After factory tests, the first two prototypes were delivered to Boscombe Down, an aircraft and weapons manufacturing plant. By June 1940, the last of the four prototypes landed here, which allowed for full-scale military tests. The third prototype, which took off in the spring of 1940, had significantly worse performance - for example, the maximum speed dropped from 539 km / h to 497 km / h at an altitude of 4572 m. The aircraft were equipped with armor plates (5-8 mm thick) in front and rear, as well as complete radio equipment.
Armament in the form of four 20 mm automatic Hispano Mk III guns (rate of fire 600 rounds / min) was installed in the lower part of the front fuselage, while the external guns were moved aft so that their magazines could fit behind the magazines of the internal guns. Each gun was equipped with 240 rounds distributed in four drum magazines. They were being recharged by a radio observer.
The units began their operations in Ukraine. Upon arrival, they were surprised by the large number of enemy soldiers and the huge amount of equipment they used and destroyed. The Pasubio Infantry Division and the 3rd High-speed Division, using trucks and horses, reached the combat area the fastest. The last to arrive was the Turin Infantry Division, which was marching. The units went into full combat readiness on August 5, 1941.
Due to the decline in the flight performance of the aircraft, work has begun to reduce aerodynamic drag. The upper fairings of the nacelles were slightly lengthened, and the air grips of the oil radiators, along with the radiators themselves, were moved from the bottom of the engines to the leading edge of the wing, outside the nacelle. In addition, separate fuel drain lines in flight were removed from the trailing edge of the wing, and exhaust ports common to both wing tanks were introduced at the rear of the nacelles. The aerodynamics of the lower part of the engine nacelles have been improved, undercarriage covers have been introduced that completely cover the wheels in the retracted position, both on the main and rear landing gear struts. Thanks to these measures, it was possible to increase the maximum speed to 515 km / h. On production aircraft, flat countersunk head rivets were additionally used.
In August 1940, when full-scale serial production of the twin-engine Beaufighter I fighter began, it was decided to equip all units except the 23rd Squadron with Blenheim IF fighters. Since October 1940, the latter has been tasked with combating German aircraft returning to its own airports over the European continent, and in March 1941 it was re-equipped with Havoc I aircraft. ¡Bienvenidos a Farmacia Mera Cerrato , tu farmacia de confianza en Parla!