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Destination Tomorrow - DT3 - Helicopters
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NASA Destination Tomorrow Segment describing how helicopters work and the different types of helicopters in use.
Some initial milestones for the Aviation Systems Capacity Program have already been accomplished
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and are currently being tested for future use in airports.
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We've all seen helicopters flying around, but do you know how they work?
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For some answers, we turn to Johnny Alonzo.
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For over 60 years, the helicopter has been one of the most versatile types of transportation around.
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It has the ability to fly forward, backwards, sideways, rise and descend vertically, and hover motionless in the air.
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Helicopters have been credited with saving over 3 million lives by transporting critically wounded people from accidents and war zones.
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They're also used for things like helping the police fight crime, fighting forest fires, and simple tasks like checking our roadway conditions.
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But have you ever wondered how helicopters fly?
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For some answers, I spoke with NASA Langley researcher Mike Watts at the Coast Guard Air Station, Elizabeth City.
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Johnny, to really understand how a helicopter flies, first let's go back to a fixed wing world, a regular airplane, the kind with wings and an engine.
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Now, a fixed wing has an engine, a jet, or a propeller to push you through the air.
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And that moves air over the wings, which provides lift that keeps it in the air.
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And obviously from this helicopter, you can see we don't have normal wings, and we don't have a jet or a propeller on it to push you forward through the air.
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But what you do have is the main rotor blades.
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You can notice that these are shaped a lot like wings for a fixed wing.
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The way you get them moving through the air is these rotate around in a circle, and that moves them through the air.
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They're shaped just like a wing, so that provides a lift force that lifts the helicopter off the ground.
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Cool. So you've tapped in on how a helicopter lifts off the ground.
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Can you explain to me how you control the altitude?
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Sure. The way you control the altitude is by generating more lift, a more upward force.
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And the way you do that is you pitch the rotor blade to a higher angle in relation to the wind.
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That generates more lift, and that lifts it off the ground.
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To go down, you just reduce the angle of the blades. That generates less lift, and gravity settles you down into the ground.
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So this is the main rotor. What is this?
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This is called a tail rotor.
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As you can see, it looks like a main rotor or a propeller on its side.
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When you turn the main rotor blades, the body of the helicopter wants to go against the rotation.
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So if the blades are turning this way, the body wants to go this way.
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Well, to keep straight, you have to provide something to counter that turn, that force pushing it sideways.
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So we provide a force that keeps it straight, and that's what the tail rotor provides.
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Wow.
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If you want to go to the left, you provide more force, and it goes this way.
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If you want to go to the right, you provide less force, and the torque turns it this way.
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So, Mike, you briefly explained to us how you keep the helicopter straight.
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How do you make it go forward?
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Well, you make it go forward by providing a force to push it forward.
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Just like in a regular airplane that has a propeller, the propeller is providing a force to push the airplane forward.
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We need to provide that somewhere.
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If you think of the main rotor as a disc in the air, and it's got a force going through the center of it,
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that's what we talked about as a thrust, that holds it in the air.
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If you tilt it forward a little bit, it's going to pull the helicopter forward.
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If you tilt it back, it's going to pull the helicopter back.
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If you want to go sideways, you just tilt it to the side, and it pulls you sideways like that.
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So you have the force pulling you backwards, forwards, and sideways.
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And if you actually take that disc and turn it all the way on its side,
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it's like the propeller is pulling you all the way forwards.
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And there's a concept being looked at by the Marines now called the V-22 tilt rotor,
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and that is to turn the rotors on their sides and make them propellers.
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You get the benefits of going farther and faster with a fixed wing than a regular airplane,
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and you can take off and land vertically, just like a helicopter.
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That's all there is to it.
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That's all there is to it.
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That's all there is to it.
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Mike, thanks for coming out and showing us everything about helicopters.
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My pleasure, my pleasure.
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You got the keys, man?
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Oh, yeah, let's go fire it up.
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Come on, let's do it.
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All right, let's go.
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So that's how it works.
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I'd like to thank the U.S. Coast Guard for letting us use their facilities here in the listening city.
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I think we're taking off now.
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Let's go to my house.
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Where are we going to park?
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- Idioma/s:
- Niveles educativos:
- ▼ Mostrar / ocultar niveles
- Nivel Intermedio
- Autor/es:
- NASA LaRC Office of Education
- Subido por:
- EducaMadrid
- Licencia:
- Reconocimiento - No comercial - Sin obra derivada
- Visualizaciones:
- 320
- Fecha:
- 28 de mayo de 2007 - 17:04
- Visibilidad:
- Público
- Enlace Relacionado:
- NASAs center for distance learning
- Duración:
- 04′ 45″
- Relación de aspecto:
- 4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.
- Resolución:
- 480x360 píxeles
- Tamaño:
- 27.69 MBytes
