MovieChat Forums > The Spirit of St. Louis (1957) Discussion > Navigating by compass and dead reckoning

Navigating by compass and dead reckoning

posted 9 years ago by paulmurphy42
4 replies | jump to latest

Does anyone know how Lindbergh knew exactly what compass heading to fly? Every so often he had to alter his compass heading to allow for the curvature of the earth, but how did he know exactly by how much? His flightpath on the map is a gentle arc...if you look at the scene where he discusses navigation with the designers in the factory, the plane makes a gentle curve on the map from the US to Europe...my question is: how does he know exactly how much to change heading by every few minutes?

[–] ex250 9 years ago

He changed heading every hour. He also had an Earth-inductor compass that was very precise which helped him hold the heading.

Promise me, no matter how hopeless things get, keep on trying, OK? Keep coming chin-up, OK?

[–] paulmurphy42 9 years ago

Yes, I realise that, but how did he know exactly how much to alter his heading by every hour? Where did he get that information?

Thanks,

Paul

[–] ex250 9 years ago

He knew before he took off by flight planning the route on a map just like ship navigators do.

Promise me, no matter how hopeless things get, keep on trying, OK? Keep coming chin-up, OK?

[–] Ranb (7172) 2 years ago

Lindbergh stated in his book that he bought maps consisting of Mercator and gnomonic projections. He also used time zone and magnetic variation charts.

He started out by drawing a straight line on the gnomonic chart from New York to Paris. Then he plotted points every 100 miles to the Mercator projection map.

With these points plotted he could change his magnetic heading every 100 miles to stay on course.

An amusing part of the book was Lindbergh wanting to ask Naval officers for navigation advice, but was too embarrassed to do so. When the Navy learned that he was navigating alone across the Atlantic, they invited him to give a little talk to them on how he was doing it.