C (Sparka - pair) - A short-range high-speed bomber, developed at the Viktor Fedorovich Bolkhovitinov Design Bureau, with a tandem arrangement of liquid-cooled engines with mechanical transmission from both to coaxial propellers. The first flight was on January 27, 1940.

The structure of the aircraft is all-metal, in the wing and fuselage - panel. A two-spar wing with a span of 11.38 m and an area of ​​22.9 m & # 178; consisted of the upper and lower skin panels between the spars, cut along their neutral axis, nose and tail. The fuselage was assembled from four panels - two side, bottom and top, which were joined on four side members-squares. The design was original, technological, progressive. A dozen years later, it was applied on the Il-28 jet aircraft.

A variable transmission device was introduced into the differential elevator control system to limit the effort on the handle. Electrical systems are widely used.

In all flights, it was noticeable that the plane slowly scatters, after taking off it slowly accelerates and gains altitude. With an increase in speed to 300 km / h (vertical speed Vу = 8 m / s), an excessive load on the wing affected, and also, apparently, that there were sensitive power losses in the transmission from the rear engine, and the ratio of the rotation speeds of the coaxial propellers was not chosen the best.

It turned out that the wing profile was not chosen very well. It was decided to change it, they re-glued it on the finished plane, but this did not help, since the plane was produced in 1941, just before the war, when the Pe-2 plane was already mass produced at the same plant.

The aircraft did not pass the tests due to unsatisfactory takeoff and landing characteristics. However, on the Bolkhovitinov plane, which was essentially experimental, for the first time in the USSR the problem of increasing the power of the VMG without increasing the drag was solved, and this problem was practically solved by the designer.

Photo	Description
	Drawing S (Sparka-pair)
	S (Sparka - pair)
	S - a pair of two M-103s. Fowler Flaps - absolutely essential for a record wing load of 247 kg / m²

The longitudinal twin of water-cooled engines can be of two types, with pushing coaxial propellers like those of the TsKB-21 fighter designed in 1935 and pulling propellers, which was cultivated in his project by V.F. two M-103 engines.

The design of the "C" aircraft began with the development of twin M-100 engines in 1936. In 1937, a preliminary design of the aircraft was drawn up, and in June 1938, the construction of the short-range bomber "C" with twin M-103 engines began, which was completed in the winter of 1939. In the summer of 1939, the oldest pilot, Boris Nikolaevich Kudrin, began the first test flights on the "C" machine.

In parallel with the construction of the short-range bomber OKB V.F. Bolkhovitinov, characterized by a regularly changing contingent of students who were part of it, began designing other aircraft equipped with a similar twin power plant. Thus, the project of the I-1 high-speed fighter with two M-107 engines was launched. The I-1 was then included in the pilot aircraft construction plan for 1941, due to the great similarity of the scheme and design with the S, 2M-103 and S-2 aircraft, equipped with one M-103 engine (the front engine for centering was left in place, but its transmission was disconnected from the second propeller.In general, the I-1 project was a kind of repetition of the tested "C" aircraft, but with much more powerful M-107 engines of the same family of engines that V.Ya Design Bureau was working on The difference from the prototype was a single-keel vertical tail and a tail crutch made in the form of a swinging heel made of steel with a shock absorber. engine mode compared to the M-103.The stabilizer was made conventional with a span of 4.5 m without the use of end washers, which were needed by the previous machine for the best view back to the gunner. The speed that the aircraft was supposed to develop was estimated in the preliminary design of 750 km / h. The time to climb 5000 m was 5 minutes. Ceiling - 9500 m. The shock was the estimated flight range - 2000 km at 0.8 V _max.

All small arms and cannon weapons were located in the wing. Two 23-mm cannons VYa of the Volkov and Yartsev system were arranged behind the fairings of the landing gear, further along the scope - four large-caliber machine gun M.E. Berezina. Under the wing consoles, an external suspension of two or four bombs of caliber from 100 kg to 250 kg was possible.

After conducting flight studies of the "C" and "2C" aircraft, their futility was clarified, and on the I-1 fighter, Bolkhovitinov tried to take his "spark" on the first flight, scheduled for mid-June 1941. However, in the light of well-known events of that time, and his fighter was not completed due to the redirection of the Design Bureau activities to a short-range fighter with a BI rocket engine. With the outbreak of war, the I-1 theme, along with other designed aircraft, was closed. The OKB suffered with the BI missile interceptor until 1947. The I-1 project outlined many new technological methods for assembling, riveting and gluing aircraft parts, ejecting a pilot in flight, corresponding to a speed range of 600-750 km / h.

A geometric summary of I-1 is given here for lack of other information on this interesting project. Wingspan - 13.8 m, aircraft length - 12.96 m, aileron area - 1.55 m², flap area - 4.155 m², GO span - 4.5 m, aileron span - 4.0 m, V wing - 4 °, chassis gauge - 2.87 m, chassis base -9.36 m, main wheel dimensions 2 × 800 × 280 mm.

Photo	Description
	Bolkhovitinov I-1 fighter

October 05, 2022.

Bolkhovitinov was one of the first graduates of VVIA them. N.E. Zhukovsky (1936) and worked there for about 45 years as a teacher, professor and head of the department of aircraft engineering. In addition, he was engaged in the construction of experimental and serial aircraft, which were built at various factories.

Bibliography

• The history of designs of planes in USSR 1938-1950 /Vadim Shavrov/