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Stealth CFSGT Davidson

Stealth is any design concept, which aims to reduce the ability of sensors to

detect, track and attack the stealth aircraft. The earliest known origins of stealth

being used in aircraft is in WWI, where aircraft were painted in camouflage to

blend in with ground clutter, and some aircraft were even covered in clear

material. Since then it has lead to more advanced aircraft such as the Horton 229in WWII, to the f-117 nighthawk in desert storm, right up to aircraft in existence

today such as the f-22, PAK FA t-50 and f-35. As technology to detect aircraft has

increased, so to has the extent to which stealth technology has been

implemented.

Today, stealth technology in aircraft focuses on 4 key areas;

Radar Cross Section reductions Acoustics Visibility; and

Infra Red

To improve these 4 areas, a number of technologies have been invented over the

past 70 years.

In an effort to minimise radar cross sections, many technologies are combined in

a symbiotic relationship. The main technologies behind radar cross-section

reduction are airframe shape, non-metallic airframes and radar absorbing

material.

The major radar reflector in airframes is the vertical and horizontal stabiliser.

This is because they form orthogonal metal plates (they form right angles withthe airframe). In an effort to stop this, modern stealth aircraft have implemented

v-tail configurations, or even gone as far as removing the tail completely (in thecase of the b-2). Other technologies in airframe shape that reduces visibility to

radar include re-entrant triangles in the internal structure, which bounce radar

signals around inside of them, the removal of sharp edges, double-w edges on

areas such as landing gear doors, bomb bays and engine exhausts, and the

blending of the engines into the body of the aircraft. Non-metallic materials are

used as they increase radar absorption and in addition to this radar absorbant

materials such as gold tinted canopies also boost this effect.

Acoustics simply mean keeping the aircraft as quiet as possible through limiting

things such as engine noise and speed (staying subsonic to prevent a sonic

boom). This however, is not always a huge design factor, as is the case with the

SR-71 Blackbird.

The most simple technology to limit visibility is the use of camouflage paint

schemes on the airframe, however much more advanced technologies are

available such as the contrail detector in the B-2, which alerts the pilot if a

contrail is detected and advises of a new height to fly at. Yahudi lights have also

been a hot topic of discussion for future stealth aircraft, having proved

themselves so well in WWII.

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Exhaust plumes in aircraft contribute to a very large infrared signature. As such

stealth aircraft are designed to hide the exhaust from sensors. This can be done

by designing the exhaust to be non-circular, placing the exhaust vents on top of

the fuselage (as with the B-2), injecting cool air into the exhaust and pumpingcoolant around the engine. These methods help to eliminate infrared signature to

both enemy ground and enemy air forces.

As has been demonstrated, designers go to significant lengths to design aircraft

with stealth characteristics. With the increases in technology methods of

concealing aircraft will only become more complicated, however under Mooreslaw the processing power of radars will always develop quicker than that of

stealth technologies and will eventually lead to the ultimate demise of physical

stealth characteristcis.