Loire-Nieuport LN.401 - Design and Development

Design and Development

Between 1932 and 1936, Loire-Nieuport had been developing a two-seat dive bomber, the Nieuport 140, for the Aéronautique Navale, the aviation arm of the French Navy. It was renamed Loire-Nieuport LN.140 after the Nieuport company was absorbed into Loire-Nieuport, in 1933. In 1936, the development of the LN.140 was abandoned after two fatal accidents.

Development efforts were then concentrated on the LN.40 project, which benefited from experience acquired with the LN.140, but was a new, and aerodynamically much more refined, design. In the second half of 1937 the LN.40 received government backing in the form of an order for a prototype, followed by orders for seven production aircraft destined for the aircraft carrier Béarn and three more for operational evaluation by the air force. The French Air Force had expressed interest in a land-based derivative of the LN.40, called LN.41. Initially it wanted to acquire 184 of these, enough to equip six dive bomber squadrons of 18 aircraft each, plus a reserve.

The prototype made its first flight on 6 July 1938, flown by Pierre Nadot. A second prototype followed in January 1939, and a third in May. Four of the pre-series LN.40 dive bombers were delivered in July, and the aircraft was declared fit for carrier operations following successful tests aboard the Béarn. Nevertheless, the flight tests were not entirely successful. The original dive brake was found ineffective and was removed in favour of extending the landing gear to act as an aerodynamic brake. It was found that the LN.40 could not fly dive bombing missions with full fuel tanks. The chief of staff of the air force, general Joseph Vuillemin, declared that the aircraft was too slow, and requested the development of a fast dive bomber for the air force, which became the Loire-Nieuport LN.42.

In July 1939, Loire-Nieuport had received orders for 36 LN.401 production dive bombers for the Navy, and 36 LN.411 aircraft for the Army. The LN.411 was almost identical to the LN.401, except for the deletion of the arrestor hook, the wing folding mechanism and the emergency floatation devices. The first LN.411s were delivered in September, in which month the air force ordered 270 more. But in October general Vuillemin refused to accept these aircraft, and the small number of LN.411 were sent to the Navy.

Loire-Nieuport also attempted to develop a faster version, by substituting a 860 hp Hispano-Suiza 12Y31 for the 690 hp Hispano-Suiza 12Xcrs engine of the LN.401. This LN.402 made its first flight on 18 November 1939. Further development of the LN.402 was prevented by the French defeat in May 1940 and the following armistice.