1
00:00:04,240 --> 00:00:07,240
Speaker 1: Welcome to Tech Stuff, a production of I Heart Radios

2
00:00:07,320 --> 00:00:13,960
Speaker 1: How Stuff Works. Hey there, and welcome to tech Stuff.

3
00:00:14,040 --> 00:00:17,080
Speaker 1: I'm your host, Jonathan Strickland. I'm an executive producer with

4
00:00:17,120 --> 00:00:19,560
Speaker 1: How Stuff Works and I Heart Radio and I love

5
00:00:19,640 --> 00:00:22,560
Speaker 1: all things tech and um I've been going on a

6
00:00:22,560 --> 00:00:26,280
Speaker 1: lot of trips lately, both for work and for my

7
00:00:26,400 --> 00:00:29,240
Speaker 1: personal life, you know, going on vacations and stuff, which

8
00:00:29,280 --> 00:00:32,440
Speaker 1: means that I tend to get on planes quite a lot.

9
00:00:32,520 --> 00:00:35,080
Speaker 1: So I thought today we talked about the history of

10
00:00:35,120 --> 00:00:38,760
Speaker 1: airplanes and how airplanes work. I've talked a lot about

11
00:00:38,880 --> 00:00:42,440
Speaker 1: different parts of planes in the past, but after doing

12
00:00:42,440 --> 00:00:44,920
Speaker 1: a quick search, I realized I never really done a

13
00:00:44,960 --> 00:00:49,280
Speaker 1: full episode about how planes themselves work. This is actually

14
00:00:49,280 --> 00:00:52,040
Speaker 1: a pretty tricky field, as it is one that has

15
00:00:52,080 --> 00:00:54,600
Speaker 1: been the subject of a lot of discussion as well

16
00:00:54,640 --> 00:00:58,600
Speaker 1: as misinformation or at least an incomplete explanation of how

17
00:00:58,680 --> 00:01:01,960
Speaker 1: things work, or an incorrect explanation of the how. The

18
00:01:02,040 --> 00:01:05,520
Speaker 1: why tends to be correct, but the how tends to

19
00:01:05,520 --> 00:01:09,280
Speaker 1: be confused, and it has led to jokes and memes

20
00:01:09,280 --> 00:01:12,560
Speaker 1: that ultimately, you know, airplanes work on some sort of

21
00:01:12,600 --> 00:01:15,720
Speaker 1: magic that depends upon us believing that it will work

22
00:01:16,160 --> 00:01:19,120
Speaker 1: sort of like the Peter Pan theory of flight, and

23
00:01:19,160 --> 00:01:21,720
Speaker 1: that's definitely taking things to extremes, and no one really

24
00:01:21,760 --> 00:01:24,559
Speaker 1: believes that. But when you consider all the various explanations

25
00:01:24,560 --> 00:01:26,680
Speaker 1: for what is going on, you can feel like the

26
00:01:26,760 --> 00:01:29,880
Speaker 1: joke might be coming from a pretty sincere place. So

27
00:01:30,040 --> 00:01:33,920
Speaker 1: let's start before we get into the how, with the

28
00:01:34,000 --> 00:01:38,280
Speaker 1: history of flight, because you guys know how much I

29
00:01:38,480 --> 00:01:42,320
Speaker 1: enjoy going into history lessons on this show. This is

30
00:01:42,760 --> 00:01:44,920
Speaker 1: no exception. So there were a lot of people who

31
00:01:45,040 --> 00:01:49,080
Speaker 1: dreamed of mastering flight over the past several hundred years,

32
00:01:49,440 --> 00:01:53,480
Speaker 1: thousands of years actually. Many attempted to emulate the way

33
00:01:53,520 --> 00:01:58,640
Speaker 1: birds fly, which seems pretty understandable. You see birds soaring

34
00:01:58,720 --> 00:02:01,600
Speaker 1: through the sky or darting about, and you think, well,

35
00:02:01,640 --> 00:02:04,680
Speaker 1: what's the secret there? How can we do the same thing,

36
00:02:05,440 --> 00:02:08,080
Speaker 1: And so lots of people tried to emulate that. They

37
00:02:08,160 --> 00:02:11,840
Speaker 1: created various rigs or devices that had moving wings, and

38
00:02:11,880 --> 00:02:14,239
Speaker 1: the thought was that if we could just build wings

39
00:02:14,280 --> 00:02:17,240
Speaker 1: of the right size that can move at the proper

40
00:02:17,360 --> 00:02:21,160
Speaker 1: speed and the proper range of motion similar to that

41
00:02:21,240 --> 00:02:25,760
Speaker 1: of a bird's wings, we too could fly through the sky. Now,

42
00:02:25,800 --> 00:02:29,040
Speaker 1: the name for this type of machine one that has

43
00:02:29,480 --> 00:02:34,120
Speaker 1: movable wings is an ornithopter, and legend has it that

44
00:02:35,280 --> 00:02:40,200
Speaker 1: Arcatas of Tarentum made a wooden bird with this type

45
00:02:40,280 --> 00:02:44,760
Speaker 1: of wing motion back in four hundred b C. And

46
00:02:44,840 --> 00:02:48,040
Speaker 1: you might know from Greek mythology the story of Daedalus

47
00:02:48,240 --> 00:02:51,919
Speaker 1: and Icarus, who are able to fly using man made

48
00:02:51,919 --> 00:02:54,880
Speaker 1: wings attached to their arms, at least they did until

49
00:02:54,960 --> 00:02:59,720
Speaker 1: Icarus flew too close to the sun spoiler alert. Leonardo

50
00:02:59,760 --> 00:03:02,680
Speaker 1: dive and she similarly worked on a few theoretical designs

51
00:03:02,760 --> 00:03:06,880
Speaker 1: that relied upon moving wings in the late fourteen hundreds. UH.

52
00:03:07,000 --> 00:03:11,360
Speaker 1: Some people argue that da Vinci's designs would ultimately lead

53
00:03:11,400 --> 00:03:15,080
Speaker 1: toward the development of the helicopter, but generally speaking, the

54
00:03:15,160 --> 00:03:19,400
Speaker 1: movable wing design remained impractical. It wasn't providing enough lift

55
00:03:19,560 --> 00:03:23,560
Speaker 1: or thrust to actually achieve flight. At best, the machines

56
00:03:23,560 --> 00:03:27,240
Speaker 1: would allow for very short, unimpressive hops, like maybe hopping

57
00:03:27,240 --> 00:03:30,040
Speaker 1: an inch off the ground, and at worst they didn't

58
00:03:30,040 --> 00:03:34,280
Speaker 1: manage to lift up anything at all. However, Leonardo da Vinci,

59
00:03:34,360 --> 00:03:37,560
Speaker 1: along with several other egg heads in history like Galileo

60
00:03:37,720 --> 00:03:41,720
Speaker 1: and Isaac Newton, among many others, would advance our understanding

61
00:03:41,880 --> 00:03:46,400
Speaker 1: of aerodynamics, which is the study of properties of moving air,

62
00:03:46,640 --> 00:03:51,080
Speaker 1: particularly as it has to do with interactions with solid objects.

63
00:03:51,560 --> 00:03:56,000
Speaker 1: By understanding how moving air affects solid objects and vice versa,

64
00:03:56,200 --> 00:03:58,600
Speaker 1: we could start to build working theories on how to

65
00:03:58,720 --> 00:04:02,320
Speaker 1: leverage that knowledge and create a working heavier than air

66
00:04:02,360 --> 00:04:07,160
Speaker 1: flying machine. Now, this work was expanded upon by mathematicians

67
00:04:07,160 --> 00:04:12,760
Speaker 1: and engineers people like John Smeaton, Daniel Bernoulli, and Leonard Euler.

68
00:04:13,280 --> 00:04:17,800
Speaker 1: They explored the relationship between air pressure and air velocity.

69
00:04:18,400 --> 00:04:21,280
Speaker 1: A hoity toity by the name of George Kyley would

70
00:04:21,440 --> 00:04:25,839
Speaker 1: prove to be incredibly important in our understanding. He proposed

71
00:04:25,839 --> 00:04:30,680
Speaker 1: that any working aircraft would need separate systems to provide lift, propulsion,

72
00:04:30,760 --> 00:04:34,360
Speaker 1: and control, something the famous Right Brothers would repeat in

73
00:04:34,400 --> 00:04:38,040
Speaker 1: the early nine hundreds. He also began to move away

74
00:04:38,120 --> 00:04:43,040
Speaker 1: from the ornithopter design to a fixed wing approach for aircraft. So,

75
00:04:43,080 --> 00:04:47,200
Speaker 1: in other words, the wing itself doesn't move with relation

76
00:04:47,279 --> 00:04:50,880
Speaker 1: to the body of the aircraft. It stays fixed in place,

77
00:04:51,400 --> 00:04:55,560
Speaker 1: and other elements are what allow the aircraft to fly.

78
00:04:56,000 --> 00:04:58,680
Speaker 1: You don't have to worry about having the wings move

79
00:04:58,760 --> 00:05:02,280
Speaker 1: in any particular path turn Now, Kayley's work led him

80
00:05:02,320 --> 00:05:05,640
Speaker 1: to the conclusion that the way to produce lift was

81
00:05:05,680 --> 00:05:08,520
Speaker 1: to design a machine that would create an area of

82
00:05:08,640 --> 00:05:12,200
Speaker 1: low pressure above the wing and an area of higher

83
00:05:12,240 --> 00:05:15,919
Speaker 1: pressure below the wing. So above the wing you have

84
00:05:16,120 --> 00:05:20,640
Speaker 1: very low pressure. Comparatively speaking, below the wing you have

85
00:05:20,760 --> 00:05:24,480
Speaker 1: very high pressure. So you've got support under you, right,

86
00:05:24,760 --> 00:05:28,800
Speaker 1: You've got air pushing up against the wing from below

87
00:05:29,600 --> 00:05:32,240
Speaker 1: and not not as much you know, air pressure above,

88
00:05:32,720 --> 00:05:35,600
Speaker 1: So the high pressure beneath would lift the wing up,

89
00:05:35,640 --> 00:05:39,880
Speaker 1: acting as a support in a way. Kayley was specifically

90
00:05:39,920 --> 00:05:43,240
Speaker 1: exploring wing designs that had an arch to them, and

91
00:05:43,279 --> 00:05:46,440
Speaker 1: his ideas were sound and in line with Bernoulli's theorem,

92
00:05:46,680 --> 00:05:49,599
Speaker 1: which describes the behavior of moving fluids. And we have

93
00:05:49,640 --> 00:05:52,840
Speaker 1: to remember that our atmosphere is a fluid. In this sense,

94
00:05:52,880 --> 00:05:58,040
Speaker 1: gases have fluid i movement. Gases are fluids, just as

95
00:05:58,080 --> 00:06:01,359
Speaker 1: liquids are fluids. It this is where a lot of

96
00:06:01,440 --> 00:06:05,520
Speaker 1: sources get things a little muddled, and it's understandable, but

97
00:06:05,600 --> 00:06:09,800
Speaker 1: it ends up being a a fundamental misunderstanding of what

98
00:06:10,000 --> 00:06:16,000
Speaker 1: is going on. So the incorrect explanations tend to be

99
00:06:16,480 --> 00:06:19,279
Speaker 1: right in describing the fact that the reason fixed wing

100
00:06:19,360 --> 00:06:21,920
Speaker 1: flight works is that the movement of the aircraft through

101
00:06:21,920 --> 00:06:24,839
Speaker 1: the air creates an area of low pressure above the

102
00:06:24,839 --> 00:06:27,560
Speaker 1: wing in an area of high pressure below the wing.

