A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2020 Sep 3, 06:57 -0700
Ludwig Schweinfurth You wrote: I just got mine but it came from a TWA plane. I came with a sextant that has no averager and stranger still, the mount has an odd modification. The sextant is fixed to the aximuth ring on the mount. When you crank in the true heading, the sextant spins in the mount. The whole thing is a well built locking mechanism screwed into a slot to calibrate the heading using the machined in the mount. It even has a 10 degree fine adjust the initial setting to the tail of the aircraft. There are detailed instuctions in the box. Do you by chance know anything about this?
It might not have been used as a sextant at all. Might it have been used in places with clear skies to aid the alignment of a heading reference gyro or an inertial platform using the Sun or a star. You might even use it for compass swinging if you knew the variation. Another possibility is trans polar navigation. Does it by any chance have a polaroid swivel attacment on the eyepiece; the UV light from the sun can be heading checked even in polar twilight conditions. With the Vulcan in cloudy UK, we had PIM aligned pans. The Vulcan being 57' jong from nosewheel to tail, you assessed how far the centre of the nosewheels where from the line on the pan; assessed the distance off of the tail; and used the one in 57 rule to work out a correction to the line direction. You then set this hearing on the HRS once it was running. DaveP