WEBVTT - How do blimps work?

0:00:00.600 --> 0:00:03.640
<v Speaker 1>Welcome to brain Stuff from how stuff works dot com

0:00:03.640 --> 0:00:12.800
<v Speaker 1>where smart Happens. Hi Marshall Brain with today's question, how

0:00:12.840 --> 0:00:17.000
<v Speaker 1>do blimps work? At any major sporting event? There is

0:00:17.120 --> 0:00:19.600
<v Speaker 1>one thing that you're sure to see if the weather

0:00:19.720 --> 0:00:24.639
<v Speaker 1>is decent. It's that gigantic skywhale known as a blimp.

0:00:25.079 --> 0:00:28.640
<v Speaker 1>Like a helicopter, a blimp can provide a hovering platform

0:00:28.760 --> 0:00:32.400
<v Speaker 1>in the sky that makes them great for aerial photography.

0:00:32.400 --> 0:00:36.319
<v Speaker 1>But unlike a helicopter, a blimp does its hovering at

0:00:36.360 --> 0:00:39.760
<v Speaker 1>a much lower fuel cost. Blimps can stand the air

0:00:39.880 --> 0:00:42.839
<v Speaker 1>for days if they need to, and don't forget the

0:00:42.840 --> 0:00:48.080
<v Speaker 1>blimp bonus, there's a huge surface for advertising displays. The

0:00:48.159 --> 0:00:51.879
<v Speaker 1>obvious first question is the size. How big is an

0:00:51.920 --> 0:00:56.920
<v Speaker 1>actual blimp? They are immense by normal human standards. According

0:00:56.920 --> 0:01:00.160
<v Speaker 1>to Goodyear, you need to imagine a six story the

0:01:00.280 --> 0:01:03.800
<v Speaker 1>office building almost two feet long to get a sense

0:01:03.840 --> 0:01:06.640
<v Speaker 1>of a blimp scale. Or to put it another way,

0:01:07.000 --> 0:01:11.440
<v Speaker 1>imagine three eighteen wheelers parked end to end that handles

0:01:11.560 --> 0:01:14.959
<v Speaker 1>the length, and then imagine stacking four rows of those

0:01:15.000 --> 0:01:18.200
<v Speaker 1>on top of each other. A blimp is about sixty

0:01:18.240 --> 0:01:21.320
<v Speaker 1>feet high, while a tractor trailer is about thirteen and

0:01:21.319 --> 0:01:25.760
<v Speaker 1>a half feet high. An uninflated blimp, including the fabric

0:01:25.800 --> 0:01:29.240
<v Speaker 1>of the blimp itself, the gondola, and the motors, weighs

0:01:29.280 --> 0:01:34.160
<v Speaker 1>about thirteen thousand pounds. A blimp is a giant balloon

0:01:34.319 --> 0:01:38.759
<v Speaker 1>made out of fabric. There is no internal frame or structure.

0:01:39.240 --> 0:01:42.520
<v Speaker 1>You might remember the famous film of the Hindenburg exploding

0:01:42.560 --> 0:01:46.480
<v Speaker 1>with its immense aluminum framework falling from the sky. A

0:01:46.600 --> 0:01:50.000
<v Speaker 1>blimp has none of that. It's a big balloon with

0:01:50.080 --> 0:01:54.440
<v Speaker 1>a gas inside giving it its shape. That gas is

0:01:54.480 --> 0:01:58.000
<v Speaker 1>the key to the blimps ability to float. Blimps are

0:01:58.080 --> 0:02:00.919
<v Speaker 1>filled with helium, and a lot of it. Think about

0:02:01.000 --> 0:02:03.600
<v Speaker 1>a normal helium balloon that a child gets at a

0:02:03.640 --> 0:02:07.080
<v Speaker 1>birthday party. The balloon holds half a cubic foot or

0:02:07.120 --> 0:02:11.600
<v Speaker 1>about fourteen leaders, and can lift about fourteen grams. Keep

0:02:11.600 --> 0:02:14.119
<v Speaker 1>in mind that there are four hundred and fifty three

0:02:14.160 --> 0:02:17.919
<v Speaker 1>grams in a pound. To get a blimp off the ground, therefore,

0:02:18.320 --> 0:02:22.080
<v Speaker 1>you need a whole bunch of helium. Just think about

0:02:22.080 --> 0:02:25.360
<v Speaker 1>a fifty pound child. It would take about sixteen hundred

0:02:25.360 --> 0:02:28.480
<v Speaker 1>birthday balloons to get the kid off the ground. To

0:02:28.560 --> 0:02:32.120
<v Speaker 1>get a thirteen thousand pound blimp off the ground, Therefore,

