WEBVTT FILE 1 00:04.245 --> 00:07.815 🎵 [music] 🎵 2 00:11.830 --> 00:15.520 KIDS: Our World! 3 00:15.521 --> 00:19.251 EVAN: Hey Globey! You're probably wondering why I'm 4 00:19.253 --> 00:22.021 wearing all of these streamers. Well, I want to find out how 5 00:22.023 --> 00:25.125 aerodynamic I am. Turn on the fan Charlie. 6 00:27.628 --> 00:31.163 See, aerodynamics is the study of how efficiently air flows 7 00:31.165 --> 00:34.766 around an object... like an airplane, or a car, or 8 00:34.768 --> 00:38.971 ...well, Me! Alright, that's enough Charlie, turn it 9 00:38.973 --> 00:43.041 off...TURN IT OFF! 10 00:44.603 --> 00:47.246 One of the best ways for scientists to study air flow 11 00:47.248 --> 00:50.250 around objects is in a wind tunnel. A wind tunnel is an 12 00:50.251 --> 00:52.951 enclosed space where the air flow over an object can be 13 00:52.953 --> 00:56.121 carefully controlled and studied. There are 4 types of 14 00:56.123 --> 00:59.791 wind tunnels: subsonic, transonic, 15 00:59.793 --> 01:03.195 supersonic and hypersonic. 16 01:03.196 --> 01:06.031 The NASA Langley Research Center has all of these types 17 01:06.033 --> 01:08.635 of tunnels and is one of the most extensive wind tunnel 18 01:08.636 --> 01:11.805 facilities in the world. Each type of wind tunnel is 19 01:11.806 --> 01:14.173 used to study an object in a different wind speed. 20 01:14.175 --> 01:17.576 These wind speeds are based on the speed of sound, which is 21 01:17.578 --> 01:21.046 about 1,235 kilometers per hour 22 01:21.048 --> 01:24.150 depending on altitude and air temperature. In warmer air, 23 01:24.151 --> 01:26.651 sound travels even faster. 24 01:26.653 --> 01:29.921 So the speed of sound is how fast sound waves travel through 25 01:29.923 --> 01:33.158 the air. For example, if I were standing in a field and I saw a 26 01:33.160 --> 01:37.363 lightening bolt 1.6 kilometers away, it would take 5 seconds 27 01:37.365 --> 01:39.765 from the time that I saw the flash to hear the thunder 28 01:39.766 --> 01:43.570 ...the thunder is traveling at the speed of sound or Mach 1. 29 01:43.571 --> 01:46.666 [thunder sfx] 30 01:47.971 --> 01:51.576 What...I was just tying my shoe. 31 01:51.578 --> 01:55.648 Wind tunnels measure air flow, or how fast the air is moving, 32 01:55.650 --> 01:58.685 using the same scale used for the speed of sound. 33 01:58.686 --> 02:02.055 Subsonic wind tunnels are used to study the airflow around 34 02:02.056 --> 02:04.456 objects that are slower than the speed of sound 35 02:04.458 --> 02:08.226 ...like cars and commercial jets. Transonic wind tunnels 36 02:08.228 --> 02:10.830 are used to study air craft that can fly around the speed 37 02:10.831 --> 02:14.433 of sound. Supersonic and hypersonic tunnels are used to 38 02:14.435 --> 02:18.303 study flight beyond the speed of sound. In fact, hypersonic 39 02:18.305 --> 02:21.340 wind tunnels can study flight at up to 7 times 40 02:21.341 --> 02:24.810 the speed of sound! But how do the engineers at NASA get a 41 02:24.811 --> 02:27.713 plane to move that fast in an enclosed area? 42 02:27.715 --> 02:30.483 They don't. The object they're testing stays 43 02:30.485 --> 02:33.453 still and the air moves instead. 44 02:33.455 --> 02:36.990 PETE JACOBS: We use wind tunnels to provide information 45 02:36.991 --> 02:40.893 on the aerodynamics of various types of vehicles. 