103
00:06:28,040 --> 00:06:31,200
Speaker 1: But they often mess up the actual explanation of how

104
00:06:31,320 --> 00:06:34,360
Speaker 1: this is happening, what is actually going on. So let

105
00:06:34,360 --> 00:06:37,520
Speaker 1: me give you the wrong way to describe it first

106
00:06:37,760 --> 00:06:40,080
Speaker 1: and we'll get that out of the way. So typically

107
00:06:40,520 --> 00:06:44,520
Speaker 1: the description starts with the design of the wing itself,

108
00:06:44,640 --> 00:06:48,000
Speaker 1: which is usually described as having a flat bottom and

109
00:06:48,080 --> 00:06:50,920
Speaker 1: a curved upper part, in which the front part of

110
00:06:50,960 --> 00:06:55,080
Speaker 1: the wing, the leading edge, ends up curving up to

111
00:06:55,279 --> 00:06:57,920
Speaker 1: become a bit thicker towards the front of the wing

112
00:06:58,440 --> 00:07:01,000
Speaker 1: and then tapers to ord the back of the wing,

113
00:07:01,520 --> 00:07:04,080
Speaker 1: where the upper surface you know, slopes back down and

114
00:07:04,120 --> 00:07:07,480
Speaker 1: meets the lower surface for the back edge or trailing

115
00:07:07,760 --> 00:07:10,720
Speaker 1: edge of the wing. And if you're looking at the

116
00:07:10,880 --> 00:07:14,120
Speaker 1: cross section of the wing, then you kind of get

117
00:07:14,120 --> 00:07:19,360
Speaker 1: a sideways tear drop shape right the the leading edge

118
00:07:20,000 --> 00:07:24,040
Speaker 1: gets thicker and then tapers back down until it meets

119
00:07:24,040 --> 00:07:27,640
Speaker 1: again at the trailing edge. Um, by the way, the

120
00:07:27,680 --> 00:07:30,440
Speaker 1: technical name for the cross section of a wing is

121
00:07:30,480 --> 00:07:34,560
Speaker 1: an airfoil. Air Foils do not necessarily have to follow

122
00:07:34,600 --> 00:07:38,119
Speaker 1: that shape, but many do. Many early air foils would

123
00:07:38,120 --> 00:07:43,080
Speaker 1: follow that curved design. Now, again, the wrong description for

124
00:07:43,280 --> 00:07:46,840
Speaker 1: what is causing lift states that when the wing moves

125
00:07:46,840 --> 00:07:50,680
Speaker 1: through a fluid, or conversely, when a fluid moves past

126
00:07:50,880 --> 00:07:53,720
Speaker 1: the wing, either way will work. There has to be motion,

127
00:07:54,120 --> 00:07:56,320
Speaker 1: but the motion can work in either way. You can

128
00:07:56,320 --> 00:07:59,840
Speaker 1: either have the fluid moving at a proper speed against

129
00:08:00,440 --> 00:08:03,600
Speaker 1: the solid object. That's the way we test things out

130
00:08:03,640 --> 00:08:06,520
Speaker 1: in wind tunnels. We have a stationary object and we

131
00:08:06,680 --> 00:08:10,880
Speaker 1: blow wind past it, or the object itself can move

132
00:08:10,960 --> 00:08:13,560
Speaker 1: through the fluid, which is the way airplanes work. They

133
00:08:13,600 --> 00:08:18,800
Speaker 1: fly through the air either way. According to this incorrect explanation,

134
00:08:18,840 --> 00:08:22,120
Speaker 1: the air molecules when they hit that leading edge, that

135
00:08:22,280 --> 00:08:25,720
Speaker 1: front edge of the wing, end up splitting into two

136
00:08:25,720 --> 00:08:29,440
Speaker 1: different pathways. Some of the air molecules are traveling over

137
00:08:29,480 --> 00:08:32,439
Speaker 1: the top surface of the wing and some are traveling

138
00:08:32,480 --> 00:08:34,480
Speaker 1: on the bottom surface of the wing. Well, the top

139
00:08:34,480 --> 00:08:36,880
Speaker 1: surface of the wing has that curve to it, which

140
00:08:36,920 --> 00:08:40,320
Speaker 1: means that the air molecules have to travel further from

141
00:08:40,320 --> 00:08:43,920
Speaker 1: the front edge to the back edge right than it

142
00:08:43,960 --> 00:08:47,080
Speaker 1: would on the lower side of the wing because the

143
00:08:47,120 --> 00:08:50,040
Speaker 1: lower side is straight, and as we know, the shortest

144
00:08:50,200 --> 00:08:53,240
Speaker 1: distance between two points is a straight line, So the

145
00:08:53,280 --> 00:08:55,760
Speaker 1: bottom edge of a wing is a straight line to

146
00:08:55,840 --> 00:08:59,400
Speaker 1: go from the leading edge to the trailing edge straight path.

147
00:08:59,840 --> 00:09:01,560
Speaker 1: The if you're going over the top, you have to

148
00:09:01,559 --> 00:09:05,240
Speaker 1: follow that curve, which means you're actually traveling more distance,

149
00:09:05,880 --> 00:09:10,200
Speaker 1: and so that is a longer way to travel. And

150
00:09:10,280 --> 00:09:16,880
Speaker 1: according to this incorrect description of lift, the air molecules

151
00:09:16,880 --> 00:09:18,800
Speaker 1: traveling on top of the wing have to go faster

152
00:09:18,920 --> 00:09:21,719
Speaker 1: than the molecules traveling below the wing, and then they

153
00:09:21,760 --> 00:09:24,560
Speaker 1: meet back up at the trailing edge. So let's say

154
00:09:24,559 --> 00:09:28,040
Speaker 1: you've got air molecule one and air molecule to. Molecule

155
00:09:28,120 --> 00:09:31,840
Speaker 1: one's traveling over the wing, Molecule two is traveling under

156
00:09:31,880 --> 00:09:36,240
Speaker 1: the wing, and they both meet at the far end.

157
00:09:36,679 --> 00:09:38,440
Speaker 1: But in order to do that, molecule one has to

158
00:09:38,480 --> 00:09:42,040
Speaker 1: travel faster than molecule two. And according to bern Newley's

159
00:09:42,080 --> 00:09:45,760
Speaker 1: theorem Daniel Burn Newley, a fast moving fluid is at

160
00:09:45,800 --> 00:09:49,920
Speaker 1: a lower press pressure than a slower moving fluid. So

161
00:09:50,120 --> 00:09:52,800
Speaker 1: says this description, the air pressure above the wing is

162
00:09:52,880 --> 00:09:56,120
Speaker 1: lower than the air pressure below the wing. Now it

163
00:09:56,240 --> 00:09:58,240
Speaker 1: is true that the air pressure above the wing is

164
00:09:58,280 --> 00:10:02,200
Speaker 1: lower and that the air pressure below the wing is higher.

165
00:10:02,800 --> 00:10:04,920
Speaker 1: I keep thinking that I've said this is the wrong way,

166
00:10:04,920 --> 00:10:07,480
Speaker 1: because I'm talking about above and below and higher and

167
00:10:07,520 --> 00:10:11,000
Speaker 1: lower than you flip them right, because everything above the

168
00:10:11,000 --> 00:10:12,800
Speaker 1: wing is a lower pressure, everything below the wing is

169
00:10:12,840 --> 00:10:16,520
Speaker 1: a higher pressure. That part is right. So the destination

170
00:10:16,600 --> 00:10:19,160
Speaker 1: is correct. It's the journey to get there that we've

171
00:10:19,200 --> 00:10:23,320
Speaker 1: got wrong, because, uh, there would need to be some

172
00:10:23,400 --> 00:10:26,960
Speaker 1: reason for the upper and lower air molecules to have

173
00:10:27,040 --> 00:10:30,000
Speaker 1: to travel to arrive at the same destination at the

174
00:10:30,040 --> 00:10:32,520
Speaker 1: same time. But there's no reason for that at all.

175
00:10:32,679 --> 00:10:35,120
Speaker 1: There's no reason why air molecule one and air molecule

176
00:10:35,160 --> 00:10:38,160
Speaker 1: to have to meet back up again at the trailing edge.

177
00:10:38,640 --> 00:10:41,360
Speaker 1: One of them can easily travel faster than the other.

178
00:10:41,720 --> 00:10:46,520
Speaker 1: There's no conservation of velocity between the two. Now, if

179
00:10:46,520 --> 00:10:48,280
Speaker 1: it were true that the air molecules on the top

180
00:10:48,280 --> 00:10:51,319
Speaker 1: and the air molecules on the below had to travel

181
00:10:52,400 --> 00:10:54,840
Speaker 1: at a speed where they would meet up again, that

182
00:10:54,840 --> 00:10:59,199
Speaker 1: that was absolutely necessary. This description would work if that

183
00:10:59,240 --> 00:11:02,040
Speaker 1: were true. If air molecule wanted two had to meet

184
00:11:02,080 --> 00:11:06,280
Speaker 1: on the far end again, this would be an accurate theory. However,

185
00:11:06,320 --> 00:11:08,560
Speaker 1: the flaw in this description goes by the name the

186
00:11:08,679 --> 00:11:13,959
Speaker 1: equal transit theory or sometimes the longer path theory. Now,

187
00:11:14,000 --> 00:11:16,559
Speaker 1: before I explain what is really going on with lift.

188
00:11:16,880 --> 00:11:20,160
Speaker 1: Let's consider for a moment how we know this common

189
00:11:20,200 --> 00:11:24,440
Speaker 1: description is incorrect. First, if this were actually how wings

190
00:11:24,440 --> 00:11:27,480
Speaker 1: would generate lift, it would mean that any plane that

191
00:11:27,600 --> 00:11:30,319
Speaker 1: did not have this wing design would fail to generate

192
00:11:30,360 --> 00:11:33,760
Speaker 1: lift because you wouldn't have that longer path on top. So,

193
00:11:33,800 --> 00:11:35,800
Speaker 1: in other words, if you had a straight wing design

194
00:11:35,880 --> 00:11:38,199
Speaker 1: for your aircraft, there's no way it would be able

195
00:11:38,240 --> 00:11:40,600
Speaker 1: to fly. It could not generate lift if this were

196
00:11:40,600 --> 00:11:43,320
Speaker 1: in fact the only way it worked, and we know

197
00:11:43,400 --> 00:11:45,719
Speaker 1: that's not the case. There are lots of aircraft out

198
00:11:45,760 --> 00:11:50,000
Speaker 1: there to have a flat wing design. A paper airplane

199
00:11:50,080 --> 00:11:52,920
Speaker 1: doesn't have a curved wing, and it can generate lift.

200
00:11:53,360 --> 00:11:55,440
Speaker 1: You just have to give it enough thrust and it

201
00:11:55,440 --> 00:11:59,120
Speaker 1: will fly. It doesn't immediately plummet um. It does lose

202
00:11:59,640 --> 00:12:02,720
Speaker 1: speed because of drag. We'll talk about dragon a little bit,

203
00:12:03,000 --> 00:12:05,679
Speaker 1: and if it loses speed then it's not generating enough

204
00:12:05,760 --> 00:12:09,080
Speaker 1: lift to maintain flight, so it will eventually fall. But

205
00:12:10,120 --> 00:12:12,880
Speaker 1: that's a flat wing and it does work. So flat

206
00:12:12,880 --> 00:12:15,640
Speaker 1: wings can work as well as curved wings, so that

207
00:12:15,679 --> 00:12:20,800
Speaker 1: part is out Further, if that explanation were absolutely true,

208
00:12:21,040 --> 00:12:23,079
Speaker 1: planes with curved wings would never be able to fly

209
00:12:23,200 --> 00:12:26,679
Speaker 1: upside down, because if they were to roll over, and

210
00:12:26,800 --> 00:12:29,920
Speaker 1: the whole reason why lift was generated was because air

211
00:12:30,040 --> 00:12:33,000
Speaker 1: was traveling further on one side than the other and

212
00:12:33,000 --> 00:12:36,120
Speaker 1: then meeting back up with the air molecules, then the

213
00:12:36,120 --> 00:12:39,640
Speaker 1: plane's wings would actually create lower air pressure below the

214
00:12:39,679 --> 00:12:42,840
Speaker 1: plane and higher air pressure above the plane that would

215
00:12:42,920 --> 00:12:48,040
Speaker 1: drive the plane downward. So instead of having lift holding

216
00:12:48,040 --> 00:12:50,439
Speaker 1: the plane up, you would be creating a force that,

217
00:12:50,679 --> 00:12:53,760
Speaker 1: combined with gravity, would pull the plane downward or push

218
00:12:53,800 --> 00:12:56,120
Speaker 1: the plane downward, and you would end up with a

219
00:12:56,160 --> 00:13:00,480
Speaker 1: catastrophic result. But we know that's not the case. Trained

220
00:13:00,480 --> 00:13:03,880
Speaker 1: pilots can fly upside down, and properly designed aircraft, you know,

221
00:13:03,920 --> 00:13:08,800
Speaker 1: aircraft that can withstand the forces of rolling over on

222
00:13:08,800 --> 00:13:13,199
Speaker 1: on to their backs. You can still fly inverted that way.

223
00:13:13,440 --> 00:13:16,560
Speaker 1: So clearly there has to be something else going on here.

224
00:13:16,679 --> 00:13:20,800
Speaker 1: The explanation does not work as it stands, so to

225
00:13:20,880 --> 00:13:23,760
Speaker 1: be clear, the end result of how lift works is

226
00:13:23,800 --> 00:13:26,400
Speaker 1: the same in that a plane's wings do create areas

227
00:13:26,400 --> 00:13:30,199
Speaker 1: of low pressure above and high pressure below the wing,

228
00:13:30,480 --> 00:13:32,720
Speaker 1: but the way they do it is different from the

229
00:13:32,760 --> 00:13:36,400
Speaker 1: explanation commonly given. So, in other words, the common explanation

230
00:13:36,440 --> 00:13:38,880
Speaker 1: gives us the right end result but uses the wrong

231
00:13:38,880 --> 00:13:41,319
Speaker 1: way to get there. So it's sort of like using

232
00:13:41,320 --> 00:13:45,359
Speaker 1: the wrong process to solve a math problem but accidentally

233
00:13:45,360 --> 00:13:50,040
Speaker 1: getting the right answer anyway. Sure, the answer is technically

234
00:13:50,080 --> 00:13:53,120
Speaker 1: what you were looking for. The important part is not

235
00:13:53,200 --> 00:13:55,920
Speaker 1: getting the right answer, it's knowing the right way to

236
00:13:56,120 --> 00:13:59,520
Speaker 1: get to that answer. So let's talk about what's actually

237
00:13:59,640 --> 00:14:04,360
Speaker 1: going on. First. Air does in fact move faster over

238
00:14:04,400 --> 00:14:06,520
Speaker 1: the top edge than the lower edge of the wing,

239
00:14:07,160 --> 00:14:09,920
Speaker 1: much faster. In fact, air molecules traveling over the top

240
00:14:09,920 --> 00:14:12,520
Speaker 1: of the wing will arrive at the trailing edge before

241
00:14:12,920 --> 00:14:16,040
Speaker 1: air molecules traveling on the lower side. So that air

242
00:14:16,120 --> 00:14:19,640
Speaker 1: molecule one and two example I gave before, air molecule

243
00:14:19,680 --> 00:14:21,920
Speaker 1: one is going over the wing, air molecule two is

244
00:14:21,960 --> 00:14:24,240
Speaker 1: going under the wing. Air molecule one is actually going

245
00:14:24,240 --> 00:14:27,200
Speaker 1: to arrive at the trailing edge first. They don't meet

246
00:14:27,280 --> 00:14:31,160
Speaker 1: up again, so there's none of those air molecules splitting

247
00:14:31,240 --> 00:14:33,520
Speaker 1: up at the leading edge meeting at the trailing edge.

248
00:14:33,560 --> 00:14:35,800
Speaker 1: The air molecules traveling beneath the wing are actually meeting

249
00:14:35,840 --> 00:14:38,520
Speaker 1: up with totally new air particles that hit the leading edge.

250
00:14:38,640 --> 00:14:43,200
Speaker 1: Later on, more importantly, a wing deflects air and then

251
00:14:43,520 --> 00:14:46,240
Speaker 1: the way it does so creates the area of lower

252
00:14:46,280 --> 00:14:49,520
Speaker 1: pressure above the wing and the area of higher pressure

253
00:14:49,600 --> 00:14:51,600
Speaker 1: below the wing. You can think of the air below

254
00:14:51,600 --> 00:14:55,280
Speaker 1: a wing as getting compressed or squished, while the air

255
00:14:55,280 --> 00:14:58,160
Speaker 1: immediately above a wing enters into more space than it

256
00:14:58,160 --> 00:15:01,160
Speaker 1: had previously occupied. And this is because we're talking about

257
00:15:01,160 --> 00:15:04,760
Speaker 1: a solid structure moving through a fluid. The difference in

258
00:15:04,800 --> 00:15:07,520
Speaker 1: air pressure is what causes the big change in the

259
00:15:07,560 --> 00:15:10,680
Speaker 1: fluids speed. So, in other words, the change in air

260
00:15:10,720 --> 00:15:14,440
Speaker 1: pressure is what is effect affecting those air molecules speed

261
00:15:14,520 --> 00:15:18,040
Speaker 1: across the wing. It's the opposite of what the equal

262
00:15:18,080 --> 00:15:21,520
Speaker 1: transit theory states, which is that the difference in speed

263
00:15:21,720 --> 00:15:24,320
Speaker 1: causes the change in pressure. Actually, it's the change in

264
00:15:24,360 --> 00:15:27,080
Speaker 1: pressure that causes the difference in speed, and the air

265
00:15:27,160 --> 00:15:29,240
Speaker 1: molecules traveling both on the top side of the wing

266
00:15:29,280 --> 00:15:31,880
Speaker 1: and the bottom will at the end have a downward

267
00:15:32,000 --> 00:15:35,080
Speaker 1: velocity once they leave the trailing edge of the wing.

268
00:15:35,640 --> 00:15:38,040
Speaker 1: So why does the air traveling over the wing move

269
00:15:38,120 --> 00:15:40,800
Speaker 1: downward at the end. If the air molecules moving over

270
00:15:40,840 --> 00:15:43,440
Speaker 1: the top of the wing this curved surface in your

271
00:15:43,480 --> 00:15:48,400
Speaker 1: typical airfoil, why would those air molecules be moving downward?

272
00:15:48,440 --> 00:15:51,240
Speaker 1: I mean surely they would just continue horizontally in a

273
00:15:51,280 --> 00:15:54,360
Speaker 1: straight line right now. It's because in our system we

274
00:15:54,440 --> 00:15:58,720
Speaker 1: still have the atmosphere above the plane to consider that.

275
00:15:58,840 --> 00:16:01,160
Speaker 1: You know, when we're first talking about air pressure around

276
00:16:01,200 --> 00:16:04,040
Speaker 1: the wing, we're looking at the immediate area around the wing,

277
00:16:04,320 --> 00:16:06,640
Speaker 1: but you still have all the rest of the atmosphere

278
00:16:06,680 --> 00:16:09,800
Speaker 1: above the plane to consider. Now, immediately over the wing,

279
00:16:09,840 --> 00:16:12,000
Speaker 1: the air pressure is lower due to the presence of

280
00:16:12,000 --> 00:16:15,280
Speaker 1: this physical object moving through a fluid, or the fluid

281
00:16:15,320 --> 00:16:18,000
Speaker 1: moving across the object, or both, because it's all a

282
00:16:18,040 --> 00:16:21,720
Speaker 1: matter of perspective. But above that you still have all

283
00:16:21,800 --> 00:16:25,760
Speaker 1: that atmosphere a normal air pressure depending on that altitude.

284
00:16:26,240 --> 00:16:29,960
Speaker 1: So all that air is still pushing down on the

285
00:16:30,160 --> 00:16:32,680
Speaker 1: area around the plane, and it starts pushing down on

286
00:16:32,720 --> 00:16:35,680
Speaker 1: that lower pressure air, and that forces that lower pressure

287
00:16:35,680 --> 00:16:38,480
Speaker 1: air downward at the trailing edge of the wing. And

288
00:16:38,560 --> 00:16:40,960
Speaker 1: this brings us to another big important factor and lift

289
00:16:41,200 --> 00:16:44,520
Speaker 1: called down wash, that is the amount of air the

290
00:16:44,520 --> 00:16:48,680
Speaker 1: wing is forcing downward. Now, according to Isaac Newton's third

291
00:16:48,760 --> 00:16:51,640
Speaker 1: law of motion, if you have a mechanical system applying

292
00:16:51,720 --> 00:16:55,600
Speaker 1: force in one direction in a system, and equal opposite

293
00:16:55,600 --> 00:16:59,880
Speaker 1: force applies to that mechanical system, so an airplane, for

294
00:17:00,120 --> 00:17:04,000
Speaker 1: saying air downward, will also experience lift upward. It's equal

295
00:17:04,040 --> 00:17:06,359
Speaker 1: to the amount of force of the air going down.

296
00:17:06,800 --> 00:17:10,399
Speaker 1: This is easier to imagine if we think about a helicopter, right.

297
00:17:10,480 --> 00:17:13,960
Speaker 1: A helicopter has rotors that act similar to the way

298
00:17:14,040 --> 00:17:18,760
Speaker 1: and airplanes air foils works. The rotors rotate in a circle,

299
00:17:19,040 --> 00:17:22,320
Speaker 1: So instead of a plane moving horizontally through a fluid,

300
00:17:22,720 --> 00:17:26,000
Speaker 1: you have this rotor that's rotating around in a circle

301
00:17:26,040 --> 00:17:29,080
Speaker 1: and that forces air downwards, and that creates the lift

302
00:17:29,119 --> 00:17:32,600
Speaker 1: that allows helicopters to fly. Airplane wings do the same thing,

303
00:17:32,640 --> 00:17:35,640
Speaker 1: but it's less obvious to us. Those downward traveling air

304
00:17:35,680 --> 00:17:38,000
Speaker 1: molecules at the trailing edge of a wing are the

305
00:17:38,040 --> 00:17:40,800
Speaker 1: down wash of a plane, and it's a secondary source

306
00:17:40,840 --> 00:17:44,080
Speaker 1: of lift along with that air pressure description I just gave,

307
00:17:44,560 --> 00:17:47,000
Speaker 1: So it's not the primary source. It's secondary, but it

308
00:17:47,080 --> 00:17:50,640
Speaker 1: does contribute to the lift that the plane experiences. Now,

309
00:17:50,680 --> 00:17:54,239
Speaker 1: this is why an airplanes wings aren't perfectly horizontal with

310
00:17:54,280 --> 00:17:56,560
Speaker 1: regard to the body of the plane. If you look

311
00:17:56,680 --> 00:17:59,000
Speaker 1: at an airplane, you will notice that the wings have

312
00:17:59,080 --> 00:18:02,280
Speaker 1: a bit of a to them, so that the leading

313
00:18:02,480 --> 00:18:06,680
Speaker 1: edge of the wing is actually pointed up a little bit,

314
00:18:07,080 --> 00:18:09,640
Speaker 1: and the trailing edge is pointed down a little bit,

315
00:18:10,359 --> 00:18:12,880
Speaker 1: and this creates what we call the angle of attack,

316
00:18:13,440 --> 00:18:16,800
Speaker 1: and the angled wings encourage this down wash effect. If

317
00:18:16,840 --> 00:18:20,520
Speaker 1: you've ever put your hand out into the wind and

318
00:18:20,600 --> 00:18:22,760
Speaker 1: you tilted your hand in different ways and you get

319
00:18:22,800 --> 00:18:26,200
Speaker 1: to that sweet spot where you feel like, oh, well,

320
00:18:26,200 --> 00:18:29,280
Speaker 1: now my hand is staying up because of the angle

321
00:18:29,320 --> 00:18:30,959
Speaker 1: it's at as it's going through the wind, like if

322
00:18:30,960 --> 00:18:33,119
Speaker 1: it's out a car window. By the way, don't do that,

323
00:18:33,160 --> 00:18:34,679
Speaker 1: it's dangerous. But if you were to do that and

324
00:18:34,680 --> 00:18:36,600
Speaker 1: you felt it, you know what I'm talking about the

325
00:18:36,680 --> 00:18:39,040
Speaker 1: same thing with airplane wings. That's why they're at that tilt,

326
00:18:39,600 --> 00:18:42,120
Speaker 1: all right. So that's the explanation of the lift. And

327
00:18:42,200 --> 00:18:44,520
Speaker 1: in a moment I'll talk more about how the right

328
00:18:44,560 --> 00:18:48,200
Speaker 1: brothers or I'm creating a working heavier than air flying machine.

329
00:18:48,600 --> 00:18:59,560
Speaker 1: But first let's take a quick break. Now, I just

330
00:18:59,640 --> 00:19:04,000
Speaker 1: spent a lot of time going over lift. But that's

331
00:19:04,119 --> 00:19:06,639
Speaker 1: just one of the forces that are acting on a

332
00:19:06,640 --> 00:19:09,520
Speaker 1: plane in flight. And I mentioned one other briefly as well.

333
00:19:10,200 --> 00:19:12,919
Speaker 1: There are three other forces that are all acting on

334
00:19:12,920 --> 00:19:15,960
Speaker 1: a plane. So for total you've got lift. That's an

335
00:19:16,040 --> 00:19:19,960
Speaker 1: upward force on the plane. There's thrust that's the forward

336
00:19:20,280 --> 00:19:23,159
Speaker 1: force of a plane then, and you have to have

337
00:19:23,200 --> 00:19:26,359
Speaker 1: your thrust to be strong enough to create an airflow

338
00:19:26,880 --> 00:19:29,320
Speaker 1: around the wings to generate the lift to keep a

339
00:19:29,320 --> 00:19:31,639
Speaker 1: plane in flight. So you need to be moving forward

340
00:19:31,720 --> 00:19:35,000
Speaker 1: enough through the fluid, fast enough through the fluid so

341
00:19:35,040 --> 00:19:38,560
Speaker 1: that you can generate lift, or the fluid has to

342
00:19:38,600 --> 00:19:41,560
Speaker 1: be moving fast enough past you in order to do that. Again,

343
00:19:41,600 --> 00:19:44,880
Speaker 1: it's all a matter of perspective. If a plane moves

344
00:19:44,880 --> 00:19:47,960
Speaker 1: too slowly through the air, it won't create the difference

345
00:19:48,000 --> 00:19:51,440
Speaker 1: in air pressure and down wash sufficient enough to maintain lift,

346
00:19:51,560 --> 00:19:55,040
Speaker 1: So thrust is really important. Drag is a force that

347
00:19:55,080 --> 00:19:58,600
Speaker 1: opposes the forward motion of the aircraft. So this is

348
00:19:58,640 --> 00:20:01,480
Speaker 1: sort of the force that's acting uh in a backward

349
00:20:01,840 --> 00:20:05,639
Speaker 1: motion against the aircraft. It's a mechanical force generated by

350
00:20:05,640 --> 00:20:08,720
Speaker 1: the interaction of a solid body with a fluid, and

351
00:20:08,760 --> 00:20:11,439
Speaker 1: it depends upon the difference in velocity between the solid

352
00:20:11,480 --> 00:20:14,760
Speaker 1: object and the fluid. You experienced drag if you've ever

353
00:20:14,800 --> 00:20:17,000
Speaker 1: been swimming pool. You're just walking through and you feel

354
00:20:17,000 --> 00:20:21,080
Speaker 1: that resistance. That resistance is drag. You're forcing water molecules

355
00:20:21,080 --> 00:20:23,680
Speaker 1: to move around you as you walk through. Uh, friction

356
00:20:23,960 --> 00:20:27,320
Speaker 1: plays a factor in this. There's also a concept called

357
00:20:27,400 --> 00:20:32,840
Speaker 1: induced drag, which involves the way that the air pressure

358
00:20:33,080 --> 00:20:37,320
Speaker 1: is is changing and sort of how that is um

359
00:20:37,320 --> 00:20:39,520
Speaker 1: reconciling at the trailing edge of a wing. But it

360
00:20:39,520 --> 00:20:42,119
Speaker 1: gets really technical, and I figure you guys probably need

361
00:20:42,160 --> 00:20:44,680
Speaker 1: a break after I tackled lift. Suffice it to say,

362
00:20:45,240 --> 00:20:50,680
Speaker 1: drag opposes forward motion. So through aircraft design and propulsion systems,

363
00:20:50,840 --> 00:20:53,720
Speaker 1: we have to overcome drag to maintain a proper forward

364
00:20:53,800 --> 00:20:57,800
Speaker 1: velocity to maintain lift. So we do that with making

365
00:20:57,840 --> 00:21:03,200
Speaker 1: aircraft more aerodynamic, you know, reducing that resistance, and by

366
00:21:03,240 --> 00:21:09,240
Speaker 1: having appropriately powerful engines to propel with enough thrust to

367
00:21:09,320 --> 00:21:14,040
Speaker 1: maintain lift. The fourth force in flight is gravity. This

368
00:21:14,119 --> 00:21:17,399
Speaker 1: is obviously the force pulling downward on the plane. So

369
00:21:17,480 --> 00:21:21,040
Speaker 1: we have thrust that's the forward force, drag which is

370
00:21:21,119 --> 00:21:24,199
Speaker 1: the backward force, lift which is the upward force, and

371
00:21:24,240 --> 00:21:26,919
Speaker 1: gravity which is the downward force. All of these are

372
00:21:27,040 --> 00:21:30,000
Speaker 1: vectors because they all have an amplitude and a direction.

373
00:21:30,440 --> 00:21:32,920
Speaker 1: So aircraft design has to take all of those forces

374
00:21:32,960 --> 00:21:36,520
Speaker 1: into account. All right, So we got the technical description

375
00:21:36,560 --> 00:21:38,639
Speaker 1: of the forces acting on the planes out of the way,

376
00:21:38,960 --> 00:21:41,439
Speaker 1: let's get back to the history of stuff. I'll keep

377
00:21:41,480 --> 00:21:44,840
Speaker 1: in mind that throughout this history description that I'm doing,

378
00:21:45,320 --> 00:21:48,240
Speaker 1: people were still sussing out the nature of lift, as

379
00:21:48,320 --> 00:21:50,800
Speaker 1: is obvious by the fact that we still today have

380
00:21:50,840 --> 00:21:53,800
Speaker 1: textbooks and articles that give an incorrect explanation of what

381
00:21:53,920 --> 00:21:56,080
Speaker 1: is going on, or maybe how I should I should

382
00:21:56,119 --> 00:21:59,560
Speaker 1: say how it is going on now. In the eighteen seventies,

383
00:21:59,600 --> 00:22:03,640
Speaker 1: a couple of engineers, one named Francis h Winham and

384
00:22:03,840 --> 00:22:07,000
Speaker 1: John Browning Is the other built the first wind tunnel

385
00:22:07,200 --> 00:22:10,120
Speaker 1: and that would become a critical component for testing wing

386
00:22:10,200 --> 00:22:14,200
Speaker 1: designs and learning more about the practical effects of those designs.

387
00:22:14,760 --> 00:22:18,200
Speaker 1: More work was done by a dude named Horatio Phillips.

388
00:22:18,359 --> 00:22:20,280
Speaker 1: A lot of really great names in this history. By

389
00:22:20,320 --> 00:22:24,280
Speaker 1: the way, Horatio Phillips built an improved wind tunnel and

390
00:22:24,280 --> 00:22:26,800
Speaker 1: created an airfoil design that would become the basis for

391
00:22:26,880 --> 00:22:29,919
Speaker 1: most wing designs in the following decades. Then we have

392
00:22:30,320 --> 00:22:34,399
Speaker 1: Auto Lelandhall. He was a or Lilonhall. He was a

393
00:22:34,400 --> 00:22:39,680
Speaker 1: German engineer who took Cayley's work and began serious testing

394
00:22:39,800 --> 00:22:43,160
Speaker 1: of various wing designs and angles of attack to find

395
00:22:43,200 --> 00:22:47,080
Speaker 1: out what would work best, what is the most efficient

396
00:22:47,119 --> 00:22:50,399
Speaker 1: way to generate lift? What's the best design and best

397
00:22:50,480 --> 00:22:53,879
Speaker 1: angle to get that effect? And he saw that different

398
00:22:53,920 --> 00:22:57,600
Speaker 1: angles of attack allowed for different results and lift. Angling

399
00:22:57,600 --> 00:23:00,280
Speaker 1: a wing could improve the ability to generate lift up

400
00:23:00,280 --> 00:23:03,000
Speaker 1: to a point, and then beyond a certain angle which

401
00:23:03,040 --> 00:23:06,840
Speaker 1: is around fifteen degrees uh, the ability to generate lift

402
00:23:06,880 --> 00:23:09,720
Speaker 1: would drop off again. So as work became the basis

403
00:23:09,760 --> 00:23:13,240
Speaker 1: for many other engineers who followed, including the Right brothers,

404
00:23:13,520 --> 00:23:17,359
Speaker 1: and Otto himself was no slouch. He built several gliders,

405
00:23:17,480 --> 00:23:22,080
Speaker 1: including biplane gliders, and he began conducting test glide flights,

406
00:23:22,160 --> 00:23:25,439
Speaker 1: both manned and unmanned ones, and he probably went on

407
00:23:25,520 --> 00:23:28,320
Speaker 1: more than two thousand, maybe as many as twenty hundred

408
00:23:28,320 --> 00:23:31,920
Speaker 1: test flights. Tragically, it was during one of those tests

409
00:23:31,920 --> 00:23:35,080
Speaker 1: that he met his end in eighteen nineties six after

410
00:23:35,160 --> 00:23:39,159
Speaker 1: a fatal crash. Next we have Samuel Langley, who was

411
00:23:39,200 --> 00:23:42,600
Speaker 1: an astronomer who seemed to have a pretty promising jump

412
00:23:42,680 --> 00:23:45,719
Speaker 1: on creating a working aircraft. He wanted to use a

413
00:23:45,800 --> 00:23:49,320
Speaker 1: steam powered engine to create the thrust needed to achieve

414
00:23:49,359 --> 00:23:52,720
Speaker 1: the lift necessary for flight, so he built a model

415
00:23:52,920 --> 00:23:56,960
Speaker 1: of a plane smaller than a full scale version, and

416
00:23:57,040 --> 00:24:00,119
Speaker 1: it was an unmanned aircraft and He called it the

417
00:24:00,240 --> 00:24:05,840
Speaker 1: Aerodrome in one so a few years before Auto would

418
00:24:05,880 --> 00:24:10,800
Speaker 1: have his his fatal crash. Langley tested this design and

419
00:24:10,880 --> 00:24:13,840
Speaker 1: the aerodrome flew for about three quarters of a mile.

420
00:24:14,560 --> 00:24:17,800
Speaker 1: At that point the aircraft ran out of fuel steam

421
00:24:17,880 --> 00:24:20,960
Speaker 1: powered aircraft. It was enough to get Langley a sizeable

422
00:24:21,040 --> 00:24:24,000
Speaker 1: grant to try and build a full scale version, but

423
00:24:24,160 --> 00:24:29,240
Speaker 1: unfortunately he discovered his design couldn't scale up because as

424
00:24:29,280 --> 00:24:31,879
Speaker 1: you got larger, you're going to need more power to

425
00:24:32,000 --> 00:24:34,639
Speaker 1: generate the thrust, and more power meant you needed a

426
00:24:34,680 --> 00:24:38,440
Speaker 1: heavier steam engine, and and eventually that that ratio just

427
00:24:38,480 --> 00:24:42,280
Speaker 1: wouldn't work out. The steam engine was just too heavy,

428
00:24:42,480 --> 00:24:45,440
Speaker 1: and so you would need even more power to generate

429
00:24:45,600 --> 00:24:49,440
Speaker 1: enough lift to get the heavier aircraft up, and there

430
00:24:49,520 --> 00:24:52,600
Speaker 1: was no way to have the steam engine actually provide

431
00:24:52,680 --> 00:24:56,280
Speaker 1: the power needed and he ultimately had to abandon his

432
00:24:56,400 --> 00:24:59,440
Speaker 1: design at the plane just needed more lift and it

433
00:24:59,480 --> 00:25:01,800
Speaker 1: could generate front thrust, and thus it could not fly.

