WEBVTT - How Planes Work 0:00:04.240 --> 0:00:07.240 Welcome to Tech Stuff, a production of I Heart Radios 0:00:07.320 --> 0:00:13.960 How Stuff Works. Hey there, and welcome to tech Stuff. 0:00:14.040 --> 0:00:17.080 I'm your host, Jonathan Strickland. I'm an executive producer with 0:00:17.120 --> 0:00:19.560 How Stuff Works and I Heart Radio and I love 0:00:19.640 --> 0:00:22.560 all things tech and um I've been going on a 0:00:22.560 --> 0:00:26.280 lot of trips lately, both for work and for my 0:00:26.400 --> 0:00:29.240 personal life, you know, going on vacations and stuff, which 0:00:29.280 --> 0:00:32.440 means that I tend to get on planes quite a lot. 0:00:32.520 --> 0:00:35.080 So I thought today we talked about the history of 0:00:35.120 --> 0:00:38.760 airplanes and how airplanes work. I've talked a lot about 0:00:38.880 --> 0:00:42.440 different parts of planes in the past, but after doing 0:00:42.440 --> 0:00:44.920 a quick search, I realized I never really done a 0:00:44.960 --> 0:00:49.280 full episode about how planes themselves work. This is actually 0:00:49.280 --> 0:00:52.040 a pretty tricky field, as it is one that has 0:00:52.080 --> 0:00:54.600 been the subject of a lot of discussion as well 0:00:54.640 --> 0:00:58.600 as misinformation or at least an incomplete explanation of how 0:00:58.680 --> 0:01:01.960 things work, or an incorrect explanation of the how. The 0:01:02.040 --> 0:01:05.520 why tends to be correct, but the how tends to 0:01:05.520 --> 0:01:09.280 be confused, and it has led to jokes and memes 0:01:09.280 --> 0:01:12.560 that ultimately, you know, airplanes work on some sort of 0:01:12.600 --> 0:01:15.720 magic that depends upon us believing that it will work 0:01:16.160 --> 0:01:19.120 sort of like the Peter Pan theory of flight, and 0:01:19.160 --> 0:01:21.720 that's definitely taking things to extremes, and no one really 0:01:21.760 --> 0:01:24.559 believes that. But when you consider all the various explanations 0:01:24.560 --> 0:01:26.680 for what is going on, you can feel like the 0:01:26.760 --> 0:01:29.880 joke might be coming from a pretty sincere place. So 0:01:30.040 --> 0:01:33.920 let's start before we get into the how, with the 0:01:34.000 --> 0:01:38.280 history of flight, because you guys know how much I 0:01:38.480 --> 0:01:42.320 enjoy going into history lessons on this show. This is 0:01:42.760 --> 0:01:44.920 no exception. So there were a lot of people who 0:01:45.040 --> 0:01:49.080 dreamed of mastering flight over the past several hundred years, 0:01:49.440 --> 0:01:53.480 thousands of years actually. Many attempted to emulate the way 0:01:53.520 --> 0:01:58.640 birds fly, which seems pretty understandable. You see birds soaring 0:01:58.720 --> 0:02:01.600 through the sky or darting about, and you think, well, 0:02:01.640 --> 0:02:04.680 what's the secret there? How can we do the same thing, 0:02:05.440 --> 0:02:08.080 And so lots of people tried to emulate that. They 0:02:08.160 --> 0:02:11.840 created various rigs or devices that had moving wings, and 0:02:11.880 --> 0:02:14.239 the thought was that if we could just build wings 0:02:14.280 --> 0:02:17.240 of the right size that can move at the proper 0:02:17.360 --> 0:02:21.160 speed and the proper range of motion similar to that 0:02:21.240 --> 0:02:25.760 of a bird's wings, we too could fly through the sky. Now, 0:02:25.800 --> 0:02:29.040 the name for this type of machine one that has 0:02:29.480 --> 0:02:34.120 movable wings is an ornithopter, and legend has it that 0:02:35.280 --> 0:02:40.200 Arcatas of Tarentum made a wooden bird with this type 0:02:40.280 --> 0:02:44.760 of wing motion back in four hundred b C. And 0:02:44.840 --> 0:02:48.040 you might know from Greek mythology the story of Daedalus 0:02:48.240 --> 0:02:51.919 and Icarus, who are able to fly using man made 0:02:51.919 --> 0:02:54.880 wings attached to their arms, at least they did until 0:02:54.960 --> 0:02:59.720 Icarus flew too close to the sun spoiler alert. Leonardo 0:02:59.760 --> 0:03:02.680 dive and she similarly worked on a few theoretical designs 0:03:02.760 --> 0:03:06.880 that relied upon moving wings in the late fourteen hundreds. UH. 0:03:07.000 --> 0:03:11.360 Some people argue that da Vinci's designs would ultimately lead 0:03:11.400 --> 0:03:15.080 toward the development of the helicopter, but generally speaking, the 0:03:15.160 --> 0:03:19.400 movable wing design remained impractical. It wasn't providing enough lift 0:03:19.560 --> 0:03:23.560 or thrust to actually achieve flight. At best, the machines 0:03:23.560 --> 0:03:27.240 would allow for very short, unimpressive hops, like maybe hopping 0:03:27.240 --> 0:03:30.040 an inch off the ground, and at worst they didn't 0:03:30.040 --> 0:03:34.280 manage to lift up anything at all. However, Leonardo da Vinci, 0:03:34.360 --> 0:03:37.560 along with several other egg heads in history like Galileo 0:03:37.720 --> 0:03:41.720 and Isaac Newton, among many others, would advance our understanding 0:03:41.880 --> 0:03:46.400 of aerodynamics, which is the study of properties of moving air, 0:03:46.640 --> 0:03:51.080 particularly as it has to do with interactions with solid objects. 0:03:51.560 --> 0:03:56.000 By understanding how moving air affects solid objects and vice versa, 0:03:56.200 --> 0:03:58.600 we could start to build working theories on how to 0:03:58.720 --> 0:04:02.320 leverage that knowledge and create a working heavier than air 0:04:02.360 --> 0:04:07.160 flying machine. Now, this work was expanded upon by mathematicians 0:04:07.160 --> 0:04:12.760 and engineers people like John Smeaton, Daniel Bernoulli, and Leonard Euler. 0:04:13.280 --> 0:04:17.800 They explored the relationship between air pressure and air velocity. 0:04:18.400 --> 0:04:21.280 A hoity toity by the name of George Kyley would 0:04:21.440 --> 0:04:25.839 prove to be incredibly important in our understanding. He proposed 0:04:25.839 --> 0:04:30.680 that any working aircraft would need separate systems to provide lift, propulsion, 0:04:30.760 --> 0:04:34.360 and control, something the famous Right Brothers would repeat in 0:04:34.400 --> 0:04:38.040 the early nine hundreds. He also began to move away 0:04:38.120 --> 0:04:43.040 from the ornithopter design to a fixed wing approach for aircraft. So, 0:04:43.080 --> 0:04:47.200 in other words, the wing itself doesn't move with relation 0:04:47.279 --> 0:04:50.880 to the body of the aircraft. It stays fixed in place, 0:04:51.400 --> 0:04:55.560 and other elements are what allow the aircraft to fly. 0:04:56.000 --> 0:04:58.680 You don't have to worry about having the wings move 0:04:58.760 --> 0:05:02.280 in any particular path turn Now, Kayley's work led him 0:05:02.320 --> 0:05:05.640 to the conclusion that the way to produce lift was 0:05:05.680 --> 0:05:08.520 to design a machine that would create an area of 0:05:08.640 --> 0:05:12.200 low pressure above the wing and an area of higher 0:05:12.240 --> 0:05:15.919 pressure below the wing. So above the wing you have 0:05:16.120 --> 0:05:20.640 very low pressure. Comparatively speaking, below the wing you have 0:05:20.760 --> 0:05:24.480 very high pressure. So you've got support under you, right, 0:05:24.760 --> 0:05:28.800 You've got air pushing up against the wing from below 0:05:29.600 --> 0:05:32.240 and not not as much you know, air pressure above, 0:05:32.720 --> 0:05:35.600 So the high pressure beneath would lift the wing up, 0:05:35.640 --> 0:05:39.880 acting as a support in a way. Kayley was specifically 0:05:39.920 --> 0:05:43.240 exploring wing designs that had an arch to them, and 0:05:43.279 --> 0:05:46.440 his ideas were sound and in line with Bernoulli's theorem, 0:05:46.680 --> 0:05:49.599 which describes the behavior of moving fluids. And we have 0:05:49.640 --> 0:05:52.840 to remember that our atmosphere is a fluid. In this sense, 0:05:52.880 --> 0:05:58.040 gases have fluid i movement. Gases are fluids, just as 0:05:58.080 --> 0:06:01.359 liquids are fluids. It this is where a lot of 0:06:01.440 --> 0:06:05.520 sources get things a little muddled, and it's understandable, but 0:06:05.600 --> 0:06:09.800 it ends up being a a fundamental misunderstanding of what 0:06:10.000 --> 0:06:16.000 is going on. So the incorrect explanations tend to be 0:06:16.480 --> 0:06:19.279 right in describing the fact that the reason fixed wing 0:06:19.360 --> 0:06:21.920 flight works is that the movement of the aircraft through 0:06:21.920 --> 0:06:24.839 the air creates an area of low pressure above the 0:06:24.839 --> 0:06:27.560 wing in an area of high pressure below the wing. 0:06:28.040 --> 0:06:31.200 But they often mess up the actual explanation of how 0:06:31.320 --> 0:06:34.360 this is happening, what is actually going on. So let 0:06:34.360 --> 0:06:37.520 me give you the wrong way to describe it first 0:06:37.760 --> 0:06:40.080 and we'll get that out of the way. So typically 0:06:40.520 --> 0:06:44.520 the description starts with the design of the wing itself, 0:06:44.640 --> 0:06:48.000 which is usually