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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Connect segment featuring two NASA experts in a question and answer session. The video involves people calling in and emailing questions for the experts to answer.

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So, how do you think you did? Well, your mathematical computations and reasoning are important skills to answering the last questions. 00:00:00

Also, are you ready with your own questions? 00:00:07

Here we are now. With me to fill my questions are Mike and Zach, and 00:00:10

shown on your set are the numbers to use. Now, 00:00:15

please note that the telephone numbers are good only for today's November 10th broadcast. All right, let me begin. 00:00:17

I've got a number of email questions that have come in, so I'm going to start with the email questions. 00:00:23

My first question, if you take a look at it, is what is glide ratio? Mike or Zach, who'd like to answer that? 00:00:28

I'll go ahead. 00:00:34

The glide ratio, as you saw earlier, is the ratio of the horizontal distance flown to the altitude drop. 00:00:36

Now, from a design standpoint, 00:00:43

we look at the glide ratio as the result of the aerodynamic efficiency, 00:00:45

which is basically the lift versus the drag ratio, or L over D. 00:00:50

So when we design an airplane, glide ratio is important. 00:00:55

That's a measure of the aerodynamic efficiency and how good the airplane is. All right, 00:00:58

we had a question that was related to that. If we look at our second email question, someone wants to know, does weather affect 00:01:02

glide ratio? It certainly can. In fact, when you 00:01:09

earlier you saw the wind and the rain, those are two factors that very heavily, in fact, impact the glide ratio. 00:01:14

The more wind that you have and the higher the rainfall, the more likely you are to have not as good a glide ratio. 00:01:20

Okay, so wind speed could be a factor here, then. All right. Well, I know that we have a caller out there, 00:01:27

so caller, how about giving us your name, please, and your question? 00:01:32

Michael Williams, Lightning Note. 00:01:41

Lightning Note, how far could the first 00:01:44

airplane in your show go? 00:01:47

If you could turn down your set and ask the question again, 00:01:50

I think we would hear a little bit more clearly. Could you repeat that again, please? That's the fun doing that. 00:01:55

Could you ask the question one more time, then, please? 00:02:00

How far did the first model go? 00:02:03

How far did 00:02:06

the model go? Are you referring to the students' model? Yeah. 00:02:09

Well, you saw there on the data that they collected that it went, 00:02:15

they tried it ten times, and we saw their data for five times, and you saw the distance for five of those flights. 00:02:19

So, your challenge is to go back and look at that data, 00:02:25

and you could calculate the mean and the median for those five flights, and then you'll have that answer. Good question. 00:02:29

All right. Well, let me go back to my email, because I know I've got several questions that have come in here. 00:02:36

Here's a question. How do researchers, in designing an airplane, decide what its wingspan should be? 00:02:41

It's a good question, Shelley. 00:02:48

It really depends on the aircraft mission. Typically, transport aircraft have very long wingspans where they need high fuel efficiency. 00:02:50

For fighter-type aircraft, you typically have shorter spans. You require a lot more structural strength out of the airplane. 00:02:58

So, you typically have a short span on fighter-type configurations. Okay. 00:03:05

All right. We've got another email question that's kind of related to this. All right. 00:03:10

And maybe you've answered this already. How important is the width of a wingspan in an airplane's performance? 00:03:14

In a very simple sense, I guess the longer the span, typically the more fuel-efficient an airplane configuration would be. 00:03:21

That's why you see long spans on commercial transport airplanes. 00:03:28

All right. Well, I know we've got another caller out there. 00:03:32

So, let's go ahead and go back to the phones. And, caller, could you give us your name, please, and your question? 00:03:34

Yes. My name is Eric Morgan. I have a question for them. 00:03:39

My question is, 00:03:42

the little 00:03:44

perforated holes, or the little holes in a golf ball, that help break down 00:03:46

wind turbulence for the golf ball, will that help on a plane's wing to reduce drag? 00:03:50

Good question. Who wants to take that one? Mike, Zach? 00:03:55

I can do that one. 00:03:57

As you know, though, the little dimples on a golf ball helps change the drag of the golf ball by creating turbulence. 00:03:59

Now, in fact, there's a similar system that can be applied to transport configurations called hybrid laminar flow control, 00:04:05

where, in fact, there's little holes that can either suck air in or blow air out that helps to create a 00:04:13

smooth layer of air near the surface of the skin. That actually can reduce the drag of the airplane as much as 15 to 16 percent. 00:04:19

All right. Good question. Did you want to add something else? 00:04:26

Yes. And, actually, a very similar application that's developed here at NASA Langley is 00:04:29

a turbulent drag reduction in the form of what we call rivulets, which are fairly rough surfaces along the airplane, 00:04:33

which actually reduce the overall drag of the wing. All right. Well, that's about all the time we have. 00:04:39

So, I'd like to thank all the guests that contributed to this program, including Mike and Zach, Paul, Karen, and Sharon. 00:04:45

I'd also like to thank Jones Magnet Middle School, Deer County Airport, 00:04:52

AirVenture 98, and Hoot Gibson, who did win his race. And, finally, the Smithsonian National Air and Space Museum. 00:04:56

Just a final reminder to check out the Shapes of Flight website, where you will see, hear, and learn more about today's topic. 00:05:05

Also, we invite you to camp out with like-minded students in our special virtual aeronautics camp. 00:05:12

No sleeping bags required. Just some creativity and mathematics and science know-how. 00:05:17

Videotape copies of this show, along with the lesson plan, may be obtained from NASA's Central Operation of Resources for Educators, or CORE. 00:05:22

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Idioma/s:

Materias:

Matemáticas

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:

330

Fecha:

28 de mayo de 2007 - 16:51

Visibilidad:

Público

Enlace Relacionado:

NASAs center for distance learning

Duración:

05′ 32″

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: