1 00:00:00,000 --> 00:00:05,240 You know, no matter what route we take, our pilot and the control centers on the ground 2 00:00:05,240 --> 00:00:07,240 are making sure we're safe in the skies. 3 00:00:07,240 --> 00:00:09,480 Would you like something to drink? 4 00:00:09,480 --> 00:00:10,480 Yes, thanks. 5 00:00:10,480 --> 00:00:11,480 Water would be great. 6 00:00:11,480 --> 00:00:12,480 Thank you. 7 00:00:12,480 --> 00:00:13,480 Thank you. 8 00:00:13,480 --> 00:00:18,160 Speaking of safety, we learned earlier that the FAA is always searching for new technologies 9 00:00:18,160 --> 00:00:21,800 and ways to maintain and improve the safety of air travel. 10 00:00:21,800 --> 00:00:23,560 That's where NASA comes in. 11 00:00:23,560 --> 00:00:28,280 Jennifer and I recently visited the NASA Langley Research Center in Hempton, Virginia to learn 12 00:00:28,280 --> 00:00:32,720 about NASA's Aviation Safety Program and the math, science, and technology they use 13 00:00:32,720 --> 00:00:34,840 in their everyday work. 14 00:00:34,840 --> 00:00:40,920 How will NASA contribute to airplane safety in the future? 15 00:00:40,920 --> 00:00:44,160 How do NASA engineers use math in their wind tunnel tests? 16 00:00:44,160 --> 00:00:48,280 What happens to an airplane when the angle of attack becomes too great? 17 00:00:48,280 --> 00:00:52,720 NASA's Aviation Safety Program is designed to make sure that airplanes remain a safe 18 00:00:52,720 --> 00:00:55,840 form of transportation for all future air travelers. 19 00:00:55,840 --> 00:01:00,600 Many pilots and engineers like me are studying new ways to prevent accidents from occurring. 20 00:01:00,600 --> 00:01:04,880 We're also looking at ways to provide new ideas and technologies to airplane manufacturers 21 00:01:04,880 --> 00:01:07,440 and airlines so they can keep our skies safe. 22 00:01:07,440 --> 00:01:10,280 Well, isn't flying already safe? 23 00:01:10,280 --> 00:01:11,760 Absolutely, Dan. 24 00:01:11,760 --> 00:01:15,640 Flying is the safest mode of transportation and passenger safety is the most important 25 00:01:15,640 --> 00:01:17,000 requirement for air travel. 26 00:01:17,000 --> 00:01:21,520 But you see, within the next 10 years, it is expected that close to 3 million people 27 00:01:21,520 --> 00:01:23,280 will be flying every day. 28 00:01:23,280 --> 00:01:25,600 That's about 1 million more than today. 29 00:01:26,360 --> 00:01:31,040 With these numbers, more airplanes will be flying in our skies in many types of flight conditions. 30 00:01:31,040 --> 00:01:34,880 NASA is working to make sure that even with that increase in air traffic, airplanes will 31 00:01:34,880 --> 00:01:37,760 remain a safe and efficient way for people to travel. 32 00:01:37,760 --> 00:01:39,360 Well, how do you do that? 33 00:01:39,360 --> 00:01:43,520 One way is to make sure that all airline pilots have the necessary training to maintain control 34 00:01:43,520 --> 00:01:47,200 of their airplane and safely maneuver them during all flight conditions. 35 00:01:47,200 --> 00:01:51,800 It's my job to predict how well airplanes can be controlled in these different conditions. 36 00:01:51,800 --> 00:01:54,120 How can you predict what an airplane will do? 37 00:01:54,120 --> 00:01:57,000 We use a wind tunnel and model of an airplane. 38 00:01:57,000 --> 00:02:01,480 A wind tunnel is a facility that blows air over a model at different speeds and angles 39 00:02:01,480 --> 00:02:03,680 to simulate the airplane flying through the air. 40 00:02:03,680 --> 00:02:09,680 You see, testing full-size airplanes is too expensive, so we use scale models. 