High Speed Bomber
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.