0:02:32.240 --> 0:02:35.840
<v Speaker 1>you need a whole lot more helium over two hundred

0:02:35.880 --> 0:02:39.679
<v Speaker 1>thousand cubic feet to be exact. That's why blimps are

0:02:39.720 --> 0:02:42.560
<v Speaker 1>so gigantic compared to an airplane that can carry the

0:02:42.600 --> 0:02:45.639
<v Speaker 1>same number of people. Of course, an airplane can't cover

0:02:45.680 --> 0:02:48.200
<v Speaker 1>in the air for days at a time either. The

0:02:48.240 --> 0:02:51.920
<v Speaker 1>pilot who operates the blimp plus any passengers right in

0:02:51.919 --> 0:02:55.920
<v Speaker 1>the gondola. Inside the gondola looks a lot like the

0:02:55.960 --> 0:02:59.280
<v Speaker 1>cabin of an eight seater airplane. There are two pilot

0:02:59.360 --> 0:03:02.800
<v Speaker 1>seats at the runt and six passenger seats behind. The

0:03:02.880 --> 0:03:05.440
<v Speaker 1>controls that the pilot uses look a lot like the

0:03:05.480 --> 0:03:08.320
<v Speaker 1>controls of an airplane as well. At the back of

0:03:08.360 --> 0:03:11.360
<v Speaker 1>the blimp there are big fins that act as the

0:03:11.440 --> 0:03:14.800
<v Speaker 1>rudder and elevator for steering the blimp, and a blimp

0:03:14.840 --> 0:03:18.679
<v Speaker 1>has two piston engines spinning normal airplane propellers to get

0:03:18.680 --> 0:03:21.840
<v Speaker 1>the blimp moving forward through the air. You might have

0:03:21.960 --> 0:03:26.040
<v Speaker 1>noticed that a birthday balloon, once set free, has this

0:03:26.120 --> 0:03:29.800
<v Speaker 1>tendency to rise until it's out of sight. Essentially, a

0:03:29.840 --> 0:03:33.280
<v Speaker 1>birthday balloon goes up until it bursts. What keeps a

0:03:33.320 --> 0:03:36.880
<v Speaker 1>blimp from doing that? For one thing, a blimp starts

0:03:36.920 --> 0:03:40.000
<v Speaker 1>its trip with enough ballast on board to be just

0:03:40.160 --> 0:03:43.360
<v Speaker 1>slightly heavier than air. If you could put a blimp

0:03:43.400 --> 0:03:45.920
<v Speaker 1>on a bathroom scale, it would weigh about a hundred

0:03:45.920 --> 0:03:48.800
<v Speaker 1>pounds at take off. That keeps it on the ground,

0:03:48.920 --> 0:03:52.440
<v Speaker 1>but just barely The slightest gust of wind could kick

0:03:52.480 --> 0:03:55.520
<v Speaker 1>it up into the air. Plus, the blimp gets lighter

0:03:55.560 --> 0:03:59.840
<v Speaker 1>as it burns fuel. Therefore, inside the blimp there are

0:04:00.080 --> 0:04:05.040
<v Speaker 1>two large balloons called balonetts. These fill with air under

0:04:05.080 --> 0:04:08.960
<v Speaker 1>the pilot's control. Since air is a lot heavier than

0:04:09.040 --> 0:04:12.760
<v Speaker 1>helium relatively speaking, the pilot puts a lot of air

0:04:12.840 --> 0:04:17.080
<v Speaker 1>into the balonets when it's time to descend. To ascend,

0:04:17.120 --> 0:04:20.320
<v Speaker 1>the pilot lets the air out of the ballonets, allowing

0:04:20.360 --> 0:04:25.880
<v Speaker 1>the helium inside to uncompressed and have its full lifting power. Essentially,

0:04:26.200 --> 0:04:30.200
<v Speaker 1>the pilot is using big tanks of air as additional

0:04:30.320 --> 0:04:35.400
<v Speaker 1>adjustable ballast. The other big thing with blimps is the advertising.

0:04:35.839 --> 0:04:38.760
<v Speaker 1>It's possible to paint ads on the blimps fabric, and

0:04:38.839 --> 0:04:43.040
<v Speaker 1>people do, but those signs are invisible at night. Therefore,

0:04:43.160 --> 0:04:46.240
<v Speaker 1>blimps also have a rays of bright l ed s

0:04:46.360 --> 0:04:51.520
<v Speaker 1>for night advertising. A blimp becomes a giant floating JumboTron

0:04:51.600 --> 0:04:51.960
<v Speaker 1>at night,