41 00:02:09,680 --> 00:02:12,440 This model is 1 thirtieth the size of the real airplane. 42 00:02:12,440 --> 00:02:13,440 1 thirtieth? 43 00:02:13,440 --> 00:02:15,960 Hey, that's a ratio. 44 00:02:15,960 --> 00:02:20,240 A ratio is a fraction used to compare the size of two numbers to each other. 45 00:02:20,240 --> 00:02:25,400 The ratio 1 thirtieth means that this model is about 30 times smaller than the real airplane. 46 00:02:25,400 --> 00:02:26,400 Right, John? 47 00:02:26,400 --> 00:02:27,400 That's right, Jennifer. 48 00:02:27,400 --> 00:02:31,600 And we use a wind tunnel to test the model in conditions that are too dangerous to test 49 00:02:31,600 --> 00:02:32,760 on the real airplane. 50 00:02:32,760 --> 00:02:36,360 When we run the wind tunnel at different air speeds, we move the model so that the wind 51 00:02:36,360 --> 00:02:38,920 hits it at various angles, like this. 52 00:02:38,920 --> 00:02:42,200 One very important angle we look at is called the angle of attack. 53 00:02:42,200 --> 00:02:43,660 Let me explain. 54 00:02:43,660 --> 00:02:47,520 When an airplane is flying through the air, the combination of air speed and the angle 55 00:02:47,520 --> 00:02:51,640 of attack produces lift, a force which holds the airplane in the air. 56 00:02:51,640 --> 00:02:55,820 In normal flight, as the angle of attack becomes greater, the lift increases. 57 00:02:55,820 --> 00:02:59,280 If you have ever held your hand out of the window of a moving car, you can feel this 58 00:02:59,280 --> 00:03:00,960 lift as you move your hand. 59 00:03:00,960 --> 00:03:05,360 However, if the angle of attack becomes too great, the air no longer flows smoothly over 60 00:03:05,360 --> 00:03:09,800 the wing, causing a condition known as aerodynamic stall, and the lift will decrease. 61 00:03:09,800 --> 00:03:14,120 Now, although this flight condition rarely occurs, the airplane's controls may not be 62 00:03:14,120 --> 00:03:17,480 effective, and the pilot may not be able to safely maneuver the airplane. 63 00:03:17,480 --> 00:03:22,360 But John, how do you know that the real airplane is going to behave the same way that the model 64 00:03:22,360 --> 00:03:23,960 does in the wind tunnel? 65 00:03:23,960 --> 00:03:25,040 Great question. 66 00:03:25,040 --> 00:03:29,020 We use math to predict how the real airplane will behave under the same conditions tested 67 00:03:29,020 --> 00:03:30,020 in the wind tunnel. 68 00:03:30,020 --> 00:03:31,020 Let me show you. 69 00:03:31,020 --> 00:03:36,000 During wind tunnel testing, a computer system electronically measures the lift. 70 00:03:36,000 --> 00:03:40,360 The computer also determines the speed of the moving air, the density of the air, and 71 00:03:40,360 --> 00:03:42,520 the area of the airplane's wing. 72 00:03:42,520 --> 00:03:46,440 Using this ratio, we can compute the lift coefficient, a number that tells engineers 73 00:03:46,440 --> 00:03:51,360 like me how the shape of the model, position of the model, and the airflow around the model 74 00:03:51,360 --> 00:03:52,360 affect lift. 75 00:03:52,360 --> 00:03:56,960 Next, we create a graph that allows us to see the relationship between the lift coefficient 76 00:03:56,960 --> 00:04:00,320 and the angle of attack we have simulated in the tunnel. 77 00:04:00,320 --> 00:04:04,400 Because this graph is the same for both the model and the full-size airplane, we can predict 78 00:04:04,400 --> 00:04:06,200 how the real airplane will fly. 79 00:04:06,200 --> 00:04:09,040 So let's put the data on the graph and interpret it. 80 00:04:09,040 --> 00:04:12,680 Under normal flight conditions, the lift coefficient increases as the angle of attack 81 00:04:12,680 --> 00:04:13,680 increases. 