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The Blériot 73 was a large First World War French heavy night bomber designed and built by Blériot to the BN3 specification. Only a single prototype was built, which crashed on landing from its first flight, killing the pilot.[1] The Blériot 74, Blériot 75 and Blériot 76, respectively, a heavy bomber / airliner, airliner and heavy bomber, directly evolved mfrom the Blériot 71 / Blériot 73 bombers.

Blériot 73
Role	Night bomber Type of aircraft
National origin	France
Manufacturer	Blériot
Designer	Touillet
First flight	July 1918
Number built	1
Developed from	Blériot 71

Design and development

Blériot 73

The Blériot 73 was a large equal-span biplane with a fuselage suspended from the lower wing and bearing a resemblance to, and slightly larger than, the Blériot 71, with the exception of the flying-boat like fuselage, attached beneath the lower mainplane, sweeping elegantly upwards to the biplane tail unit with twin rudders..[2] Four 300 hp (224 kW) Hispano-Suiza 8Fb water-cooled V-8 engines were mounted as close to the centreline as possible, two on the upper wing leading edge and two on the lower wing. The fixed landing gear had two twin wheel-wheel units, with large track, on struts and no tailskid. During flight testing the Bl 73 disintegrated on 22 January 1919, killing the pilot: One prototype built.[1]

Blériot 74

After the poor performance and crash of the Blériot 73, Touillet developed a heavy bomber/airliner with a large double bubble fuselage on top of the lower wing. The wings were similar to those of the Blériot 73, similarly with four 300 hp (220 kW) Hispano-Suiza 8Fb engines grouped around the fuselage. Flight testing at Villacoubly was abruptly terminated on 22 January 1920 when oscillations in the tail unit caused a structural failure and the fatal crash of the sole Blériot 74. Only one prototype was built.[1][3]

Blériot 75 Aerobus

The airliner version of the Blériot 74 had a new wing with dihedral on both upper and lower mainplanes, a longer rear fuselage and enlarged vertical tail surface. Despite promising flight-test results of the sole Blériot 75, the design did not attract any orders. One prototype was built.[1][4]

Blériot 76

Designed for the wartime BN4 specification the Blériot 76 bomber followed the same configuration as the previous members of the Blériot 73 family, but had the lower 300 hp (220 kW) Hispano-Suiza 8Fb engines further outboard than the upper 300 hp (220 kW) Hispano-Suiza 8Fb engines, slightly swept-back wings and a pair of very large mainwheels: Design only, not built.[1]

Specifications (Blériot 73)

Data from Aviafrance: Bleriot Bl-73,[2] French aircraft of the First World War[1]

General characteristics

• Crew: 3
• Length: 14.5 m (47 ft 7 in)
• Wingspan: 28 m (91 ft 10 in)
• Height: 6.15 m (20 ft 2 in)
• Wing area: 148 m² (1,590 sq ft)
• Empty weight: 3,230 kg (7,121 lb)
• Gross weight: 6,980 kg (15,388 lb)
• Powerplant: 4 × Hispano-Suiza 8Fb V-8 water-cooled piston engine, 220 kW (300 hp) each
• Propellers: 2-bladed fixed-pitch propellers

Performance

• Maximum speed: 130 km/h (81 mph, 70 kn) at sea level
• Endurance: 6 hours 40 minutes

Armament

• Guns: 2x 7.7 mm (0.303 in) machine-guns, one on a flexible mount in the rear gunners cockpit and one on a flexible mount in the nose gunners cockpit.
• Bombs: 1,000 kg (2,200 lb) of bombs

References

Notes

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