46 02:40.895 --> 02:44.830 We can do that in a safe way Ėvery controlled conditions in 47 02:44.831 --> 02:48.200 the wind tunnel. We don't have to build a full size airplane 48 02:48.201 --> 02:52.438 and risk a pilot's life. We always test new configurations 49 02:52.440 --> 02:55.141 in a wind tunnel first. Make sure they're safe. 50 02:55.143 --> 02:57.510 Understand their characteristics, and then we 51 02:57.511 --> 03:00.680 move on to the full size airplane. 52 03:00.681 --> 03:04.250 EVAN: So different types of wind tunnels are used to test 53 03:04.251 --> 03:06.986 different effects the wind has on an air craft flying through 54 03:06.988 --> 03:12.591 the air. For example, The NASA Langley 14 x 22 Foot Sub Sonic 55 03:12.593 --> 03:15.428 Tunnel is used to test certain objects that travel at less 56 03:15.430 --> 03:18.598 than Mach 1 or less than the speed of sound. 57 03:18.600 --> 03:22.001 FRANK QUINTO: The 14x22 is mainly designed to test low 58 03:22.003 --> 03:25.405 speed performance of aircrafts. Low speed testing is important 59 03:25.406 --> 03:29.408 to airplanes in that it's very important to safely take off 60 03:29.410 --> 03:32.745 and land. We consider take off and landing the most important 61 03:32.746 --> 03:35.681 part of a flight. Because if you don't take off and land 62 03:35.683 --> 03:38.951 safely, the rest of the flight doesn't mean anything. On the 63 03:38.953 --> 03:41.955 other hand, we also test other things besides aircraft in our 64 03:41.956 --> 03:45.225 facility. We test structures 65 03:45.226 --> 03:48.628 to see how wind flows around it. Anywhere from large 66 03:48.630 --> 03:51.330 buildings to radar structures. 67 03:51.331 --> 03:54.966 We also test vehicles such as Humvees. 68 03:54.968 --> 03:58.738 And recently, we just got into testing motor sports 69 03:58.740 --> 04:01.741 such as Nascar and indy racers. 70 04:01.743 --> 04:06.980 And we also test parachutes as well as a wheel chair in 1979. 71 04:06.981 --> 04:10.250 EVAN: The NASA National Transonic Facility uses 72 04:10.251 --> 04:13.520 nitrogen gas to study the flow over wing sections and other 73 04:13.521 --> 04:17.023 models. Because this wind tunnel is Transonic, it's used 74 04:17.025 --> 04:20.560 to test objects that are meant to fly at speeds around Mach 1. 75 04:20.561 --> 04:24.996 Just as sound moves faster in warmer air, warmer temperatures 76 04:24.998 --> 04:28.468 in the wind tunnel make the air move faster. The Langley 8- 77 04:28.470 --> 04:31.671 Foot High Temperature Tunnel is a hypersonic tunnel that uses 78 04:31.673 --> 04:35.208 super heated gas to simulate speeds up to Mach 7. 79 04:35.210 --> 04:39.211 That's 7 times the speed of sound! NASA even has a wind 80 04:39.213 --> 04:42.215 tunnel that's built just to study how air flow affects air 81 04:42.216 --> 04:44.916 craft that are spinning out of control. 82 04:44.918 --> 04:49.321 That makes Globey and me dizzy. 83 04:49.323 --> 04:52.091 Hold on GLOBEY!! 84 04:52.093 --> 04:54.960 You know, Globey, the wind tunnels at NASA Langley 85 04:54.961 --> 04:57.996 Research Center are helping to make air travel even safer and 86 04:57.998 --> 05:01.233 a lot faster. And you won't believe some of the other 87 05:01.235 --> 05:03.970 things that are tested in NASA's wind tunnels Ė cars and 88 05:03.971 --> 05:07.173 boats and even the material for Olympic swimsuits. Leave it to 89 05:07.175 --> 05:09.841 NASA to find a way to test aerodynamics 90 05:09.843 --> 05:13.618 without even stepping outside! 91 05:13.620 --> 05:16.948 ? [music] ? 92 05:23.013 --> 05:26.158 KIDS: Our World! 93 05:29.035 --> 05:31.883 .