Recent news has led to a few questions being raised as to what makes a stealth aircraft and how effective stealth really is. I’m going to attempt to address these issues and hopefully inspire some creativity in your builds.

Although, I admit this piece probably contains a bit of opinion on my behalf for reasons that’ll become evident.

Background

Stealth in aircraft is a phrase commonly used to describe an aircraft’s ability to avoid radar detection. Although this is perhaps misleading and a better way to describe stealth in aircraft as an attempt to delay detection.

The F-22 was the first aircraft to enter production where the integration of stealth was a priority item and because of this radical difference between it and its contemporaries amongst other small differences, it landed it the title of being a “5th generation plane”.

Although, admittedly, this is more of a marketing term than something that can be easily defined. Especially, when companies making stealth planes change the definition depending on what their latest aircraft can or rather can’t do.

I’m looking at you Lockheed and your removal of supercruise in your definition.

As a result, it’s actually surprisingly hard to define what a 5th generation plane is due to how volatile and vague the definition is. So it shouldn't come as a surprise that it's basically just a marketing buzzword than something that holds any real weight to it.

So, instead of defining what a stealth aircraft is, we’re going to look at arguments surrounding planes not being “5th generation” and their validity.

What is Stealth

First of all, stealth comes in a surprising amount of shapes and sizes. Examples of stealth in aircraft can be related to its camouflage, size (smaller being generally harder to see visually and on radar) and if you’re Russia, making a plane transparent. Because why not.

But, for the context of this article we’ll be looking at how a normal plane can become stealthy by incorporating some design techniques:

RAM (not the stuff you use in your computer)

RAM or radar absorbent material is basically what it says on the tin. Traditionally, aircraft use metallic materials as a major part of their construction, such as aluminium, steel and titanium (along with their alloys). However, while these materials were generally preferred for their strength and in some cases weight too, they don’t hold up well when it comes to not reflecting radar.

Using metal on an aircraft is the stealth equivalent of bouncing sunlight off your watch and onto the ceiling for the amusement of yourself and fellow classmates, as well as the disappointment of your teacher. Clearly, this is a problem if you wish to remain stealthy.

Introducing composite materials. These being your usual fibreglass, carbon fibre, etc. These materials by contrast generally let radar pass though them, which is why they’re commonly used on radomes. Otherwise it would be a bit pointless putting a radar on your plane if the only thing it did was show yourself. Or maybe your plane likes that. Who am I to judge?

Planform Alignment

Planform Alignment on an F-22

Planform alignment is a fairly simple concept, but quite difficult to implement in practice to to the precision and amount of it involved.

Planform alignment is -as the name suggests- the alignment of surfaces so that they run parallel to each other and is generally speaking, the defining feature of a stealth plane. This ensures that any radar reflection is reflected back within a certain range, reducing the size of the signature. Misalignment or no alignment means the radar reflection range is greater and thus the radar signature is greater too. Generally, this technique is combined with another that includes the avoidance of right angles.

Right angles on an aircraft where radar detection is concerned is very much like shining a light at a bicycle reflector. The electromagnetic waves bounce directly back towards the source they were emitted from. So, you’ll be hard pressed to find two surfaces perpendicular to each other on a stealth aircraft.

The Effect of RIght Angles on Radar

With all that in mind, let’s dive into the meat of the arguments proposed by some “news” articles and even military spokesmen:

The SU-57 isn’t a 5th Generation Aircraft

The SU-57

The short answer is it objectively is. And if it isn’t, we should be taking a hard look at both the F-22 or the F-35 depending on how we define it.

“The SU-57s stealth isn’t good and thus it isn’t a stealth plane.”

The short answer is that this is false.

First of all, there isn’t really a set threshold on where 4+ generation stealth ends and where 5th generation stealth begins. However, as alluded to before, the SU-57 does utilise the defining feature of a stealth plane. Planform alignment. It also utilises RAM.

How well both of these features are implemented is subjective to which aircraft you compare it to and how much speculation you’re willing to throw in.

