Stealth technology

:For the 2005 movie, see Stealth.

Measuring stealth

The size of a plane's image on radar is measured by the Radar Cross Section or RCS. Imagine a metal plate of area A square metres held perpendicular to the beam of radar transmitter. It reflects most of the radar energy back to the source, and thus is easily detected. It is said to have an RCS of A square metres. If you rotate it, the amount of energy reflected directly back to the transmitter is reduced, as some is reflected to the side, so the RCS is reduced and the value will be less than A. Modern stealth aircraft are said to have an RCS comparable with small birds or large insects, though this varies widely depending on aircraft and radar.

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The RCS is not directly related to the aircraft's cross-sectional area; if it was, the only way to reduce the RCS would be to make the aircraft's physical profile smaller. Rather, by reflecting much of the radiation away or absorbing it altogether, the aircraft has an effectively smaller radar cross section.

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