Blériot-SPAD S.91

S.91

A SPAD S.91/2 on display at the Paris Aero Salon
Role	Fighter Type of aircraft
Manufacturer	Blériot
Designer	André Herbemont
First flight	23 August 1927
Primary user	Spanish Republican Air Force
Number built	3
Developed into	Blériot-SPAD S.510

The Blériot-SPAD S.91 was a French light-weight fighter aircraft. It would be later developed into the Blériot-SPAD S.510, the last biplane produced by the French aeronautic industries.

Development

The S.91 was a single-seat single-bay biplane developed towards the end of the 1920s by Blériot in order to meet the requirements of a French government program for a light fighter plane type designated as "Jockey".^[1]

The first prototype was flown on 23 August 1927. It featured a wooden fuselage of monocoque construction and metal wings skinned in fabric. This prototype was destroyed in a crash and a second prototype followed. Even after the French government dropped interest in the program seeking a light fighter for the French Air Force, André Herbemont designed a further prototype with an inverted sesquiplane wing configuration.

Operational history

Despite flight demonstrations in Romania and Greece no orders followed. André Herbemont would use his experience with the S.91 prototypes in order to develop the S.510, another biplane fighter which would go into production and would be later used by the French Air Force.

In 1936 at least one of the surviving S.91 prototypes ended up in the Spanish Republican Air Force.^[2]

Variants

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).^[3]

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.^[4]

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).^[5]

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.^[6]

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.^[7]

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.^[8]

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.^[1]^[9]

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).^[1]^[10]^[11]

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.^[1]^[12]

Operators

Spain

Spanish Republican Air Force

Specifications (S.91 Leger)

Data from Jane's all the World's Aircraft 1928,^[13] Aviafrance:S.91 Leger^[3]

General characteristics

Crew: 1
Length: 6.52 m (21 ft 5 in)
Wingspan: 8.65 m (28 ft 5 in)
Height: 2.94 m (9 ft 8 in)
Wing area: 22 m² (240 sq ft)
Empty weight: 1,120 kg (2,469 lb)
Gross weight: 1,450 kg (3,197 lb)
Powerplant: 1 × Hispano-Suiza 12Hb V-12 water-cooled piston engine, 370 kW (500 hp)
Propellers: 2-bladed fixed pitch propeller

Performance

Maximum speed: 270 km/h (170 mph, 150 kn) at 4,000 m (13,000 ft)
Range: 400 km (250 mi, 220 nmi)
Service ceiling: 8,000 m (26,000 ft)

Armament

Guns: 2x 7.7 mm (0.303 in) Vickers machine-guns in the forward fuselage

References

^ ^a ^b ^c ^d "Blérriot-SPAD S.91/6". 1000aircraftphotos.com. Archived from the original on 2014-12-15. Retrieved 2021-06-21.
^ "Aircraft that took part in the Spanish Civil War". Archived from the original on 2015-02-05. Retrieved 2014-12-15.
^ ^a ^b Parmentier, Bruno (18 April 1999). "SPAD S-91". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (18 April 1999). "SPAD S-91/2". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (1 August 2001). "SPAD S-91/3". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (6 Mar 2001). "SPAD S-91/4". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (1 August 2001). "SPAD S-91/5". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (28 April 2001). "SPAD S-91/6". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (14 April 2000). "SPAD S-91/7". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ "Le monoplace de chasse Blériot"91"". Les Ailes (590): 3. 6 October 1932.
^ Parmentier, Bruno (28 April 2001). "SPAD S-91/8". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Parmentier, Bruno (1 August 2001). "SPAD S-91/9". Aviafrance (in French). Paris. Retrieved 26 February 2018.
^ Grey, C.G., ed. (1928). Jane's all the World's Aircraft 1928. London: Sampson Low, Marston & company, ltd. pp. 86c–87c.

Bibliography

Cortet, Pierre (March 2001). "Les chasseurs SPAD-Herbemont de l'entre-deux guerres" [The SPAD-Herbemont Fighters Between the Wars]. Avions: Toute l'Aéronautique et Son Histoire (in French) (96): 8–12. ISSN 1243-8650.
Cortet, Pierre (April 2001). "Les chasseurs SPAD-Herbemont de l'entre-deux guerres". Avions: Toute l'Aéronautique et Son Histoire (in French) (97): 42–46. ISSN 1243-8650.

From Wikipedia, the free encyclopedia