Stealth Week

The Absence Is Noticeable: Yehudi Lights

During WW2, the British learned a lesson that modern submarine warfare would have to relearn decades later: absence is noticeable.

There is ambient light everywhere except in deep mines and caves. Our eyes may not always perceive that ambient light, especially during a new moon, but it’s there. And when it suddenly is not there in a plane-shaped spot in the sky, it does become noticeable.

This was the problem Shorts Sunderland submarine hunters faced in WW2. So, a solution was devised. Place lights on the underside of a plane that could be used to mask the plane against a “bright” night sky. Called Yehudi lights, it worked so well that even by 1945, despite the increasingly widespread use of radar, a Grumman Avenger was able to get within 3000 yards of a ship before being spotted.

Once radar became standard on aircraft, ships and even the ground, the Yehudi light found itself out of a job. However, the concept was revived in submarine warfare when it was found the Soviet submarines could track ultra-quiet American boats not by looking for a sound signature, but by looking for an area with an absence of sound.

[Image Credit: www.aircraftinformation.info]

  • OA5599

    Given the apparent total absence of prior comments, I presume something brilliant lurks above.

  • The Shorts brothers. Man, I love the names that are coming up in Stealth Week.

    • Deartháir

      I'm just loving Stealth week. So much cool shit is being dug up by everyone! The suggestions that have been coming in have been so cool!

  • coupeZ600

    Slightly off subject, but have any of you seen a "New Moon?" I've only seen two that I can recollect, and both were as I was staring right into the Sun. It's a bad habit, I know, but when you're a Night-Guy, that mysterious orb of heat tends to draw your focus (and then, "Hey, there's the Moon! It's New!)

  • Charles_Barrett

    As a sixteen year-old nerd watching Star Trek: The Motion Picture in the theater on its opening day, I was thrilled to see the Enterprise in drydock use floodlights to illuminate its registration designation on the hull. Sure, the old TV Enterprise had its blinky-blinky running lights, but how would you see the NCC-1701…? Of course, floodlights…!

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