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radio-controlled model aircraft flying

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is one of america's most popular hobbies

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the people who fly these small-scale

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versions of their favorite planes have

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many reasons why they are interested

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some like the excitement of flying some

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like building them

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engineers at nasa's dryden flight

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research center in california

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use radio control aircraft for another

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reason research

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they know that meaningful data can be

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obtained from radio controlled aircraft

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they are using a 15 percent model of

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dry-in zone f-18

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high alpha research vehicle that has

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been built as a proof-of-concept

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the model was made at dryden almost

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exclusively from standard rc model

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industry equipment

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like this aeron servo but a number of

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modifications had to be made in order to

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meet research specifications

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the fuselage made of fiberglass comes

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from an off-the-shelf model kit

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the wings and tail surfaces are made out

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of a styrofoam core and sheeted with

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entirely new engine inlets and exhaust

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stucks were made in order to more

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accurately represent

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the true f-18 inlet configuration

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this included functional boundary layer

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diverters

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stress carrying bulkheads made of a

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special laminate of end grain balsa wood

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and fiberglass

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had to be installed to handle the

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stresses encountered by the model in

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some parts like the stabilator pivot

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mechanism were made by hand

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other types of material used were

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plywood carbon fiber and balsa wood

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the model's thrust comes from two

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commercially available ducted fan units

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that are 85 percent efficient in

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converting horsepower to thrust

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two model airplane engines power the fan

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units producing 11 pounds of static

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the plane has been tracked on radar at

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160 knots a speed which should be

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increased with the installation of

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liquid propane fuel mini turbo jets

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thrust vectoring vanes have been added

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to the model to make it true to the real

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aircraft but are not operational

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however an operational system has been

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designed for a future project

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the plane is fully instrumented to

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measure air speed angle of attack

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side slip and control surface positions

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three axis rate gyros measure the rate

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of rotation

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and three accelerometers measure the

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g-forces experienced by the model in

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flight

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it took six months to build at a cost of

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approximately twenty five thousand

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dollars

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these modifications make it truly

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capable performing as a flight research

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vehicle

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like its full-scale big brother rc

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subscale models like this have a unique

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quality that allows researchers to

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gather aerodynamic data

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which is difficult and expensive to

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obtain in wind tunnels

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models like this are especially suited

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for getting aerodynamic data

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like performing parameter identification

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studies and for confirming the basic

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airworthiness of unique

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aircraft configurations research and

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advanced control theory can also be done

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by using existing technology

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a flight control computer can be

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installed that would allow the aircraft

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to gather data at specific flight

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conditions

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radio-controlled model aircraft flying

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is a great hobby but for nasa's dryden

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flight research center

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they are just another innovative tool in