1 00:00:00,000 --> 00:00:04,000 Okay, now that you've gotten some facts on NASA and NASA Langley, 2 00:00:04,000 --> 00:00:10,000 let's see what type of extreme tests NASA Langley conducts at the Aircraft Landing Dynamics Facility. 3 00:00:10,000 --> 00:00:12,000 The what? 4 00:00:12,000 --> 00:00:14,000 The Aircraft Landing Dynamics Facility. 5 00:00:14,000 --> 00:00:18,000 But that's a mouthful, so they call it ALDF, or ALDIP for short. 6 00:00:18,000 --> 00:00:22,000 Let's find out how NASA engineers are using math, science, and technology 7 00:00:22,000 --> 00:00:25,000 to solve the problems they're faced with every day. 8 00:00:26,000 --> 00:00:30,000 How is the test set up to solve the problem? 9 00:00:30,000 --> 00:00:33,000 How are graphs used to find possible solutions? 10 00:00:33,000 --> 00:00:37,000 What visual method did NASA engineers use to represent their solutions? 11 00:00:37,000 --> 00:00:41,000 The ALDF allows NASA Langley to test tires, wheels, and brakes 12 00:00:41,000 --> 00:00:45,000 of vehicles like airplanes, cars, trucks, even the Space Shuttle Orbiter, 13 00:00:45,000 --> 00:00:47,000 and makes them safer for everyone. 14 00:00:47,000 --> 00:00:51,000 For example, because jet airplanes and the Space Shuttle land at really high speeds, 15 00:00:51,000 --> 00:00:56,000 we have to simulate those speeds here at the ALDF if we want our test to be accurate. 16 00:00:56,000 --> 00:01:01,000 This is done with the use of pressurized water, a carriage, and the tire or gear being tested. 17 00:01:01,000 --> 00:01:04,000 10,000 gallons of water push the carriage down a track. 18 00:01:04,000 --> 00:01:08,000 When the desired speed is reached, the tire is lowered onto the test surface. 19 00:01:08,000 --> 00:01:13,000 Instruments are used to measure the forces acting between the tires and the test surface. 20 00:01:13,000 --> 00:01:16,000 These data are collected by a computer and made into a graph. 21 00:01:16,000 --> 00:01:22,000 By comparing many graphs, we are able to predict how a tire might behave under conditions other than what we test. 22 00:01:22,000 --> 00:01:27,000 Some of the many tests we've conducted at the ALDF include something known as hydroplaning. 23 00:01:27,000 --> 00:01:32,000 That's when you drive your car or land an airplane too fast on a water-covered road or runway, 24 00:01:32,000 --> 00:01:34,000 and you actually start skiing on the water. 25 00:01:34,000 --> 00:01:38,000 That's fun if you're boating, but not very fun if you're in an airplane. 26 00:01:38,000 --> 00:01:42,000 So the engineers at the ALDF figured out that putting grooves in the runway 27 00:01:42,000 --> 00:01:46,000 gives the water a way to get out of the tire footprint to keep you from hydroplaning. 28 00:01:46,000 --> 00:01:51,000 This idea found its way to the highways you and your family drive on to keep you safe in the rain. 29 00:01:51,000 --> 00:01:55,000 Wow, so NASA Langley engineers have solved lots of real-world problems. 30 00:01:55,000 --> 00:02:00,000 That's right, but remember the ALDF only simulates tire wear, landing speed, and runway surfaces. 31 00:02:00,000 --> 00:02:05,000 Sometimes in order to solve real-world problems, you have to go to where the problem really exists. 32 00:02:05,000 --> 00:02:08,000 Take Kennedy Space Center in Florida, for example. 33 00:02:08,000 --> 00:02:11,000 Kennedy is the number one landing site for space shuttle launches and landings, 34 00:02:11,000 --> 00:02:16,000 and the conditions have to be just right for the space shuttle orbiter to take off for land. 35 00:02:16,000 --> 00:02:19,000 Conditions? Like the weather? 