Myth busting: Is a stealth aircraft unnecessary?

That's the thrust of many critics today.  They contend that "low observable" or "stealth" isn't all it is cracked up to be and costs to much for too little effect.

So you see various critics saying that instead of concentrating on stealth, aircraft designers should be putting that money into more simple but effective systems.

You also see statements like this by those who think stealth is a waste of money as a means of justifying their recommendations to drop the stealth requirement:

In any case, detection by radar matters less and less because by switching on its radar a fighter becomes as visible as someone turning on a flashlight in a dark room.

Is that true? Well, that depends on the radar and the fighter, which is what you're never told. And in the case of F-35, that's simply not the case as explained here:

F-22 and F-35 AESA radars are of the very latest generation of Active Electronic Scanned Array (AESA) systems. AESA’s are such a good idea, ‘4th Gen’ aircraft makers (including LM with the F-16) are scrambling to field AESAs on older aircraft. Installations on older designs can be problematic from a power/cooling perspective so there may tend to be more trade offs in radar performance to make the newer radars compatible with older systems, but that is beside the point. The point is, there is a tremendous effort going on to come up with ways that would make AESAs more ‘detectable’ because finding them, tracking them, and locking on to them is for all practical purposes, nearly impossible to do reliably. And that my friends is NOT at all the same as becoming “as visible as someone turning on a flashlight in a dark room”.

The point of stealth or low observable technology is not to make the aircraft invisible, but instead make it hard to detect and lock on too.  One way to do that is to equip it with a radar system that doesn't light up the aircraft like "turning on a flashlight in a dark room".

Here's a little ground truth on "stealth":

Stealth is worth it as long as it doesn’t completely compromise everything else. Otherwise one breakthrough and you are a sitting duck with your very expensive white elephant (please excuse the mixed metaphors).

Therefore, we shouldn’t think of stealth as a be all and end all. Rather, we should think of stealth as a form of passive radar countermeasure. It means that even if the airborne attacking adversary has long wave radars that will tell them roughly where their targets are, they no longer have the option of a long range shot with a BVR missile, because the stealth effect has reduced its detection range enough to make it less useful as a fire and forget weapon.

Those two paragraphs sum up the most important points about low observability or stealth. If the passive countermeasure of stealth keeps an enemy from "locking on" because its weaponry can't get a good target resolution, then the stealth aircraft survives where another aircraft of the 4th generation most likely is engaged and defeated.

That allows the stealth aircraft the ability to penetrate deeper into enemy territory to fulfill its mission.  Stealth reduces the effectiveness of enemy radar by shortening its range and ability to command large portions of the sky.

As for the acquisition radars in aircraft like the F-35, they too make detection much more difficult - by design.  Obviously potential enemies will do all in their power to develop technologies to detect low observable aircraft, but that's the nature of warfare.  Point/counterpoint.

The bottom line is our potential enemies are very involved in developing 5th generation stealth fighters of their own. One must assume they too see the utility of low observability for survivability and mission accomplishment in the future.  It is probable that if there were a real option that didn't involve the high cost of making an aircraft stealthy, someone would be pursuing it.

@Graff48099375