Drift Sights, Mk II-B Pelorus, and Mk IIC with Recording Base
This artifact resides in our Private Collection, yet we welcome inquiries from restorers, museums, or serious enthusiasts. Please email us with the name of the artifact at Curator@AeroAntique.com.
Here are two types of aircraft Pelorus Drift Sight. A Pelorus Drift Sight is designed to function either as a Pelorus, for taking bearings on objects, or for improving dead reckoning aircraft navigation by measuring the angle between the heading and the track of an airplane. It consists of a small 'telescope' viewing vertically towards the ground, angled toward the direction of the aircraft. When viewing the ground through the scope while in flight, the navigator observes the travel of fixed objects across the lens. By rotating the scope on its base to align the path of these objects, the drift angle is determined by reading the location of the pointer on the base's scale. Once done, the course correction is calculated and communicated to the pilot.
Mark II-B consists of the sighting scope, the upright post, and the base mount.
Mark II-C consists of a battery-powered/illuminated sighting scope with interchangeble filters for overcoming the difficulty of seeing the ground through smoke, fog, or bright sun, the upright post, made by Maxwell Smith Co., and a recording base, made by Waltham Watch Co. The recording base permits the drift angle to be plotted over time onto a strip of paper contained within the base to more accurately determine the drift.