S.91 Leger
Powered by a 370 kW (500 hp) Hispano-Suiza 12Hb V-12 water-cooled engine with twin-leg radiators mounted on the undercarriage, (1 built).

S.91/1
The S.91 Leger fitted with a frontal radiator design.

S.91/2
The S.91/1 prototype fitted with a 370 kW (500 hp) Hispano-Suiza 12Gb W-12 water-cooled engine.
It was displayed in Romania and Greece.

S.91/3
The S.91/2 was fitted with a 310 kW (420 hp) Gnome-Rhône 9A Jupiter nine-cylinder air-cooled radial engine, (1 built).

S.91/4
The S.91 Leger, fitted with a 370 kW (500 hp) Hispano-Suiza 12Mb V-12 engine, flew again on 4 July 1930 with some modifications, including radiators mounted on top of the upper wing.

S.91/5
The sole S.91/3, fitted with a 360 kW (480 hp) Gnome-Rhône 9Ae Jupiter, which crashed on the day of its first flight killing the pilot.

S.91/6
This S.91/4 conversion flew in November 1930 and differed from the prototype in having rounded wingtips, a lengthened fuselage and a tailplane lowered to the fuselage base.
Later the tailplane was restored to its former position.

S.91/7
A new prototype with inverted sesquiplane wing configuration in which only the lower wing had ailerons.
It flew on 23 December 1931 and was fitted with a 370 kW (500 hp) Hispano-Suiza 12Mc V-12 engine.
On 2 June 1932 this plane established a record of 308.78 km/h (191.87 mph; 166.73 kn) in a 500 km (310 mi) closed-circuit.

S.91/8
The S.91/7 prototype fitted with a supercharged Hispano-Suiza 12Xbrs engine and a variable-pitch Ratier propeller made its maiden flight on 20 August 1932.
This version is reported to have achieved a speed of 360 km/h (220 mph; 190 kn).

S.91/9
The S.91/8 became a testbed for Hispano-Suiza's engine-mounted 20 mm (0.787 in) cannon, after being leased to the company in December 1932.
Besides the cannon it was also fitted with a large-diameter Levasseur fixed-pitch propeller.
S.91 Leger
Powered by a 370 kW (500 hp) Hispano-Suiza 12Hb V-12 water-cooled engine with twin-leg radiators mounted on the undercarriage, (1 built).
S.91/1
The S.91 Leger fitted with a frontal radiator design.
S.91/2
The S.91/1 prototype fitted with a 370 kW (500 hp) Hispano-Suiza 12Gb W-12 water-cooled engine. It was displayed in Romania and Greece.
S.91/3
The S.91/2 was fitted with a 310 kW (420 hp) Gnome-Rhône 9A Jupiter nine-cylinder air-cooled radial engine, (1 built).
S.91/4
The S.91 Leger, fitted with a 370 kW (500 hp) Hispano-Suiza 12Mb V-12 engine, flew again on 4 July 1930 with some modifications, including radiators mounted on top of the upper wing.
S.91/5
The sole S.91/3, fitted with a 360 kW (480 hp) Gnome-Rhône 9Ae Jupiter, which crashed on the day of its first flight killing the pilot.
S.91/6
This S.91/4 conversion flew in November 1930 and differed from the prototype in having rounded wingtips, a lengthened fuselage and a tailplane lowered to the fuselage base. Later the tailplane was restored to its former position.
S.91/7
A new prototype with inverted sesquiplane wing configuration in which only the lower wing had ailerons. It flew on 23 December 1931 and was fitted with a 370 kW (500 hp) Hispano-Suiza 12Mc V-12 engine. On 2 June 1932 this plane established a record of 308.78 km/h (191.87 mph; 166.73 kn) in a 500 km (310 mi) closed-circuit.
S.91/8
The S.91/7 prototype fitted with a supercharged Hispano-Suiza 12Xbrs engine and a variable-pitch Ratier propeller made its maiden flight on 20 August 1932. This version is reported to have achieved a speed of 360 km/h (220 mph; 190 kn).
S.91/9
The S.91/8 became a testbed for Hispano-Suiza's engine-mounted 20 mm (0.787 in) cannon, after being leased to the company in December 1932. Besides the cannon it was also fitted with a large-diameter Levasseur fixed-pitch propeller.
Blériot-SPAD S.91