EMIT - Questions And Answers

ESD on helicopter. As you already know that helicopter generates thousand of volts of ESD, 400K Volts on the one I'm working on. Questions:I have a device that is lower down to the water from the aircraft with a cable attaching the device and the helicopter. As soon as I lower the device in the water, ESD will discharge thought the device and to the water, which will damage some the electronics inside the device. Do you have any source regarding ESD on helicopter or any idea that I can do to protect the electronics inside the device when it hit the water. Thanks - Anonymous, Panama City, Florida

Your inquiry is rather intriguing. In lieu of completely shielding the device, your best alternative is to set down a separate conductor (weighted wire) from the helicopter to in essence ‘ground’ the aircraft or bring the craft to the same potential as the water. You can then safely set the device into the water without fear of discharge assuming the wire and device are at the same potential as the aircraft (via conductive cable). Another alternative, would be to put a bleeding resistor in series from the device to the water via a cable to control the rate of discharge from the device to the water as it is lowered in. This would look something like a tail hanging from the device to touch the water first, removing charge from the device through the bleed resistor. As long as this is the only conducting path from the device to the water, it should work.

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