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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Index arm angle for Artificial Horizon sights
From: David Pike
Date: 2023 Apr 20, 07:04 -0700
From: David Pike
Date: 2023 Apr 20, 07:04 -0700
In the diagram below:
BA and CE are parallel, BA is the perpendicular to the index mirror, and CD is the perpendicular to the horizon mirror.
Angle GAB is the angle to be measured a. Angle BAC (a) = Angle GAB (a) ____Newton
Angle ACE (a) = Angle BAC (a) ________Alternate angles
Therefore, Angle ACD = a/2__________Newton
Angle AFB = the angle between the mirrors =b, so in the triangle BAF angle ABF = 90-b
And in the triangle BAC, (90-b) + a + (90-a/2)=180
Which simplifies to b=a/2. QED
Brain oiled for another month with only three pieces of pad wasted and without opening ‘A Level Physics’-------Nelkon.
This also shows why the marine sextant is impervious to fore and aft tilt and is therefore the sailors’ choice. DaveP
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