A deep modification of the Yak-25 was the long-range high-altitude single-scout Yak-25RV (sometimes referred to as the Yak-RV), which was designed in 1957-1958. The NATO code is Mandrake. For flights at high altitude, the aircraft was equipped with a new wing of an area enlarged to 55 sq. M, the load on which turned out to be even less than that of the Yak-3 fighter, and amounted to 175-178 kg / sq. M. The sweep of the straight wing with an extension of about 10 reached 23.5 m (in Yak-25 - 10.964 m). Increased aircraft performacne was obtained installing high-altitude engines R-11V-300 with static thrust at a maximum mode of 3,900-4,000 kgf (in the nominal mode - 3,250 kgf).
Factory tests of the experimental Yak-25RV were carried out at the airfield of the LII from March 1 to May 29, 1959, by the leading test pilot V.P. Smirnov and test pilot LII AA. Shcherbakov. The leading aircraft engineer was VA. The fence. The weight of the empty aircraft was 6,175 kg, takeoff - 9,800 kg. Experienced scout had a good LTX: it was able to reach a height of 21 000 m and a maximum speed M = 0.82. According to Smirnov, climbing to 18,500 - 19,500 m did not cause difficulties, but a further set required increased attention. Established horizontal flight at altitudes of more than 19 600 - 20 100 m could not be achieved due to self-exclusion of the engines.
The flights were carried out in the SI-3M high-altitude spacesuit, which received a number of comments from the pilots. Yak-25RV had a characteristic feature: the decrease from high altitudes occurred quite slowly. In one of the flights Smirnov for a long time could not decrease, and only after the release of the chassis began a slow descent. Shcherbakov also faced a similar situation.
After the completion of the factory tests, the experimental Yak-25RV was prepared for setting world records of flight altitude. July 13, 1959 Smirnov lifted a plane with a cargo of 1 ton to 20,456 m, and on July 29, with a cargo of 2 tons, he managed to reach 20,174 m. In FAI documents, the record aircraft was designated as "RV". April 10, 1961 test pilot LII BV Polovnikov performed a flight on an experimental machine to control the technical duration of the flight - it was 5 hours and 30 minutes. August 11, 1965 on the converted serial "RV" test pilot M.L. Popovich set a world record for the speed of flight along a closed route of 2,000 km - 753 km / h. On September 18, 1967, it also flew along a closed route 2,497 km, which was registered as the official world record of the flight range.
The air force was not completely satisfied with the TTX Yak-25RV, but the large ceiling and the duration of the flight forced the military, with no choice, to agree to its serial production. After some improvements and state tests, the aircraft was put into production at the N99 plant in Ulan-Ude ("25RV edition").
The pilot OKB-115 LA was sent to this enterprise. Smirnova recalls: "Up to 11 000 m Yak-25RV from the point of view of piloting was not much different from other aircraft, but at altitudes close to 20 000 m, it demanded increased attention of the pilot, since the difference between the maximum and minimum speeds at these heights was only 10 km / h. It was necessary to accelerate a little, and the loud "trembling" of the whole aircraft began, and when the speed approached the minimum, the aircraft began to swing along the bank with an ever-increasing amplitude. Being guided by these signs, the pilots tried to keep in the "speed corridor" and forced Yak to fly in the stratosphere. From pilots, this required a lot of energy and created considerable discomfort."
For about 15 years the aircraft were operated by the Air Force prior to the arrival in the regiments of high-speed high-altitude scouts MiG-25R / RB. According to Western sources, high-rise Yaks were not seen above the countries of Western Europe, but their flights were recorded over China, India and Pakistan. A total of 155 Yak-25RVs of various modifications were manufactured at the N99 plant in 1961-1965, of which 74 were manned and 81 were unmanned (Yak-25RV-II).
Yak-25RB-I, -II. In 1958, even before the testing of an experienced scout, the Yakovlev Design Bureau began designing a manned target aircraft on its base (sometimes called the "target aircraft"). This modification was intended for development by fighters of air defense of interception of the target without shooting in non-polygon conditions. Its main difference from the basic scout was the lack of photographic equipment. According to the Government Decree, the maximum speed of the manned target at an altitude of 15,000 m was to be 900 km / h, the ceiling - 20,000 - 21,000 m, and the range at an altitude of 20,000 m - 2,500 km.
After the factory tests, the experimental Yak-25RV-I target aircraft was sent to the state tests, which ended in 1961. The aircraft had take off weight 9 935 kg and empty weight - 6 285 kg. The results achieved were not much different from those of an experienced scout, and the military's remarks relied mainly on design flaws. The manned target was launched into a series, and it was produced in small quantities in Ulan-Ude. In August-September 1962, the serial test aircraft Yak-25RV-I N0302 was tested. The weight of this machine was about 240 kg less than that of the prototype, which was important, because Each kilogram influenced the high-altitude characteristics.
If necessary, the Yak-25RV-I could be re-equipped for an unmanned flight. The standard unmanned radio-controlled variant was designated Yak-25RV-II, intended for testing by air defense fighters of high-altitude interceptions with the use of weapons and also was produced serially. It was additionally installed autopilot AP-28 and other equipment for unmanned flight. The aircraft was driven from a converted Yak-30 sports aircraft. After decommissioning, part of the "RV" was converted into a target. Squadrons or links of such vehicles and serial RV-I and RV-II were based on parts of the air force and air defense, for example, in Mukachevo, Savostlake, Belaya.
Yak-25RRV. In the late sixties a small number of Yak-25RV was equipped with two underwing pylons for suspension of unified filter gondola type PP8311-100. The new modification of the Yak-25RV was designed to register radioactive contamination. From October 9 to October 26, 1971, special ground and flight tests were carried out on the Yak-25RV N25991201, equipped instead of standard filter gondolas with containers with IRIS equipment (Wave-C), which was designed to detect and record electromagnetic pulses from various radiators. The machine received the designation Yak-25RRV. The IRIS control panel was in the cockpit. The aircraft was equipped with a system for boosting and heating the containers by taking hot air from the engine compressors. Minor changes affected other equipment.
Yak-25PA. In August 1971, the Yakovlev Design Bureau began to develop a Yak-25Pa interceptor interceptor project based on the Yak-25RV. The aircraft was to have an enlarged wing (up to 58 square meters), carry armament and have the ability to destroy balloons at altitudes up to 19,400 m. However, the R-11V-300 engine had insufficient traction for this purpose, and therefore the project was not realized.
|Join the GlobalSecurity.org mailing list|