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since its introduction three decades ago

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the helicopter has been a valuable

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more recently the tilt rotor aircraft

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has demonstrated it can do almost

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everything the helicopter does and more

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including flying like a fixed-wing plane

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as our airports and air space become

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more congested and the demand for

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short-range commuter flights grows the

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appeal of rotorcraft is becoming greater

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but current systems are too noisy burn

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too much fuel and require expensive

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maintenance

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it is problems like these which nasa's

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ames research center in mountain view

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california is studying

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here engineers use wind tunnels to carry

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out aerodynamic tests similar to those

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done on conventional planes and

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automobiles

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a rotor blade section is mounted in

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front of a sophisticated instrument

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called a laser velocimeter or lv

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once setup is complete air along with a

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fine oil mist is blown through the

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tunnel

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tiny oil particles reflect light back

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into the air

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allowing researchers to determine how

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fast air flows around any area of the

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blade being tested

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related work is underway at the ames

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outdoor aerodynamic research facility

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in this particular study engineers are

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investigating how certain aerodynamic

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characteristics of rotor systems

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influence overall performance according

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to the chief of the rotary wing

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aeromechanics branch at ames ten percent

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of a rotor system's total energy is

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wasted because downward forces generated

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by the spinning blades push other parts

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of the aircraft towards the ground bill

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warnbrook

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consequently the rotor system has to

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work 10

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harder

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to develop an equivalent amount of lift

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say to lift

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a crew and useful cargo complementing

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these experimental studies are computer

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simulations when a blade rotates it is

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constantly colliding with tornado-like

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pockets of turbulence created by other

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blades in front of it the result is less

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efficiency and greater noise

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simulations like these cut costs by

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allowing researchers to study

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aerodynamic problems before building the

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nasa's rotorcraft research an approach