Ryan NYP Periscope Optical Alignment and Instrument Cluster Strip (1927)

Three-frame vertical test strip recording the cockpit instrument panel and periscope mirror opening. — Ryan NYP Periscope Optical Alignment and Instrument Cluster Strip (1927) · Donald A. Hall Estate Collection

A three-frame vertical engineering strip recording the interior cockpit enclosure of the Spirit of St. Louis. The sequential exposures evaluate periscope mirror clarity and ambient cabin illumination across the central instrument panel. The images demonstrate Donald A. Hall's integrated optical solution, which compensated for the blind forward cockpit angle necessitated by the central fuel tank placement.