1 00:00:00,000 --> 00:00:02,640 Okay, let's review. 2 00:00:02,640 --> 00:00:08,440 So far we've learned how NASA engineers use geometry and algebra, flow visualization and 3 00:00:08,440 --> 00:00:12,060 glowing paints to help them create more aerodynamic vehicles. 4 00:00:12,060 --> 00:00:14,840 And how shape and surface area affect drag. 5 00:00:14,840 --> 00:00:18,640 We've also learned how computer technology can help you solve problems that are out of 6 00:00:18,640 --> 00:00:19,640 this world. 7 00:00:19,640 --> 00:00:25,360 Now, let's learn how NASA engineers are using geometry to create a concept airplane that 8 00:00:25,360 --> 00:00:31,880 looks a lot like a flying wing. 9 00:00:31,880 --> 00:00:36,160 Describe the differences between the blended wing body and today's commercial airplanes. 10 00:00:36,160 --> 00:00:41,080 How do NASA engineers use geometry to estimate frontal surface area? 11 00:00:41,080 --> 00:00:45,080 What design features would increase the drag on a low speed vehicle? 12 00:00:45,080 --> 00:00:48,360 How could engineers compensate for that drag? 13 00:00:48,360 --> 00:00:54,680 The blended wing body, or BWB as we call it for short, is an advanced concept passenger 14 00:00:55,480 --> 00:00:59,280 That means that we're still in the process of deciding and testing what will be the best 15 00:00:59,280 --> 00:01:00,500 design. 16 00:01:00,500 --> 00:01:05,600 So far, early studies estimate the blended wing body will hold up to 500 passengers, 17 00:01:05,600 --> 00:01:12,600 have a wingspan of 247 feet, a length of 160 feet and be more than 40 feet or four stories 18 00:01:12,600 --> 00:01:13,600 high. 19 00:01:13,600 --> 00:01:16,640 It kind of resembles a flying wing. 20 00:01:16,640 --> 00:01:20,640 Engineers believe the BWB has potential to perform better than traditional tube with 21 00:01:20,640 --> 00:01:24,120 wings airplane, like the Boeing 747. 22 00:01:24,120 --> 00:01:28,440 Some estimates predict that this new airplane will reduce operating costs and the amount 23 00:01:28,440 --> 00:01:30,240 of fuel the airplane uses. 24 00:01:30,240 --> 00:01:34,360 This means your airline tickets may cost less. 25 00:01:34,360 --> 00:01:38,200 So Wendy, what makes the blended wing body so special? 26 00:01:38,200 --> 00:01:39,200 It's shape. 27 00:01:39,200 --> 00:01:44,040 Since we've been discussing shape and geometry in today's program, let me show you what makes 28 00:01:44,040 --> 00:01:47,800 the BWB different from other airplanes today. 29 00:01:47,800 --> 00:01:51,400 If you look down on the top of the plane, you can see that it's fuselage, that's the 30 00:01:51,400 --> 00:01:55,320 part that people ride in, and the wing are blended together. 31 00:01:55,320 --> 00:01:58,000 That's how it got its name, the blended wing body. 32 00:01:58,000 --> 00:02:04,400 Now, from the front of the BWB or the frontal view, we can see that there's a smooth transition 33 00:02:04,400 --> 00:02:06,560 from the fuselage to the wings. 34 00:02:06,560 --> 00:02:11,800 This shape allows more people to sit in the fuselage and even out into the wings. 35 00:02:11,800 --> 00:02:15,560 Remember the picture of the streamlined car Luther showed you? 36 00:02:15,560 --> 00:02:20,080 Just like a car, when an airplane has a smooth shape, it can help reduce drag. 37 00:02:20,720 --> 00:02:25,160 Do you see anything else that makes the BWB different from other airplanes? 38 00:02:25,160 --> 00:02:26,160 Hmm. 39 00:02:26,160 --> 00:02:29,920 You know, it doesn't have a tail like other airplanes. 40 00:02:29,920 --> 00:02:30,920 Right. 