|SCOUT||Virtual Aircraft Museum / USA / Curtiss|
This was a triplane similar to the S-3 intended as a seaplane Scout for the US Navy. This was Curtiss's first experience with the twin-float configuration. As with other Curtiss seaplanes, it became necessary to increase the span of the S-4 to carry the extra weight. The front float struts collapsed during a heavy alighting in January 1918 and the aircraft was struck off charge.