Ball Lightning

The weather was good the day of the first test. There was practically no wind at ground level in the early morning. Everyone involved in the project was at the test site. We were few in number: just twenty-odd engineers, staff, and ground crew. An ambulance was parked not far from the helicopter pad, the medics in their snow-white uniforms conspicuous in the dawn light. I had an odd feeling, and got a vague sense of fear from the two empty stretchers sitting on the grass. But the men who might be carried on those stretchers before long were standing beside them joking easily with the two pretty nurses they’d just met. My sense of inferiority came welling up again. The stormy night that had decided the course of my life had given me a far deeper fear of death than most people.

Lin Yun came over with two yellow jumpsuits for the pilots to put on. “These shielded uniforms are from the municipal power bureau, where they’re worn by workmen doing jobs on live high-tension wires. They’re shielded using the principle of the Faraday cage and will offer some protection against lightning.”

One pilot laughed as he took the shielded uniform and said to Lin Yun, “Don’t worry, Major. Your little electric arc won’t be any worse than a Stinger missile.”

Lin Yun described the test procedure for them: “First, ascend to five thousand meters, and then bring the two craft as close together as is safe. When you’re at that distance, ignite the arc, then gradually separate the two craft and hover just under the arc’s maximum range. Then fly forward at the speed given by the ground commander. Pay attention to arc stability and hover if you need to—you’ve done that before. One more thing to watch out for: if the arc goes out, then disengage as fast as possible and turn off the generator. Don’t try to reestablish the arc, since if it’s ignited at long range, it may strike the aircraft! Make sure you remember that. Don’t die a martyr.”

According to the plan, the helicopters would fly with the wind to minimize the relative airspeed. Then they would ignite the arc and fly for a while until it went out, at which point they would come back and repeat the process.

The test helicopters quickly ascended to the predetermined altitude. At this point we had to use binoculars to see them. They flew with the wind and drew closer to each other until it looked from the ground like their rotors were practically touching. Then a bright electric arc appeared between the two craft, projecting a dim yet crisp popping sound down to earth. The helicopters slowly separated, and the arc stretched out, its initial straight line becoming more turbulent as the distance increased. At maximum separation, it seemed like a piece of light gauze dancing on the wind, liable to slip its bindings and fly off into the sky. The sun was still below the horizon, and the bright blue-purple electric arc looked unreal against the dark blue of the sky between the helicopters’ black silhouettes, like the projection of scratched film on a cinema screen.

I had a sudden chill, my stomach tightened, and I began shivering uncontrollably. I set down the binoculars. With the naked eye, all I could see was a blue dot high in the sky, like a nearby star.

When I picked them up again, the helicopters were flying forward at maximum separation, taking with them that dancing, hundred-meter electric arc. Their speed was so low that it was only by comparing them to the thin high clouds, lit by the sun below the horizon, that you could tell they were moving. As they flew east, their sunlit bodies turned into two orange dots, and the arc dimmed slightly.

I exhaled, but then heard shouts from the binocular watchers beside me. I grabbed up my own pair to catch the scene: on the receptor side, the arc had forked. Its main branch still contacted the electrode, but a smaller branch moved erratically along the helicopter’s tail like it was a thin hand searching for something. It lasted only three or four seconds, and then the arc went out altogether.

The situation didn’t look scary and seemed unlikely to have any disastrous consequence on the helicopter. But I was wrong. The instant the arc vanished, I saw a bright light in the tail rotor. It vanished immediately, but then smoke appeared at that spot, and shortly after, the helicopter began to rotate, faster and faster. Later I learned that the lightning had struck a control line for the tail rotor, causing it to stop. Since that rotor was used to balance the rotational torque generated by the main rotor, once it lost power, the helicopter began to rotate in the opposite direction from the main rotor. Through the binoculars I saw the rotation accelerate and the helicopter gradually lose lift, then start a shaky fall.

“Bail!” Colonel Xu shouted into the radio.