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Re: Tilt Errors in Artificial Horizons
From: Lars Bergman
Date: 2015 Jan 8, 05:07 -0800

Dave wrote: "I’m making myself dizzy trying to draw the diagram"

Maybe this is what you looked for?

Lars

59N 18E

Lars.  It took me a while to see what you were getting at, but in the mean time I drew it all out.  I did it with real numbers.  The true altitude of the body is 30.  Assuming a perfect sextant and a perfectly horizontal Artificial Horizon (AH), the angle between the direct ray and the ray from the AH at sextant position A will be 60°, so the measured altitude will be 60/2 = 30°. 
If the AH is tilted 10°, the angle of incidence changes from 60° to 70°, and as the angle of reflection equals the angle if incidence, the reflected ray is deflected 20° .   Therefore, the angle between the direct ray and the ray from the AH at sextant position B will be 40° , so the measured altitude will be 40/2 = 20° .  Therefore, the error due to AH tilt in the direction of the body is the same value as the tilt error itself.  That is 10° in this example. Dave

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