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I-Z
Role	Fighter
National origin	Soviet Union
Manufacturer	Grigorovich
First flight	1931
Primary user	Soviet Air Force
Number built	73

The Grigorovich I-Z was a fighter aircraft developed in the Soviet Union during the 1930s. Advances in aircraft survivability thanks to all-metal construction and self-sealing and inert gas-filled fuel tanks led to experimentation with large-caliber weapons to shoot them down. In Soviet Union, Leonid Kurchevsky developed a series of recoilless rifles in various calibers and in 1930 was decided to adapt the 76.2 mm (3 in) weapons for aircraft use.^[1]

Design and development

The Grigorovich I-Z was a conventional strut-braced monoplane with fixed landing gear. A pair of Kurchevsky APK (APK - Aviatsionnaya Pushka Kurchevsky - aircraft cannon Kurchevsky) rifles were mounted under the wings outside the propeller arc and the rear fuselage and tail assembly were of reinforced metal construction to withstand the blast. A single small-caliber synchronized machine gun in the left fuselage was added to aid the pilot in aiming.^[1]

Two prototypes were built, the first flying in mid-1931. The second strengthened I-Zbis flew at the beginning of the following year. These were followed by 21 examples ordered as evaluation aircraft and 50 production machines. By the time this last batch was being delivered, however, it was already apparent that the concept of a "single-shot" fighter was flawed and the I-Zs that had been built were relegated to various testing roles. One such role was as a parasite fighter in the Zveno project.^[1]

Operators

Soviet Union

Soviet Air Force

Specifications (I-Z)

Data from Istoriia konstruktskii samoletov v SSSR do 1938 ^[1]

General characteristics

Crew: 1
Length: 7.65 m (25 ft 1 in)
Wingspan: 11.5 m (37 ft 9 in)
Wing area: 19.5 m² (210 sq ft)
Airfoil: Göttingen 436^[2]
Empty weight: 1,180 kg (2,601 lb)
Gross weight: 1,648 kg (3,633 lb)
Powerplant: 1 × Shvetsov M-22 9-cylinder air-cooled radial piston engine, 358 kW (480 hp)
Propellers: 2-bladed fixed-pitch propeller

Performance

Maximum speed: 259 km/h (161 mph, 140 kn)
Range: 600 km (370 mi, 320 nmi)
Service ceiling: 7,000 m (23,000 ft)
Time to altitude: 5,000 m (16,000 ft) in 14 minutes
Wing loading: 85 kg/m² (17 lb/sq ft)
Power/mass: 0.22 kW/kg (0.13 hp/lb)
Horizontal turn time: 17 seconds

Armament

Guns:

1×7.62 mm (0.3 in) PV-1 machine gun
2×76.2 mm (3 in) single-shot Kurchevsky APK recoilless rifles

References

^ ^a ^b ^c ^d Shavrov V.B. (1985). Istoriia konstruktskii samoletov v SSSR do 1938 g. (3izd.) (in Russian). Mashinostroenie. ISBN 5-217-03112-3.
^ Lednicer, David. "The Incomplete Guide to Airfoil Usage". m-selig.ae.illinois.edu. Retrieved 16 April 2019.

Bibliography

Lesnitchenko, Vladimir (November–December 1999). "Combat Composites: Soviet Use of 'Mother-ships' to Carry Fighters, 1939–1941". Air Enthusiast (84): 4–21. ISSN 0143-5450.