The Curtiss CS (or Model 31) was a reconnaissance and torpedo bomber aircraft used by the United States Navy during the 1920s.

The pilot and gunner sat in tandem open cockpits, while accommodation inside the fuselage was provided for a third crewmember who served as bombardier and radio operator.

Two examples of the improved CS-2 were built the following year and set a number of world speed, distance, and endurance records for seaplanes in its class.

On September 23, 1925, the U.S. Navy flew 23 Curtiss CS-1 floatplanes to Bay Shore Park on the Chesapeake Bay, 14 miles SE of Baltimore, Maryland, on a Friday with the intention of an air show demonstration before the 1925 Schneider Cup Race on Saturday, but that night gale-force winds broke three-inch mooring and anchor ropes on 17 of the biplanes and they were blown onto shore or dashed against seawalls, destroying seven and damaging ten.

The next afternoon's Baltimore Evening Sun had the headline "Plane Disaster in Harbor Called Hard Blow to Navy" and quoted General William "Billy" Mitchell, who called the loss of the CS-1s "staggering" and blamed it on Navy mismanagement of its aviation program.