A Nation of Giants
Russia has always had a weakness for oversized machines and weapons. When it comes to designing or building something, they prefer it to stand out by its size. In fact, such dimensions often proved to be more of a hindrance than an advantage, but they insisted anyway. The Kalinin K-7 flying fortress, built almost 90 years ago, fits this profile perfectly. Here is the story of a giant aircraft capable of carrying 9,000 kg of bombs, yet it flew for only four months.
If this were a children's tale, the story of the Kalinin K-7 would begin with "Once upon a time there was a nation where everything was done on a grand scale": communication towers, bombs, tanks, and, of course, airplanes. Indeed, the Russian government demonstrated over the years that building enormous examples of machines or weapons was a good way to show friends and enemies their technical capability. It mattered little that such inventions later proved impractical or useless. The goal was to make clear that no one could surpass those marks. The Kalinin K-7 flying fortress, designed and tested in the 1930s, was no exception.
Design and Capabilities
It is one of the most important works of designer Kalinin. Sometimes called just "K-7" (or Калинин К-7 in Russian), the Kalinin K-7 was a super-heavy bomber that required eleven crew members to fly. It was designed in the period between the two world wars, but did not participate in any conflict.
The "civil version" - the engineers assured - would be capable of carrying up to 120 passengers. But they were more interested in the military version, capable of carrying up to 9,000 kg of bombs distributed between its two holds. It had a total length of nearly thirty meters, and its wingspan - the length of the wings - was 53 meters. It weighed more than 24 tons, and could stay in the air thanks to a wing area of 450 square meters.
Pushing such a mass was not an easy task. The work was handled, at least initially, by six Mikulin AM-34 F engines of 750 hp each, distributed along the main wing. But when testing the first K-7, engineers had to add an extra engine in the central part of the rear wing, because the aircraft's weight was greater than planned. Its maximum speed was 225 kilometers per hour. To withstand all this weight, the fuselage structure was built as a chrome-molybdenum steel structure welded autogenously.
The pilot and navigator cabin, the bow gunner's cabin, and the bombardier compartments projected from the gigantic main wing structure. The twin tail was supported on two spars, at whose rear end there were two more gunners. The double landing gear was located under two kinds of gondolas that in turn supported the weight of the wing. Above them were the bomb bays and space for two more gunners. The armament consisted of six 7.62 mm ShKAS machine guns.
Fate and Legacy
The only K-7 built made its maiden flight on August 11, 1933. It is not hard to imagine the enormous joy that event must have caused among the people who worked on the project. We must not forget that at that time there was nothing remotely similar, and seeing a plane fly that, according to Jim Winchester's "The World's Worst Aircraft - From Pioneering Failures to Multimillion Dollar Disasters", was almost the same size as a B-52.
However, the joy would not last long. Only a few weeks later, on November 21 of the same year, the Kalinin K-7 crashed due to damage to the structure of one of the two tails. Besides destroying the aircraft, the 14 people on board died, plus one more who was on the ground. The Russian government ordered the construction of two more prototypes, but in 1935 the project was abandoned before the aircraft were finished.
The history of the K-7 was very short, but no less interesting. Would such an aircraft have changed the course of World War II? It is difficult to answer that question, especially because its low speed and large size would have made it a perfect target for enemy aircraft and defenses. Perhaps in the few years between the K-7's development and World War II, the Russians might have had the opportunity to improve its design, although it seems unlikely. However, this giant of the air earned its place in aviation history by its own merit.
For further reading, see The K-7 on Wikipedia.
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