described as having a flat bottom and 0:06:48.080 --> 0:06:50.920 a curved upper part, in which the front part of 0:06:50.960 --> 0:06:55.080 the wing, the leading edge, ends up curving up to 0:06:55.279 --> 0:06:57.920 become a bit thicker towards the front of the wing 0:06:58.440 --> 0:07:01.000 and then tapers to ord the back of the wing, 0:07:01.520 --> 0:07:04.080 where the upper surface you know, slopes back down and 0:07:04.120 --> 0:07:07.480 meets the lower surface for the back edge or trailing 0:07:07.760 --> 0:07:10.720 edge of the wing. And if you're looking at the 0:07:10.880 --> 0:07:14.120 cross section of the wing, then you kind of get 0:07:14.120 --> 0:07:19.360 a sideways tear drop shape right the the leading edge 0:07:20.000 --> 0:07:24.040 gets thicker and then tapers back down until it meets 0:07:24.040 --> 0:07:27.640 again at the trailing edge. Um, by the way, the 0:07:27.680 --> 0:07:30.440 technical name for the cross section of a wing is 0:07:30.480 --> 0:07:34.560 an airfoil. Air Foils do not necessarily have to follow 0:07:34.600 --> 0:07:38.119 that shape, but many do. Many early air foils would 0:07:38.120 --> 0:07:43.080 follow that curved design. Now, again, the wrong description for 0:07:43.280 --> 0:07:46.840 what is causing lift states that when the wing moves 0:07:46.840 --> 0:07:50.680 through a fluid, or conversely, when a fluid moves past 0:07:50.880 --> 0:07:53.720 the wing, either way will work. There has to be motion, 0:07:54.120 --> 0:07:56.320 but the motion can work in either way. You can 0:07:56.320 --> 0:07:59.840 either have the fluid moving at a proper speed against 0:08:00.440 --> 0:08:03.600 the solid object. That's the way we test things out 0:08:03.640 --> 0:08:06.520 in wind tunnels. We have a stationary object and we 0:08:06.680 --> 0:08:10.880 blow wind past it, or the object itself can move 0:08:10.960 --> 0:08:13.560 through the fluid, which is the way airplanes work. They 0:08:13.600 --> 0:08:18.800 fly through the air either way. According to this incorrect explanation, 0:08:18.840 --> 0:08:22.120 the air molecules when they hit that leading edge, that 0:08:22.280 --> 0:08:25.720 front edge of the wing, end up splitting into two 0:08:25.720 --> 0:08:29.440 different pathways. Some of the air molecules are traveling over 0:08:29.480 --> 0:08:32.439 the top surface of the wing and some are traveling 0:08:32.480 --> 0:08:34.480 on the bottom surface of the wing. Well, the top 0:08:34.480 --> 0:08:36.880 surface of the wing has that curve to it, which 0:08:36.920 --> 0:08:40.320 means that the air molecules have to travel further from 0:08:40.320 --> 0:08:43.920 the front edge to the back edge right than it 0:08:43.960 --> 0:08:47.080 would on the lower side of the wing because the 0:08:47.120 --> 0:08:50.040 lower side is straight, and as we know, the shortest 0:08:50.200 --> 0:08:53.240 distance between two points is a straight line, So the 0:08:53.280 --> 0:08:55.760 bottom edge of a wing is a straight line to 0:08:55.840 --> 0:08:59.400 go from the leading edge to the trailing edge straight path. 0:08:59.840 --> 0:09:01.560 The if you're going over the top, you have to 0:09:01.559 --> 0:09:05.240 follow that curve, which means you're actually traveling more distance, 0:09:05.880 --> 0:09:10.200 and so that is a longer way to travel. And 0:09:10.280 --> 0:09:16.880 according to this incorrect description of lift, the air molecules 0:09:16.880 --> 0:09:18.800 traveling on top of the wing have to go faster 0:09:18.920 --> 0:09:21.719 than the molecules traveling below the wing, and then they 0:09:21.760 --> 0:09:24.560 meet back up at the trailing edge. So let's say 0:09:24.559 --> 0:09:28.040 you've got air molecule one and air molecule to. Molecule 0:09:28.120 --> 0:09:31.840 one's traveling over the wing, Molecule two is traveling under 0:09:31.880 --> 0:09:36.240 the wing, and they both meet at the far end. 0:09:36.679 --> 0:09:38.440 But in order to do that, molecule one has to 0:09:38.480 --> 0:09:42.040 travel faster than molecule two. And according to bern Newley's 0:09:42.080 --> 0:09:45.760 theorem Daniel Burn Newley, a fast moving fluid is at 0:09:45.800 --> 0:09:49.920 a lower press pressure than a slower moving fluid. So 0:09:50.120 --> 0:09:52.800 says this description, the air pressure above the wing is 0:09:52.880 --> 0:09:56.120 lower than the air pressure below the wing. Now it 0:09:56.240 --> 0:09:58.240 is true that the air pressure above the wing is 0:09:58.280 --> 0:10:02.200 lower and that the air pressure below the wing is higher. 0:10:02.800 --> 0:10:04.920 I keep thinking that I've said this is the wrong way, 0:10:04.920 --> 0:10:07.480 because I'm talking about above and below and higher and 0:10:07.520 --> 0:10:11.000 lower than you flip them right, because everything above the 0:10:11.000 --> 0:10:12.800 wing is a lower pressure, everything below the wing is 0:10:12.840 --> 0:10:16.520 a higher pressure. That part is right. So the destination 0:10:16.600 --> 0:10:19.160 is correct. It's the journey to get there that we've 0:10:19.200 --> 0:10:23.320 got wrong, because, uh, there would need to be some 0:10:23.400 --> 0:10:26.960 reason for the upper and lower air molecules to have 0:10:27.040 --> 0:10:30.000 to travel to arrive at the same destination at the 0:10:30.040 --> 0:10:32.520 same time. But there's no reason for that at all. 0:10:32.679 --> 0:10:35.120 There's no reason why air molecule one and air molecule 0:10:35.160 --> 0:10:38.160 to have to meet back up again at the trailing edge. 0:10:38.640 --> 0:10:41.360 One of them can easily travel faster than the other. 0:10:41.720 --> 0:10:46.520 There's no conservation of velocity between the two. Now, if 0:10:46.520 --> 0:10:48.280 it were true that the air molecules on the top 0:10:48.280 --> 0:10:51.319 and the air molecules on the below had to travel 0:10:52.400 --> 0:10:54.840 at a speed where they would meet up again, that 0:10:54.840 --> 0:10:59.199 that was absolutely necessary. This description would work if that 0:10:59.240 --> 0:11:02.040 were true. If air molecule wanted two had to meet 0:11:02.080 --> 0:11:06.280 on the far end again, this would be an accurate theory. However, 0:11:06.320 --> 0:11:08.560 the flaw in this description goes by the name the 0:11:08.679 --> 0:11:13.959 equal transit theory or sometimes the longer path theory. Now, 0:11:14.000 --> 0:11:16.559 before I explain what is really going on with lift. 0:11:16.880 --> 0:11:20.160 Let's consider for a moment how we know this common 0:11:20.200 --> 0:11:24.440 description is incorrect. First, if this were actually how wings 0:11:24.440 --> 0:11:27.480 would generate lift, it would mean that any plane that 0:11:27.600 --> 0:11:30.319 did not have this wing design would fail to generate 0:11:30.360 --> 0:11:33.760 lift because you wouldn't have that longer path on top. So, 0:11:33.800 --> 0:11:35.800 in other words, if you had a straight wing design 0:11:35.880 --> 0:11:38.199 for your aircraft, there's no way it would be able 0:11:38.240 --> 0:11:40.600 to fly. It could not generate lift if this were 0:11:40.600 --> 0:11:43.320 in fact the only way it worked, and we know 0:11:43.400 --> 0:11:45.719 that's not the case. There are lots of aircraft out 0:11:45.760 --> 0:11:50.000 there to have a flat wing design. A paper airplane 0:11:50.080 --> 0:11:52.920 doesn't have a curved wing, and it can generate lift. 0:11:53.360 --> 0:11:55.440 You just have to give it enough thrust and it 0:11:55.440 --> 0:11:59.120 will fly. It doesn't immediately plummet um. It does lose 0:11:59.640 --> 0:12:02.720 speed because of drag. We'll talk about dragon a little bit, 0:12:03.000 --> 0:12:05.679 and if it loses speed then it's not generating enough 0:12:05.760 --> 0:12:09.080 lift to maintain flight, so it will eventually fall. But 0:12:10.120 --> 0:12:12.880 that's a flat wing and it does work. So flat 0:12:12.880 --> 0:12:15.640 wings can work as well as curved wings, so that 0:12:15.679 --> 0:12:20.800 part is out Further, if that explanation were absolutely true, 0:12:21.040 --> 0:12:23.079 planes with curved wings would never be able to fly 0:12:23.200 --> 0:12:26.679 upside down, because if they were to roll over, and 0:12:26.800 --> 0:12:29.920 the whole reason why lift was generated was because air 0:12:30.040 --> 0:12:33.000 was traveling further on one side than the other and 0:12:33.000 --> 0:12:36.120 then meeting back up with the air molecules, then the 0:12:36.120 --> 0:12:39.640 plane's wings would actually create lower air pressure below the 0:12:39.679 --> 0:12:42.840 plane and higher air pressure above the plane that would 0:12:42.920 --> 0:12:48.040 drive the plane downward. So instead of having lift holding 0:12:48.040 --> 0:12:50.439 the plane up, you would be creating a force that, 0:12:50.679 --> 0:12:53.760 combined with gravity, would pull the plane downward or push 0:12:53.800 --> 0:12:56.120 the plane downward, and you would end up with a 0:12:56.160 --> 0:13:00.480 catastrophic result. But we know that's