Grigorovich IP-1

The Grigorovich IP-1 (for Истребитель Пушечный - "Cannon fighter") was a fighter aircraft produced in the Soviet Union in the 1930s. When the performance of both the Grigorovich I-Z and its single-shot Kurchevski DRP cannon armament proved disappointing, the development of that particular system did not halt development of the basic underlying concept of a cannon-armed bomber destroyer. 

                                                      IP-1

Leonid Kurchevsky developed a new, 75 mm cannon designated the Kurchevski APK-4 which could fire five shots instead of just one, and once again the Grigorovich design bureau created an aircraft to carry it. The IP-1 was a conventional, low-wing cantilever monoplane with retractable tailskid undercarriage and an open cockpit. 

Construction throughout was all-metal, and like it predecessor, its horizontal stabiliser was mounted high to avoid gasses from the underwing cannons. 
Once again, however, trials proved the concept a failure.

Nevertheless, the IP-1 was ordered into production, with a modified version that dispensed with the cannon and instead carried a 20 mm autocannon and three 7.62 mm machine guns in and under each wing. Some 90 of these were supplied to the Soviet Air Force in 1936 and 1937, but were outclassed and overshadowed by the Polikarpov I-16.

                                                         IP-4

A final development was the IP-4 prototype, which was armed with four 45 mm Kurchevski APK-11 cannon, but this was no more successful than any of the other Kurchevski-armed types, and a second prototype was abandoned before it was completed.

Operators: Soviet Air Force
Specifications IP-1

Crew: One pilot
Length: 7.23 m (23 ft 9 in)
Wingspan: 10.97 m (36 ft 0 in)
Wing area: 20.0 m2 (215 ft2)
Empty weight: 1,200 kg (2,646 lb)
Gross weight: 1,880 kg (4,145 lb)
Powerplant: 1 × Shvetsov M-25, 530 kW (710 hp)
Maximum speed: 410 km/h (255 mph)
Range: 600 km (373 miles)
Service ceiling: 8,300 m (27,230 ft)
Rate of climb: 12.8 m/s (2,520 ft/min)

Armament: 2 × fixed, forward-firing 7.62 mm mg guns in forward fuselage
2 × fixed, forward-firing 20 mm ShVAK cannons in wing roots
6 × fixed, forward-firing 7.62 mm ShKAS machine guns in trays under wings