The Morane-Saulnier Type AC (MoS 23) was a shoulder winged single-seat fighter of 1916 was developed from a string of earlier designs, and that was only produced in small numbers. The first Morane-Saulnier fighter was the Type N. This was a shoulder winged monoplane, with a faired fuselage with a circular cross section. It was one of the first aircraft to be armed with a fixed forward firing machine gun, using armoured plated deflectors on the propeller blades to protect against bullet hits. A small number were purchased by the RFC, and it was British interest that led to the development of the Type I and Type V. These both used 110hp engines. The Type I was a simple conversion with one and a half hours worth of fuel, while the Type V had larger wings and a modified fuselage and an endurance of three hours. Neither was a great success, but Morane-Saulnier continued to work on the basic design. Next came a single prototype of the experimental Type U. This was followed in the autumn of 1916 by the Type AC.
The biggest changes came on the wings. The wing warping control system used on earlier Morane-Saulnier fighters was replaced by ailerons. This also allowed the adoption of a rigid wing bracing system, with a framework of steel tubes mounted below the wings and removing the need for bracing wires above the wings. The fuselage was similar to that used since the Type N. The aircraft had a rotary engine with a large conical spinner, which was faired into the fuselage, which had a circular cross section. The tail was a standard Morane-Saulnier model, with a long triangular fin and rudder and straight horizontal controls with tapered ends. The main undercarriage had a cross axle and V struts. The Type AC had a wider wingspan and was longer than the earlier Type V, and was slightly faster. Endurance was two and a half hours, down from the three hours required on the Type V. The Type AC was armed with a single synchronised 7.7mm Vickers gun that was partly enclosed in a fairing on the forward decking
The French Aviation Militaire received thirty Type ACs, while two went to the RFC. The British aircraft were evaluated but not used operationally, but the French aircraft were scattered amongst operational escadrilles along the Western Front. Although the Type AC performed well, it wasn't as good as the contemporary Spad S.VIIa and so wasn’t ordered into production in large numbers. This was the end of the line for Morane-Saulnier's shoulder winged fighters, and the company turned its attention to parasol winged aircraft and biplanes, eventually producing large numbers of the parasol monoplane Type AI.
Engine: La Rhône 9J or 9Jb rotary engine
Power: 110hp or 120hp
Wing span: 32ft 1 3/4in
Length: 23ft 1.5in
Height: 8ft 11.5in
Empty Weight: 959lb
Maximum take-off weight: 1,450lb
Max Speed: 111mph
Climb rate: 5.92 min to 6,560ft
Endurance: 2.5 hours
Armament: One fixed forward firing 7.7mm Vickers machine gun