The Cox-Klemin XS was a 1920s American experimental scout biplane, it was meant to be launched and recovered from a submarine. Based on a design by the US Bureau of Aeronautics a total of 13 were build, 6 Cox-Klemin XS-1, 1 Cox-Klemin XS-2 and 6 Martin MS-1. After the trials ended somewhere during 1926 all aircraft were scrapped.