I read a lot about 5th-generation aircraft, and one thing I noticed they do to induce stealth is through the usage of Radar-Absorment Material (RAM) coating & certain geometry. And I’m focusing on the latter.
What I know about these are…
* The geometry of these aircraft makes sure that as many surfaces of the aircraft reflect radar waves AWAY from the source. Via flat surfaces. Enemy radar waves of course.
* Engine blades & vanes give out a lot of RCS. (Which is what the Su-57 suffers from)
What I’m still confused is that…
* Flying wing stealth bombers (B-2, B-21) have curved shapes under them where radar waves are most probably going to be blasted to.
* Do radar waves need to have the least amount of times they bounce from each surfaces, that if, for instance, radar waves pointed towards the aircraft in such a way that it bounces 3 times on the aircraft before being reflected away from the aircraft at an angle of 70 degrees away from the incidence ‘ray’, it will increase the RCS of the aircraft?
* Does Point no. 2 the reason why canards are not preferred on stealth aircraft?
* Why is the vanes on the the YF-23 [not properly hidden from the front](https://data3.primeportal.net/hangar/howard_mason4/yf-23/images/yf-23_06_of_51.jpg), despite being deemed “stealthier than the F-22”? Or does it depend on the distance of the aircraft from radars to hide the vanes from radars via perspective?
In: Physics
RCS is calculated using standard radio frequency simulation techniques. You can load up your model into a sim and hit it with a bunch of frequencies at different aspects.
Curved surfaces also work for reflecting the RF away from the source. Doesn’t have to be a flat surface *per se*.
Reflections at joins can indeed be problematic for RCS reduction. In fact, this effect is used in certain decoys (called “corner reflectors”) and can be a cause of “glint” (where the reflected power spikes for a short period of time). If you ever go down to a marina and look at smaller seagoing boats (perhaps small fishing vessels) you’ll often see them with metal diamond-looking things high up; these are corner reflectors, to increase their signature on other ships’ radar.
Aspect does indeed matter. The production version of the YF-23 would likely have S-ducted those fan blades away, though. Remember that what you’re looking at there is a testbed, not a production platform.
In the broader sense, RCS depends on 5 things
– Materials from which the target is constructed
– Shape of the target
– Frequency of the radar
– Aspect angle
– Elevation
Which is why in real use-cases we don’t use a single number to describe an RCS. Instead, we plot diagrams (one for each frequency that we care about) which show the variation of RCS with aspect and elevation.
Radar Cross-Section (RCS) is a measure of how detectable an object is by radar. It quantifies the power reflected back toward the radar system and is an important factor in determining the detectability of an object by radar systems.
Here’s a simplified explanation of how RCS works and is calculated:
Reflection of Radar Signals:
When a radar signal encounters an object, part of the signal is reflected back toward the radar transmitter. The amount of signal reflected depends on various factors, including the size, shape, and material composition of the object.
Scattering:
The RCS is influenced by the scattering of the radar signal as it interacts with the object. The object’s geometry and surface features play a crucial role in determining how the radar energy scatters in different directions.
Calculation:
The RCS is typically calculated using mathematical models and simulations. Computational methods, such as the Method of Moments (MoM) or Physical Optics (PO), may be employed to simulate the interaction between the radar waves and the target object. These calculations take into account factors like the object’s shape, size, orientation, and the material properties of its surface.
Frequency Dependence:
RCS is often frequency-dependent. Different objects may have different RCS values at different radar frequencies. Stealth technologies, for example, aim to reduce the RCS of military aircraft, making them less detectable by radar systems across various frequencies.
Reducing RCS:
Designing objects with a low RCS is essential in certain applications. This involves shaping the object to minimize the reflection of radar signals, incorporating radar-absorbing materials, and employing other techniques to reduce radar detectability.
It’s important to note that RCS is a complex topic, and the actual calculation involves advanced electromagnetic principles and computational techniques. Engineers and researchers use sophisticated tools to model and predict RCS for different objects in various scenarios.
Latest Answers