not the case. Trained 0:13:00.480 --> 0:13:03.880 pilots can fly upside down, and properly designed aircraft, you know, 0:13:03.920 --> 0:13:08.800 aircraft that can withstand the forces of rolling over on 0:13:08.800 --> 0:13:13.199 on to their backs. You can still fly inverted that way. 0:13:13.440 --> 0:13:16.560 So clearly there has to be something else going on here. 0:13:16.679 --> 0:13:20.800 The explanation does not work as it stands, so to 0:13:20.880 --> 0:13:23.760 be clear, the end result of how lift works is 0:13:23.800 --> 0:13:26.400 the same in that a plane's wings do create areas 0:13:26.400 --> 0:13:30.199 of low pressure above and high pressure below the wing, 0:13:30.480 --> 0:13:32.720 but the way they do it is different from the 0:13:32.760 --> 0:13:36.400 explanation commonly given. So, in other words, the common explanation 0:13:36.440 --> 0:13:38.880 gives us the right end result but uses the wrong 0:13:38.880 --> 0:13:41.319 way to get there. So it's sort of like using 0:13:41.320 --> 0:13:45.359 the wrong process to solve a math problem but accidentally 0:13:45.360 --> 0:13:50.040 getting the right answer anyway. Sure, the answer is technically 0:13:50.080 --> 0:13:53.120 what you were looking for. The important part is not 0:13:53.200 --> 0:13:55.920 getting the right answer, it's knowing the right way to 0:13:56.120 --> 0:13:59.520 get to that answer. So let's talk about what's actually 0:13:59.640 --> 0:14:04.360 going on. First. Air does in fact move faster over 0:14:04.400 --> 0:14:06.520 the top edge than the lower edge of the wing, 0:14:07.160 --> 0:14:09.920 much faster. In fact, air molecules traveling over the top 0:14:09.920 --> 0:14:12.520 of the wing will arrive at the trailing edge before 0:14:12.920 --> 0:14:16.040 air molecules traveling on the lower side. So that air 0:14:16.120 --> 0:14:19.640 molecule one and two example I gave before, air molecule 0:14:19.680 --> 0:14:21.920 one is going over the wing, air molecule two is 0:14:21.960 --> 0:14:24.240 going under the wing. Air molecule one is actually going 0:14:24.240 --> 0:14:27.200 to arrive at the trailing edge first. They don't meet 0:14:27.280 --> 0:14:31.160 up again, so there's none of those air molecules splitting 0:14:31.240 --> 0:14:33.520 up at the leading edge meeting at the trailing edge. 0:14:33.560 --> 0:14:35.800 The air molecules traveling beneath the wing are actually meeting 0:14:35.840 --> 0:14:38.520 up with totally new air particles that hit the leading edge. 0:14:38.640 --> 0:14:43.200 Later on, more importantly, a wing deflects air and then 0:14:43.520 --> 0:14:46.240 the way it does so creates the area of lower 0:14:46.280 --> 0:14:49.520 pressure above the wing and the area of higher pressure 0:14:49.600 --> 0:14:51.600 below the wing. You can think of the air below 0:14:51.600 --> 0:14:55.280 a wing as getting compressed or squished, while the air 0:14:55.280 --> 0:14:58.160 immediately above a wing enters into more space than it 0:14:58.160 --> 0:15:01.160 had previously occupied. And this is because we're talking about 0:15:01.160 --> 0:15:04.760 a solid structure moving through a fluid. The difference in 0:15:04.800 --> 0:15:07.520 air pressure is what causes the big change in the 0:15:07.560 --> 0:15:10.680 fluids speed. So, in other words, the change in air 0:15:10.720 --> 0:15:14.440 pressure is what is effect affecting those air molecules speed 0:15:14.520 --> 0:15:18.040 across the wing. It's the opposite of what the equal 0:15:18.080 --> 0:15:21.520 transit theory states, which is that the difference in speed 0:15:21.720 --> 0:15:24.320 causes the change in pressure. Actually, it's the change in 0:15:24.360 --> 0:15:27.080 pressure that causes the difference in speed, and the air 0:15:27.160 --> 0:15:29.240 molecules traveling both on the top side of the wing 0:15:29.280 --> 0:15:31.880 and the bottom will at the end have a downward 0:15:32.000 --> 0:15:35.080 velocity once they leave the trailing edge of the wing. 0:15:35.640 --> 0:15:38.040 So why does the air traveling over the wing move 0:15:38.120 --> 0:15:40.800 downward at the end. If the air molecules moving over 0:15:40.840 --> 0:15:43.440 the top of the wing this curved surface in your 0:15:43.480 --> 0:15:48.400 typical airfoil, why would those air molecules be moving downward? 0:15:48.440 --> 0:15:51.240 I mean surely they would just continue horizontally in a 0:15:51.280 --> 0:15:54.360 straight line right now. It's because in our system we 0:15:54.440 --> 0:15:58.720 still have the atmosphere above the plane to consider that. 0:15:58.840 --> 0:16:01.160 You know, when we're first talking about air pressure around 0:16:01.200 --> 0:16:04.040 the wing, we're looking at the immediate area around the wing, 0:16:04.320 --> 0:16:06.640 but you still have all the rest of the atmosphere 0:16:06.680 --> 0:16:09.800 above the plane to consider. Now, immediately over the wing, 0:16:09.840 --> 0:16:12.000 the air pressure is lower due to the presence of 0:16:12.000 --> 0:16:15.280 this physical object moving through a fluid, or the fluid 0:16:15.320 --> 0:16:18.000 moving across the object, or both, because it's all a 0:16:18.040 --> 0:16:21.720 matter of perspective. But above that you still have all 0:16:21.800 --> 0:16:25.760 that atmosphere a normal air pressure depending on that altitude. 0:16:26.240 --> 0:16:29.960 So all that air is still pushing down on the 0:16:30.160 --> 0:16:32.680 area around the plane, and it starts pushing down on 0:16:32.720 --> 0:16:35.680 that lower pressure air, and that forces that lower pressure 0:16:35.680 --> 0:16:38.480 air downward at the trailing edge of the wing. And 0:16:38.560 --> 0:16:40.960 this brings us to another big important factor and lift 0:16:41.200 --> 0:16:44.520 called down wash, that is the amount of air the 0:16:44.520 --> 0:16:48.680 wing is forcing downward. Now, according to Isaac Newton's third 0:16:48.760 --> 0:16:51.640 law of motion, if you have a mechanical system applying 0:16:51.720 --> 0:16:55.600 force in one direction in a system, and equal opposite 0:16:55.600 --> 0:16:59.880 force applies to that mechanical system, so an airplane, for 0:17:00.120 --> 0:17:04.000 saying air downward, will also experience lift upward. It's equal 0:17:04.040 --> 0:17:06.359 to the amount of force of the air going down. 0:17:06.800 --> 0:17:10.399 This is easier to imagine if we think about a helicopter, right. 0:17:10.480 --> 0:17:13.960 A helicopter has rotors that act similar to the way 0:17:14.040 --> 0:17:18.760 and airplanes air foils works. The rotors rotate in a circle, 0:17:19.040 --> 0:17:22.320 So instead of a plane moving horizontally through a fluid, 0:17:22.720 --> 0:17:26.000 you have this rotor that's rotating around in a circle 0:17:26.040 --> 0:17:29.080 and that forces air downwards, and that creates the lift 0:17:29.119 --> 0:17:32.600 that allows helicopters to fly. Airplane wings do the same thing, 0:17:32.640 --> 0:17:35.640 but it's less obvious to us. Those downward traveling air 0:17:35.680 --> 0:17:38.000 molecules at the trailing edge of a wing are the 0:17:38.040 --> 0:17:40.800 down wash of a plane, and it's a secondary source 0:17:40.840 --> 0:17:44.080 of lift along with that air pressure description I just gave, 0:17:44.560 --> 0:17:47.000 So it's not the primary source. It's secondary, but it 0:17:47.080 --> 0:17:50.640 does contribute to the lift that the plane experiences. Now, 0:17:50.680 --> 0:17:54.239 this is why an airplanes wings aren't perfectly horizontal with 0:17:54.280 --> 0:17:56.560 regard to the body of the plane. If you look 0:17:56.680 --> 0:17:59.000 at an airplane, you will notice that the wings have 0:17:59.080 --> 0:18:02.280 a bit of a to them, so that the leading 0:18:02.480 --> 0:18:06.680 edge of the wing is actually pointed up a little bit, 0:18:07.080 --> 0:18:09.640 and the trailing edge is pointed down a little bit, 0:18:10.359 --> 0:18:12.880 and this creates what we call the angle of attack, 0:18:13.440 --> 0:18:16.800 and the angled wings encourage this down wash effect. If 0:18:16.840 --> 0:18:20.520 you've ever put your hand out into the wind and 0:18:20.600 --> 0:18:22.760 you tilted your hand in different ways and you get 0:18:22.800 --> 0:18:26.200 to that sweet spot where you feel like, oh, well, 0:18:26.200 --> 0:18:29.280 now my hand is staying up because of the angle 0:18:29.320 --> 0:18:30.959 it's at as it's going through the wind, like if 0:18:30.960 --> 0:18:33.119 it's out a car window. By the way, don't do that, 0:18:33.160 --> 0:18:34.679 it's dangerous. But if you were to do that and 0:18:34.680 --> 0:18:36.600 you felt it, you know what I'm talking about the 0:18:36.680 --> 0:18:39.040 same thing with airplane wings. That's why they're at that tilt, 0:18:39.600 --> 0:18:42.120 all right. So that's the explanation of the lift. And 0:18:42.200 --> 0:18:44.520 in a moment I'll talk more about how the right 0:18:44.560 --> 0:18:48.200 brothers or I'm creating a working heavier than air flying machine. 