41 00:02:30,920 --> 00:02:35,480 Just like blending the wing and fuselage together helps to reduce drag, taking off both the 42 00:02:35,480 --> 00:02:38,840 horizontal and vertical tails also helps reduce drag. 43 00:02:38,840 --> 00:02:42,000 Drag, which you learned about earlier, resists thrust. 44 00:02:42,000 --> 00:02:46,240 Thrust, the force that propels the airplane, is usually provided by jet engine. 45 00:02:46,400 --> 00:02:51,240 If an airplane has too much drag, it will need more thrust or engine power. 46 00:02:51,240 --> 00:02:57,280 However, when the airplane is designed for less drag, like the BWB, less thrust is needed. 47 00:02:57,280 --> 00:02:59,800 So, what does this all mean? 48 00:02:59,800 --> 00:03:02,440 Less thrust means less fuel is needed. 49 00:03:02,440 --> 00:03:05,760 And less fuel means less money to buy a ticket. 50 00:03:05,760 --> 00:03:06,760 You got it. 51 00:03:06,760 --> 00:03:10,120 Now, Wendy, you said earlier that the BWB is just a concept airplane, so I guess that 52 00:03:10,120 --> 00:03:11,520 means it hasn't been built yet. 53 00:03:11,520 --> 00:03:12,520 Right. 54 00:03:12,520 --> 00:03:15,160 It would be too expensive to build the full-size BWB. 55 00:03:15,160 --> 00:03:19,200 NASA and Boeing engineers come together and design some scale models. 56 00:03:19,200 --> 00:03:22,840 That way, they can test it before they build the full-size blended wing body. 57 00:03:22,840 --> 00:03:25,240 Now, you said some scale models. 58 00:03:25,240 --> 00:03:28,720 Does that mean there's going to be more than one model of the BWB? 59 00:03:28,720 --> 00:03:29,880 Absolutely. 60 00:03:29,880 --> 00:03:32,720 If we only built one model, we couldn't collect enough information. 61 00:03:32,720 --> 00:03:37,560 So, we've built a model that's approximately 1% the size of the BWB. 62 00:03:37,560 --> 00:03:40,960 Hey, let's do the math. 63 00:03:40,960 --> 00:03:44,800 What would a 1% model of the BWB look like? 64 00:03:44,800 --> 00:03:48,120 Would it fit in your classroom or in a shoebox? 65 00:03:48,120 --> 00:03:49,120 I know. 66 00:03:49,120 --> 00:03:50,560 Let's figure it out. 67 00:03:50,560 --> 00:03:58,680 Wendy told us earlier that the BWB will be 247 feet wide, 160 feet long, and 40 feet 68 00:03:58,680 --> 00:03:59,680 tall. 69 00:03:59,680 --> 00:04:03,400 Using middle math, let's take 1% of each of those measurements. 70 00:04:03,400 --> 00:04:04,400 Okay. 71 00:04:04,400 --> 00:04:10,480 1% of 247 is 2.47 or about two and a half feet wide. 72 00:04:10,480 --> 00:04:17,040 1% of 160 is 1.6 or about one and a half feet long. 73 00:04:17,040 --> 00:04:23,240 1% of 40 is .4 or about a half foot tall. 74 00:04:23,240 --> 00:04:30,560 So, yeah, 1% model of the BWB should definitely fit in your classroom, right, Wendy? 75 00:04:30,560 --> 00:04:31,560 That's right. 76 00:04:31,560 --> 00:04:32,560 And here it is. 77 00:04:32,680 --> 00:04:36,720 As I said earlier, building just one scale model like this didn't give us all the information 78 00:04:36,720 --> 00:04:37,720 we needed. 79 00:04:37,720 --> 00:04:40,920 So, we built a 2%, 3%, and a 4% model. 80 00:04:40,920 --> 00:04:45,560 They'll all be tested here at NASA Langley in the wind tunnels to determine performance 81 00:04:45,560 --> 00:04:47,000 and stability. 82 00:04:47,000 --> 00:04:51,800 While wind tunnel tests can help us predict how the BWB will perform, it can't tell us 83 00:04:51,800 --> 00:04:54,920 how a real pilot will be able to control it in the air. 84 00:04:54,920 --> 00:05:00,760 So, NASA Langley is building another subscale model called the Low-Speed Vehicle, or LSV, 85 00:05:00,760 --> 00:05:02,500 and it will actually fly. 86 00:05:02,500 --> 00:05:07,100 We will take our LSV wind tunnel predictions and compare them to actual flight test data. 87 00:05:07,100 --> 00:05:11,620 The flight test will take place at NASA Dryden Flight Research Center in California. 