1 00:00:04,245 --> 00:00:07,815 ? [music] ? 2 00:00:11,830 --> 00:00:15,520 KIDS: Our World! 3 00:00:15,521 --> 00:00:19,251 EVAN: Hey Globey! You’re probably wondering why I’m 4 00:00:19,253 --> 00:00:22,021 wearing all of these streamers. Well, I want to find out how 5 00:00:22,023 --> 00:00:25,125 aerodynamic I am. Turn on the fan Charlie. 6 00:00:27,628 --> 00:00:31,163 See, aerodynamics is the study of how efficiently air flows 7 00:00:31,165 --> 00:00:34,766 around an object... like an airplane, or a car, or 8 00:00:34,768 --> 00:00:38,971 ...well, Me! Alright, that’s enough Charlie, turn it 9 00:00:38,973 --> 00:00:43,041 off...TURN IT OFF! 10 00:00:44,603 --> 00:00:47,246 One of the best ways for scientists to study air flow 11 00:00:47,248 --> 00:00:50,250 around objects is in a wind tunnel. A wind tunnel is an 12 00:00:50,251 --> 00:00:52,951 enclosed space where the air flow over an object can be 13 00:00:52,953 --> 00:00:56,121 carefully controlled and studied. There are 4 types of 14 00:00:56,123 --> 00:00:59,791 wind tunnels: subsonic, transonic, 15 00:00:59,793 --> 00:01:03,195 supersonic and hypersonic. 16 00:01:03,196 --> 00:01:06,031 The NASA Langley Research Center has all of these types 17 00:01:06,033 --> 00:01:08,635 of tunnels and is one of the most extensive wind tunnel 18 00:01:08,636 --> 00:01:11,805 facilities in the world. Each type of wind tunnel is 19 00:01:11,806 --> 00:01:14,173 used to study an object in a different wind speed. 20 00:01:14,175 --> 00:01:17,576 These wind speeds are based on the speed of sound, which is 21 00:01:17,578 --> 00:01:21,046 about 1,235 kilometers per hour 22 00:01:21,048 --> 00:01:24,150 depending on altitude and air temperature. In warmer air, 23 00:01:24,151 --> 00:01:26,651 sound travels even faster. 24 00:01:26,653 --> 00:01:29,921 So the speed of sound is how fast sound waves travel through 25 00:01:29,923 --> 00:01:33,158 the air. For example, if I were standing in a field and I saw a 26 00:01:33,160 --> 00:01:37,363 lightening bolt 1.6 kilometers away, it would take 5 seconds 27 00:01:37,365 --> 00:01:39,765 from the time that I saw the flash to hear the thunder 28 00:01:39,766 --> 00:01:43,570 ...the thunder is traveling at the speed of sound or Mach 1. 29 00:01:43,571 --> 00:01:46,666 [thunder sfx] 30 00:01:47,971 --> 00:01:51,576 What...I was just tying my shoe. 31 00:01:51,578 --> 00:01:55,648 Wind tunnels measure air flow, or how fast the air is moving, 32 00:01:55,650 --> 00:01:58,685 using the same scale used for the speed of sound. 33 00:01:58,686 --> 00:02:02,055 Subsonic wind tunnels are used to study the airflow around 34 00:02:02,056 --> 00:02:04,456 objects that are slower than the speed of sound 35 00:02:04,458 --> 00:02:08,226 ...like cars and commercial jets. Transonic wind tunnels 36 00:02:08,228 --> 00:02:10,830 are used to study air craft that can fly around the speed 37 00:02:10,831 --> 00:02:14,433 of sound. Supersonic and hypersonic tunnels are used to 38 00:02:14,435 --> 00:02:18,303 study flight beyond the speed of sound. In fact, hypersonic 39 00:02:18,305 --> 00:02:21,340 wind tunnels can study flight at up to 7 times 40 00:02:21,341 --> 00:02:24,810 the speed of sound! But how do the engineers at NASA get a 41 00:02:24,811 --> 00:02:27,713 plane to move that fast in an enclosed area? 42 00:02:27,715 --> 00:02:30,483 They don’t. The object they’re testing stays 43 00:02:30,485 --> 00:02:33,453 still and the air moves instead. 44 00:02:33,455 --> 00:02:36,990 PETE JACOBS: We use wind tunnels to provide information 45 00:02:36,991 --> 00:02:40,893 on the aerodynamics of various types of vehicles. 