The Curtiss CR was a racing aircraft designed for the United States Navy in 1921. It was a conventional single-seater biplane with a monocoque fuselage and staggered single-bay wings of equal span braced with N-struts. Two essentially similar landplane versions were built as the CR-1 and CR-2, which were both eventually converted to seaplanes as the CR-3 in 1923 and CR-4 in 1924. A refined version was developed for the US Army Air Service under the designation R-6.