As part of a series of studies conducted by the United States Navy after World War I into the possibility of submarine-borne observation and scouting aircraft, "S-1" became the experimental platform for this project late in 1923. She was altered by having a steel capsule mounted abaft the conning tower; a cylindrical pod which could house a small collapsible seaplane, the Martin MS-1. After surfacing, this plane could be rolled out, quickly assembled, and launched by ballasting the sub until the deck was awash. These experiments were carried out into 1926 using the Martin-built plane, constructed of wood and fabric, and the all-metal Cox-Klemin versions, XS-1 and XS-2. The first full cycle of surfacing, assembly, launching, retrieving, disassembly, and submergence took place on 28 July 1926, on the Thames River at New London.