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    213: Time and Navigation

Time and Navigation (Gallery 213)

The name of this room doesn’t sound all that fun, but this is a remarkably interesting set of exhibits, and definitely worth a visit. If you used a GPS or SatNav system to get to DC, this gallery explains part of how it did that.

Even before Christopher Columbus sailed to the Americas in the late 15th century, European countries were sending out explorers to find and claim new areas of land. Each new land found meant more natural resources and wealth to the country that claimed it.

By Columbus’ time, sailors had developed some basic techniques for navigation; using charts and measuring the positions of certain stars in the sky, they were able to roughly determine their latitude – how for north or south they were on the globe. But because the Earth is round, those same techniques can’t be used to accurately determine how far east or west you are.

That was bad, because as anyone who’s ever bought a house knows, to claim ownership of land, you need to be very specific about where your land is. To have a really precise idea of where he was in the world, surprisingly, a sailor needed a clock.

The problem was that reliable clocks of that era used pendulums – weighted sticks that swing back and forth – to keep time. And the up-and-down bobbing of a ship on the ocean wreaked havoc on pendulums, making them useless. Another method was needed, and several countries offered big bucks to anyone who could come up with a clock that worked on a ship. And between 1735 and 1772, Englishman John Harrison did just that.

What does any of this have to do with flight? A lot, because early pilots faced exactly the same navigation problems as early sailors, especially when flying over water. In fact, pilots initially adapted a sailor’s tool – the sextant – for use on planes. It was complicated to use, however, slow at the airplane’s fast speeds, and didn’t work in bad weather. In a section of the gallery dedicated to Charles Lindbergh’s transatlantic flight, it’s noted that good weather played a significant part in his success. Clouds prevented him from using a sextant for navigation, but winds were light and only pushed him off course by a few miles from his course; things could have ended much worse for Lindy.

The middle part of this gallery highlights the efforts in World War II to develop radio navigation, including radio beacons, and LORAN (Long Range Navigation) that worked in all weather conditions, and gave time measurements to within a fraction of a second.

After World War II, the U.S. and Soviet Union both needed more precise clocks for their global militaries, which grew to include fast, precise missiles; and submarines that couldn’t see the stars in the sky. The gallery’s display on how the U.S. military merged various timekeeping satellite systems into the Global Positioning System (GPS), and how it works, is an excellent conclusion to the theme of time and navigation.

Other Lands at Smithsonian National Air and Space Museum