Many peoplehave never flown in a helicopter and consider them playthings of the rich. Butthese vertical-takeoff, vertical-landing aircraft impact our lives in many surprisingways.
"Thepublic isn?t aware of all the things helicopters do that affect their lives ona daily basis," said Matt Zuccaro, president of the Helicopter Association International (HAI).
Intensiveuse of helicopters by the offshore oil community also benefits the public."Helicopters provide a major contribution to the oil industry in producingand delivering in a timely manner the petroleum products that we use everyday," said Zuccaro.
They canhave a positive environmental impact. The U.S. timber industry often uses largehelicopters such as the Boeing 234 Chinook to lift logs from remote sites,"obviating the need for cutting logging roads," he said.
But theirability to take off and land vertically in city centers or inaccessible placescomes at a price. Helicopters are noisy, relatively slow and fuel-hungry. Theyare expensive to operate and haven't yet proved suitable for city-to-cityservice.
HAI's"Fly Neighborly" program, used successfully in New York for years,ensures that helicopter operators consult with communities to locate heliportsand develop routes in ways that minimize the environmental impact of theiraircraft.
One area inwhich manufacturers are concentrating their technological development effortsis in reducing the aerodynamic noise made by helicopters' main and tail rotors.Aerodynamic noise is responsible for most helicopter noise that people on theground hear.
Manufacturersare now designing new helicopters with four or more main rotor blades. Thisavoids the distinctive chopping noise that the older, twin-bladed Bell UH-1"Huey" helicopter makes, which can be heard miles away.
Meanwhile,Eurocopter uses a technology called the "fenestron" to reduce thenoise made by tail rotors. The tail rotor produces a small portion of ahelicopter's lift, but its main roles are to prevent the helicopter's fuselagefrom spinning around (by counteracting the torque produced by the main rotors)and to provide side-to-side control of the aircraft.
Thefenestron is a tail rotor enclosed within a duct and positioned in line with the fuselage. This reduces noiseand improves safety. Eurocopter also spaces its helicopters' tail-rotor bladesunevenly, reducing "phase modulation" effects to make the tail rotorsquieter and more pleasant-sounding.
Manufacturersare now using composite materials in helicopter fuselages and rotor blades tomake their aircraft lighter and more fuel-efficient. But what preventshelicopters from going faster is "retreating blade stall."
Activeblade control is also being studied closely. This technology seeks to controlindividually the angle at which each rotor blade meets the air during each partof the rotation cycle, rather than controlling the angle communally by means ofa "swash plate" attached to the rotor hub, as happens now.
Anotherapproach, being flown experimentally by Piasecki Aircraft on the X-49A (amodified Sikorsky UH-60 helicopter) is to make the tail rotor a "vectoredthrust ducted propeller" that faces aft and drives air past a rudder andtailplanes.
Increasingly,organizations are realizing the benefits helicopters can offer. At the recentHeli-Expo show in Orlando, nearly $700 million of orders were placed. "Theindustry is extremely healthy," said Zuccaro.