434
00:25:02,640 --> 00:25:08,720
Speaker 1: In Octave, Chanut, another great name, published a collection of

435
00:25:08,760 --> 00:25:12,680
Speaker 1: works called Progress in Flying Machines. He collected the wisdom

436
00:25:12,840 --> 00:25:18,160
Speaker 1: and experimental results of numerous efforts throughout the aeronautic societies

437
00:25:18,200 --> 00:25:22,600
Speaker 1: out there and and essentially wrote down everything that had

438
00:25:22,600 --> 00:25:24,680
Speaker 1: been done up to that point in the efforts to

439
00:25:24,760 --> 00:25:28,640
Speaker 1: achieve powered flight. Then we get to Orville and Wilbur

440
00:25:28,800 --> 00:25:33,439
Speaker 1: right the right brothers. They recognized Cayley's wisdom and the

441
00:25:33,520 --> 00:25:36,280
Speaker 1: need for separate systems to provide the lift, thrust, and

442
00:25:36,320 --> 00:25:39,880
Speaker 1: control of the aircraft. They also relied upon Chanut's book

443
00:25:39,920 --> 00:25:42,680
Speaker 1: to help guide their own efforts. They came up with

444
00:25:42,720 --> 00:25:46,160
Speaker 1: their own experiment with regard to controlling a flying body's

445
00:25:46,240 --> 00:25:49,879
Speaker 1: motion through flight, the whole steering part of the equation.

446
00:25:50,200 --> 00:25:52,680
Speaker 1: They believe that by controlling the shape of the wing

447
00:25:53,119 --> 00:25:56,320
Speaker 1: they can control the flight itself, including stuff like roll

448
00:25:56,760 --> 00:26:00,480
Speaker 1: and pitch. So the three types of movement you need

449
00:26:00,520 --> 00:26:03,520
Speaker 1: to know about with aircraft once they're flying in three

450
00:26:03,520 --> 00:26:09,480
Speaker 1: dimensional space are roll, pitch, and yaw. Roll is sort

451
00:26:09,480 --> 00:26:12,960
Speaker 1: of the the tilt, the side to side tilt of

452
00:26:13,000 --> 00:26:15,560
Speaker 1: an aircraft, so whether it's tilting to the left or

453
00:26:15,600 --> 00:26:19,480
Speaker 1: tilting to the right. Um as I'll talk about later,

454
00:26:19,920 --> 00:26:23,200
Speaker 1: this tilting becomes a very important part of steering. Pitch

455
00:26:23,880 --> 00:26:27,399
Speaker 1: is the uh the angle of the nose and the

456
00:26:27,400 --> 00:26:32,160
Speaker 1: tail right. So if if you are um pitching up,

457
00:26:32,240 --> 00:26:37,159
Speaker 1: then the aircraft's nose is at a higher altitude than

458
00:26:37,200 --> 00:26:40,359
Speaker 1: the tail, and the aircraft is climbing pitched down, and

459
00:26:40,400 --> 00:26:42,840
Speaker 1: the nose is at a lower altitude than the tail,

460
00:26:43,040 --> 00:26:48,800
Speaker 1: and the aircraft is descending. And then yaw involves turning

461
00:26:48,840 --> 00:26:52,240
Speaker 1: to the left or to the right, although yaw and

462
00:26:52,520 --> 00:26:56,280
Speaker 1: roll are very very important components for steering. Anyway, those

463
00:26:56,320 --> 00:27:00,560
Speaker 1: are the three ways of thinking about the three different

464
00:27:00,560 --> 00:27:05,440
Speaker 1: axes of flight controls in three dimensional space. So we'll

465
00:27:05,440 --> 00:27:07,480
Speaker 1: come back to that in a little bit. So anyway,

466
00:27:07,760 --> 00:27:10,399
Speaker 1: the Right brothers said, all right, well, by manipulating the

467
00:27:10,440 --> 00:27:16,560
Speaker 1: shape of the wing, we can add steering to an aircraft. Um.

468
00:27:16,640 --> 00:27:20,720
Speaker 1: They built several gliders, both unmanned and manned gliders, and

469
00:27:20,760 --> 00:27:25,080
Speaker 1: tested different wing shapes and designs, including in wind tunnels,

470
00:27:25,119 --> 00:27:27,919
Speaker 1: and they worked on perfecting that. And this brings us

471
00:27:27,960 --> 00:27:32,560
Speaker 1: to another important component of the design. Getting up in

472
00:27:32,600 --> 00:27:34,719
Speaker 1: the air is one thing, but from that point on,

473
00:27:34,720 --> 00:27:36,919
Speaker 1: how do you control where you're going? Right? How do

474
00:27:36,960 --> 00:27:39,560
Speaker 1: you actually maneuver a solid object through the air that

475
00:27:39,640 --> 00:27:42,960
Speaker 1: three dimensional space there's no ground to brace against, and

476
00:27:42,960 --> 00:27:45,399
Speaker 1: how do you steer the darn thing? And that was

477
00:27:45,440 --> 00:27:47,240
Speaker 1: what the Right brothers were really working on. In those

478
00:27:47,240 --> 00:27:49,680
Speaker 1: early tests trying to determine the most effective way to

479
00:27:49,720 --> 00:27:52,560
Speaker 1: control the flight of an aircraft once it's airborne. So

480
00:27:52,640 --> 00:27:54,920
Speaker 1: we'll talk about that for a second. Steering something means

481
00:27:55,080 --> 00:27:56,879
Speaker 1: you have to be able to control the direction in

482
00:27:56,920 --> 00:28:01,360
Speaker 1: which that something is traveling. It's very basic and obvious observation,

483
00:28:01,480 --> 00:28:03,960
Speaker 1: but I feel like we have to start somewhere. So

484
00:28:04,040 --> 00:28:06,600
Speaker 1: you need to be able to change the object's velocity

485
00:28:06,640 --> 00:28:10,720
Speaker 1: because velocity is a vector. Again, a vector is something

486
00:28:10,760 --> 00:28:13,960
Speaker 1: that has both an amplitude and a direction, has an

487
00:28:13,960 --> 00:28:17,960
Speaker 1: amount and a direction associated with it. So even if

488
00:28:18,000 --> 00:28:21,480
Speaker 1: the speed of the moving object doesn't change, it's moving

489
00:28:21,520 --> 00:28:24,560
Speaker 1: at the same rate of travel even as you change

490
00:28:24,560 --> 00:28:28,800
Speaker 1: its direction. If you change the direction, you've also changed

491
00:28:28,840 --> 00:28:34,280
Speaker 1: the velocity because the direction part of a vector has changed. So, uh,

492
00:28:34,320 --> 00:28:36,840
Speaker 1: that's an important thing to remember that a velocity can

493
00:28:36,920 --> 00:28:39,560
Speaker 1: change even if the speed stays the same because you've

494
00:28:39,600 --> 00:28:43,080
Speaker 1: changed the direction of travel. Tilting the plane having one

495
00:28:43,080 --> 00:28:46,400
Speaker 1: wing dip lower than the other side means that some

496
00:28:46,520 --> 00:28:48,920
Speaker 1: of the lift acting on the plane is now actually

497
00:28:48,920 --> 00:28:52,080
Speaker 1: pushing the plane in a sideways motion. So when you

498
00:28:52,200 --> 00:28:55,080
Speaker 1: roll the plane a little bit, you are actually changing

499
00:28:55,120 --> 00:28:58,480
Speaker 1: the lift dynamics, and some of that lift that otherwise

500
00:28:58,480 --> 00:29:01,040
Speaker 1: would be holding the plane up is pushing the plane

501
00:29:01,200 --> 00:29:05,560
Speaker 1: to UH to a side. It creates centripetal force, and

502
00:29:05,600 --> 00:29:08,400
Speaker 1: it eventually will make the plane move in a circular path.

503
00:29:08,480 --> 00:29:11,200
Speaker 1: You know, the more the dramatic the roll up to

504
00:29:11,240 --> 00:29:15,680
Speaker 1: a point, the more tight that circle is going to be. However,

505
00:29:17,160 --> 00:29:18,720
Speaker 1: this is, by the way, as known as banking. When

506
00:29:18,720 --> 00:29:22,640
Speaker 1: you talk about airplanes banking, it's because they're they're tilting

507
00:29:22,680 --> 00:29:25,960
Speaker 1: this way and the rolling and UH starting to turn.

508
00:29:26,440 --> 00:29:29,200
Speaker 1: But another thing you have to remember is this reduces

509
00:29:29,240 --> 00:29:33,440
Speaker 1: the amount of lift actually holding the aircraft up. So

510
00:29:33,680 --> 00:29:37,160
Speaker 1: you know, you're dedicating some of the lift to turning

511
00:29:37,200 --> 00:29:39,640
Speaker 1: the aircraft, not just holding it up. So if you

512
00:29:39,680 --> 00:29:42,720
Speaker 1: don't do anything, if you're maintaining the same speed, you're

513
00:29:42,760 --> 00:29:46,840
Speaker 1: changing the velocity by changing the direction. That reduction in

514
00:29:46,960 --> 00:29:48,840
Speaker 1: lift means that your aircraft is going to start to

515
00:29:48,840 --> 00:29:52,600
Speaker 1: lose altitude, So you've got to do something to counteract that.

516
00:29:53,600 --> 00:29:56,840
Speaker 1: Typically you do something like increase the angle of attack

517
00:29:57,000 --> 00:30:01,360
Speaker 1: of the wings or using the tail u to compensate

518
00:30:01,800 --> 00:30:05,640
Speaker 1: for this loss of lift of upward lift so that

519
00:30:05,720 --> 00:30:08,640
Speaker 1: you don't lose altitude. Modern aircraft do this with a

520
00:30:08,640 --> 00:30:11,920
Speaker 1: flight control surface called an elevator, often on the tail,

521
00:30:12,320 --> 00:30:15,840
Speaker 1: and the elevator can adjust its angle to change the

522
00:30:15,840 --> 00:30:18,800
Speaker 1: angle of attack with the fluid that the aircraft is

523
00:30:18,840 --> 00:30:22,080
Speaker 1: moving through the air itself and provide more upward lift.

524
00:30:22,640 --> 00:30:26,640
Speaker 1: Other movable control surfaces can affect the plane's pitch, um

525
00:30:26,840 --> 00:30:29,840
Speaker 1: and the yaw. The yaws typically a it's a rudder

526
00:30:30,000 --> 00:30:33,640
Speaker 1: that's attached to the tail of a plane, and steering

527
00:30:33,680 --> 00:30:37,160
Speaker 1: actually involves controlling the roll and yaw of the aircraft.

528
00:30:37,520 --> 00:30:40,440
Speaker 1: So you have both the yaw and the tilt of

529
00:30:40,480 --> 00:30:45,360
Speaker 1: the plane that allows you to make more controlled turns

530
00:30:45,720 --> 00:30:49,120
Speaker 1: with the aircraft. Each of these systems has its own controls,

531
00:30:49,200 --> 00:30:53,080
Speaker 1: and in modern aircraft uh the ailerons controlled the role.

532
00:30:53,480 --> 00:30:55,840
Speaker 1: These are on the outer rear edge of the wings

533
00:30:56,160 --> 00:30:58,160
Speaker 1: and they can move in opposite directions. So if you

534
00:30:58,240 --> 00:31:02,360
Speaker 1: ever sat on window seat that's right next to a

535
00:31:02,400 --> 00:31:04,520
Speaker 1: wing and you see this little thing at the very

536
00:31:04,640 --> 00:31:07,880
Speaker 1: end of the planes wing and it's either tilting down

537
00:31:07,960 --> 00:31:11,960
Speaker 1: or it's tilting up, that's part of this system that's

538
00:31:12,000 --> 00:31:14,840
Speaker 1: meant to control the role of the plane and allow

539
00:31:14,920 --> 00:31:19,560
Speaker 1: for turns. Um. The yaw, like I said, comes from

540
00:31:19,560 --> 00:31:23,160
Speaker 1: the plane's rudder. It's typically a vertical tail fin that

541
00:31:23,240 --> 00:31:26,239
Speaker 1: can swivel left or right, and the pitch comes from

542
00:31:26,320 --> 00:31:29,080
Speaker 1: the elevators like I mentioned earlier, those are typically on

543
00:31:29,120 --> 00:31:32,040
Speaker 1: the aircraft's tail as well, on a horizontal plane, not

544
00:31:32,120 --> 00:31:34,680
Speaker 1: a vertical plane, like the rudder is, and the elevators

545
00:31:34,720 --> 00:31:37,840
Speaker 1: can also tilt up or down, decreasing or increasing lift

546
00:31:37,960 --> 00:31:40,480
Speaker 1: on the tail, which makes the airplane behave a little

547
00:31:40,480 --> 00:31:43,840
Speaker 1: bit like a lever. Right. If you increase the lift

548
00:31:43,920 --> 00:31:46,280
Speaker 1: on a tail, then the tail gets lifted up and

549
00:31:46,280 --> 00:31:49,800
Speaker 1: the nose the airplane gets tilted downward, and vice versa.