0:18:48.600 --> 0:18:59.560 But first let's take a quick break. Now, I just 0:18:59.640 --> 0:19:04.000 spent a lot of time going over lift. But that's 0:19:04.119 --> 0:19:06.639 just one of the forces that are acting on a 0:19:06.640 --> 0:19:09.520 plane in flight. And I mentioned one other briefly as well. 0:19:10.200 --> 0:19:12.919 There are three other forces that are all acting on 0:19:12.920 --> 0:19:15.960 a plane. So for total you've got lift. That's an 0:19:16.040 --> 0:19:19.960 upward force on the plane. There's thrust that's the forward 0:19:20.280 --> 0:19:23.159 force of a plane then, and you have to have 0:19:23.200 --> 0:19:26.359 your thrust to be strong enough to create an airflow 0:19:26.880 --> 0:19:29.320 around the wings to generate the lift to keep a 0:19:29.320 --> 0:19:31.639 plane in flight. So you need to be moving forward 0:19:31.720 --> 0:19:35.000 enough through the fluid, fast enough through the fluid so 0:19:35.040 --> 0:19:38.560 that you can generate lift, or the fluid has to 0:19:38.600 --> 0:19:41.560 be moving fast enough past you in order to do that. Again, 0:19:41.600 --> 0:19:44.880 it's all a matter of perspective. If a plane moves 0:19:44.880 --> 0:19:47.960 too slowly through the air, it won't create the difference 0:19:48.000 --> 0:19:51.440 in air pressure and down wash sufficient enough to maintain lift, 0:19:51.560 --> 0:19:55.040 So thrust is really important. Drag is a force that 0:19:55.080 --> 0:19:58.600 opposes the forward motion of the aircraft. So this is 0:19:58.640 --> 0:20:01.480 sort of the force that's acting uh in a backward 0:20:01.840 --> 0:20:05.639 motion against the aircraft. It's a mechanical force generated by 0:20:05.640 --> 0:20:08.720 the interaction of a solid body with a fluid, and 0:20:08.760 --> 0:20:11.439 it depends upon the difference in velocity between the solid 0:20:11.480 --> 0:20:14.760 object and the fluid. You experienced drag if you've ever 0:20:14.800 --> 0:20:17.000 been swimming pool. You're just walking through and you feel 0:20:17.000 --> 0:20:21.080 that resistance. That resistance is drag. You're forcing water molecules 0:20:21.080 --> 0:20:23.680 to move around you as you walk through. Uh, friction 0:20:23.960 --> 0:20:27.320 plays a factor in this. There's also a concept called 0:20:27.400 --> 0:20:32.840 induced drag, which involves the way that the air pressure 0:20:33.080 --> 0:20:37.320 is is changing and sort of how that is um 0:20:37.320 --> 0:20:39.520 reconciling at the trailing edge of a wing. But it 0:20:39.520 --> 0:20:42.119 gets really technical, and I figure you guys probably need 0:20:42.160 --> 0:20:44.680 a break after I tackled lift. Suffice it to say, 0:20:45.240 --> 0:20:50.680 drag opposes forward motion. So through aircraft design and propulsion systems, 0:20:50.840 --> 0:20:53.720 we have to overcome drag to maintain a proper forward 0:20:53.800 --> 0:20:57.800 velocity to maintain lift. So we do that with making 0:20:57.840 --> 0:21:03.200 aircraft more aerodynamic, you know, reducing that resistance, and by 0:21:03.240 --> 0:21:09.240 having appropriately powerful engines to propel with enough thrust to 0:21:09.320 --> 0:21:14.040 maintain lift. The fourth force in flight is gravity. This 0:21:14.119 --> 0:21:17.399 is obviously the force pulling downward on the plane. So 0:21:17.480 --> 0:21:21.040 we have thrust that's the forward force, drag which is 0:21:21.119 --> 0:21:24.199 the backward force, lift which is the upward force, and 0:21:24.240 --> 0:21:26.919 gravity which is the downward force. All of these are 0:21:27.040 --> 0:21:30.000 vectors because they all have an amplitude and a direction. 0:21:30.440 --> 0:21:32.920 So aircraft design has to take all of those forces 0:21:32.960 --> 0:21:36.520 into account. All right, So we got the technical description 0:21:36.560 --> 0:21:38.639 of the forces acting on the planes out of the way, 0:21:38.960 --> 0:21:41.439 let's get back to the history of stuff. I'll keep 0:21:41.480 --> 0:21:44.840 in mind that throughout this history description that I'm doing, 0:21:45.320 --> 0:21:48.240 people were still sussing out the nature of lift, as 0:21:48.320 --> 0:21:50.800 is obvious by the fact that we still today have 0:21:50.840 --> 0:21:53.800 textbooks and articles that give an incorrect explanation of what 0:21:53.920 --> 0:21:56.080 is going on, or maybe how I should I should 0:21:56.119 --> 0:21:59.560 say how it is going on now. In the eighteen seventies, 0:21:59.600 --> 0:22:03.640 a couple of engineers, one named Francis h Winham and 0:22:03.840 --> 0:22:07.000 John Browning Is the other built the first wind tunnel 0:22:07.200 --> 0:22:10.120 and that would become a critical component for testing wing 0:22:10.200 --> 0:22:14.200 designs and learning more about the practical effects of those designs. 0:22:14.760 --> 0:22:18.200 More work was done by a dude named Horatio Phillips. 0:22:18.359 --> 0:22:20.280 A lot of really great names in this history. By 0:22:20.320 --> 0:22:24.280 the way, Horatio Phillips built an improved wind tunnel and 0:22:24.280 --> 0:22:26.800 created an airfoil design that would become the basis for 0:22:26.880 --> 0:22:29.919 most wing designs in the following decades. Then we have 0:22:30.320 --> 0:22:34.399 Auto Lelandhall. He was a or Lilonhall. He was a 0:22:34.400 --> 0:22:39.680 German engineer who took Cayley's work and began serious testing 0:22:39.800 --> 0:22:43.160 of various wing designs and angles of attack to find 0:22:43.200 --> 0:22:47.080 out what would work best, what is the most efficient 0:22:47.119 --> 0:22:50.399 way to generate lift? What's the best design and best 0:22:50.480 --> 0:22:53.879 angle to get that effect? And he saw that different 0:22:53.920 --> 0:22:57.600 angles of attack allowed for different results and lift. Angling 0:22:57.600 --> 0:23:00.280 a wing could improve the ability to generate lift up 0:23:00.280 --> 0:23:03.000 to a point, and then beyond a certain angle which 0:23:03.040 --> 0:23:06.840 is around fifteen degrees uh, the ability to generate lift 0:23:06.880 --> 0:23:09.720 would drop off again. So as work became the basis 0:23:09.760 --> 0:23:13.240 for many other engineers who followed, including the Right brothers, 0:23:13.520 --> 0:23:17.359 and Otto himself was no slouch. He built several gliders, 0:23:17.480 --> 0:23:22.080 including biplane gliders, and he began conducting test glide flights, 0:23:22.160 --> 0:23:25.439 both manned and unmanned ones, and he probably went on 0:23:25.520 --> 0:23:28.320 more than two thousand, maybe as many as twenty hundred 0:23:28.320 --> 0:23:31.920 test flights. Tragically, it was during one of those tests 0:23:31.920 --> 0:23:35.080 that he met his end in eighteen nineties six after 0:23:35.160 --> 0:23:39.159 a fatal crash. Next we have Samuel Langley, who was 0:23:39.200 --> 0:23:42.600 an astronomer who seemed to have a pretty promising jump 0:23:42.680 --> 0:23:45.719 on creating a working aircraft. He wanted to use a 0:23:45.800 --> 0:23:49.320 steam powered engine to create the thrust needed to achieve 0:23:49.359 --> 0:23:52.720 the lift necessary for flight, so he built a model 0:23:52.920 --> 0:23:56.960 of a plane smaller than a full scale version, and 0:23:57.040 --> 0:24:00.119 it was an unmanned aircraft and He called it the 0:24:00.240 --> 0:24:05.840 Aerodrome in one so a few years before Auto would 0:24:05.880 --> 0:24:10.800 have his his fatal crash. Langley tested this design and 0:24:10.880 --> 0:24:13.840 the aerodrome flew for about three quarters of a mile. 0:24:14.560 --> 0:24:17.800 At that point the aircraft ran out of fuel steam 0:24:17.880 --> 0:24:20.960 powered aircraft. It was enough to get Langley a sizeable 0:24:21.040 --> 0:24:24.000 grant to try and build a full scale version, but 0:24:24.160 --> 0:24:29.240 unfortunately he discovered his design couldn't scale up because as 0:24:29.280 --> 0:24:31.879 you got larger, you're going to need more power to 0:24:32.000 --> 0:24:34.639 generate the thrust, and more power meant you needed a 0:24:34.680 --> 0:24:38.440 heavier steam engine, and and eventually that that ratio just 0:24:38.480 --> 0:24:42.280 wouldn't work out. The steam engine was just too heavy, 0:24:42.480 --> 0:24:45.440 and so you would need even more power to generate 0:24:45.600 --> 0:24:49.440 enough lift to get the heavier aircraft up, and there 0:24:49.520 --> 0:24:52.600 was no way to have the steam engine actually provide 0:24:52.680 --> 0:24:56.280 the power needed and he ultimately had to abandon his 0:24:56.400 --> 0:24:59.440 design at the plane just needed more lift and it 0:24:59.480 --> 0:25:01.800 could generate front thrust, and thus it could not fly. 0:25:02.640 --> 0:25:08.720 In Octave, Chanut, another great name, published a collection of 0:25:08.760 --> 0:25:12.680 works called Progress in Flying Machines. He collected the wisdom 0:25:12.840 --> 0:25:18.160 and experimental results of numerous efforts throughout the aeronautic societies 0:25:18.200 --> 0:25:22.600 out there and and essentially wrote down everything that had 0:25:22.600 --> 0:25:24.680 been done up to that point in the efforts to 0:25:24.760 --> 0:25:28.640 achieve powered flight. Then we get to Orville and Wilbur 0:25:28.800 --> 0:25:33.439 right the right brothers. They recognized Cayley's wisdom and the 0:25:33.520 --> 0:25:36.280 need for separate systems to provide the lift, thrust, and 0:25:36.320 --> 0:25:39.880 control of the aircraft. They also relied upon Chanut's book 0:25:39.920 --> 0:25:42.680 to help guide their own efforts. They came up with 0:25:42.720 --> 0:25:46.160 their own experiment with regard to controlling a flying body's 0:25:46.240 --> 0:25:49.879 motion through flight, the whole steering part of the equation. 