Role Observation
National origin United States
Manufacturer Glenn L. Martin Company
Status Canceled
Number built 0

The Martin XO-4 (Model 71) was a proposed observation aircraft designed by the Glenn L. Martin Company.[1][2] It was designed to compete with the Curtiss XO-1, Douglas XO-2, and Dayton-Wright XO-3, and was to be powered by a Wright T-3 Tornado or a Liberty V-1650.[3][4] Although it failed to receive a contract from the United States Navy, a single prototype (allocated the serial number 23-1255) was ordered by the United States Army Air Service, but this contract was canceled before the prototype could be built.[3][5]


  1. ^ "Martin Aircraft Model Designations, Built and Unbuilt" (PDF). Glenn L. Martin Maryland Aviation Museum. Archived from the original (PDF) on May 17, 2008.
  2. ^ Duell, Sloan and Pearce (1947). The Official Pictorial History of the AAF. United States Army Air Forces Historical Office.
  3. ^ a b Air Service Information Circular. Director of Air Service. 1923.
  4. ^ "O - Observation Aircraft". 2007-03-16. Archived from the original on 2007-03-16. Retrieved 2020-06-15.
  5. ^ "USAF Serial Number Search Results". cgibin.rcn.com. Retrieved 2020-06-15.