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Stealth - How Does it Work? (Northrop B-2 Spirit)

The B-2 Stealth Bomber is probably one of the most iconic planes to have ever been built.

It’s sleek flying wing design makes it practically invisible to radar and incredibly fuel efficient.

Allowing it to penetrate even the most sophisticated of enemy defenses, but how did this incredible

aircraft come into existence and what technological advancements made it possible?

The rise of stealth aircraft can be tracked back to World War One, when the Germans attempted

to use transparent canvas to make their planes difficult to spot. That plan backfired, as

the glossy canvas made the aircraft even more visible in sunlight.

The demand for stealth aircraft, as we think of them today, rose with the advancement of

practical radar technology in the late 1930s. The technology formed the backbone of Britain’s

early warning system during the battle of Britain, saving uncountable lives from German

bombing runs. Let’s see how the technology works.

Radar works be sending short pulses of electromagnetic energy in the form of radio waves outwards,

the antenna then switches to receiver mode and waits to detect the reflections of these

radio waves off distant objects. The radar now receives a blip on the screen called a

radar cross-section and it’s size changes with the magnitude of radio waves returning

to the antenna. The Radar Cross-Section is a measure of how

detectable an object is with radar. The size of the object is just one factor and can be mitigated with clever engineering.

The B-2 has a 52 m wingspan, yet it has been reported to have the same radar cross-section as a large bird. So how does the B-2 manage to

achieve this incredible feat? The core concept behind the B-2 is reflection.

It was designed to reflect the radio waves away from the source, so that they never get

the chance to be detected. What is amazing is that every surface of the B-2 has been

designed with this in mind. The aircraft was designed with the aid of computational models

and a supercomputer, which resulted in an incredibly complex curved shape. This technology

was not available during the development of the F-117 Nighthawk, resulting in its much

simpler faceted flat panels. The B-2s radar cross section is further reduced

by its streamlined flying wing design, with its highly reflective engines embedded within

the aircraft where radar cannot see them. Even the engines air intakes and exhaust vents

are located on top of the plane to ensure they cannot be detected by ground based devices.

But the flying wing has some unique flying characteristics that took many years for Northtrop

to perfect. One of the most notable is the lack of a tail rudder to control yaw. The

B-2 instead uses a split rudders, on the tips of the left and right wing. They act as airbrakes

to slow either side of the wing and cause a yawing motion. But, when in use, split rudders

can increase the radar cross section of the plane and so the B-2 can also use differential

thrusting of its left and right engines to allow it be controlled when stealth is a priority.

Beyond its shape the B-2 is also made with advanced composite materials capable of absorbing

and dissipating incoming radio energy. The exact composition of the B-2 is classified,

but we know that the skin is made from a carbon fiber reinforced plastic, while the leading

edge of the B-2 is likely painted with a paint which contains small particles of iron, which

absorb electromagnetic energy and converts it to heat.

With these technologies combined the B-2 barely even registers on radar screens. What is even

more terrifying to think about is the fact the Nazi ’s had created a very similar plane

all the way back in 1944. The Horten 229 incorporated many of the same principles as the B-2, long

before the stealth technology that made the B-2 possible was fully understood. Today,

we can only imagine what the impact this plane would have had, if it was ready before the

wars end.