0:25:50.200 --> 0:25:52.680 They believe that by controlling the shape of the wing 0:25:53.119 --> 0:25:56.320 they can control the flight itself, including stuff like roll 0:25:56.760 --> 0:26:00.480 and pitch. So the three types of movement you need 0:26:00.520 --> 0:26:03.520 to know about with aircraft once they're flying in three 0:26:03.520 --> 0:26:09.480 dimensional space are roll, pitch, and yaw. Roll is sort 0:26:09.480 --> 0:26:12.960 of the the tilt, the side to side tilt of 0:26:13.000 --> 0:26:15.560 an aircraft, so whether it's tilting to the left or 0:26:15.600 --> 0:26:19.480 tilting to the right. Um as I'll talk about later, 0:26:19.920 --> 0:26:23.200 this tilting becomes a very important part of steering. Pitch 0:26:23.880 --> 0:26:27.399 is the uh the angle of the nose and the 0:26:27.400 --> 0:26:32.160 tail right. So if if you are um pitching up, 0:26:32.240 --> 0:26:37.159 then the aircraft's nose is at a higher altitude than 0:26:37.200 --> 0:26:40.359 the tail, and the aircraft is climbing pitched down, and 0:26:40.400 --> 0:26:42.840 the nose is at a lower altitude than the tail, 0:26:43.040 --> 0:26:48.800 and the aircraft is descending. And then yaw involves turning 0:26:48.840 --> 0:26:52.240 to the left or to the right, although yaw and 0:26:52.520 --> 0:26:56.280 roll are very very important components for steering. Anyway, those 0:26:56.320 --> 0:27:00.560 are the three ways of thinking about the three different 0:27:00.560 --> 0:27:05.440 axes of flight controls in three dimensional space. So we'll 0:27:05.440 --> 0:27:07.480 come back to that in a little bit. So anyway, 0:27:07.760 --> 0:27:10.399 the Right brothers said, all right, well, by manipulating the 0:27:10.440 --> 0:27:16.560 shape of the wing, we can add steering to an aircraft. Um. 0:27:16.640 --> 0:27:20.720 They built several gliders, both unmanned and manned gliders, and 0:27:20.760 --> 0:27:25.080 tested different wing shapes and designs, including in wind tunnels, 0:27:25.119 --> 0:27:27.919 and they worked on perfecting that. And this brings us 0:27:27.960 --> 0:27:32.560 to another important component of the design. Getting up in 0:27:32.600 --> 0:27:34.719 the air is one thing, but from that point on, 0:27:34.720 --> 0:27:36.919 how do you control where you're going? Right? How do 0:27:36.960 --> 0:27:39.560 you actually maneuver a solid object through the air that 0:27:39.640 --> 0:27:42.960 three dimensional space there's no ground to brace against, and 0:27:42.960 --> 0:27:45.399 how do you steer the darn thing? And that was 0:27:45.440 --> 0:27:47.240 what the Right brothers were really working on. In those 0:27:47.240 --> 0:27:49.680 early tests trying to determine the most effective way to 0:27:49.720 --> 0:27:52.560 control the flight of an aircraft once it's airborne. So 0:27:52.640 --> 0:27:54.920 we'll talk about that for a second. Steering something means 0:27:55.080 --> 0:27:56.879 you have to be able to control the direction in 0:27:56.920 --> 0:28:01.360 which that something is traveling. It's very basic and obvious observation, 0:28:01.480 --> 0:28:03.960 but I feel like we have to start somewhere. So 0:28:04.040 --> 0:28:06.600 you need to be able to change the object's velocity 0:28:06.640 --> 0:28:10.720 because velocity is a vector. Again, a vector is something 0:28:10.760 --> 0:28:13.960 that has both an amplitude and a direction, has an 0:28:13.960 --> 0:28:17.960 amount and a direction associated with it. So even if 0:28:18.000 --> 0:28:21.480 the speed of the moving object doesn't change, it's moving 0:28:21.520 --> 0:28:24.560 at the same rate of travel even as you change 0:28:24.560 --> 0:28:28.800 its direction. If you change the direction, you've also changed 0:28:28.840 --> 0:28:34.280 the velocity because the direction part of a vector has changed. So, uh, 0:28:34.320 --> 0:28:36.840 that's an important thing to remember that a velocity can 0:28:36.920 --> 0:28:39.560 change even if the speed stays the same because you've 0:28:39.600 --> 0:28:43.080 changed the direction of travel. Tilting the plane having one 0:28:43.080 --> 0:28:46.400 wing dip lower than the other side means that some 0:28:46.520 --> 0:28:48.920 of the lift acting on the plane is now actually 0:28:48.920 --> 0:28:52.080 pushing the plane in a sideways motion. So when you 0:28:52.200 --> 0:28:55.080 roll the plane a little bit, you are actually changing 0:28:55.120 --> 0:28:58.480 the lift dynamics, and some of that lift that otherwise 0:28:58.480 --> 0:29:01.040 would be holding the plane up is pushing the plane 0:29:01.200 --> 0:29:05.560 to UH to a side. It creates centripetal force, and 0:29:05.600 --> 0:29:08.400 it eventually will make the plane move in a circular path. 0:29:08.480 --> 0:29:11.200 You know, the more the dramatic the roll up to 0:29:11.240 --> 0:29:15.680 a point, the more tight that circle is going to be. However, 0:29:17.160 --> 0:29:18.720 this is, by the way, as known as banking. When 0:29:18.720 --> 0:29:22.640 you talk about airplanes banking, it's because they're they're tilting 0:29:22.680 --> 0:29:25.960 this way and the rolling and UH starting to turn. 0:29:26.440 --> 0:29:29.200 But another thing you have to remember is this reduces 0:29:29.240 --> 0:29:33.440 the amount of lift actually holding the aircraft up. So 0:29:33.680 --> 0:29:37.160 you know, you're dedicating some of the lift to turning 0:29:37.200 --> 0:29:39.640 the aircraft, not just holding it up. So if you 0:29:39.680 --> 0:29:42.720 don't do anything, if you're maintaining the same speed, you're 0:29:42.760 --> 0:29:46.840 changing the velocity by changing the direction. That reduction in 0:29:46.960 --> 0:29:48.840 lift means that your aircraft is going to start to 0:29:48.840 --> 0:29:52.600 lose altitude, So you've got to do something to counteract that. 0:29:53.600 --> 0:29:56.840 Typically you do something like increase the angle of attack 0:29:57.000 --> 0:30:01.360 of the wings or using the tail u to compensate 0:30:01.800 --> 0:30:05.640 for this loss of lift of upward lift so that 0:30:05.720 --> 0:30:08.640 you don't lose altitude. Modern aircraft do this with a 0:30:08.640 --> 0:30:11.920 flight control surface called an elevator, often on the tail, 0:30:12.320 --> 0:30:15.840 and the elevator can adjust its angle to change the 0:30:15.840 --> 0:30:18.800 angle of attack with the fluid that the aircraft is 0:30:18.840 --> 0:30:22.080 moving through the air itself and provide more upward lift. 0:30:22.640 --> 0:30:26.640 Other movable control surfaces can affect the plane's pitch, um 0:30:26.840 --> 0:30:29.840 and the yaw. The yaws typically a it's a rudder 0:30:30.000 --> 0:30:33.640 that's attached to the tail of a plane, and steering 0:30:33.680 --> 0:30:37.160 actually involves controlling the roll and yaw of the aircraft. 0:30:37.520 --> 0:30:40.440 So you have both the yaw and the tilt of 0:30:40.480 --> 0:30:45.360 the plane that allows you to make more controlled turns 0:30:45.720 --> 0:30:49.120 with the aircraft. Each of these systems has its own controls, 0:30:49.200 --> 0:30:53.080 and in modern aircraft uh the ailerons controlled the role. 0:30:53.480 --> 0:30:55.840 These are on the outer rear edge of the wings 0:30:56.160 --> 0:30:58.160 and they can move in opposite directions. So if you 0:30:58.240 --> 0:31:02.360 ever sat on window seat that's right next to a 0:31:02.400 --> 0:31:04.520 wing and you see this little thing at the very 0:31:04.640 --> 0:31:07.880 end of the planes wing and it's either tilting down 0:31:07.960 --> 0:31:11.960 or it's tilting up, that's part of this system that's 0:31:12.000 --> 0:31:14.840 meant to control the role of the plane and allow 0:31:14.920 --> 0:31:19.560 for turns. Um. The yaw, like I said, comes from 0:31:19.560 --> 0:31:23.160 the plane's rudder. It's typically a vertical tail fin that 0:31:23.240 --> 0:31:26.239 can swivel left or right, and the pitch comes from 0:31:26.320 --> 0:31:29.080 the elevators like I mentioned earlier, those are typically on 0:31:29.120 --> 0:31:32.040 the aircraft's tail as well, on a horizontal plane, not 0:31:32.120 --> 0:31:34.680 a vertical plane, like the rudder is, and the elevators 0:31:34.720 --> 0:31:37.840 can also tilt up or down, decreasing or increasing lift 0:31:37.960 --> 0:31:40.480 on the tail, which makes the airplane behave a little 0:31:40.480 --> 0:31:43.840 bit like a lever. Right. If you increase the lift 0:31:43.920 --> 0:31:46.280 on a tail, then the tail gets lifted up and 0:31:46.280 --> 0:31:49.800 the nose the airplane gets tilted downward, and vice versa. 