"KOPP-ETCHELLS EFFECT"

In fact, the Kopp-Etchells Effect is a new name. The Kopp-Etchells Effect was named after two soldiers, Benjamin S. Koop (U.S. Army) and Joseph Etchells (U.K. Army) who died in Afghanistan in July 2009, by Michael Yon (a former Green Beret and now a independent combat journalist ) .

The Kopp-Etchells effect is a result of dust striking helicopter blades as they take off or land at night, causing a bright 'halo' effect around the spinning rotor disk. When helicopters pass through dust storms, contact of the particles with the rotating blades produces either sparks or static electricity.

The electro-luminescence captured by Michael Yon is a phenomenon I'm sure most helicopter pilots and crews are familiar with. It might be akin to St. Elmo's Fire. The phenomenon has been observed during combat operations in Afghanistan; Michael Yon has documented the effect in the CH-47 photos below.

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Helicopter pilots didn’t have a name for the effect, but one explained to Yon, “Basically it is a result of static electricity created by friction as…dissimilar material strike against each other. In this case, titanium/nickel blades moving through the air and striking dust.” Yon says, however, that a researcher studying helicopter brownout emailed him to say that scientists are not 100 percent sure what causes the effect. Depending on the viewing angle, it creates dazzling little galaxies.

If anyone has photos of this effect on Air Force helicopters we would like to add those photos to our website.