88 00:05:11,620 --> 00:05:15,860 Engineers want to learn how to control and stabilize this new concept airplane so it 89 00:05:15,860 --> 00:05:16,860 will fly safely. 90 00:05:16,860 --> 00:05:20,020 In a wind tunnel, you just can't simulate that. 91 00:05:20,020 --> 00:05:24,900 The LSV is about 14% the size of a full-size BWB. 92 00:05:25,100 --> 00:05:32,780 The 14% model of the BWB is about 35 feet wide, 22 feet long, and 6 feet high. 93 00:05:32,780 --> 00:05:36,220 Remember in the classroom activity when you determined that a greater frontal surface 94 00:05:36,220 --> 00:05:38,660 area produced greater drag? 95 00:05:38,660 --> 00:05:42,260 Let's look at the frontal view of the 14% BWB model. 96 00:05:42,260 --> 00:05:46,940 To estimate the frontal surface area, all we need is the width, the height, and a little 97 00:05:46,940 --> 00:05:47,940 geometry. 98 00:05:47,940 --> 00:05:52,660 First, we take the frontal view and divide it into parts using geometric shapes like 99 00:05:52,660 --> 00:05:53,660 this. 100 00:05:53,900 --> 00:05:58,620 Then, we estimate the area of each geometric shape and add them together to get the total 101 00:05:58,620 --> 00:06:00,420 frontal surface area. 102 00:06:00,420 --> 00:06:05,680 Next, we combine the total frontal surface area with all the flight test data we've collected 103 00:06:05,680 --> 00:06:09,340 and calculate the drag force for this particular model. 104 00:06:09,340 --> 00:06:13,140 We know that to fly, we need a certain amount of thrust to overcome the drag force. 105 00:06:13,140 --> 00:06:17,780 Okay, so figuring out the frontal surface area of the 14% model helps you calculate 106 00:06:17,780 --> 00:06:21,940 drag, which then determines how much thrust is needed, right? 107 00:06:21,940 --> 00:06:23,820 But this is just a concept airplane, right? 108 00:06:23,820 --> 00:06:29,900 I mean, what if you wanted to add something, maybe like an observation deck on top? 109 00:06:29,900 --> 00:06:33,760 An observation deck would definitely increase the frontal surface area, Van, which would 110 00:06:33,760 --> 00:06:35,380 then increase drag. 111 00:06:35,380 --> 00:06:39,300 In order to overcome that amount of drag, we need to increase thrust by adding more 112 00:06:39,300 --> 00:06:40,540 powerful engines. 113 00:06:40,540 --> 00:06:42,320 You know what? 114 00:06:42,320 --> 00:06:45,220 That applies to the go-kart race I had with Van. 115 00:06:45,220 --> 00:06:50,500 My frontal surface area was greater than his because I didn't crouch down into an aerodynamic 116 00:06:50,500 --> 00:06:51,580 shape. 117 00:06:51,580 --> 00:06:55,700 This greater frontal surface area created more drag, and I lost. 118 00:06:55,700 --> 00:07:01,780 However, if I had more thrust, I could have easily overcome the drag and left Van in the 119 00:07:01,780 --> 00:07:02,780 dust. 120 00:07:02,780 --> 00:07:03,780 Well, you know what? 121 00:07:03,780 --> 00:07:04,780 That's all we have time for today. 122 00:07:04,780 --> 00:07:05,780 Yep. 123 00:07:05,780 --> 00:07:10,260 We hope you've all made the connection between the aeronautical research conducted here at 124 00:07:10,260 --> 00:07:14,580 NASA and the math, science, and technology that you do in your classrooms every day. 125 00:07:14,580 --> 00:07:18,860 Jennifer and I would love to hear from you with your questions, comments, or suggestions, 126 00:07:18,940 --> 00:07:26,300 so write us at nasaconnect, NASA Langley Research Center, Mailstop 400, Hampton, Virginia 23681, 127 00:07:26,300 --> 00:07:31,420 or send us an email at connect at edu.larc.nasa.gov.