Letord Let. 4

The Letord Let. 4 was a French two‑seat reconnaissance and artillery‑observation biplane produced by the Société d’Aviation Letord in the final years of World War I. Designed by Robert Letord, the aircraft first flew in late 1917 and entered limited service with the French Aéronautique Militaire in early 1918. Its wooden frame and fabric covering followed conventional construction methods, while the staggered sesquiplane wings gave it a relatively compact wingspan of 11 meters and improved upward visibility for the observer. Power was supplied by a 180 hp Clerget 9B rotary engine, delivering a top speed of about 170 km/h and a service ceiling near 5 500 meters, sufficient for low‑level battlefield surveillance. The Let. 4 featured a forward‑firing Vickers machine gun for the pilot and a flexible Lewis gun on a ring mount for the observer, allowing defensive fire during reconnaissance missions. Although only a few dozen were built before the armistice ended production, the aircraft demonstrated Letord’s ability to integrate reliable rotary power with a sturdy biplane layout. Its brief operational record contributed to the evolution of French tactical reconnaissance doctrine and paved the way for post‑war designs such as the Letord Let. 7 series.