The Grigorovich I-1 (Russian: Григорович И-1) was designed by DP Grigorovich as a fighter. Knowing that NN Polikarpov was designing a new fighter, Grigorovich decided at all costs to take on a similar task.
The general design was carried out by Grigorovich with the help of VV Kalinin. Engineer AA Krylov was in charge of the aerodynamic calculations. The concept design was conceived in just three days and submitted to the Department of Aviation almost in parallel with that of NN Polikarpov’s fighter of the same name.
The I-1 fighter was a single-seat biplane built basically of wood covered with fabric. The fuselage with a wooden structure was characterized by its constructive simplicity. The sides were straight, with some curvature at the top and bottom. At the bow and with a large aerodynamic hub covering the propeller was the 400 hp M-5 water-cooled engine (licensed copy of the North American Liberty L-12), completely covered by an aerodynamic aluminum hood. The original cooling system included a circular-type Lamblin radiator located between the main landing gear. Problems with motor heating motivated several modifications of this radiator. The entire rear region of the fuselage was covered in fabric.
The wing, of a single section, had planes of equal span linked by means of parallel interplane uprights made of wood and 12 mm bracing straps. The selected airfoil was the Gettingen 436. The upper plane had shutter-type ailerons.
The tail was monoplane, of conventional configuration. The construction was of wood covered with fabric. The horizontal, cantilever-type planes featured large-area elevators. The rudder was attached to a small triangular keel.
The landing gear was of the conventional type, with a tail skid and fixed landing gear, linked by a bar.
The pilot was located in an open cockpit located behind the wing trailing edge. The control system was rigid.
The armament designed two 7.62 mm machine guns, although there is no evidence that they were ever installed in the prototype.
The construction of the Grigorovich I-1 was developed within the experimental construction plan of the GAZ No.1. The biplane was completed in September 1923 and on October 5, after receiving the approval of the Scientific Committee of the VVS Directorate (UVVS), it was approved to begin flight tests.
It is noteworthy, that despite Grigorovich’s efforts, NN Polikarpov’s IL-400 (Fighter with Liberty 400 hp) or I-1 monoplane would be ready some time before, but unsuccessful attempts to make it fly on August 15 of 1923 definitively reaffirmed Grigorovich’s position.
The first flight of the I-1 took place on October 30, 1923. The Grigorovich I-1 managed to take off without difficulty and during the test flights it was possible to set a maximum speed of 238 – 240 km/h with climb times to 2,000 meters in 5 minutes and to 5,000 meters in 19 minutes. This made it the fastest aircraft on the Moscow airfield. It was defined that the I-1 was the first successful attempt to create a fighter since the end of the war.
The general opinion was that the plane was stable in the air and responded correctly to the controls. As a problem, the presence of overheating in the engine was highlighted, despite the modification on several occasions of the shape of the radiator.
Despite this, the I-1 was considered only as an experimental model and from the very beginning of the tests Grigorovich and his team began to design the improvements, in parallel with the modifications demanded by the flight tests. All these changes and improvements delayed the delivery of the plane for the development of tests at the NOA (acronym for Nauchno Opytni Aerodrom or Scientific Experimental Aerodrome), so that at the time of its appearance there, the plane had been surpassed by the design improved I-2. This new design seemed to present a better disposition for military use.
I-1
Engine: 400 hp M-5
Wingspan: 10.80m (9.0m)
Wing area: 26.80 m²
Length: 7.32m
Empty weight: 1188 kg
Speed at sea level: 238 – 240 km/h
Landing speed: 95 km/h
Range: 600 km
Endurance: 2 h30 min
Practical ceiling: 6000m
Time to 2000m: 5min
Time to 3000m: 8min
Time to 5000m: 19min
Accommodation: 1
Armament: Two 7.62mm machine guns
All Aero 