[Graham Boak]

According to Gerald Howson's "Aircraft of the Spanish Civil War" from Putnam, the prototype D.XXI was diverted at sea whilst returning from the Netherlands East Indies in 1937. Production of the D.XXI began by SAF-15 at Santa Faz convent. By mid summer 1938 only one aircraft had been completed, using a second-hand M-25 from a crashed I-16. When the Nationalist occupied Alicante they found fifty wingsets, twentyfive fuselages and twentyfive undercarriages, but not the two complete airframes. The undercarriages were later used on the Hispano HS 42 trainers.