Designed by André Herbemont to meet a 1930 French Air Ministry specification for a single-seat fighter capable of 325–350 km/h at 3,500 m altitude.
It was the only biplane among 11 submissions, derived from Herbemont’s earlier S.91 design.
Prototype (S.510.01)
First flight on 6 January 1933.
Constructed with an all-metal monocoque rear fuselage, fabric-covered wings and tail, and fixed landing gear with faired mainwheels and tailskid.
Engine and Armament
Powered by a Hispano-Suiza 12Xbrs V-12 liquid-cooled engine (690 hp), driving a two-bladed wooden propeller.
Initially armed with two 7.5 mm MAC 1934 machine guns in the fuselage and two underwing gondolas.
Flight Testing
Revealed instability and spin recovery issues.
Modifications included a 40 cm fuselage stretch and enlarged vertical tail surfaces.
Production and Specifications
Order and Delivery
After outperforming the Dewoitine D.500 in manoeuvrability and climb rate during 1935 CEAM trials, 60 production aircraft were ordered on 30 August 1935.
Standard Armament
Four 7.5 mm MAC 1934 machine guns mounted under the wings.
The final two aircraft featured the 12Xcrs engine with a 20 mm cannon firing through the propeller hub.
Performance
Max speed
372 km/h (231 mph)
Ceiling
10,500 m (34,450 ft)
Range
875 km (544 miles)
Rate of climb
890 m/min (2,900 ft/min)
Dimensions
Wingspan 8.84 m,
Length 7.46 m,
Height 3.41 m
Operational History
Frontline Service
Entered service in 1936 with GC I/7 and GC II/7 of the 7ème Escadre de Chasse at Dijon.
Used until 1938, when replaced by Morane-Saulnier M.S.405s.
Training and Defence Role
Reassigned to Escadrilles Régionales de Chasse (ERC) for coastal defence at the outbreak of WWII.
ERC 3/561 and ERC 4/561 operated the type from St Inglevert and Le Havre.
Final Use
Gradually replaced by Bloch MB.151/152 monoplanes from December 1939.
Some remained in service until France’s collapse in June 1940; one was found abandoned at Bergerac on 20 June.
Variant – S.710
Experimental Prototype
Featured a butterfly (V-tail) and upgraded Hispano-Suiza 12Ycrs engine (860 hp).
Armament
One 20 mm HS.404 cannon firing through the propeller hub, plus two wing-mounted MAC 1934 machine guns.
Outcome
Only one built.
The concept was abandoned as France shifted to monoplane fighters.