82 00:04:13,680 --> 00:04:16,400 The pilot should have no trouble controlling the plane. 83 00:04:16,400 --> 00:04:20,720 However, if the angle of attack becomes so great that stall occurs, the lift coefficient 84 00:04:20,720 --> 00:04:23,960 decreases and the airplane may be difficult to control. 85 00:04:23,960 --> 00:04:27,240 From this graph, we can determine how the airplane will respond in different flight 86 00:04:27,240 --> 00:04:28,240 conditions. 87 00:04:28,240 --> 00:04:32,760 Knowing this information allows us to find ways to help pilots prevent or avoid entering 88 00:04:32,760 --> 00:04:36,240 unsafe conditions and to make the airplane easier to fly. 89 00:04:36,440 --> 00:04:41,640 So once you've tested the model and determined how the real plane will behave, how do you 90 00:04:41,640 --> 00:04:44,440 make sure the pilots are trained in these situations? 91 00:04:44,440 --> 00:04:48,480 Today's airline pilots are highly trained using very sophisticated devices known as 92 00:04:48,480 --> 00:04:49,800 flight simulators. 93 00:04:49,800 --> 00:04:54,320 The simulator looks and feels just like a real airplane from takeoff through landing, 94 00:04:54,320 --> 00:04:57,920 and it allows pilots to practice many different flying procedures that they may encounter 95 00:04:57,920 --> 00:04:59,520 during a real flight. 96 00:04:59,520 --> 00:05:03,240 All of the graphs created from the wind tunnel test are given to people whose job it is to 97 00:05:03,240 --> 00:05:07,200 input these data into the flight simulator, making pilots feel like they're flying a real 98 00:05:07,200 --> 00:05:08,200 airplane. 99 00:05:08,200 --> 00:05:12,040 The simulator is designed to respond like the real airplane that has accidentally entered 100 00:05:12,040 --> 00:05:15,920 unsafe flight conditions, like the ones we've tested in the wind tunnel. 101 00:05:15,920 --> 00:05:19,920 Using simulators, pilots are especially trained to prevent loss of control and learn how to 102 00:05:19,920 --> 00:05:24,080 operate the airplane under conditions that would normally not be safe in a real airplane. 103 00:05:24,080 --> 00:05:27,600 This training will help to ensure that air travel remains safe for everyone. 104 00:05:27,600 --> 00:05:31,440 In fact, many of today's students who are interested in becoming airline pilots will 105 00:05:31,440 --> 00:05:35,440 be trained in simulators that use the research we are conducting here at NASA. 106 00:05:35,440 --> 00:05:39,920 The goal of NASA's Aviation Safety Program is to prevent accidents from occurring and 107 00:05:39,920 --> 00:05:43,600 for all future air travelers to know they will safely reach their destination. 108 00:05:43,600 --> 00:05:44,600 Thanks, John. 109 00:05:44,600 --> 00:05:48,960 You know, it's really cool that- Hey, Jen, check it out. 110 00:05:48,960 --> 00:05:49,960 It's Colorado. 111 00:05:49,960 --> 00:05:50,960 It sure is, Dan. 112 00:05:50,960 --> 00:05:55,720 Well, like I was saying, it's really cool how NASA is testing models in wind tunnels 113 00:05:55,720 --> 00:05:59,080 and then using technology to help pilots fly safely. 114 00:05:59,320 --> 00:06:04,040 Speaking of technology, Dan, didn't you find a really cool CD that takes you on an airplane's 115 00:06:04,040 --> 00:06:05,240 journey from gate to gate? 116 00:06:05,240 --> 00:06:06,600 I sure did. 117 00:06:06,600 --> 00:06:10,720 This CD-ROM lets you meet some of the people who operate the air traffic control system. 118 00:06:10,720 --> 00:06:14,040 Join me next in Dan's domain and I'll show you some of the tools they use.