Quieter Copters

Posted on 30 July 2009

By Karl Grossman

A few weeks ago, after another weekend of raucous noise from the helicopters ferrying people between the Hamptons and Manhattan, I heard a guest on National Public Radio talking about how helicopters can, in fact, run quietly.

What’s that? The conventional thinking is that choppers are noisy, period, and the only relief for folks on the ground is their flying much higher or out over the water.

But James R. Chiles, interviewed on his book on the history of helicopters, was talking about a helicopter called the “Quiet One.” As he described it in his book—which I quickly obtained—“probably the quietest turbine helicopter ever fielded was the limited edition Hughes 500P, dubbed the Quiet One” used by the CIA “for a secret mission to wiretap North Vietnamese telephone lines in 1972.”

 “How quiet was the 500P?” he asks in the book. The “average person would not hear the Quiet One when it was 500 feet above his neighborhood.”

If only the helicopter industry, I thought, would be subjected to the same kind of pressure applied by the federal government to the airplane industry, also because of noise, which resulted in a new generation of much quieter jet aircraft. Or maybe helicopter manufacturers could produce quiet helicopters voluntarily.

Mr. Chiles writes about the “Quiet One” not only his book, The God Machine, From Boomerangs to Black Hawks: The Story of the Helicopter, but in a March 2008 article in the Smithsonian Institution’s Air & Space Magazine (available on-line) in which he provides even more detail.

He begins noting—as folks on eastern Long Island are quite familiar because of the Hamptons choppers—how “a helicopter is a one-man band, its turbine exhaust blaring a piercing whine, the fuselage skin’s vibration rumbling like a drum, the tail rotor rasping like a buzzsaw.”

But then there was the “Quiet One.” He quotes “Don Stephens, who managed the Quiet One’s secret base in Laos for the CIA” as saying, “It was absolutely amazing just how quiet these copters were. I’d stand on the [landing pad] and try to figure out the first time I could hear it and which direction it was coming from. I couldn’t place it until it was one or two hundred yards away.” And he also quotes “Rod Taylor, who served as project engineer for Hughes, [saying] ‘There is no helicopter today that is as quiet.’” That’s an understatement.

Mr. Chiles explains: “The slapping noise that some helicopters produce, which can be heard two miles away or more, is caused by ‘blade vortex interaction,’ in which the tip of each whirling rotor blade makes tiny tornadoes that are then struck by oncoming blades. The Quiet One’s modifications included an extra main rotor blade, changes to the tips on the main blades, and engine adjustments that allowed the pilot to slow the main rotor speed, making the blades quieter.”

He writes that the “idea of using hushed helicopters in Southeast Asia came from the CIA’s Special Operations Division Air Branch, which wanted them to quietly drop off and pick up agents in enemy territory.”

By the time the quiet choppers were ready, the Vietnam War was nearly over and their only mission involved dropping commandos to place taps on the North Vietnam phone lines. Then, after the war, “no more were built.” And the near-silent chopper “remained a secret for more than two decades,” until a 1995 book, Shadow War.

A reader of Mr. Chiles’ on-line Air & Space Magazine article asks: “why” doesn’t the helicopter industry make “less noisy helicopters now” as long as “the technology exists?” That is an important question not just to us on eastern Long Island but to others around the nation besieged by helicopter noise (another focus in the Chiles’ book.)

I called the offices of some of the public officials—Congressman Tim Bishop, Suffolk County Legislator Edward Romaine, Senator Chuck Schumer—involved in trying to do something about the Hamptons helicopter racket. Their staffers, like I had been, were not familiar with the technology mastered decades ago of producing extremely quiet helicopters.

If only now the helicopter industry could do it again.

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