NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: The development of bubble sextants
From: Gary LaPook
Date: 2009 Aug 15, 12:59 +0200
From: Gary LaPook
Date: 2009 Aug 15, 12:59 +0200
Having fired many artillery projectiles over many miles of the earth's surface I am familiar with coriolis. I can assure that once the projectile leaves the tube that it flies in a straight line though space but for an observer on earth, say an enemy platoon, it appears to curve to the right. This is because the earth is turning under the path of the projectile so we had to use tables to allow for this "Coriolis" and ended up pointing the guns to the left of the target so the target would rotate to the place that the projectile was aimed and they both arrived at the same point at the same time. Coriolis is a fictitious force use to explain the perceived curve of the flight path as observed by an observer on earth of other rotating frame of reference. See: http://en.wikipedia.org/wiki/Fictitious_force gl douglas.denny@btopenworld.com wrote: > Dear Gary, > > Coriolis is a very real acceleration. It is not fictional at all. > > The sextant (and person ) is being carried through space in a curved motion by the Earth itself, and the acceleration due to curved motion is real enough, just the same as if you are in the big Millenium Ferris Wheel in London, or in a fairground 'Skyboat' device whizzing around in circular motion. > Coriolis just happens to be a small quantity - though relevant in calculation if you are in a jet moving at around 400 knots. > > I have a theodolite made by British Aerospace with a North seeking gyro built in which 'feels' the acceleration right enough to provide North to within a few second of arc. > > Coriolis can be allowed for because the motion of the Earth is 'constant' so the parameters can be calculated for the direction of travel and Latitude, the main components affecting the apparent local gravitational field due to Coriolis. > > Douglas Denny. > Chichester. England. > > > > > > --~--~---------~--~----~------------~-------~--~----~ NavList message boards: www.fer3.com/arc Or post by email to: NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---