A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2018 Jan 6, 14:27 -0800
Tracy you wrote under Re: Solstice Sun Lines: The CRJ cockpit and window geomertry allow me to take sights comfortably up to around 45°, I have very few higher that that. I do apply the 'standard dome' corrections for looking through the windows, it always seems to bring greater accuracy.
Do they provide a refraction table for airliner cabin windows? I’d always assumed the cockpit ones would be laminated glass, almost parallel, and quite thick, and cabin windows must all be different depending on the manufacturer. The ‘standard’ table in HO249/AP3270 was for a Perspex hemi-spherical dome, which was almost impossible to pull or blow without it getting thinner nearer the top. The table was only correct if your sextant was held in the correct position by hanging it from the little hook in the centre of the top. I often wondered how they achieved the ‘standard’ table. Did they just pull a dome off the production line and calibrate it? When you consider how many tens of thousands of astrodomes were made, and probably by several manufacturers, that seems a bit hit and miss. What did they do with this dome (or set of domes) when they'd finished with it? Is it hidden away at the back of a cupboard in a museum (Smithsonian?) or research lab (NACA?) somewhere? I’ve done an internet and book search in the past and found nothing. DaveP.