) into one.

Lastly as alluded to earlier there is a hierarchy to the importance of design features. In general it goes like this. By far the most important one is tolerance of the parts and elimination of gaps. Then in a distant second is RAM and other coatings. Lastly there is shape though unlike the other two this is still required by some degree to any stealthy aircraft whereas you can go without the other two but with a much more easily detectable object. It illustrate this and to show how all of this starts to fit together look below at the four aircraft's. Now rank them in order of smallest RCS to largest.......Scroll down past them for the answer.
F-22A Raptor

Su-57 Felon
F/A-18E/F Block III Super Hornet
KF-21 Boramae (fighting hawk)
Ok good here are the results

1. F-22
   
2. F/A-18 E/F Block III
   
3. KF-21
   
4. Su-57
   

so how many of you thought that the KF-21 would be 3rd, or that the Su-57 would be last? This illustrates the importance of both keeping tight tolerances and in the heavy use of RAM and other skin (and some sub-skin) treatments. Both of the planes have shaping that is conducive to having a low RCS but are not able to match the 4.5 gen Superhornet’s latest version due to the latter's better tolerance control and increased use of RAM materials. This much has been admitted by the Korean government which has admitted that the Block one KF-21 which has no RAM and looser tolerance levels than they would have wished. They do plan on incorporating those as well as including a full internal bay rather than the semi-recessed hardpoints it currently has. This shows the difficulty in mastering those two elements since the South Koreans have a lot of experience building and even decent experience designing planes. The Su-57 is a bit of the different case. Teasing out the failings of the Su-57 has taken more work given the Russian government claims that its stealth feature are some of the best in the world. However pictures of the Su-57 during construction shows a complete lack of sub-surface shaping, as well as a lack of RAM coating on many surfaces that should have it. Furthermore riveting and screw attachment of parts are massive no no’s in stealth and the Su-57 has those in droves. Furthermore the engine's turbine blades are visible through the air intake something even the KF-21 avoids limiting the ability to actually improve the RCS. It also has clearly visible gaps at locations where they would significantly contribute to increasing the RCS. Lastly the paint on the plane does not exhibit any metallic properties meaning that it likely is derived from first gen stealth paint, most likely from samples of the F-117 that was shot down in the Balkans. Based on this and knowledge that tolerances have always been a weakness of Russian manufacturing (though in the past this was deliberate as low tolerances allow for more rugged machines) thus the Su-57 probably doesn't have a ton of RCS reduction and is probably on the level of the Eurofighter in terms of RCS.

Ok so now withe the brief overview out of the way you are probably wondering how Flyout's “RCS” system fits into all of this. The answer is not at all. There is almost no connection between the games determination and reality. This can be deduced by the lack of most properties that are needed to define RCS. Some of the notable ones needed are wavelength of the radar used and given radar itself isn't in game we know that's not yet on the table, the electrical conductive properties of a aircraft's paint and skin/structures are very important to any radar return modeling and so far materials used in game are purely cosmetic. There also is no RAM material and even how that works is highly variable in real life but even a massively simplistic implementation doesn't exist so we can cross that out. There also is no setting for tolerances of parts of the plane and given that is the most important contributor to reducing RCS the lack of all these features means that the game’s RCS has no real connection with how real RCS works. Lastly, I don’t expect there to be a accurate system implemented. This is due to the massive computing power needed to model the subtle interactions of radar waves with all of these factors. As mentioned before there is a reason faceting was used heavily in early stealth aircraft despite it being less than optimal. It would take several months of using 1970’s supercomputers specially programed to just do this calculation to get a RCS model for a given aircraft shape. Even then it had to have data from real world RCS testing added to achieve this. While computing power has exponentially increased since then the ability to actively simulate a planes RCS in real time, is still well beyond anything a desktop computer can do. Especially given you would need a completely custom engine just for that part. And none of what I have said touches on other parts that can contribute to RCS like degradation of RAM coatings, or the fact that the exhaust from planes in afterburner shows up on radar (this is due to the lower density of hot air coupled with changes in the airs natural radar absorbing properties due to being at a different temperature). So for everyone out there, don't worry about or look too far into the RCS of your stealth plane be as creative as you want. That being said it is possible that IR reduction could be better simulated in game and might be a possible thing to have added. Real RCS will likely be limited to at best massively approximated stand-in values. Though there is a way to achieve a real world stealth parameter which is visual stealth, ie cammo or other tech that reduces a aircrafts visual signature. Along with some tech (like the hole material that is fictional but renders the plane truly invisible)
Implementing the \"hole\" surface material to a plane in real life
On a side tangent I want to point out that the exhaust phenomenon is something that has effected all stealth aircraft and the main reason the A-12 and SR-71 had no real RCS reduction since the massive amount of air the moved through the planes engines meant they were usually spotted at the maximum range of whatever radar they flew near. And while on the A-12 they tried to eliminate this through a combination of using a cesium fuel additive(which did absolutely nothing), and plasma stealth to shield the air intake so the fan blades would not reflect (which apparently worked ok but used a enormous amount of power, led to airflow disruptions that made the engine both less efficient, even more prone to flameouts, and caused the formation of nitric acid and other corrosive compounds the hurt the engine.). For the reasons I just showed the cesium and plasma stealth systems were disabled on the A-12 by the time it entered its brief service and not used at all on the SR-71, which instead used it’s extreme speed, altitude and what can be argued was the most extensive ECM suit ever fitted to a aircraft at the time, to ensure that any missile that got close could be jammed.
Hope this helps people.

