1 00:00:01,920 --> 00:00:07,120 Speaker 1: Welcome to brain Stuff production of iHeart Radio. Hey brain Stuff, 2 00:00:07,160 --> 00:00:11,360 Speaker 1: Lauren bog Obam. Here, we're used to seeing square and 3 00:00:11,520 --> 00:00:16,120 Speaker 1: rectangular windows in most building structures. There are, of course, 4 00:00:16,239 --> 00:00:20,680 Speaker 1: rounded windows or oculi in architectural parlance, that lend character 5 00:00:20,840 --> 00:00:25,920 Speaker 1: and intrigue to design. But think about airplanes and jetliners 6 00:00:25,960 --> 00:00:29,360 Speaker 1: always round windows. How strange would it be to walk 7 00:00:29,360 --> 00:00:31,720 Speaker 1: down the aisle of a jetliner and buckle up next 8 00:00:31,760 --> 00:00:35,720 Speaker 1: to a square window. Our ancestors may have done just 9 00:00:35,880 --> 00:00:38,720 Speaker 1: that once upon a time, as square windows were in 10 00:00:38,800 --> 00:00:43,440 Speaker 1: fact the norm in early commercial airplane manufacturing. They worked 11 00:00:43,520 --> 00:00:46,480 Speaker 1: just fine for centuries and homes and buildings, so why 12 00:00:46,600 --> 00:00:51,160 Speaker 1: change a perfectly good design. Unfortunately, it took a few 13 00:00:51,200 --> 00:00:54,120 Speaker 1: tragic events for engineers to take a fresh look at 14 00:00:54,160 --> 00:00:57,960 Speaker 1: aircraft window design. It was in the nineteen fifties when 15 00:00:58,000 --> 00:01:02,600 Speaker 1: commercial airliners were getting bigger, and they also started disintegrating 16 00:01:02,680 --> 00:01:06,280 Speaker 1: in mid air. Two of those were to have land Comets, 17 00:01:06,400 --> 00:01:09,560 Speaker 1: which were the first commercial airliner powered by jet engines. 18 00:01:10,000 --> 00:01:12,679 Speaker 1: Their debut flight was May second of nineteen fifty two 19 00:01:12,760 --> 00:01:15,840 Speaker 1: and their last was in September of nineteen eighty one. 20 00:01:16,640 --> 00:01:19,399 Speaker 1: But the two that experienced this type of failure fell 21 00:01:19,440 --> 00:01:22,559 Speaker 1: apart in flight in separate events in nineteen fifty three 22 00:01:22,680 --> 00:01:25,720 Speaker 1: and nineteen fifty four. The cause was found to be 23 00:01:26,160 --> 00:01:31,520 Speaker 1: those square windows. Engineers determined that the sharp edges of 24 00:01:31,560 --> 00:01:35,960 Speaker 1: the plain squared windows created natural weak spots, causing metal 25 00:01:36,040 --> 00:01:40,759 Speaker 1: fatigue failure. Metal fatigue failure is basically what happens when 26 00:01:40,760 --> 00:01:43,839 Speaker 1: a piece of metal is subjected to repeated stresses, which 27 00:01:43,880 --> 00:01:46,640 Speaker 1: cause micro cracks in the metal, which can grow to 28 00:01:46,720 --> 00:01:49,440 Speaker 1: the point that the piece of metal snaps or tears. 29 00:01:50,200 --> 00:01:53,080 Speaker 1: It can be catastrophic, but the cracks can be so 30 00:01:53,160 --> 00:01:58,240 Speaker 1: small that it happens without any visual warning. So the 31 00:01:58,360 --> 00:02:02,400 Speaker 1: corners of these square aircraft windows were easily stressed then 32 00:02:02,480 --> 00:02:06,120 Speaker 1: further weakened by air pressure at high altitude. By the 33 00:02:06,200 --> 00:02:09,840 Speaker 1: nineteen fifties, aircraft like that the Haveland Comets were flying 34 00:02:09,919 --> 00:02:14,240 Speaker 1: faster and higher than industry predecessors, meaning after multiple flights 35 00:02:14,240 --> 00:02:18,639 Speaker 1: and repeated pressurization, those square windows basically broke apart from 36 00:02:18,639 --> 00:02:22,800 Speaker 1: the pressure. Rounded windows, on the other hand, are able 37 00:02:22,840 --> 00:02:25,840 Speaker 1: to distribute the pressure evenly because they have no corners 38 00:02:25,880 --> 00:02:30,360 Speaker 1: for stressed to concentrate, reducing the likelihood of cracks or brakes. 39 00:02:30,240 --> 00:02:34,080 Speaker 1: The circular shapes are also stronger in resist deformation, making 40 00:02:34,120 --> 00:02:37,160 Speaker 1: them more able to withstand the repeated pressure differences between 41 00:02:37,160 --> 00:02:41,359 Speaker 1: the inside and outside of the aircraft. You might also 42 00:02:41,480 --> 00:02:44,320 Speaker 1: notice that there are multiple layers of acrylic, not glass 43 00:02:44,440 --> 00:02:47,480 Speaker 1: between you and the outside of the aircraft. Those layers 44 00:02:47,520 --> 00:02:51,160 Speaker 1: offer additional protection from weather events like rain, wind, and fog, 45 00:02:51,960 --> 00:02:55,120 Speaker 1: and that tiny hole at the bottom. Those are called 46 00:02:55,280 --> 00:02:58,880 Speaker 1: bleed holes, and they add another layer of protection, helping 47 00:02:59,080 --> 00:03:01,760 Speaker 1: keep the air pressure on board at a relatively constant 48 00:03:01,840 --> 00:03:04,760 Speaker 1: level by allowing the air to pass through the various 49 00:03:04,800 --> 00:03:08,600 Speaker 1: window layers. So the next time you're on a flight, 50 00:03:08,800 --> 00:03:11,760 Speaker 1: be thankful for those rounded windows, whether you're enjoying the 51 00:03:11,840 --> 00:03:14,320 Speaker 1: view or avoiding it because you don't want to be 52 00:03:14,360 --> 00:03:16,880 Speaker 1: reminded of just how high off the ground you are. 53 00:03:22,480 --> 00:03:25,200 Speaker 1: Today's episode is based on the article why are airplane 54 00:03:25,200 --> 00:03:29,079 Speaker 1: windows round? On how stuffworks dot com, written by Schrei's Cunningham. 55 00:03:29,080 --> 00:03:31,320 Speaker 1: Brainstuff is production of by Heart Radio and partnership with 56 00:03:31,360 --> 00:03:33,720 Speaker 1: how stuff works dot Com, and it's produced by Tyler Clang. 57 00:03:34,240 --> 00:03:37,280 Speaker 1: Four more podcasts my Heart Radio, visit the iHeart Radio app, 58 00:03:37,400 --> 00:03:40,080 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.