NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: "Improved" sextants
From: Alexandre Eremenko
Date: 2006 Jul 5, 14:58 -0500
From: Alexandre Eremenko
Date: 2006 Jul 5, 14:58 -0500
Dear Red,
> Some call it stronger than some steel alloys (but
> then again, isn't aluminum generally stronger than steel by weight?)
> breaking strength
> of 190MPa versus 250 for brass and 300 for tinned bronze.
The important characteristics for sextant frame
are not the breaking strenth,
but rigidity and probably termal expansion properties.
(For example, the graduated arcs of some theodolites
are made of glass which has low breaking strength but high
rigidity).
In Heath booklet, they compare duraluminium and brass
("gun metal" as they call it) by these parameters.
Alex.
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