550
00:31:50,800 --> 00:31:54,400
Speaker 1: But that's just one part of the equation, or really,

551
00:31:54,560 --> 00:31:56,280
Speaker 1: I guess you could say two parts of the equation,

552
00:31:56,280 --> 00:31:59,480
Speaker 1: because wing design contributes to both flight control and lift.

553
00:32:00,040 --> 00:32:02,480
Speaker 1: But they also needed to work on thrust. They needed

554
00:32:02,480 --> 00:32:05,200
Speaker 1: a propulsion system that we get their aircraft up to

555
00:32:05,200 --> 00:32:08,800
Speaker 1: a sufficient speed to generate the lift needed to sustain flight.

556
00:32:09,440 --> 00:32:12,520
Speaker 1: They had bill gliders and done manned and unmanned tests

557
00:32:12,520 --> 00:32:16,080
Speaker 1: at Kitty Hawk, North Carolina. They chose Kittie Hawk, by

558
00:32:16,080 --> 00:32:18,360
Speaker 1: the way, they were not natives to North Carolina, but

559
00:32:18,360 --> 00:32:21,360
Speaker 1: they chose kitty Hawk because it was pretty dependable for

560
00:32:21,440 --> 00:32:24,479
Speaker 1: some good winds due to being on the Atlantic coast,

561
00:32:25,040 --> 00:32:27,440
Speaker 1: so um you get a good stiff breeze over at

562
00:32:27,480 --> 00:32:30,240
Speaker 1: Kittie Hawk. I've been there, and one of the most

563
00:32:30,240 --> 00:32:33,400
Speaker 1: popular activities over at Kittie Hawk is kite flying. A

564
00:32:33,440 --> 00:32:37,480
Speaker 1: lot of people flying kites, big elaborate ones way up

565
00:32:37,480 --> 00:32:40,040
Speaker 1: in the sky because they get these nice strong winds.

566
00:32:40,560 --> 00:32:42,320
Speaker 1: By the way, if you get a chance to visit

567
00:32:42,360 --> 00:32:46,040
Speaker 1: Kitty Hawk and to go visit the site of the

568
00:32:46,120 --> 00:32:49,880
Speaker 1: first flight from the right Brothers, I highly recommend it.

569
00:32:49,880 --> 00:32:53,760
Speaker 1: It is a very interesting location, a lot of cool

570
00:32:54,120 --> 00:32:57,640
Speaker 1: information there, and you can actually walk the pathway of

571
00:32:57,640 --> 00:33:00,880
Speaker 1: those test flights. It's pretty neat any way. As part

572
00:33:00,880 --> 00:33:03,720
Speaker 1: of this work, the brothers had designed a movable tail

573
00:33:03,800 --> 00:33:07,800
Speaker 1: component that would help with the flight stability, particularly when

574
00:33:07,800 --> 00:33:11,240
Speaker 1: the pilot of the glider wanted to steer. And now

575
00:33:11,280 --> 00:33:13,200
Speaker 1: it was time to work on an aircraft capable of

576
00:33:13,240 --> 00:33:16,360
Speaker 1: generating its own thrust to maintain flight, not just to

577
00:33:16,400 --> 00:33:19,320
Speaker 1: be able to glide, and this required a lot more research,

578
00:33:19,560 --> 00:33:21,840
Speaker 1: as the brothers had to not only design a motor

579
00:33:22,120 --> 00:33:25,200
Speaker 1: that could turn a propeller fast enough to generate enough thrust,

580
00:33:25,680 --> 00:33:28,400
Speaker 1: but also an airplane frame capable of both supporting the

581
00:33:28,400 --> 00:33:31,760
Speaker 1: motor's weight and to withstand the vibrations the motor created

582
00:33:31,800 --> 00:33:35,200
Speaker 1: during operation. The result of all their research was the

583
00:33:35,240 --> 00:33:39,040
Speaker 1: design of an aircraft they simply called the Flyer, and

584
00:33:39,120 --> 00:33:42,479
Speaker 1: some people refer to it as the Right Flyer. A

585
00:33:42,480 --> 00:33:46,280
Speaker 1: bicycle mechanic named Charles Taylor would build the motor for

586
00:33:46,320 --> 00:33:49,280
Speaker 1: the Brothers. It was a custom built motor, a gasolene

587
00:33:49,360 --> 00:33:52,760
Speaker 1: fueled twelve horsepower motor, and the motor was used to

588
00:33:52,840 --> 00:33:56,440
Speaker 1: drive a chain that in turn would link to gears

589
00:33:56,480 --> 00:34:00,560
Speaker 1: that would turn the two propellers, So it's like a bicycle,

590
00:34:00,720 --> 00:34:03,320
Speaker 1: you know, a bicycles wheels. The propellers were changed driven

591
00:34:03,680 --> 00:34:07,560
Speaker 1: this motor. Through powering the propellers would provide the needed thrust.

592
00:34:08,280 --> 00:34:11,160
Speaker 1: The Right Flyer had a wingspan of twelve point two

593
00:34:11,160 --> 00:34:14,719
Speaker 1: meters or forty point three feet, and the right wing

594
00:34:15,120 --> 00:34:18,399
Speaker 1: was four inches longer than the left wing. So why

595
00:34:18,440 --> 00:34:21,080
Speaker 1: is that? Why was the right wing longer? Well, that

596
00:34:21,160 --> 00:34:24,440
Speaker 1: was because the Right Brothers design meant that the engine

597
00:34:24,480 --> 00:34:26,960
Speaker 1: for the plane would sit a little to the right

598
00:34:27,320 --> 00:34:31,280
Speaker 1: of the center line. It was not centered along the

599
00:34:31,360 --> 00:34:34,719
Speaker 1: axis of the airplane. It actually went a little to

600
00:34:34,760 --> 00:34:38,120
Speaker 1: the right side that meant the pilot would actually laid

601
00:34:38,160 --> 00:34:41,160
Speaker 1: down on the left side of the center line. But

602
00:34:41,360 --> 00:34:44,560
Speaker 1: the engine weighed seventy seven point one ms or a

603
00:34:44,640 --> 00:34:48,719
Speaker 1: hundred seventy pounds, the pilot weighed only sixty five point

604
00:34:48,760 --> 00:34:52,960
Speaker 1: eight kilograms or one five pounds, So the brothers needed

605
00:34:53,000 --> 00:34:55,839
Speaker 1: some way to balance the scales as it were, so

606
00:34:55,880 --> 00:34:58,520
Speaker 1: that the plane would fly properly without the constant need

607
00:34:58,600 --> 00:35:01,560
Speaker 1: for adjustment. Since had a heavier engine on one side

608
00:35:01,560 --> 00:35:04,560
Speaker 1: and a lighter pilot on the other, and so they

609
00:35:04,600 --> 00:35:07,040
Speaker 1: made the right wing a little longer than the left

610
00:35:07,080 --> 00:35:09,360
Speaker 1: in order to generate a bit more lift than the

611
00:35:09,440 --> 00:35:12,400
Speaker 1: left side and thus compensate for the added weight on

612
00:35:12,440 --> 00:35:15,200
Speaker 1: the right side of the plane. The Right brothers held

613
00:35:15,239 --> 00:35:19,839
Speaker 1: the first test flight on December seventeenth three. Orville Right

614
00:35:20,280 --> 00:35:22,720
Speaker 1: was the pilot, and the plane lifted off the ground

615
00:35:22,719 --> 00:35:26,000
Speaker 1: and traveled about one twenty feet or thirty five meters.

616
00:35:26,360 --> 00:35:29,239
Speaker 1: It flew just twelve seconds, but it was enough to

617
00:35:29,280 --> 00:35:32,360
Speaker 1: secure the Right brothers the acknowledgement that they had created

618
00:35:32,360 --> 00:35:37,440
Speaker 1: the first heavier than air manned, steerable flying machine. They

619
00:35:37,440 --> 00:35:40,200
Speaker 1: would build other aircraft based off that design, but the

620
00:35:40,239 --> 00:35:43,279
Speaker 1: only one they ever attempted to preserve was the original

621
00:35:43,360 --> 00:35:46,680
Speaker 1: Right Flyer, and for a short while that airplane called

622
00:35:46,719 --> 00:35:50,800
Speaker 1: the Kensington Science Museum in London home. But in nineteen

623
00:35:51,560 --> 00:35:54,279
Speaker 1: the Flyer returned to the United States to become part

624
00:35:54,360 --> 00:35:57,400
Speaker 1: of the Smithsonian's exhibits, and it is now in the

625
00:35:57,520 --> 00:36:01,399
Speaker 1: National Air and Space Museum in Washington, d C. When

626
00:36:01,400 --> 00:36:03,520
Speaker 1: we come back, I'll talk about some other elements of

627
00:36:03,560 --> 00:36:14,759
Speaker 1: aircraft and how those contribute to flight. Okay, so the

628
00:36:14,880 --> 00:36:18,400
Speaker 1: Right Brothers were two of the many pioneers of piloted

629
00:36:18,440 --> 00:36:21,280
Speaker 1: heavier than air aircraft. There were lots of other people,

630
00:36:21,400 --> 00:36:23,680
Speaker 1: and I hope I've made it clear that the success

631
00:36:23,760 --> 00:36:26,480
Speaker 1: of the Right Brothers depended heavily on the research and

632
00:36:26,520 --> 00:36:29,759
Speaker 1: work of numerous people before them. Also, they weren't the

633
00:36:29,800 --> 00:36:32,839
Speaker 1: only ones working on the problem when they achieved their

634
00:36:32,840 --> 00:36:36,680
Speaker 1: success in North Carolina. It's why I define their successes

635
00:36:36,719 --> 00:36:39,000
Speaker 1: being the first to pilot a heavier than air aircraft

636
00:36:39,160 --> 00:36:42,440
Speaker 1: that had at least some rudimentary flight controls, because otherwise

637
00:36:42,440 --> 00:36:44,239
Speaker 1: you have to talk about a whole bunch of people

638
00:36:44,239 --> 00:36:47,160
Speaker 1: who did lighter than air aircraft and and some other stuff,

639
00:36:47,680 --> 00:36:50,120
Speaker 1: and many people would quickly follow in the footsteps or

640
00:36:50,719 --> 00:36:54,560
Speaker 1: flight steps of the right brothers building better aircraft with

641
00:36:54,640 --> 00:36:58,840
Speaker 1: more sophisticated control mechanisms and development and innovation were in

642
00:36:58,960 --> 00:37:01,080
Speaker 1: the fast lane. So just going to cover a few

643
00:37:01,080 --> 00:37:03,400
Speaker 1: more basics, and I might have to do a future

644
00:37:03,400 --> 00:37:06,120
Speaker 1: episode to talk about some of the more modern systems

645
00:37:06,120 --> 00:37:08,879
Speaker 1: aboard aircraft, because that would make this show run way

646
00:37:08,920 --> 00:37:10,960
Speaker 1: too long if I were to keep up with that.

647
00:37:11,360 --> 00:37:14,480
Speaker 1: So let's talk about propellers. The propellers on a prop

648
00:37:14,640 --> 00:37:17,880
Speaker 1: plane are effectively doing the same thing that the wings

649
00:37:17,960 --> 00:37:20,960
Speaker 1: do on a plane by creating lift, only in this case,

650
00:37:21,239 --> 00:37:24,920
Speaker 1: the direction of the lift is forward with respect to

651
00:37:24,960 --> 00:37:29,120
Speaker 1: the plane. It's like a helicopter's rotors. Moving the blades

652
00:37:29,120 --> 00:37:31,799
Speaker 1: of a propeller in a circular path at a fast

653
00:37:31,920 --> 00:37:36,360
Speaker 1: enough rotational speed creates the force and drives the aircraft forward.

654
00:37:36,680 --> 00:37:39,080
Speaker 1: But unlike a wing, which tends to have a fixed

655
00:37:39,080 --> 00:37:42,600
Speaker 1: angle of attack across the entire length of the wings surface,

656
00:37:42,960 --> 00:37:46,279
Speaker 1: a propeller blade has a twist in it so that

657
00:37:46,320 --> 00:37:49,520
Speaker 1: the pitch angle varies along the length of the blade.