In fact, saying the SU-57 isn’t stealthy insinuates that the SU-57 isn’t stealthier than its predecessors, like the SU-35, which is largely regarded as an exceptional 4th generation aircraft with some stealth characteristics. It seems odd that a country would throw so much money into developing a plane that’s just on par with existing aircraft they already have.

“It can’t supercruise.”

Technically speaking, neither can the F-35. At least not for long durations as it damages the engine and was likely the driving force behind why Lockheed changed their definition on what makes a 5th generation plane.

Even then the aircraft’s new Izdeliye 30 engines (which are currently being tested) will grant the SU-57 supercruise ability.

For those of you that don’t know, supercruise is an aircrafts ability to go supersonic without the use of afterburner.

“It’s data linking capabilities aren’t the same as the F-35s”

I admit, if I wasn’t qualified for a response before, I’m certainly not now. But I’ll do my best to explain this one. Data linking is a form of sensor fusion. The ability to link different strains of information from various sources and present this information to the pilot in a digestible form that doesn’t overload the pilot with information.

As I understand it, data linking on the F-35 is sensor fusion on steroids that allows the aircraft to send and receive data not only within the aircraft, but also to and from surrounding compatible systems. It’s what makes the F-35 such an attractive plane to air forces, as the implications of such technology have a huge impact on your capabilities. You can command drone swarms, share data between yourself and systems on the ground as well as with other aircraft in the surrounding area. If information grants a key to winning a war, then the F-35 is a game changer.

However, as I currently understand it, the F-22 does not have this capability. At least not to the extent the F-35 does. Meaning, if the SU-57 isn’t a 5th generation aircraft because it doesn’t have comparable data linking technology, then like it or not, the F-22 has to be booted out the group as well.
Which seems rather ironic really.

To conclude the SU-57 is undeniably a 5th generation aircraft. Not because it’s better than the F-22 or F-35. But because saying it isn’t for the reasons mentioned above effectively means there are no 5th generation aircraft. Anything to the contrary presents a double standard.

The J-20 isn’t a 5th Generation Aircraft

The J-20

“C a N a R d S.”

For those of you that don’t know canards are for some reason, regarded as a terrible design decision for how stealthy an aircraft is. In fact, it was this very argument that triggered me into writing this article.

If you’re like me from a few years ago, then you’re probably sitting there feeling a little disappointed that the “stealth plane” you designed in SimplePlanes isn’t as stealthy as you thought it was. But fear not, for I -the squirrel in shining armour- am here to revive your inner designer.

Long story short, the argument against canards in stealth planes basically boils down to “other stealth planes don’t use them so they must be bad.”

That’s literally it.

I’m actually disappointed that this on its own is even considered a legitimate argument.

After searching for hours and going back through my own experience in learning about aircraft at uni and in industry (albeit limited industry experience), I couldn’t find a single shred of information that backs up the idea that canards aren’t stealthy.

But even then, the argument that no other stealth aircraft has this design detail is a bit flawed too.

Introducing the X-36. While not a full-blown piloted aircraft, it is widely regarded as an exceptional airframe design where agility and stealth are concerned. And this airframe does indeed have canards slapped on it. It’s also got the NASA approves sticker slapped on the side, so it must be good.

The X-36

Additionally, if the YF-23 was converted to a naval variant, it’s largely speculated that it too would have canards. Furthermore, the Mig 1.42 was touted to have a similar RCS to the F-22. Although, I found it difficult to verify the accuracy of this statement.

Regardless, it’s pretty clear that canards are frequently looked at when designing a stealth plane which reinforces the notion that they don’t negatively impact stealth to the extent that’s implied. Which makes sense since canards are basically repositioned elevators.

That said, I’m not a top-secret aircraft designer, I just help design modifications to aircraft, so maybe I’m missing a trade secret.

But for now, at least, there doesn’t seem to be anything concrete stopping you from putting canards on your stealth plane.

Next Post: Aircraft Configuration: Part 1 (Introduction and The Basics)
Previous Post: Engine Types: Part 5 (Wankel Engines)