Mikoyan-Gurevich I-250 (N)

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The first I-250 prototype

In order to counter the introduction of German turbojet-powered aircraft such as the Me-262, the Soviet Union began a crash program in 1944 to develop a high-performance fighter which resulted in the Mikoyan-Gurevich I-250 (N).

Although the aircraft was largely conventional in layout, it featured a novel propulsion system — a thermojet. This rudimentary type of jet engine consisted of a Klimov VK-107R V-12 piston engine mounted conventionally and driving a tractor propeller, which was in turn connected via an extension shaft to a compressor with seven fuel burners. This design produced a propulsive jet which was directed and accelerated through a variable rear nozzle. This mixed powerplant configuration enabled the I-250 to reach a maximum speed of 513 mph (825 km/h), but for no more than 10 minutes. Without the jet engine working, maximum speed was 421 mph (677 km/h). The plane was named I-250 (for istrebitel – "fighter", literally meaning "destroyer"), it also bore the factory code designation: aircraft N.

The first prototype was flown on March 3 1945. On July 5 1945 it crashed due to tail damage, killing its test pilot, Alexander Deyev. Tests continued on the second prototype. At the same time, the first batch of 50 aircraft were ordered. However, the aircraft's development met with numerous problems, and it was not ready to pass state evaluation. In the meantime, Soviet designers constructed their first real jet fighters, MiG-9 and Yak-15, which made the I-250 obsolete. Therefore, in early 1947 the VVS cancelled its further development. It was decided to pass the completed planes to Naval Aviation, but the aircraft still did not pass state evaluation, which ended in April 1948.

According to older sources, 50 aircraft were built from late 1945, and served with the Baltic Fleet and some Northern fighter units until 1950 under the designation MiG-13. However, recent Russian sources claim that the number of completed planes was lower — possibly only 10-20 — and there is no evidence of their having entered operational service, nor of their having officially been assigned the MiG-13 designation, which might have been reserved for the serial-production aircraft had the I-250 passed its state trials.