36 00:02:19,000 --> 00:02:20,000 Well, that's part of it. 37 00:02:20,000 --> 00:02:23,000 If conditions like the runway texture and the winds aren't just right, 38 00:02:23,000 --> 00:02:26,000 the space shuttle tires will wear out and could fail. 39 00:02:26,000 --> 00:02:29,000 You see, the runway at Kennedy Space Center was built very, very rough, 40 00:02:29,000 --> 00:02:33,000 so the water would drain off of it, and it wouldn't be too slippery when it was wet. 41 00:02:33,000 --> 00:02:35,000 We didn't want the orbiter to hydroplane. 42 00:02:35,000 --> 00:02:42,000 But because the orbiter tires land with the weight of about 150 cars and as fast as 250 miles per hour, 43 00:02:42,000 --> 00:02:45,000 the rough runway was like a cheese grater on the tires. 44 00:02:45,000 --> 00:02:50,000 Too much wear could cause the tires to fail during a landing, and we want to prevent that. 45 00:02:50,000 --> 00:02:54,000 Tire wear gets even worse when the orbiter lands in a crosswind. 46 00:02:54,000 --> 00:02:58,000 I've heard that term before, but what exactly is a crosswind? 47 00:02:58,000 --> 00:03:03,000 Well, a crosswind is the wind blowing at an angle across the path of an aircraft. 48 00:03:03,000 --> 00:03:07,000 Landing in a crosswind actually causes all of your tires to roll slightly sideways. 49 00:03:07,000 --> 00:03:09,000 We call that a yaw angle. 50 00:03:09,000 --> 00:03:13,000 And just a small amount of yaw angle can cause a tremendous amount of tire wear. 51 00:03:13,000 --> 00:03:18,000 This tire wear limits the amount of crosswind the shuttle can land or launch in, which causes delays. 52 00:03:18,000 --> 00:03:23,000 NASA wanted to double the crosswind limit that the shuttle could launch or land in safely. 53 00:03:23,000 --> 00:03:27,000 Our job was to find out how to smooth the rough runway surface to reduce tire wear 54 00:03:27,000 --> 00:03:30,000 without making it too slippery when it was wet. 55 00:03:30,000 --> 00:03:37,000 So, Bob, I guess you used the ALDEF to figure out which runway surface to use at Kennedy. 56 00:03:37,000 --> 00:03:39,000 That's right. We started right here. 57 00:03:39,000 --> 00:03:42,000 But because the test track here at the ALDEF is only a half mile long 58 00:03:42,000 --> 00:03:45,000 and the runway at Kennedy is three miles long, 59 00:03:45,000 --> 00:03:49,000 we really couldn't take a bunch of short-distance runs here and add them together 60 00:03:49,000 --> 00:03:52,000 and accurately predict the wear for a whole shuttle landing. 61 00:03:52,000 --> 00:03:54,000 We needed a full-scale test. 62 00:03:54,000 --> 00:03:57,000 Somehow we had to make the shuttle tire think it was on the real shuttle. 63 00:03:57,000 --> 00:04:00,000 How did you do that, then, without using the real shuttle? 64 00:04:00,000 --> 00:04:05,000 Well, some very smart people at NASA Dryden Flight Research Facility in Edwards, California, 65 00:04:05,000 --> 00:04:08,000 came up with the Convair 990 program. 66 00:04:08,000 --> 00:04:11,000 This took the idea of the ALDEF one big step forward 67 00:04:11,000 --> 00:04:16,000 and allowed us to land an orbiter tire on whatever runway we want, all at full scale. 68 00:04:16,000 --> 00:04:21,000 A large fixture was built in the belly of the airplane that could apply the correct weight to a shuttle tire 69 00:04:21,000 --> 00:04:25,000 while the pilots landed the airplane at about 250 miles per hour. 70 00:04:25,000 --> 00:04:30,000 Okay, so the Convair 990 could simulate a shuttle tire landing pretty well, 71 00:04:30,000 --> 00:04:33,000 but how did you figure out the best runway surface? 72 00:04:33,000 --> 00:04:35,000 Well, that's a good question. 73 00:04:35,000 --> 00:04:37,000 Before we put the Convair 990 to the test, 74 00:04:37,000 --> 00:04:41,000 we had to get an idea of what kind of runway texture might or might not reduce tire wear. 75 00:04:41,000 --> 00:04:45,000 Building lots of three-mile-long test strips would be very expensive, 76 00:04:45,000 --> 00:04:50,000 so we conducted a sub- or small-scale test using a test vehicle from Langley. 