1 00:00:02,040 --> 00:00:07,160 Speaker 1: Welcome to brain Stuff from How Stuff Works Fay brain Stuff. 2 00:00:07,200 --> 00:00:10,479 Speaker 1: It's Christian Sager. When you think about it, airplanes they're 3 00:00:10,520 --> 00:00:15,240 Speaker 1: pretty amazing, right, Despite their weight, these enormous metal contraptions 4 00:00:15,520 --> 00:00:18,680 Speaker 1: can lift hundreds of people into the air, and most 5 00:00:18,720 --> 00:00:21,360 Speaker 1: of the time they can do this safely, if not 6 00:00:21,720 --> 00:00:26,000 Speaker 1: kind of comfortably. Take the Boeing seven forty seven eight, 7 00:00:26,200 --> 00:00:29,600 Speaker 1: for example, it has a maximum takeoff weight of four 8 00:00:29,680 --> 00:00:34,040 Speaker 1: hundred and eighty seven point five tons. Now, for comparison, 9 00:00:34,479 --> 00:00:37,400 Speaker 1: that's about the same weight as almost a hundred and 10 00:00:37,440 --> 00:00:42,720 Speaker 1: forty average sized African elephants. And that's a bunch of 11 00:00:42,720 --> 00:00:45,680 Speaker 1: weight to move. And the engines need a lot of 12 00:00:45,760 --> 00:00:48,879 Speaker 1: fuel to make that happen. But how much fuel do 13 00:00:48,960 --> 00:00:53,000 Speaker 1: they need exactly? Now, Before we can answer that, let's 14 00:00:53,040 --> 00:00:57,560 Speaker 1: ask another question. Why should we care? Well? Fuel efficiency 15 00:00:57,640 --> 00:01:00,680 Speaker 1: and fuel cost is part of how an airline determines 16 00:01:00,800 --> 00:01:05,080 Speaker 1: your ticket prices, So a more efficient airline can theoretically 17 00:01:05,400 --> 00:01:09,440 Speaker 1: result in lower ticket prices for you and me. Let's 18 00:01:09,480 --> 00:01:12,160 Speaker 1: look at a plane on an international trip to see 19 00:01:12,200 --> 00:01:15,680 Speaker 1: how much fuel it uses per person. And since we're 20 00:01:15,680 --> 00:01:18,320 Speaker 1: dealing with a lot of numbers, let's set it up 21 00:01:18,400 --> 00:01:22,480 Speaker 1: this way. I will use US standard measurements, but since 22 00:01:22,520 --> 00:01:25,000 Speaker 1: the rest of the world uses the metric system, I'm 23 00:01:25,000 --> 00:01:27,480 Speaker 1: going to pop those in two. So here we go. 24 00:01:27,720 --> 00:01:30,320 Speaker 1: We're ready for takeoff. A plane like the seven forty 25 00:01:30,400 --> 00:01:34,800 Speaker 1: seven eight can carry around sixty three thousand, thirty four 26 00:01:34,880 --> 00:01:38,560 Speaker 1: gallons of fuel or two hundred thirty eight thousand, six 27 00:01:38,640 --> 00:01:42,200 Speaker 1: hundred and ten leaders, giving it the ability to make 28 00:01:42,360 --> 00:01:46,720 Speaker 1: extremely long flights, so flying from say, l A to 29 00:01:46,800 --> 00:01:50,680 Speaker 1: Australia is no problem as long as it's gassed up. However, 30 00:01:50,960 --> 00:01:55,160 Speaker 1: the plane uses approximately one gallon or four leaders of 31 00:01:55,240 --> 00:01:59,040 Speaker 1: fuel every second, and this means that over the course 32 00:01:59,160 --> 00:02:02,720 Speaker 1: of a ten hour flight, it might burn thirty six 33 00:02:02,800 --> 00:02:06,120 Speaker 1: thousand gallons or a hundred and thirty six thousand, two 34 00:02:06,200 --> 00:02:09,800 Speaker 1: hundred and seventy five liters of fuel, which sounds like 35 00:02:09,840 --> 00:02:13,280 Speaker 1: a lot right now. According to Boeing, this works out 36 00:02:13,320 --> 00:02:18,760 Speaker 1: to approximately five gallons of fuel per mile or nineteen 37 00:02:18,919 --> 00:02:22,920 Speaker 1: leaders per one point five kilometers when the plane is 38 00:02:23,040 --> 00:02:26,040 Speaker 1: in flight, And at first this might sound like the 39 00:02:26,040 --> 00:02:29,440 Speaker 1: plane gets a terrible miles per gallon rating and that's 40 00:02:29,480 --> 00:02:33,400 Speaker 1: not efficient, but let's remember that the seven eight isn't 41 00:02:33,440 --> 00:02:35,560 Speaker 1: the same as something like I don't know a four 42 00:02:35,639 --> 00:02:39,120 Speaker 1: door sedan. It can carry as many as five hundred 43 00:02:39,160 --> 00:02:43,960 Speaker 1: and sixty eight people on a very uncomfortable flight. So 44 00:02:44,400 --> 00:02:47,080 Speaker 1: how does all of that fuel workout per person? Well, 45 00:02:47,320 --> 00:02:49,840 Speaker 1: let's say, for example, that there are five hundred people 46 00:02:49,919 --> 00:02:52,840 Speaker 1: on a plane. So a seven forty seven eight is 47 00:02:52,880 --> 00:02:57,440 Speaker 1: transporting five hundred people one mile using five gallons of 48 00:02:57,440 --> 00:03:01,960 Speaker 1: fuel or again nineteen liters per one point five kilometer. Now, 49 00:03:02,040 --> 00:03:05,600 Speaker 1: this means that the plane is burning about point zero 50 00:03:05,720 --> 00:03:10,920 Speaker 1: one gallons per person per mile or point zero four 51 00:03:11,040 --> 00:03:15,760 Speaker 1: leaders per person per point six kilometers. Now, in other words, 52 00:03:16,000 --> 00:03:19,640 Speaker 1: the plane is getting a hundred miles per gallon per 53 00:03:19,680 --> 00:03:25,520 Speaker 1: person or forty two point five kilometers per leader per person. Now, 54 00:03:25,680 --> 00:03:29,600 Speaker 1: for comparison, your typical car gets around twenty five miles 55 00:03:29,600 --> 00:03:32,959 Speaker 1: per gallon or ten point six kilometers per leader. So 56 00:03:33,040 --> 00:03:36,600 Speaker 1: in this respect, the seven forty seven is actually much 57 00:03:36,680 --> 00:03:40,200 Speaker 1: better than a car carrying one person, and it compares 58 00:03:40,280 --> 00:03:43,960 Speaker 1: favorably even if there are four people in the car. Now, 59 00:03:44,000 --> 00:03:47,400 Speaker 1: of course, this isn't exactly an apples to apples comparison 60 00:03:47,600 --> 00:03:51,080 Speaker 1: for a number of reasons, but still, a hundred miles 61 00:03:51,120 --> 00:03:54,040 Speaker 1: per gallon per person isn't all that bad When you 62 00:03:54,080 --> 00:03:57,600 Speaker 1: consider that the seven forty seven is flying at about 63 00:03:57,640 --> 00:04:01,160 Speaker 1: five hundred and fifty miles per hour. I mean, how 64 00:04:01,240 --> 00:04:10,560 Speaker 1: fuel efficient is your private plane? Check out the brainstuff 65 00:04:10,640 --> 00:04:12,960 Speaker 1: channel on YouTube, and for more on this and thousands 66 00:04:12,960 --> 00:04:28,840 Speaker 1: of other topics, visit how stuff works dot com.