Bolkhovitinov S (Sparka)

History

Not only the UK, US, Germany, and France carried out special aircraft projects before World War II (1937-1945), as Soviet engineers were also working to perfect the various types. The Bolkhovitinov "S" - or "Sparka" - was one such entry into the Soviet stable, appearing in the pre-war period in 1937 and making its first flight in 1940.

Envisioned as a high-speed/light bomber, only two such bombers were built for the program.

One of the Sparka's unique features is its integrated engine fit, which connects a pair of Klimov M-103 inline piston engines (960 hp each) and uses them to drive a pair of three-blade counter-rotating propeller units in on the nose. Inline engines allow for a streamlined shape resulting in a sleek fuselage with cockpit/crew areas midship and stern. This section is known for its durable greenhouse-style canopy (standard for two crew members). The main-wing aircraft are also amidships, they are straight, low-mounted appendages with the trailing edge swept forward.

The fins are another unique feature of the design, featuring a dual rudder arrangement with a horizontal plane between the two fins. The tail unit is mounted on the fuselage spine. The landing gear had a typical trailing arrangement consistent with developments at the time. Light alloys are used throughout the construction of the aircraft. The dimensions of the aircraft include a length of 43.3 feet and a wingspan of 45.2 feet.

Gross weight is 12,460 lbs.

The proposed weapon is a 1 x 7.62mm ShKAS machine gun for the rear crew (the gun is on a trainable mount). This weapon was later modified as a 2 x 12.7mm UBT series machine gun for a more powerful defensive "strike". For the light bomber role, up to 882 pounds of internal reserves can be carried.

The bomb bay separated the two cockpits, and the ammunition was kept vertical to save space.

Design work on the Sparka began in 1937 and led to the construction of the first prototype the following year. By 1939, the first airworthy form was ready as the "S-1", but the example lacked the proposed armament, wheeled landing gear (with skids installed), and only had two of the proposed engines installed. One. The first flight was recorded on January 29, 1940. S-1 is followed by "S-2", which includes all proposed components that the S-1 is missing.

In testing, the pair performed wellhandling is an advantagebut not as quick as expected and proved tricky on takeoff and landing maneuvers.

The design was further developed into the permanently obsolete Bolkhovitinov "I" - with two M-107 engines and other minor modifications - and the Bolkhovitinov "D", a form of heavy bomber that never existed. Other proposed forms related to the Sparka project are a dedicated attack aircraft (equipped with a down-firing heavy machine gun) and a dedicated interceptor (equipped with an up-firing 37mm automatic cannon).

As tested, the Sparka has a top speed of 354 mph and a range of up to 435 miles. Apart from the two prototypes mentioned above, nothing came of the project.

Specification

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