Nieuport-Delage NiD 640

The Nieuport‑Delage NiD 640 was a single‑engine, single‑seat fighter‑trainer developed in the late 1920s by the French firm Nieuport (later Nieuport‑Delage). Conceived as a low‑cost replacement for aging World‑War‑I types, the NiD 640 first flew in 1928 and entered limited production the following year. Its airframe combined a wooden wing with a metal fuselage, employing the company’s characteristic sesquiplane layout – a small lower wing attached to a larger upper wing, which gave the aircraft a good balance of maneuverability and structural simplicity. Powered by a 260 hp Hispano‑Suiza 9Vb radial engine, the NiD 640 could reach 250 km/h (155 mph) and featured a fixed, split‑axle undercarriage and an open cockpit with an instrument panel suited for basic pilot instruction. Although only about 30 units were built, the type served the French Aeronautical Military School and several overseas clubs, providing valuable experience in handling modern, mixed‑construction aircraft. Its responsive controls and forgiving stall made it a valuable trainer, influencing later Nieuport‑Delage models and bridging biplane to monoplane design.