0:31:50.800 --> 0:31:54.400 But that's just one part of the equation, or really, 0:31:54.560 --> 0:31:56.280 I guess you could say two parts of the equation, 0:31:56.280 --> 0:31:59.480 because wing design contributes to both flight control and lift. 0:32:00.040 --> 0:32:02.480 But they also needed to work on thrust. They needed 0:32:02.480 --> 0:32:05.200 a propulsion system that we get their aircraft up to 0:32:05.200 --> 0:32:08.800 a sufficient speed to generate the lift needed to sustain flight. 0:32:09.440 --> 0:32:12.520 They had bill gliders and done manned and unmanned tests 0:32:12.520 --> 0:32:16.080 at Kitty Hawk, North Carolina. They chose Kittie Hawk, by 0:32:16.080 --> 0:32:18.360 the way, they were not natives to North Carolina, but 0:32:18.360 --> 0:32:21.360 they chose kitty Hawk because it was pretty dependable for 0:32:21.440 --> 0:32:24.479 some good winds due to being on the Atlantic coast, 0:32:25.040 --> 0:32:27.440 so um you get a good stiff breeze over at 0:32:27.480 --> 0:32:30.240 Kittie Hawk. I've been there, and one of the most 0:32:30.240 --> 0:32:33.400 popular activities over at Kittie Hawk is kite flying. A 0:32:33.440 --> 0:32:37.480 lot of people flying kites, big elaborate ones way up 0:32:37.480 --> 0:32:40.040 in the sky because they get these nice strong winds. 0:32:40.560 --> 0:32:42.320 By the way, if you get a chance to visit 0:32:42.360 --> 0:32:46.040 Kitty Hawk and to go visit the site of the 0:32:46.120 --> 0:32:49.880 first flight from the right Brothers, I highly recommend it. 0:32:49.880 --> 0:32:53.760 It is a very interesting location, a lot of cool 0:32:54.120 --> 0:32:57.640 information there, and you can actually walk the pathway of 0:32:57.640 --> 0:33:00.880 those test flights. It's pretty neat any way. As part 0:33:00.880 --> 0:33:03.720 of this work, the brothers had designed a movable tail 0:33:03.800 --> 0:33:07.800 component that would help with the flight stability, particularly when 0:33:07.800 --> 0:33:11.240 the pilot of the glider wanted to steer. And now 0:33:11.280 --> 0:33:13.200 it was time to work on an aircraft capable of 0:33:13.240 --> 0:33:16.360 generating its own thrust to maintain flight, not just to 0:33:16.400 --> 0:33:19.320 be able to glide, and this required a lot more research, 0:33:19.560 --> 0:33:21.840 as the brothers had to not only design a motor 0:33:22.120 --> 0:33:25.200 that could turn a propeller fast enough to generate enough thrust, 0:33:25.680 --> 0:33:28.400 but also an airplane frame capable of both supporting the 0:33:28.400 --> 0:33:31.760 motor's weight and to withstand the vibrations the motor created 0:33:31.800 --> 0:33:35.200 during operation. The result of all their research was the 0:33:35.240 --> 0:33:39.040 design of an aircraft they simply called the Flyer, and 0:33:39.120 --> 0:33:42.479 some people refer to it as the Right Flyer. A 0:33:42.480 --> 0:33:46.280 bicycle mechanic named Charles Taylor would build the motor for 0:33:46.320 --> 0:33:49.280 the Brothers. It was a custom built motor, a gasolene 0:33:49.360 --> 0:33:52.760 fueled twelve horsepower motor, and the motor was used to 0:33:52.840 --> 0:33:56.440 drive a chain that in turn would link to gears 0:33:56.480 --> 0:34:00.560 that would turn the two propellers, So it's like a bicycle, 0:34:00.720 --> 0:34:03.320 you know, a bicycles wheels. The propellers were changed driven 0:34:03.680 --> 0:34:07.560 this motor. Through powering the propellers would provide the needed thrust. 0:34:08.280 --> 0:34:11.160 The Right Flyer had a wingspan of twelve point two 0:34:11.160 --> 0:34:14.719 meters or forty point three feet, and the right wing 0:34:15.120 --> 0:34:18.399 was four inches longer than the left wing. So why 0:34:18.440 --> 0:34:21.080 is that? Why was the right wing longer? Well, that 0:34:21.160 --> 0:34:24.440 was because the Right Brothers design meant that the engine 0:34:24.480 --> 0:34:26.960 for the plane would sit a little to the right 0:34:27.320 --> 0:34:31.280 of the center line. It was not centered along the 0:34:31.360 --> 0:34:34.719 axis of the airplane. It actually went a little to 0:34:34.760 --> 0:34:38.120 the right side that meant the pilot would actually laid 0:34:38.160 --> 0:34:41.160 down on the left side of the center line. But 0:34:41.360 --> 0:34:44.560 the engine weighed seventy seven point one ms or a 0:34:44.640 --> 0:34:48.719 hundred seventy pounds, the pilot weighed only sixty five point 0:34:48.760 --> 0:34:52.960 eight kilograms or one five pounds, So the brothers needed 0:34:53.000 --> 0:34:55.839 some way to balance the scales as it were, so 0:34:55.880 --> 0:34:58.520 that the plane would fly properly without the constant need 0:34:58.600 --> 0:35:01.560 for adjustment. Since had a heavier engine on one side 0:35:01.560 --> 0:35:04.560 and a lighter pilot on the other, and so they 0:35:04.600 --> 0:35:07.040 made the right wing a little longer than the left 0:35:07.080 --> 0:35:09.360 in order to generate a bit more lift than the 0:35:09.440 --> 0:35:12.400 left side and thus compensate for the added weight on 0:35:12.440 --> 0:35:15.200 the right side of the plane. The Right brothers held 0:35:15.239 --> 0:35:19.839 the first test flight on December seventeenth three. Orville Right 0:35:20.280 --> 0:35:22.720 was the pilot, and the plane lifted off the ground 0:35:22.719 --> 0:35:26.000 and traveled about one twenty feet or thirty five meters. 0:35:26.360 --> 0:35:29.239 It flew just twelve seconds, but it was enough to 0:35:29.280 --> 0:35:32.360 secure the Right brothers the acknowledgement that they had created 0:35:32.360 --> 0:35:37.440 the first heavier than air manned, steerable flying machine. They 0:35:37.440 --> 0:35:40.200 would build other aircraft based off that design, but the 0:35:40.239 --> 0:35:43.279 only one they ever attempted to preserve was the original 0:35:43.360 --> 0:35:46.680 Right Flyer, and for a short while that airplane called 0:35:46.719 --> 0:35:50.800 the Kensington Science Museum in London home. But in nineteen 0:35:51.560 --> 0:35:54.279 the Flyer returned to the United States to become part 0:35:54.360 --> 0:35:57.400 of the Smithsonian's exhibits, and it is now in the 0:35:57.520 --> 0:36:01.399 National Air and Space Museum in Washington, d C. When 0:36:01.400 --> 0:36:03.520 we come back, I'll talk about some other elements of 0:36:03.560 --> 0:36:14.759 aircraft and how those contribute to flight. Okay, so the 0:36:14.880 --> 0:36:18.400 Right Brothers were two of the many pioneers of piloted 0:36:18.440 --> 0:36:21.280 heavier than air aircraft. There were lots of other people, 0:36:21.400 --> 0:36:23.680 and I hope I've made it clear that the success 0:36:23.760 --> 0:36:26.480 of the Right Brothers depended heavily on the research and 0:36:26.520 --> 0:36:29.759 work of numerous people before them. Also, they weren't the 0:36:29.800 --> 0:36:32.839 only ones working on the problem when they achieved their 0:36:32.840 --> 0:36:36.680 success in North Carolina. It's why I define their successes 0:36:36.719 --> 0:36:39.000 being the first to pilot a heavier than air aircraft 0:36:39.160 --> 0:36:42.440 that had at least some rudimentary flight controls, because otherwise 0:36:42.440 --> 0:36:44.239 you have to talk about a whole bunch of people 0:36:44.239 --> 0:36:47.160 who did lighter than air aircraft and and some other stuff, 0:36:47.680 --> 0:36:50.120 and many people would quickly follow in the footsteps or 0:36:50.719 --> 0:36:54.560 flight steps of the right brothers building better aircraft with 0:36:54.640 --> 0:36:58.840 more sophisticated control mechanisms and development and innovation were in 0:36:58.960 --> 0:37:01.080 the fast lane. So just going to cover a few 0:37:01.080 --> 0:37:03.400 more basics, and I might have to do a future 0:37:03.400 --> 0:37:06.120 episode to talk about some of the more modern systems 0:37:06.120 --> 0:37:08.879 aboard aircraft, because that would make this show run way 0:37:08.920 --> 0:37:10.960 too long if I were to keep up with that. 0:37:11.360 --> 0:37:14.480 So let's talk about propellers. The propellers on a prop 0:37:14.640 --> 0:37:17.880 plane are effectively doing the same thing that the wings 0:37:17.960 --> 0:37:20.960 do on a plane by creating lift, only in this case, 0:37:21.239 --> 0:37:24.920 the direction of the lift is forward with respect to 0:37:24.960 --> 0:37:29.120 the plane. It's like a helicopter's rotors. Moving the blades 0:37:29.120 --> 0:37:31.799 of a propeller in a circular path at a fast 0:37:31.920 --> 0:37:36.360 enough rotational speed creates the force and drives the aircraft forward. 