77 00:04:50,000 --> 00:04:55,000 This truck allowed us to wear out smaller airplane tires by rolling and yawing them on lots of different textures, 78 00:04:55,000 --> 00:05:01,000 and it allowed us to predict which surfaces might be worthwhile to install in three-mile-long test strips. 79 00:05:01,000 --> 00:05:04,000 How do you measure tire wear? 80 00:05:04,000 --> 00:05:07,000 Well, after rolling these smaller tires a certain distance, 81 00:05:07,000 --> 00:05:09,000 we would weigh them and see how much rubber was worn off. 82 00:05:09,000 --> 00:05:12,000 Then we graphed that lost weight with distance. 83 00:05:12,000 --> 00:05:16,000 This graph shows tire wear for some of the different surfaces we tested. 84 00:05:16,000 --> 00:05:19,000 We tested 18 different textures in all. 85 00:05:19,000 --> 00:05:25,000 On the graph, we put a line showing the maximum amount of wear that we could live with to reach our new crosswind limit. 86 00:05:25,000 --> 00:05:29,000 Any surface that showed wear higher than that limit would be out of the question, 87 00:05:29,000 --> 00:05:31,000 and you can see that limits our choices. 88 00:05:31,000 --> 00:05:36,000 Cool! So now you had five runway surfaces instead of 18. What's next? 89 00:05:36,000 --> 00:05:42,000 Next, we conducted friction tests on the surfaces when they were wet to see how slippery they might get in the rain. 90 00:05:42,000 --> 00:05:45,000 This graph shows the results of those tests. 91 00:05:45,000 --> 00:05:49,000 We also put a line on this graph showing the minimum friction level that we could live with. 92 00:05:49,000 --> 00:05:55,000 A surface with less friction would make it too hard to steer or stop the shuttle if the surface were wet. 93 00:05:55,000 --> 00:05:59,000 This also limits our choices, and when we combined these two graphs, 94 00:05:59,000 --> 00:06:06,000 it said that we could only predict that three of the original 18 surface ideas would both reduce wear but not be too slippery. 95 00:06:06,000 --> 00:06:12,000 With our top three choices, we built three test strips and landed the Convair 990 on each of them. 96 00:06:12,000 --> 00:06:17,000 Comparing graphs and making predictions really helped us to narrow down our selection of expensive test strips. 97 00:06:17,000 --> 00:06:22,000 Okay, so how did you collect data from the Convair 990? 98 00:06:22,000 --> 00:06:26,000 Well, during our tests, we measured the tire forces with sensitive instruments, 99 00:06:26,000 --> 00:06:28,000 and then we used a computer to graph the results. 100 00:06:28,000 --> 00:06:35,000 We also combined video footage of each test to find out when each of the tire's cord layers were worn through by counting them. 101 00:06:35,000 --> 00:06:41,000 Finally, we could graph the forces in the tire wear and compare the performance of the new surface with the rough surface. 102 00:06:41,000 --> 00:06:46,000 This graph showed that we got less tire wear for the same forces on the new surface, just like we predicted. 103 00:06:46,000 --> 00:06:51,000 Using all these test results, NASA shuttle managers now had the information they needed 104 00:06:51,000 --> 00:06:55,000 to decide to change the texture of the entire runway surface at Kennedy Space Center. 105 00:06:55,000 --> 00:06:58,000 That's almost the equivalent of 100 football fields. 106 00:06:58,000 --> 00:07:04,000 Today, the shuttle orbiter has the ability to withstand twice the amount of crosswind without worrying about tire wear, 107 00:07:04,000 --> 00:07:07,000 and we use measurement, graphs, and predictions to do it.