Curtiss R-4

The Curtiss R-4 was an American two-seat observation and general-purpose biplane, an improved development of the earlier Model R series ordered by the U.S. Army in 1916. Built by the Curtiss Aeroplane & Motor Company, it was a conventional two-bay biplane with staggered, unequal-span wings, tandem open cockpits, and a fixed tailskid undercarriage, powered by a 200-horsepower Curtiss V-2-3 engine that made it considerably more capable than the OX-5-powered Jenny.

During World War I, R-4s served in roles ranging from observation and liaison to training, mail carrying, and air-ambulance work, and a number were used along the Mexican border. Although overshadowed by the JN-4 and never built in large numbers, the R-4 was one of the more powerful American military aircraft of its day and represented an important step in Curtiss's family of multipurpose biplanes during the formative years of U.S. military aviation.