658
00:37:50,200 --> 00:37:53,920
Speaker 1: Some modern planes have a controllable pitch propeller, which allows

659
00:37:53,960 --> 00:37:56,520
Speaker 1: the pilot to change this rotation in order to have

660
00:37:56,600 --> 00:37:59,960
Speaker 1: the plane perform at optimal efficiencies at different air speed

661
00:38:00,000 --> 00:38:03,520
Speaker 1: eads now Jet engines are different, and I've covered them

662
00:38:03,560 --> 00:38:07,160
Speaker 1: in past episodes, but here's a quick rundown. From the outside,

663
00:38:07,200 --> 00:38:10,120
Speaker 1: a jet engine looks like a tube. If you look

664
00:38:10,160 --> 00:38:12,479
Speaker 1: at one head on, you'll see a big fan thing

665
00:38:12,600 --> 00:38:15,120
Speaker 1: in the front of that tube. Then at first you

666
00:38:15,200 --> 00:38:18,040
Speaker 1: might think that a jet is similar to a propeller plane,

667
00:38:18,080 --> 00:38:22,040
Speaker 1: that it's generating forward thrust by just rotating that fan

668
00:38:22,120 --> 00:38:27,080
Speaker 1: super fast. But that's not quite right. The purpose of

669
00:38:27,080 --> 00:38:30,040
Speaker 1: the fan is to suck air into the jet engine.

670
00:38:30,400 --> 00:38:34,120
Speaker 1: The fan attaches to a shaft and it spinds rapidly

671
00:38:34,160 --> 00:38:38,400
Speaker 1: and it pulls air into the engine. Behind the fan

672
00:38:38,560 --> 00:38:41,759
Speaker 1: on that same shaft, or on a shaft around the

673
00:38:41,800 --> 00:38:46,000
Speaker 1: fans shaft, there are a bunch of other blades attached,

674
00:38:46,480 --> 00:38:49,680
Speaker 1: and these blades are compressors. They compress the air. They

675
00:38:49,760 --> 00:38:52,880
Speaker 1: squeeze that air down into a smaller and smaller space.

676
00:38:53,800 --> 00:38:56,560
Speaker 1: That also increases the pressure obviously of the air, and

677
00:38:56,640 --> 00:38:59,200
Speaker 1: also the temperature of the air and gets it to

678
00:38:59,280 --> 00:39:02,360
Speaker 1: the right temperature for the next stage, which involves combustion.

679
00:39:03,040 --> 00:39:07,280
Speaker 1: So behind the compressor is a combustion chamber or series

680
00:39:07,320 --> 00:39:11,239
Speaker 1: of combustion chambers, and the compressed air enters into the chambers,

681
00:39:11,280 --> 00:39:14,720
Speaker 1: and nozzles that also enter the chambers spray a fine

682
00:39:14,760 --> 00:39:19,000
Speaker 1: mist of fuel there, and an ignition component creates an

683
00:39:19,040 --> 00:39:22,960
Speaker 1: electric spark that lights the mixture of compressed air and fuel,

684
00:39:23,640 --> 00:39:27,720
Speaker 1: and you get burning gases inside the chamber. Those burning

685
00:39:27,719 --> 00:39:32,400
Speaker 1: gases expand as the heat up. The only exit out

686
00:39:32,560 --> 00:39:35,440
Speaker 1: of this engine is a nozzle at the back, So

687
00:39:35,480 --> 00:39:39,360
Speaker 1: the expanding gases escape out the nozzle at a tremendous

688
00:39:39,440 --> 00:39:42,560
Speaker 1: amount of force. And because we know every action has

689
00:39:42,560 --> 00:39:46,240
Speaker 1: an equal but opposite reaction, we know that this backward

690
00:39:46,360 --> 00:39:50,440
Speaker 1: pushing force of escaping gas creates a forward pushing force

691
00:39:50,600 --> 00:39:53,239
Speaker 1: on the aircraft itself. So if you can generate enough

692
00:39:53,280 --> 00:39:55,839
Speaker 1: force to overcome the weight of the jet and get

693
00:39:55,880 --> 00:39:58,280
Speaker 1: it up to speed, you can use it to provide

694
00:39:58,280 --> 00:40:02,080
Speaker 1: the thrust needed to get lift and take off. Oh

695
00:40:02,120 --> 00:40:06,200
Speaker 1: and that escaping gas also turns a turbine at the end,

696
00:40:06,520 --> 00:40:09,680
Speaker 1: So you've got the combustion chamber, you've got an exit

697
00:40:09,680 --> 00:40:12,200
Speaker 1: out the back of the combustion chamber where the gas

698
00:40:12,239 --> 00:40:15,120
Speaker 1: is passing through a nozzle. It also ends up turning

699
00:40:15,120 --> 00:40:18,719
Speaker 1: a turbine, and that turbine provides the rotational force for

700
00:40:18,880 --> 00:40:23,279
Speaker 1: the UH, the compression blades on that rotating shaft, and

701
00:40:23,320 --> 00:40:26,399
Speaker 1: also the fan. You know I mentioned those earlier. That's

702
00:40:26,400 --> 00:40:29,359
Speaker 1: what's actually causing the rotational force. So not only does

703
00:40:29,400 --> 00:40:32,680
Speaker 1: the jet engine provide thrust for the aircraft, it also

704
00:40:32,760 --> 00:40:36,680
Speaker 1: harnesses some of that energy to operate the components of

705
00:40:36,719 --> 00:40:40,640
Speaker 1: the engine itself. There are variations on this design. There

706
00:40:40,640 --> 00:40:43,440
Speaker 1: are two or three spool jet engines, for example, but

707
00:40:43,480 --> 00:40:47,440
Speaker 1: they all work on the same basic principle. UM. One variation,

708
00:40:47,520 --> 00:40:49,560
Speaker 1: the one we see in commercial jets. A very popular

709
00:40:49,560 --> 00:40:52,960
Speaker 1: one is the turbo fan jet. In this version, the

710
00:40:53,000 --> 00:40:57,040
Speaker 1: engine casing is much larger than the combustion section, so

711
00:40:57,120 --> 00:40:59,400
Speaker 1: you can think of it as a big tube around

712
00:40:59,480 --> 00:41:02,919
Speaker 1: a much smaller tube. The smaller tube is the combustion part.

713
00:41:03,400 --> 00:41:05,799
Speaker 1: So you've got the fan that's pulling air in, You've

714
00:41:05,800 --> 00:41:09,080
Speaker 1: got the compressor blades that are compressing the air down,

715
00:41:09,320 --> 00:41:11,920
Speaker 1: but there's also space for the for some of that

716
00:41:11,960 --> 00:41:16,360
Speaker 1: air to pass along the outside of the combustion chamber,

717
00:41:16,440 --> 00:41:19,440
Speaker 1: so some air is kind of going in between the

718
00:41:19,480 --> 00:41:23,080
Speaker 1: combustion chamber and the casing for the jet engine itself,

719
00:41:23,800 --> 00:41:27,279
Speaker 1: and the air coming in is compressed and most of

720
00:41:27,320 --> 00:41:29,600
Speaker 1: that air is passing along the outside of the engine

721
00:41:29,840 --> 00:41:32,520
Speaker 1: that provides the majority of the thrust. It's not the

722
00:41:32,560 --> 00:41:36,799
Speaker 1: superheated stuff. It's this compressed air that's passing through this

723
00:41:36,960 --> 00:41:44,080
Speaker 1: bleed bypass UH section. And it also not just provides thrust,

724
00:41:44,080 --> 00:41:47,359
Speaker 1: but it also is able to cool the engine so

725
00:41:47,400 --> 00:41:51,120
Speaker 1: that remains in operating operating temperatures. It it avoids overheating,

726
00:41:51,719 --> 00:41:53,520
Speaker 1: so the air that passes through the engine still goes

727
00:41:53,520 --> 00:41:56,520
Speaker 1: through the same combustion process I mentioned earlier and provides

728
00:41:56,560 --> 00:42:00,880
Speaker 1: additional thrust as it escapes, plus provides the UH the

729
00:42:00,920 --> 00:42:05,320
Speaker 1: force necessary to rotate that turbine and keep everything in motion.

730
00:42:06,000 --> 00:42:07,719
Speaker 1: By the way, jet engines can also be used to

731
00:42:07,760 --> 00:42:10,479
Speaker 1: power stuff other than aircraft, or rather, I should say

732
00:42:10,719 --> 00:42:14,240
Speaker 1: turbine engines like this can be used to power stuff

733
00:42:14,280 --> 00:42:18,720
Speaker 1: like tanks, or they can help power helicopters. They don't

734
00:42:18,880 --> 00:42:20,920
Speaker 1: do it the exact same way as a jet plane,

735
00:42:21,080 --> 00:42:24,480
Speaker 1: which has this exhaust be part of the thrust mechanism.

736
00:42:25,120 --> 00:42:28,920
Speaker 1: Instead the tail end of that engine, there's another turbine

737
00:42:28,920 --> 00:42:31,719
Speaker 1: that connects to some sort of drive mechanism, such as

738
00:42:31,719 --> 00:42:36,520
Speaker 1: the tank's treads or helicopters rotors. So the the turbine

739
00:42:36,520 --> 00:42:40,200
Speaker 1: engine pulls air in, you've got the combustion. All of

740
00:42:40,239 --> 00:42:43,440
Speaker 1: this is used to create the energy needed to rotate

741
00:42:43,520 --> 00:42:48,080
Speaker 1: a different turbine that then sends that power onto the

742
00:42:48,120 --> 00:42:52,760
Speaker 1: propulsion system of the tank or the helicopter. Uh. These

743
00:42:52,760 --> 00:42:54,839
Speaker 1: engines also have to have an exhaust port for all

744
00:42:54,880 --> 00:42:57,560
Speaker 1: that hot air to escape, but it's not used like

745
00:42:57,600 --> 00:43:00,359
Speaker 1: a thruster on a jet plane. But hey, for these

746
00:43:00,360 --> 00:43:02,760
Speaker 1: engines to work, you still got to get that turbine

747
00:43:02,840 --> 00:43:08,839
Speaker 1: spinning right. And that presents a challenge because these are

748
00:43:09,000 --> 00:43:11,800
Speaker 1: engines that work fine while the jet is in operation,

749
00:43:11,840 --> 00:43:15,719
Speaker 1: while it's actually moving through the air, because the process

750
00:43:16,000 --> 00:43:18,799
Speaker 1: of the jet engine working provides the energy needed to

751
00:43:18,920 --> 00:43:22,240
Speaker 1: turn the turbine that pulls more air in through the system.

752
00:43:22,239 --> 00:43:25,439
Speaker 1: By the way, you're not generating more energy than you're

753
00:43:25,480 --> 00:43:28,279
Speaker 1: expending here, I want to make that clear. Just rather

754
00:43:28,320 --> 00:43:31,960
Speaker 1: that the process is not just providing thrust, but providing

755
00:43:32,040 --> 00:43:35,839
Speaker 1: the force needed to turn those turbines and those fan

756
00:43:35,880 --> 00:43:38,360
Speaker 1: blades and compressor blades. But in order to do that,

757
00:43:38,400 --> 00:43:40,040
Speaker 1: you have to get up to speed in the first place.

758
00:43:40,040 --> 00:43:43,000
Speaker 1: How do you get it started? Well, the turbines are

759
00:43:43,239 --> 00:43:45,799
Speaker 1: too heavy and need to turn too quickly to rely

760
00:43:45,920 --> 00:43:48,560
Speaker 1: upon an electric motor to do it. So you can't

761
00:43:48,600 --> 00:43:51,080
Speaker 1: just have an electric motor attached to this thing to

762
00:43:51,400 --> 00:43:55,720
Speaker 1: jump start the turbine engine. That's not going to work.