46 00:02:40,895 --> 00:02:44,830 We can do that in a safe way –very controlled conditions in 47 00:02:44,831 --> 00:02:48,200 the wind tunnel. We don’t have to build a full size airplane 48 00:02:48,201 --> 00:02:52,438 and risk a pilot’s life. We always test new configurations 49 00:02:52,440 --> 00:02:55,141 in a wind tunnel first. Make sure they’re safe. 50 00:02:55,143 --> 00:02:57,510 Understand their characteristics, and then we 51 00:02:57,511 --> 00:03:00,680 move on to the full size airplane. 52 00:03:00,681 --> 00:03:04,250 EVAN: So different types of wind tunnels are used to test 53 00:03:04,251 --> 00:03:06,986 different effects the wind has on an air craft flying through 54 00:03:06,988 --> 00:03:12,591 the air. For example, The NASA Langley 14 x 22 Foot Sub Sonic 55 00:03:12,593 --> 00:03:15,428 Tunnel is used to test certain objects that travel at less 56 00:03:15,430 --> 00:03:18,598 than Mach 1 or less than the speed of sound. 57 00:03:18,600 --> 00:03:22,001 FRANK QUINTO: The 14x22 is mainly designed to test low 58 00:03:22,003 --> 00:03:25,405 speed performance of aircrafts. Low speed testing is important 59 00:03:25,406 --> 00:03:29,408 to airplanes in that it’s very important to safely take off 60 00:03:29,410 --> 00:03:32,745 and land. We consider take off and landing the most important 61 00:03:32,746 --> 00:03:35,681 part of a flight. Because if you don’t take off and land 62 00:03:35,683 --> 00:03:38,951 safely, the rest of the flight doesn’t mean anything. On the 63 00:03:38,953 --> 00:03:41,955 other hand, we also test other things besides aircraft in our 64 00:03:41,956 --> 00:03:45,225 facility. We test structures 65 00:03:45,226 --> 00:03:48,628 to see how wind flows around it. Anywhere from large 66 00:03:48,630 --> 00:03:51,330 buildings to radar structures. 67 00:03:51,331 --> 00:03:54,966 We also test vehicles such as Humvees. 68 00:03:54,968 --> 00:03:58,738 And recently, we just got into testing motor sports 69 00:03:58,740 --> 00:04:01,741 such as Nascar and indy racers. 70 00:04:01,743 --> 00:04:06,980 And we also test parachutes as well as a wheel chair in 1979. 71 00:04:06,981 --> 00:04:10,250 EVAN: The NASA National Transonic Facility uses 72 00:04:10,251 --> 00:04:13,520 nitrogen gas to study the flow over wing sections and other 73 00:04:13,521 --> 00:04:17,023 models. Because this wind tunnel is Transonic, it’s used 74 00:04:17,025 --> 00:04:20,560 to test objects that are meant to fly at speeds around Mach 1. 75 00:04:20,561 --> 00:04:24,996 Just as sound moves faster in warmer air, warmer temperatures 76 00:04:24,998 --> 00:04:28,468 in the wind tunnel make the air move faster. The Langley 8- 77 00:04:28,470 --> 00:04:31,671 Foot High Temperature Tunnel is a hypersonic tunnel that uses 78 00:04:31,673 --> 00:04:35,208 super heated gas to simulate speeds up to Mach 7. 79 00:04:35,210 --> 00:04:39,211 That’s 7 times the speed of sound! NASA even has a wind 80 00:04:39,213 --> 00:04:42,215 tunnel that’s built just to study how air flow affects air 81 00:04:42,216 --> 00:04:44,916 craft that are spinning out of control. 82 00:04:44,918 --> 00:04:49,321 That makes Globey and me dizzy. 83 00:04:49,323 --> 00:04:52,091 Hold on GLOBEY!! 84 00:04:52,093 --> 00:04:54,960 You know, Globey, the wind tunnels at NASA Langley 85 00:04:54,961 --> 00:04:57,996 Research Center are helping to make air travel even safer and 86 00:04:57,998 --> 00:05:01,233 a lot faster. And you won’t believe some of the other 87 00:05:01,235 --> 00:05:03,970 things that are tested in NASA’s wind tunnels – cars and 88 00:05:03,971 --> 00:05:07,173 boats and even the material for Olympic swimsuits. Leave it to 89 00:05:07,175 --> 00:05:09,841 NASA to find a way to test aerodynamics 90 00:05:09,843 --> 00:05:13,618 without even stepping outside! 91 00:05:13,620 --> 00:05:16,948 ? [music] ? 92 00:05:23,013 --> 00:05:26,158 KIDS: Our World! 93 00:05:29,035 --> 00:05:31,883 .