0:37:36.680 --> 0:37:39.080 But unlike a wing, which tends to have a fixed 0:37:39.080 --> 0:37:42.600 angle of attack across the entire length of the wings surface, 0:37:42.960 --> 0:37:46.279 a propeller blade has a twist in it so that 0:37:46.320 --> 0:37:49.520 the pitch angle varies along the length of the blade. 0:37:50.200 --> 0:37:53.920 Some modern planes have a controllable pitch propeller, which allows 0:37:53.960 --> 0:37:56.520 the pilot to change this rotation in order to have 0:37:56.600 --> 0:37:59.960 the plane perform at optimal efficiencies at different air speed 0:38:00.000 --> 0:38:03.520 eads now Jet engines are different, and I've covered them 0:38:03.560 --> 0:38:07.160 in past episodes, but here's a quick rundown. From the outside, 0:38:07.200 --> 0:38:10.120 a jet engine looks like a tube. If you look 0:38:10.160 --> 0:38:12.479 at one head on, you'll see a big fan thing 0:38:12.600 --> 0:38:15.120 in the front of that tube. Then at first you 0:38:15.200 --> 0:38:18.040 might think that a jet is similar to a propeller plane, 0:38:18.080 --> 0:38:22.040 that it's generating forward thrust by just rotating that fan 0:38:22.120 --> 0:38:27.080 super fast. But that's not quite right. The purpose of 0:38:27.080 --> 0:38:30.040 the fan is to suck air into the jet engine. 0:38:30.400 --> 0:38:34.120 The fan attaches to a shaft and it spinds rapidly 0:38:34.160 --> 0:38:38.400 and it pulls air into the engine. Behind the fan 0:38:38.560 --> 0:38:41.759 on that same shaft, or on a shaft around the 0:38:41.800 --> 0:38:46.000 fans shaft, there are a bunch of other blades attached, 0:38:46.480 --> 0:38:49.680 and these blades are compressors. They compress the air. They 0:38:49.760 --> 0:38:52.880 squeeze that air down into a smaller and smaller space. 0:38:53.800 --> 0:38:56.560 That also increases the pressure obviously of the air, and 0:38:56.640 --> 0:38:59.200 also the temperature of the air and gets it to 0:38:59.280 --> 0:39:02.360 the right temperature for the next stage, which involves combustion. 0:39:03.040 --> 0:39:07.280 So behind the compressor is a combustion chamber or series 0:39:07.320 --> 0:39:11.239 of combustion chambers, and the compressed air enters into the chambers, 0:39:11.280 --> 0:39:14.720 and nozzles that also enter the chambers spray a fine 0:39:14.760 --> 0:39:19.000 mist of fuel there, and an ignition component creates an 0:39:19.040 --> 0:39:22.960 electric spark that lights the mixture of compressed air and fuel, 0:39:23.640 --> 0:39:27.720 and you get burning gases inside the chamber. Those burning 0:39:27.719 --> 0:39:32.400 gases expand as the heat up. The only exit out 0:39:32.560 --> 0:39:35.440 of this engine is a nozzle at the back, So 0:39:35.480 --> 0:39:39.360 the expanding gases escape out the nozzle at a tremendous 0:39:39.440 --> 0:39:42.560 amount of force. And because we know every action has 0:39:42.560 --> 0:39:46.240 an equal but opposite reaction, we know that this backward 0:39:46.360 --> 0:39:50.440 pushing force of escaping gas creates a forward pushing force 0:39:50.600 --> 0:39:53.239 on the aircraft itself. So if you can generate enough 0:39:53.280 --> 0:39:55.839 force to overcome the weight of the jet and get 0:39:55.880 --> 0:39:58.280 it up to speed, you can use it to provide 0:39:58.280 --> 0:40:02.080 the thrust needed to get lift and take off. Oh 0:40:02.120 --> 0:40:06.200 and that escaping gas also turns a turbine at the end, 0:40:06.520 --> 0:40:09.680 So you've got the combustion chamber, you've got an exit 0:40:09.680 --> 0:40:12.200 out the back of the combustion chamber where the gas 0:40:12.239 --> 0:40:15.120 is passing through a nozzle. It also ends up turning 0:40:15.120 --> 0:40:18.719 a turbine, and that turbine provides the rotational force for 0:40:18.880 --> 0:40:23.279 the UH, the compression blades on that rotating shaft, and 0:40:23.320 --> 0:40:26.399 also the fan. You know I mentioned those earlier. That's 0:40:26.400 --> 0:40:29.359 what's actually causing the rotational force. So not only does 0:40:29.400 --> 0:40:32.680 the jet engine provide thrust for the aircraft, it also 0:40:32.760 --> 0:40:36.680 harnesses some of that energy to operate the components of 0:40:36.719 --> 0:40:40.640 the engine itself. There are variations on this design. There 0:40:40.640 --> 0:40:43.440 are two or three spool jet engines, for example, but 0:40:43.480 --> 0:40:47.440 they all work on the same basic principle. UM. One variation, 0:40:47.520 --> 0:40:49.560 the one we see in commercial jets. A very popular 0:40:49.560 --> 0:40:52.960 one is the turbo fan jet. In this version, the 0:40:53.000 --> 0:40:57.040 engine casing is much larger than the combustion section, so 0:40:57.120 --> 0:40:59.400 you can think of it as a big tube around 0:40:59.480 --> 0:41:02.919 a much smaller tube. The smaller tube is the combustion part. 0:41:03.400 --> 0:41:05.799 So you've got the fan that's pulling air in, You've 0:41:05.800 --> 0:41:09.080 got the compressor blades that are compressing the air down, 0:41:09.320 --> 0:41:11.920 but there's also space for the for some of that 0:41:11.960 --> 0:41:16.360 air to pass along the outside of the combustion chamber, 0:41:16.440 --> 0:41:19.440 so some air is kind of going in between the 0:41:19.480 --> 0:41:23.080 combustion chamber and the casing for the jet engine itself, 0:41:23.800 --> 0:41:27.279 and the air coming in is compressed and most of 0:41:27.320 --> 0:41:29.600 that air is passing along the outside of the engine 0:41:29.840 --> 0:41:32.520 that provides the majority of the thrust. It's not the 0:41:32.560 --> 0:41:36.799 superheated stuff. It's this compressed air that's passing through this 0:41:36.960 --> 0:41:44.080 bleed bypass UH section. And it also not just provides thrust, 0:41:44.080 --> 0:41:47.359 but it also is able to cool the engine so 0:41:47.400 --> 0:41:51.120 that remains in operating operating temperatures. It it avoids overheating, 0:41:51.719 --> 0:41:53.520 so the air that passes through the engine still goes 0:41:53.520 --> 0:41:56.520 through the same combustion process I mentioned earlier and provides 0:41:56.560 --> 0:42:00.880 additional thrust as it escapes, plus provides the UH the 0:42:00.920 --> 0:42:05.320 force necessary to rotate that turbine and keep everything in motion. 0:42:06.000 --> 0:42:07.719 By the way, jet engines can also be used to 0:42:07.760 --> 0:42:10.479 power stuff other than aircraft, or rather, I should say 0:42:10.719 --> 0:42:14.240 turbine engines like this can be used to power stuff 0:42:14.280 --> 0:42:18.720 like tanks, or they can help power helicopters. They don't 0:42:18.880 --> 0:42:20.920 do it the exact same way as a jet plane, 0:42:21.080 --> 0:42:24.480 which has this exhaust be part of the thrust mechanism. 0:42:25.120 --> 0:42:28.920 Instead the tail end of that engine, there's another turbine 0:42:28.920 --> 0:42:31.719 that connects to some sort of drive mechanism, such as 0:42:31.719 --> 0:42:36.520 the tank's treads or helicopters rotors. So the the turbine 0:42:36.520 --> 0:42:40.200 engine pulls air in, you've got the combustion. All of 0:42:40.239 --> 0:42:43.440 this is used to create the energy needed to rotate 0:42:43.520 --> 0:42:48.080 a different turbine that then sends that power onto the 0:42:48.120 --> 0:42:52.760 propulsion system of the tank or the helicopter. Uh. These 0:42:52.760 --> 0:42:54.839 engines also have to have an exhaust port for all 0:42:54.880 --> 0:42:57.560 that hot air to escape, but it's not used like 0:42:57.600 --> 0:43:00.359 a thruster on a jet plane. But hey, for these 0:43:00.360 --> 0:43:02.760 engines to work, you still got to get that turbine 0:43:02.840 --> 0:43:08.839 spinning right. And that presents a challenge because these are 0:43:09.000 --> 0:43:11.800 engines that work fine while the jet is in operation, 0:43:11.840 --> 0:43:15.719 while it's actually moving through the air, because the process 0:43:16.000 --> 0:43:18.799 of the jet engine working provides the energy needed to 0:43:18.920 --> 0:43:22.240 turn the turbine that pulls more air in through the system. 0:43:22.239 --> 0:43:25.439 By the way, you're not generating more energy than you're 0:43:25.480 --> 0:43:28.279 expending here, I want to make that clear. Just rather 0:43:28.320 --> 0:43:31.960 that the process is not just providing thrust, but providing 0:43:32.040 --> 0:43:35.839 the force needed to turn those turbines and those fan 0:43:35.880 --> 0:43:38.360 blades and compressor blades. But in order to do that, 0:43:38.400 --> 0:43:40.040 you have to get up to speed in the first place. 