The Truth About ‘Stealth Aircraft’ and Why They Are Very Difficult to Hide in the Sky

Stealth should be understood as a combination of technologies, designs, manufacturing methods, and combat tactics.

When discussing stealth capabilities, especially in relation to aircraft, it is not uncommon for people to view it as if stealth is a peculiar feature that fighter jets or bombers will either “have or not have.”

The reality is a bit more complex. However, the simplest way to think about it is as a combination of elements that delay or limit detection by adversaries, allowing an aircraft to survive longer.

Stealth is not invisible on radar

An F-35 takes off.

Famous stealth aircraft you may have heard of, such as the B-2 Spirit or F-35 Joint Strike Fighter, incorporate several features to minimize their visual signatures or ease of detection in the sky, but they are certainly not invisible.

Contrary to popular misconception, stealth does not actually make an aircraft invisible to radar. In fact, many stealth aircraft can be clearly seen on radar designed to exploit lower VHF and UHF frequency bands.

Therefore, the goal of stealth is not always to avoid detection… but rather to avoid being shot down.

The aspect of stealth that is most commonly understood is how it can defeat, prevent, or delay detection from enemy radar systems both on the ground and from enemy fighter jets.

Modern stealth programs take a multifaceted approach to this issue, utilizing advanced designs to deflect radar waves away from the aircraft, as well as radar-absorbing materials…

Stealth Design

An F-117 Nighthawk

Having a design specifically suited to deflect radar waves away from the aircraft is an intrinsic part of the fifth-generation fighter jet design trend, with the F-117 Nighthawk being the most highly regarded example.

The Nighthawk’s unusually angular appearance represents how today’s best computers have been able to calculate radar deflection. Meanwhile, the sleek and smooth design of the F-35 Joint Strike Fighter further demonstrates how far our computational power has advanced in this area. The F-35 features more curves than hard angles, but the design goal remains the same.

“The shape of the aircraft is designed to deflect radar energy away from the source like a tilted mirror,” stated Harold Carter, senior research scientist at Lockheed Martin, the manufacturer of the F-35. “Its surface is also blended and smoothed to allow radar energy to pass over it smoothly – similar to water flowing over a smooth surface.”

Radar Absorbing Materials

F-22 Raptor fighter jet.

However, design alone is not sufficient. The leading edge of the aircraft’s wings, air intake vents, parts of the vertical tail surface, and other components of the fighter jet tend to create radar return signals, and they cannot be eliminated through advanced designs.

As a result, you will often see radar-absorbing materials (RAM) used on these parts of the aircraft.

“RAM works on the principle that the aircraft absorbs electromagnetic wave energy to minimize the intensity of the reflected signal,” Adrian Mouritz wrote in the academic textbook “Introduction to Aerospace Materials.”

“It can reduce the radar cross-section of a fighter jet to that of a medium-sized bird, through optimal design and the application of stealth technologies.”

The RAM used by modern U.S. fighter jets is crucial, as it is rated to absorb up to 70%-80% of incoming electromagnetic energy. However, it is also expensive and time-consuming to maintain. Its high thermal handling capabilities can also be an issue, and it is even known to limit the supersonic speed capabilities of some stealth fighter jets.

Manufacturing Tolerances

A B-2 stealth bomber refueling in flight.

But if it were only about design calculations and RAM costs, it would not be as challenging to operate a stealth fighter or bomber. One of the least discussed yet most critical factors is the ability to manufacture them with extremely tight tolerances.

Even a small gap between the skin panels on a stealth fighter can make it more detectable on radar, so the assembly process for stealth aircraft is arduous, requiring a great deal of expertise and some quite expensive equipment.

“If the external structural parts of the aircraft are machined precisely to fit together with exceptionally small tolerances, then the stealth requirements can be met more easily,” Robert Jones wrote in a paper published by the Society of Manufacturing Engineers.

“This means that minimizing and nearly eliminating gaps between structural parts is highly anticipated in achieving the stealth characteristics of an aircraft.”

The ability to manufacture aircraft with extremely low tolerances is one of the ways the U.S. maintains its stealth advantage, even as competitors have begun equipping their own stealth aircraft.

After all, stealth capability is a broad concept, and the tighter your manufacturing tolerances, the lower the likelihood of the aircraft being detected.

For example, the stealthy F-22 Raptors manufactured in the 1990s and 2000s were built with manufacturing tolerances of about 1/10,000 inch. This sounded quite incredible at the time, but gaps still had to be dealt with using tape, shims, and RAM to maintain the aircraft’s stealth capabilities.

Today’s F-35s are said to be assembled with even tighter manufacturing tolerances, even according to “order scale.” However, it is not unusual to see potential gaps on the aircraft’s fuselage shielded by RAM.

Infrared and Electromagnetic Components

A stealth F-35 aircraft

Modern stealth aircraft must not only contend with enemy radar, and thus, modern stealth programs must also limit the infrared and electromagnetic signatures of the enemy’s jets.

An easy way to conceptualize the infrared signature of an aircraft is the heat it generates. The hotter something is, the easier it is to see, track, and potentially shoot down. Of course, the problem is that we power our stealth aircraft by mixing air with fuel and creating an explosion… and explosions are generally quite hot.

To mitigate all that heat, stealth aircraft typically position their engines deep within the fuselage with shrouds around the exhaust openings to dissipate heat as it radiates. This approach also helps reduce the sound and visual signatures of the aircraft, or simply its noise level and ease of detection in the sky by the naked eye.

Therefore, comprehensive research and design of the exhaust system is very significant for the stealth performance of the aircraft. However, not all “stealth” aircraft effectively shield their engines. But that does not make them non-stealthy; it merely means they lack these stealth features and move closer to the threshold of being “detectable.”

But that is not the end of the stealth story, as modern stealth aircraft also leverage electronic warfare systems designed to interfere with detection or even nearby communication devices. Because even a “stealthy” fighter jet can still be detected in various situations, sometimes stealth means taking a proactive approach to survive.

Stealth Tactics

A U.S. Air Force pilot climbing into an F-22 Raptor.

Ultimately, even with all the stealth features you can pack into an aircraft, the job is not done. U.S. pilots spend countless hours planning their combat operations to ensure they are operating with a greater advantage whenever possible.

This means using terrain maps, known enemy positions and equipment, as well as understanding your aircraft to develop plans that minimize exposure to enemy defense systems.

It also entails creating strategies for how to evade if an incident occurs, without sending a $100 million stealth fighter into the danger zone.

But after all, as Ward Carroll, the Radar Intercept Officer (RIO) on the famous F-14 fighter, once shared: “Stealth doesn’t work against bullets.“