Yehudi lights are lamp

Lamp (electrical component)

A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity. These components usually have a base of ceramic, metal, glass or plastic, which makes an electrical connection in the socket of a light fixture. This connection may be made...

s placed on the underside or wing leading edge of an aircraft

Aircraft

An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...

 to raise luminance

Luminance

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for luminance is candela per square...

, to disguise the aircraft against the background sky. The technique was successfully employed in World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 by RAF

Royal Air Force

The Royal Air Force is the aerial warfare service branch of the British Armed Forces. Formed on 1 April 1918, it is the oldest independent air force in the world...

 Short Sunderland

Short Sunderland

The Short S.25 Sunderland was a British flying boat patrol bomber developed for the Royal Air Force by Short Brothers. It took its service name from the town and port of Sunderland in northeast England....

 aircraft in attacks on U-boat

U-boat

U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...

s.

In 1945 a Grumman Avenger with Yehudi lights got within 3000 yards (2,743.2 m) of a ship

Ship

Since the end of the age of sail a ship has been any large buoyant marine vessel. Ships are generally distinguished from boats based on size and cargo or passenger capacity. Ships are used on lakes, seas, and rivers for a variety of activities, such as the transport of people or goods, fishing,...

 before being sighted. This ability was rendered obsolete by the radar

Radar

Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...

 of the time. Since the development of stealth technology

Stealth technology

Stealth technology also termed LO technology is a sub-discipline of military tactics and passive electronic countermeasures, which cover a range of techniques used with personnel, aircraft, ships, submarines, and missiles, to make them less visible to radar, infrared, sonar and other detection...

, Yehudi lights have come under renewed interest.

External links

• NRDC Report entitled "Visibility Studies and Some Applications in the field of Camouflage" contains a detailed history of the Yehudi lights project
• Skunk Works Digest