Firstly im not english and i will write quite a bit, so hope what i write is understandable.
I have had pain a long time, especially felt when pushing arm sideways supinated. i know alot of people have this problem, and i thought it was chronic by now. I got diagnosed by my doctor after having an ultrasound, and i had a version of Cubital tunnel syndrome. This week i magically fixed it in a wierd way in a 10 minute timespan. it seems like my CTS was just my nerve getting stuck in a position around the insertion point of the flexor carpi muscle, and it have been reliably stuck there for a long time. I have therefore had this "achy" and "inflamed" feeling at the spot showed by the first picture, as well as alot of sidepressure pain. Even just pushing the arm a little sideways supinated has been hurting for many many months, especially flaring up every time i armwrestle.
How i magically fixed it:
Believe me, i have tried alot of things, and especially the ulnar nerve flossing, which is this variation: https://www.youtube.com/watch?v=ieH5q3gt3yo
But this time i sat in my office chair and just started doing the nerve flossing again(the same as in videolink) as my arm was very achy at that point. I tried looking both ways while doing the exercise, and i started feeling small "pops" while releasing and pronating / supinating the arm. i had felt this before. On my second set i felt a big "pop", but area was still achy, all though i felt some immediate relief. Afterwards i sat in the exact position shown by the second picture for 2 hours (with a computer mouse in my hand), but with arms completely straight so the load is on the elbow. I also sit abit above my table.
This of course hurts a bit when you have this pain, as many of you may know that have had this pain. I decided to do this because i know it is optimal to have straight arms, and years of computer use has probably helped to cause this(is what i thought), so i did it even thought i feel some unease in my elbow doing it. After doing this for 2 minutes i heard another weird pop while working with the mouse, and pain immedietaly went away. i was somewhat shocked so i pushed a bit down on my elbow etc to figure out of it still hurts. It now hurt a lot less, so i kept pushing it a bit at times until another now small "pop" came yet again after maybe 7-8 minutes. I felt immediate relief in my pinky and ring fingers. I then decided to just sit like this now, in this exact position (second picture) for almost 2 hours. After the two hours i took my arm up and tried pushing it sideways supinated. NO PAIN, but elbow a little bit sore.
My theory now, without having talked about it with fysio or doctor, is that the side pressure from armwrestling (in a hook in my case) can pinch the ulnar nerve with the wrist flextion tendon connecting to the elbow, or potentially other soft tissues. nevertheless I finally feel strong again, and this worked for my specific case, where the pain is at the place shown in the first picture. Many times this seems to be fixable, and it is most likely an impingement of the nerve that you have to get into the right position to let loose.
second picture
first picture