Electro-Static Discharge Rods for Aircraft Wings

Electricity builds up on surfaces as a result of friction (triboelectricity) from airborne particles, such as the dust stirred up by helicopters or rocket exhaust, or it builds up as the result of receiving charge from another source, such as lightning. The result can be radio static that impairs intelligibility, or sparks that cause explosions during refueling or during such operations as cleaning the hold of a ship that hauls grain.

SRI's J.E. Nanevicz and his colleagues developed the device used on airplane wings to discharge static electricity as it is produced--say, by the friction of water droplets as the plane flies through a cloud--so that it does not build to levels that might cause radio interference or other problems. They developed a variety of other devices and techniques as well, to prevent explosions and occurrences such as the Apollo 13 disaster. In addition, their work added considerably to the body of knowledge of triboelectricity and its effects.

Although the design has since been modified many times by others, the initial electrostatic discharge (ESD) device for Boeing airliners was developed by SRI. Aircraft, spacecraft, and tankers (rail, highway, and marine) all now routinely carry static discharge devices.