Comments: The Curtiss R4 was introduced in 1916, when a total of 53 of them were ordered by the Army. The early version used the Curtiss 200 HP V-2-3 engine, but later the airplane was fitted with a Liberty engine and designated R4-L and then later the R6 and R9. Some of these were used in General Pershing's Punitive Expedition in Mexico, and some ended up in usage with the early U.S. Airmail service. This very large propeller was for the earlier Curtiss engine and is identical to this propeller, although the varnish is less pristine on this one. It is aslo in original condition, however. The drawing number, 11612, is referenced in a 1919 document from McCook Field and indicates this propeller's usage on the R4 with the Curtiss engine.