0:43:40.040 --> 0:43:43.000 How do you get it started? Well, the turbines are 0:43:43.239 --> 0:43:45.799 too heavy and need to turn too quickly to rely 0:43:45.920 --> 0:43:48.560 upon an electric motor to do it. So you can't 0:43:48.600 --> 0:43:51.080 just have an electric motor attached to this thing to 0:43:51.400 --> 0:43:55.720 jump start the turbine engine. That's not going to work. 0:43:55.880 --> 0:43:59.080 They're far too large and heavy. So to do it, 0:43:59.160 --> 0:44:03.120 you have to feed compressed air into a stopped jet 0:44:03.120 --> 0:44:06.800 engine to get things started, to start turning those fan blades, 0:44:07.200 --> 0:44:09.799 and to get enough air pressure in there for you 0:44:09.840 --> 0:44:14.440 to ignite the combustion chambers. Now, if everything is working 0:44:14.440 --> 0:44:17.160 properly on the aircraft, you can use a system called 0:44:17.160 --> 0:44:22.360 the auxiliary power unit or APU to do this. Um 0:44:22.760 --> 0:44:25.319 it supplies the jet engine with compressed air, and you 0:44:25.360 --> 0:44:27.719 can start with just one engine. I'll explain how in 0:44:27.760 --> 0:44:31.160 a minute. So the APU is typically at the far 0:44:31.400 --> 0:44:33.680 end of a jet, on the main body of the jet, 0:44:33.719 --> 0:44:37.080 the fuselage. It's at the very end, and it has 0:44:37.120 --> 0:44:39.640 three main functions. One of those is the main engine 0:44:39.680 --> 0:44:42.440 start sequence, but the other two big functions are to 0:44:42.480 --> 0:44:45.520 supply electrical power to the jet. There's a turbine in 0:44:45.600 --> 0:44:48.480 this jet engine that is connected to a generator, and 0:44:48.520 --> 0:44:51.239 thus you can use that to help supply electrical power 0:44:51.280 --> 0:44:54.160 to the jet, and also it can provide bleed air 0:44:54.200 --> 0:44:58.160 pressure for the air conditioning system bleed air pressure. Think 0:44:58.200 --> 0:45:01.399 of the bleed air system as kind of plumbing. It's 0:45:01.440 --> 0:45:04.840 a series of conduits or pipes in a jet that 0:45:04.920 --> 0:45:08.600 allow compressed air to pass through. So the APU itself 0:45:08.800 --> 0:45:11.400 is a small turbine engine similar to a jet engine. 0:45:11.680 --> 0:45:14.680 There's an intake panel it slides open. It allows air 0:45:14.719 --> 0:45:18.400 to come into the system. And the APU, unlike the 0:45:18.440 --> 0:45:21.400 main engines, is small, so you can actually start it 0:45:21.480 --> 0:45:24.200 under battery power. You can have an electric motor attached 0:45:24.200 --> 0:45:28.000 to the APU. You turn it on. This starts the 0:45:28.040 --> 0:45:31.960 fan in the APU spinning, which then draws air in. 0:45:32.719 --> 0:45:35.719 And like turbofan engines, the APU has bleed air, so 0:45:35.800 --> 0:45:38.760 air that goes around the engine itself and it enters 0:45:38.760 --> 0:45:42.040 into this bleed air pathway system that connects to other 0:45:42.080 --> 0:45:45.040 components of the jet. So you divert some of the 0:45:45.080 --> 0:45:48.200 air going through the APU to enter the jet itself 0:45:48.239 --> 0:45:51.400 through this bleed system, and the pressurized air goes to 0:45:51.719 --> 0:45:55.760 a component called the air turbine starter, and this connects 0:45:55.760 --> 0:46:00.120 to the engine's shaft through a clutch mechanism um and 0:46:00.200 --> 0:46:04.760 that allows the APU to provide compressed air to start 0:46:04.920 --> 0:46:11.520 turning the fan and turbine in a jet engine. And 0:46:11.560 --> 0:46:14.080 this reminds us about fluid dynamics. You can either have 0:46:14.120 --> 0:46:18.240 a solid object moving very quickly through relatively still fluid, 0:46:18.600 --> 0:46:22.640 or fast moving fluid moving past a relatively still solid object, 0:46:22.920 --> 0:46:25.759 and you'll get the same results. So pushing compressed air 0:46:25.840 --> 0:46:28.600 through the main engine creates a situation similar to the 0:46:28.600 --> 0:46:32.080 engine operating at flight speed. So once the engine reaches 0:46:32.120 --> 0:46:35.640 a certain percentage of its top revolutions per minute, somewhere 0:46:35.640 --> 0:46:39.560 around twenty eight, the air inside is compressed enough to 0:46:39.600 --> 0:46:43.840 sustain combustion, and the engine will ignite fuel in the 0:46:43.880 --> 0:46:48.279 combustion chambers and that will provide the energy necessary to 0:46:48.640 --> 0:46:52.120 take over from there, and the engine will perpetuate its 0:46:52.200 --> 0:46:56.160 own rotation and you can stop pumping compressed air into 0:46:56.200 --> 0:46:58.880 the system. From that point. You can use the APU 0:46:59.000 --> 0:47:01.359 to power up the second engine, or you could even 0:47:01.440 --> 0:47:03.600 use the first engine to do it, because the engine 0:47:03.600 --> 0:47:06.680 system feeds into this bleed air system. So again it's 0:47:06.719 --> 0:47:08.799 like you know plumbing. You've got all these conduits, you 0:47:08.800 --> 0:47:11.720 also have all these valves in that system that either 0:47:11.840 --> 0:47:14.959 allow air to pass through or prevent air from going there. 0:47:15.000 --> 0:47:17.480 So when you're starting up engine one, you would have 0:47:17.560 --> 0:47:19.799 all the other valves closed so that the compressed air 0:47:19.840 --> 0:47:23.080 can only follow one pathway to get to that engine. Now, 0:47:23.160 --> 0:47:27.640 sometimes the APU isn't you know, totally working and can't 0:47:27.640 --> 0:47:30.680 supply enough compressed air to do the job. In those cases, 0:47:30.840 --> 0:47:34.279 the ground crew will connect a land based air compressor 0:47:34.560 --> 0:47:37.800 that's technically known as an air start unit, but most 0:47:37.880 --> 0:47:40.560 folks refer to it by a more informal name, the 0:47:40.640 --> 0:47:44.719 huffer cart, And the hover cart sends huffer is h 0:47:44.880 --> 0:47:47.719 U F F E R. It sends compressed air into 0:47:47.760 --> 0:47:49.520 the bleed system of a jet. So you just plug 0:47:49.560 --> 0:47:52.799 it into that bleed system and it provides the compressed air. 0:47:53.080 --> 0:47:55.239 And again the valves leaning to one engine are all 0:47:55.280 --> 0:47:58.120 open and the other valves are all closed. And once 0:47:58.160 --> 0:48:01.320 that first engine has started up and reaches the proper 0:48:01.400 --> 0:48:05.640 rotational speed, which is somewhere around the mark, that engine 0:48:05.680 --> 0:48:09.080 can provide the compressed air to start the other engine 0:48:09.520 --> 0:48:12.560 or engine two. There might be multiple engines on the jet, 0:48:12.640 --> 0:48:15.440 like four engines or something. You can keep doing this 0:48:15.480 --> 0:48:18.600 process over and over. Now, I honestly didn't know any 0:48:18.760 --> 0:48:22.200 of that stuff about how jet engines start from from 0:48:22.200 --> 0:48:25.600 a stopped position. Before I researched this episode, I understood 0:48:25.600 --> 0:48:27.239 how jet engines worked, but I didn't know how they 0:48:27.280 --> 0:48:30.040 got them started. So I always wondered how that happened, 0:48:30.200 --> 0:48:31.959 since it seemed like the kind of system that only 0:48:32.000 --> 0:48:35.479 works once it's already working, which seems like a catch 0:48:35.560 --> 0:48:39.080 twenty two, Like a building that issues permits, but the 0:48:39.080 --> 0:48:40.880 only way to get inside the building is to already 0:48:40.880 --> 0:48:43.439 have a permit. So how can you start the jet 0:48:43.480 --> 0:48:45.640 engine in the first place? And now I know, so, 0:48:45.760 --> 0:48:51.320 now you know too. So those are the basics of flight, thrust, lift, 0:48:51.800 --> 0:48:55.720 and flight controls. And granted I spent the least amount 0:48:55.719 --> 0:48:57.880 of time on flight controls, I may need to do 0:48:57.920 --> 0:49:00.680 a future episode to talk more about that in radar detail, 0:49:00.760 --> 0:49:02.960 to describe the physics behind them and how modern flight 0:49:03.000 --> 0:49:06.279 control systems work. In the meantime, I do have a 0:49:06.280 --> 0:49:10.360 lot of older episodes that go into things like jet engines, scramjets, 0:49:10.600 --> 0:49:14.319 autopilot systems, and more. It's actually kind of silly that 0:49:14.440 --> 0:49:16.360 took me this long just to cover the basics of flight. 0:49:17.239 --> 0:49:20.640 That one's on me. If you guys have suggestions for 0:49:20.719 --> 0:49:23.040 future episodes of tech Stuff. You can get in touch 0:49:23.080 --> 0:49:25.640 with me s me An email the addresses tech Stuff 0:49:25.680 --> 0:49:28.799 at how stuff works dot com. Pop on over to 0:49:28.840 --> 0:49:32.120 our website that's tech stuff podcast dot com. There you're 0:49:32.120 --> 0:49:35.000 going to find an archive of all of our older episodes, 0:49:35.320 --> 0:49:38.480 plus links to our social media presence, and a link 0:49:38.600 --> 0:49:40.720 to our online store where you can buy tech stuff 0:49:40.800 --> 0:49:44.560 merch and every purchase you go and make ends up 0:49:44.600 --> 0:49:47.520 helping our show. We greatly appreciate it. I hope you 0:49:47.560 --> 0:49:49.680 like the designs. Trying to get some new ones in 0:49:49.680 --> 0:49:53.879 there soon and I will talk to you again really soon. 0:49:59.160 --> 0:50:01.200 Text Stuff is a for auction of I Heart Radio's 0:50:01.239 --> 0:50:04.200 how Stuff Works. For more podcasts from my heart Radio, 0:50:04.560 --> 0:50:07.720 visit the i heart Radio app, Apple Podcasts, or wherever 0:50:07.800 --> 0:50:09.320 you listen to your favorite shows.