763
00:43:55,880 --> 00:43:59,080
Speaker 1: They're far too large and heavy. So to do it,

764
00:43:59,160 --> 00:44:03,120
Speaker 1: you have to feed compressed air into a stopped jet

765
00:44:03,120 --> 00:44:06,800
Speaker 1: engine to get things started, to start turning those fan blades,

766
00:44:07,200 --> 00:44:09,799
Speaker 1: and to get enough air pressure in there for you

767
00:44:09,840 --> 00:44:14,440
Speaker 1: to ignite the combustion chambers. Now, if everything is working

768
00:44:14,440 --> 00:44:17,160
Speaker 1: properly on the aircraft, you can use a system called

769
00:44:17,160 --> 00:44:22,360
Speaker 1: the auxiliary power unit or APU to do this. Um

770
00:44:22,760 --> 00:44:25,319
Speaker 1: it supplies the jet engine with compressed air, and you

771
00:44:25,360 --> 00:44:27,719
Speaker 1: can start with just one engine. I'll explain how in

772
00:44:27,760 --> 00:44:31,160
Speaker 1: a minute. So the APU is typically at the far

773
00:44:31,400 --> 00:44:33,680
Speaker 1: end of a jet, on the main body of the jet,

774
00:44:33,719 --> 00:44:37,080
Speaker 1: the fuselage. It's at the very end, and it has

775
00:44:37,120 --> 00:44:39,640
Speaker 1: three main functions. One of those is the main engine

776
00:44:39,680 --> 00:44:42,440
Speaker 1: start sequence, but the other two big functions are to

777
00:44:42,480 --> 00:44:45,520
Speaker 1: supply electrical power to the jet. There's a turbine in

778
00:44:45,600 --> 00:44:48,480
Speaker 1: this jet engine that is connected to a generator, and

779
00:44:48,520 --> 00:44:51,239
Speaker 1: thus you can use that to help supply electrical power

780
00:44:51,280 --> 00:44:54,160
Speaker 1: to the jet, and also it can provide bleed air

781
00:44:54,200 --> 00:44:58,160
Speaker 1: pressure for the air conditioning system bleed air pressure. Think

782
00:44:58,200 --> 00:45:01,399
Speaker 1: of the bleed air system as kind of plumbing. It's

783
00:45:01,440 --> 00:45:04,840
Speaker 1: a series of conduits or pipes in a jet that

784
00:45:04,920 --> 00:45:08,600
Speaker 1: allow compressed air to pass through. So the APU itself

785
00:45:08,800 --> 00:45:11,400
Speaker 1: is a small turbine engine similar to a jet engine.

786
00:45:11,680 --> 00:45:14,680
Speaker 1: There's an intake panel it slides open. It allows air

787
00:45:14,719 --> 00:45:18,400
Speaker 1: to come into the system. And the APU, unlike the

788
00:45:18,440 --> 00:45:21,400
Speaker 1: main engines, is small, so you can actually start it

789
00:45:21,480 --> 00:45:24,200
Speaker 1: under battery power. You can have an electric motor attached

790
00:45:24,200 --> 00:45:28,000
Speaker 1: to the APU. You turn it on. This starts the

791
00:45:28,040 --> 00:45:31,960
Speaker 1: fan in the APU spinning, which then draws air in.

792
00:45:32,719 --> 00:45:35,719
Speaker 1: And like turbofan engines, the APU has bleed air, so

793
00:45:35,800 --> 00:45:38,760
Speaker 1: air that goes around the engine itself and it enters

794
00:45:38,760 --> 00:45:42,040
Speaker 1: into this bleed air pathway system that connects to other

795
00:45:42,080 --> 00:45:45,040
Speaker 1: components of the jet. So you divert some of the

796
00:45:45,080 --> 00:45:48,200
Speaker 1: air going through the APU to enter the jet itself

797
00:45:48,239 --> 00:45:51,400
Speaker 1: through this bleed system, and the pressurized air goes to

798
00:45:51,719 --> 00:45:55,760
Speaker 1: a component called the air turbine starter, and this connects

799
00:45:55,760 --> 00:46:00,120
Speaker 1: to the engine's shaft through a clutch mechanism um and

800
00:46:00,200 --> 00:46:04,760
Speaker 1: that allows the APU to provide compressed air to start

801
00:46:04,920 --> 00:46:11,520
Speaker 1: turning the fan and turbine in a jet engine. And

802
00:46:11,560 --> 00:46:14,080
Speaker 1: this reminds us about fluid dynamics. You can either have

803
00:46:14,120 --> 00:46:18,240
Speaker 1: a solid object moving very quickly through relatively still fluid,

804
00:46:18,600 --> 00:46:22,640
Speaker 1: or fast moving fluid moving past a relatively still solid object,

805
00:46:22,920 --> 00:46:25,759
Speaker 1: and you'll get the same results. So pushing compressed air

806
00:46:25,840 --> 00:46:28,600
Speaker 1: through the main engine creates a situation similar to the

807
00:46:28,600 --> 00:46:32,080
Speaker 1: engine operating at flight speed. So once the engine reaches

808
00:46:32,120 --> 00:46:35,640
Speaker 1: a certain percentage of its top revolutions per minute, somewhere

809
00:46:35,640 --> 00:46:39,560
Speaker 1: around twenty eight, the air inside is compressed enough to

810
00:46:39,600 --> 00:46:43,840
Speaker 1: sustain combustion, and the engine will ignite fuel in the

811
00:46:43,880 --> 00:46:48,279
Speaker 1: combustion chambers and that will provide the energy necessary to

812
00:46:48,640 --> 00:46:52,120
Speaker 1: take over from there, and the engine will perpetuate its

813
00:46:52,200 --> 00:46:56,160
Speaker 1: own rotation and you can stop pumping compressed air into

814
00:46:56,200 --> 00:46:58,880
Speaker 1: the system. From that point. You can use the APU

815
00:46:59,000 --> 00:47:01,359
Speaker 1: to power up the second engine, or you could even

816
00:47:01,440 --> 00:47:03,600
Speaker 1: use the first engine to do it, because the engine

817
00:47:03,600 --> 00:47:06,680
Speaker 1: system feeds into this bleed air system. So again it's

818
00:47:06,719 --> 00:47:08,799
Speaker 1: like you know plumbing. You've got all these conduits, you

819
00:47:08,800 --> 00:47:11,720
Speaker 1: also have all these valves in that system that either

820
00:47:11,840 --> 00:47:14,959
Speaker 1: allow air to pass through or prevent air from going there.

821
00:47:15,000 --> 00:47:17,480
Speaker 1: So when you're starting up engine one, you would have

822
00:47:17,560 --> 00:47:19,799
Speaker 1: all the other valves closed so that the compressed air

823
00:47:19,840 --> 00:47:23,080
Speaker 1: can only follow one pathway to get to that engine. Now,

824
00:47:23,160 --> 00:47:27,640
Speaker 1: sometimes the APU isn't you know, totally working and can't

825
00:47:27,640 --> 00:47:30,680
Speaker 1: supply enough compressed air to do the job. In those cases,

826
00:47:30,840 --> 00:47:34,279
Speaker 1: the ground crew will connect a land based air compressor

827
00:47:34,560 --> 00:47:37,800
Speaker 1: that's technically known as an air start unit, but most

828
00:47:37,880 --> 00:47:40,560
Speaker 1: folks refer to it by a more informal name, the

829
00:47:40,640 --> 00:47:44,719
Speaker 1: huffer cart, And the hover cart sends huffer is h

830
00:47:44,880 --> 00:47:47,719
Speaker 1: U F F E R. It sends compressed air into

831
00:47:47,760 --> 00:47:49,520
Speaker 1: the bleed system of a jet. So you just plug

832
00:47:49,560 --> 00:47:52,799
Speaker 1: it into that bleed system and it provides the compressed air.

833
00:47:53,080 --> 00:47:55,239
Speaker 1: And again the valves leaning to one engine are all

834
00:47:55,280 --> 00:47:58,120
Speaker 1: open and the other valves are all closed. And once

835
00:47:58,160 --> 00:48:01,320
Speaker 1: that first engine has started up and reaches the proper

836
00:48:01,400 --> 00:48:05,640
Speaker 1: rotational speed, which is somewhere around the mark, that engine

837
00:48:05,680 --> 00:48:09,080
Speaker 1: can provide the compressed air to start the other engine

838
00:48:09,520 --> 00:48:12,560
Speaker 1: or engine two. There might be multiple engines on the jet,

839
00:48:12,640 --> 00:48:15,440
Speaker 1: like four engines or something. You can keep doing this

840
00:48:15,480 --> 00:48:18,600
Speaker 1: process over and over. Now, I honestly didn't know any

841
00:48:18,760 --> 00:48:22,200
Speaker 1: of that stuff about how jet engines start from from

842
00:48:22,200 --> 00:48:25,600
Speaker 1: a stopped position. Before I researched this episode, I understood

843
00:48:25,600 --> 00:48:27,239
Speaker 1: how jet engines worked, but I didn't know how they

844
00:48:27,280 --> 00:48:30,040
Speaker 1: got them started. So I always wondered how that happened,

845
00:48:30,200 --> 00:48:31,959
Speaker 1: since it seemed like the kind of system that only

846
00:48:32,000 --> 00:48:35,479
Speaker 1: works once it's already working, which seems like a catch

847
00:48:35,560 --> 00:48:39,080
Speaker 1: twenty two, Like a building that issues permits, but the

848
00:48:39,080 --> 00:48:40,880
Speaker 1: only way to get inside the building is to already

849
00:48:40,880 --> 00:48:43,439
Speaker 1: have a permit. So how can you start the jet

850
00:48:43,480 --> 00:48:45,640
Speaker 1: engine in the first place? And now I know, so,

851
00:48:45,760 --> 00:48:51,320
Speaker 1: now you know too. So those are the basics of flight, thrust, lift,

852
00:48:51,800 --> 00:48:55,720
Speaker 1: and flight controls. And granted I spent the least amount

853
00:48:55,719 --> 00:48:57,880
Speaker 1: of time on flight controls, I may need to do

854
00:48:57,920 --> 00:49:00,680
Speaker 1: a future episode to talk more about that in radar detail,

855
00:49:00,760 --> 00:49:02,960
Speaker 1: to describe the physics behind them and how modern flight

856
00:49:03,000 --> 00:49:06,279
Speaker 1: control systems work. In the meantime, I do have a

857
00:49:06,280 --> 00:49:10,360
Speaker 1: lot of older episodes that go into things like jet engines, scramjets,

858
00:49:10,600 --> 00:49:14,319
Speaker 1: autopilot systems, and more. It's actually kind of silly that

859
00:49:14,440 --> 00:49:16,360
Speaker 1: took me this long just to cover the basics of flight.

860
00:49:17,239 --> 00:49:20,640
Speaker 1: That one's on me. If you guys have suggestions for

861
00:49:20,719 --> 00:49:23,040
Speaker 1: future episodes of tech Stuff. You can get in touch

862
00:49:23,080 --> 00:49:25,640
Speaker 1: with me s me An email the addresses tech Stuff

863
00:49:25,680 --> 00:49:28,799
Speaker 1: at how stuff works dot com. Pop on over to

864
00:49:28,840 --> 00:49:32,120
Speaker 1: our website that's tech stuff podcast dot com. There you're

865
00:49:32,120 --> 00:49:35,000
Speaker 1: going to find an archive of all of our older episodes,

866
00:49:35,320 --> 00:49:38,480
Speaker 1: plus links to our social media presence, and a link

867
00:49:38,600 --> 00:49:40,720
Speaker 1: to our online store where you can buy tech stuff

868
00:49:40,800 --> 00:49:44,560
Speaker 1: merch and every purchase you go and make ends up

869
00:49:44,600 --> 00:49:47,520
Speaker 1: helping our show. We greatly appreciate it. I hope you

870
00:49:47,560 --> 00:49:49,680
Speaker 1: like the designs. Trying to get some new ones in

871
00:49:49,680 --> 00:49:53,879
Speaker 1: there soon and I will talk to you again really soon.

872
00:49:59,160 --> 00:50:01,200
Speaker 1: Text Stuff is a for auction of I Heart Radio's

873
00:50:01,239 --> 00:50:04,200
Speaker 1: how Stuff Works. For more podcasts from my heart Radio,

874
00:50:04,560 --> 00:50:07,720
Speaker 1: visit the i heart Radio app, Apple Podcasts, or wherever

875
00:50:07,800 --> 00:50:09,320
Speaker 1: you listen to your favorite shows.