Aviation of World War II
UTI-26-1 was a training fighter and was intended for training and transporting pilots when they switched to high-speed fighters. The aircraft was designed and built by the Design Bureau from January 25 to June 17, 1940 in accordance with the government decree of March 4, 1940.
The prototype aircraft UTI-26, later named Yak-7UTI, was built in two copies, designated UTI-26-1 and UTI-26-2.
According to its design, the UTI-26-1 is a single-engine, double-seat, dual-control monoplane with a low-lying cantilever wing and retractable main and tail wheels. The UTI-26-1, as well as the I-26, was equipped with an M-105P liquid-cooled engine with a capacity of 1050 hp with at an altitude of 4,000 m and a metal three-blade propeller VISH-61P with a diameter of 3.0 m.
Enclosed student and instructor cabins are placed in tandem. The student was in the front cockpit, and the instructor was in the back. The equipment of the front cockpit, basically similar to the typical equipment of the cockpit of the I-26 combat fighter aircraft, contributed to the student's assimilation of the necessary skills for independent flight on a combat aircraft.
The front and rear cabs are covered by one common plexiglass canopy, but with separate moving parts moving back. Communication between the instructor and the student was maintained visually and with the help of a standard rubber intercom (hose), and serial Yak-7UTI - at first in the same way, and later with the help of SPU-3*.
Aeronautical and electrical equipment ensured the performance of daytime flights in the conditions of visibility of earth landmarks. Armament consisted of two synchronous machine guns ShKAS with 500 rounds of ammunition.
UTI-26-1 was designed and built on the basis of the I-26, as a result of which their designs had much in common. According to the piloting technique, the UTI-26-1 was very close to the I-26 and resembled other fighters with liquid-cooled engines (I-301 and I-200), as a result of which it was a successful version of the aircraft for transporting and training pilots during their transition to high-speed fighters .
UTI-26-1 passed factory tests from July 23 to August 25, 1940 on taxiing, the left landing gear was formed, as a result of which the propeller was bent and the wing console was damaged. The aircraft was returned to the Design Bureau for repairs.
September 21-25 state tests were completed. UTI-26-1 passed them with a "satisfactory" rating and was recommended for serial construction. The act on the results of state tests noted that at present it is the only training aircraft transitional to other types of aircraft (Yak-1, LaGG-3, MiG-3), on which the flight personnel of all reserve regiments are trained.
The UTI-26-2 was a stand-in for the UTI-26-1. It was designed and built from January 25 to September 17, 1940. Structurally, this aircraft was more advanced, which is natural, since it was built later than the UTI-26-1, and most of the identified defects were eliminated on it.
From September 16 to December 12, 1940, the UTI-26-2 passed factory flight tests, and from January 1 to February 14, 1941 - special state tests for overflight by pilots of the Air Force Research Institute to identify features in piloting techniques due to changes horizontal plumage. These tests were carried out by a team of the Air Force Research Institute consisting of: lead pilot A.G. Kubyshkin, lead engineer A.T. Stepanets, technician F.Z. Sbitnev. 8 flights were made with a total duration of 5 hours and another 13 flights (7 hours 55 minutes) in preparation for the parade.
In the report on state tests UTI-26-2, it was noted that the conclusion on UTI-26-1 remains entirely valid: the training fighter designed by engineer A.S. Yakovlev is the most successful option for training, retraining and testing piloting techniques fighter pilots, as a result of which it is urgent to speed up the final refinement of the aircraft and its launch in a series.
UTI-26-2 was at the NII VVS for some time, where its full dive and spin characteristics were determined, after which it was transferred to the 12th IAP for use in combat training of flight personnel.
* SPU-3 - Samoletnoye peregovornoye ustroystvo - Aircraft intercom
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When developing a new modification of the training machine, the operating experience of the Yak-7 UTI was taken into account. Yak-7V was developed in accordance with the installation - to produce faster and cheaper. This time the landing gear was made non-retractable. This was not something new; back in the summer of 1941, such changes were proposed by the head of the design bureau of plant No. 301 Cherenkov. The chassis niches were sewn up, but there were small hatches for inspecting the mounting of the racks. In order for the trainees to acquire the skill of retracting the chassis, a simulator of the lever for retracting and releasing them was installed in the cockpit. The armament was removed, which is actually surprising, given that a fighter pilot must be able not only to fly, but also to shoot.
Some devices were not installed in the cockpit, for example, the remote control was removed. The absence of a transparent partition between the cabins caused very great inconvenience. During the flight with the front light open, the instructor was mercilessly blown by the oncoming air flow, and it was necessary to fly with the light shifted, as the plexiglass, which quickly turned yellow and easily scratched, made it difficult to see.
Starting from the second series, some of the previously removed equipment was installed again, but until the end of the production of this modification, the partition between the cockpits of the cadet and the instructor was not installed.
During state tests (from February 18 to March 4, 1942) it turned out that the non-retractable landing gear practically did not reduce the performance of the machine and did not affect the aerobatics. The aircraft flew almost as fast as a fighter jet, and could be controlled from the front and rear cockpits.
The Yak-7V was mass-produced from March 1942 to December 1943. 510 examples were built, and another 87 converted from the Yak-7B. This is not much, given the huge number of pilots trained during the war. Almost every Soviet fighter pilot was trained on this machine.