tiistai 11. elokuuta 2015

Yakovlev Yak-25

The Yakovlev Yak-25 (NATO designation Flashlight-A/Mandrake) was a swept wing, turbojet-powered interceptor aircraft and reconnaissance aircraft built by Yakovlev and used by the Soviet Union.
The Yak-25 originated from a need for long-range interceptors to protect the USSR's northern and eastern territory. The specification for a two-seat, twin-engine jet fighter and a related reconnaissance aircraft was issued by Joseph Stalin on 6 August 1951. The aircraft was to use the new Mikulin AM-5 turbojet. The first prototype, the Yak-120, flew on 19 June 1952.

The new design mounted the turbojets in pods in the wings, with bicycle landing gear, leaving the fuselage volume free for the two crewmen and a substantial fuel load, giving an unrefueled range (with external tank) of about 2,560 km (1,600 mi). The large, blunt nose contained the radome for the air-interception radar. Armament was two 37 mm NL-37L cannon with 50 rounds per gun.
General characteristics
Crew: two
Length: 15.67 m (51 ft 5 in)
Wingspan: 10.94 m (35 ft 10 in)
Height: 4.4 m (14 ft 5 in)
Wing area: 28.94 m² (311.51 ft²)
Empty weight: 5,675 kg (12,510 lb)
Loaded weight: 8,675 kg (19,125 lb)
Max. takeoff weight: 9,450 kg (29,760 lb)
Powerplant: 2 × Mikulin AM-5 (RD-5A) turbojets, 23 kN (5,000 lbf) each
Maximum speed: 1,090 km/h (680 mph)
Range: 2,700 km with external tank (1,687 mi)
Service ceiling: 15,200 m (50,000 ft)
Rate of climb: 30 m/s (5,960 ft/min)
Wing loading: 327 kg/m² (67 lb/ft²)
Thrust/weight: 0.53

Armament: 2× 37 mm Nudelman NL-37 cannon (50 rounds per gun)
Despite some significant problems the type was cleared for production in 1953 and the first were produced in 1954. Early production models, designated Yak-25, were delivered the following year, although they were not yet to operational capacity because of problems with the 'Sokol' radar. As a result early aircraft used a modified version of the RP-1D 'Izumrud' (NATO 'High Fix') ranging radar instead. When the 'Sokol' (RP-6) was finally available, the newly equipped aircraft were designated Yak-25M, with deliveries starting in January 1955. The Yak-25M received a number of other improvements, including recoil dampers for the cannon, upgraded AM-5A engines (with the same thrust), and a slight increase in fuel capacity. In 1955 and 1956 several Yak-25Ms were refitted as testbeds for air-to-air missile armament.

A reconnaissance derivative of the Yak-25, the Yak-25RV (Razvedchick Vysotnyj, "high-altitude reconnaissance"), was developed in 1959 (NATO codename 'Mandrake'). It had a completely new, long-span straight wing of 23.4 meters (more than twice that of the Yak-25M interceptor) with a total area of 55 square meters. Camera and sensor packs were added in the fuselage. Some versions may have retained one cannon.
Despite its low wing loading, the 'Mandrake's' altitude performance was marginal at best, with considerable engine problems at high altitudes, excessive vibration, and primitive equipment that imposed high workloads for the crews. The Soviet Air Force nevertheless kept the Yak-25RV in service until 1974. A few were used in the late 1970s for monitoring of radioactive contamination, with specialized sensors; these were designated Yak-25RRV. Efforts in 1971 to develop the 'Mandrake' as a high-altitude interceptor (Yak-25PA) proved unsuccessful.

The derivative Yak-26 was developed as a bomber, but only nine were built.

In 1961 a series of lightened 'Mandrakes' were produced as high-altitude target drones. The Yak-25RV-I was used as a manned target for unarmed (no live fire) interception practice, the Yak-25RV-II as a remote-piloted drone.

483 were built at Saratov plant, including 406 in Yak-25M variant, and 10 in Yak-25R reconnaissance variant. Additionally, 155 Yak-25RV reconnaissance high-altitude planes were built.
Yak-25 was first displayed at Tushino in July 1955, and received the NATO designation Flashlight-A. They started to equip air defence units from 1955. They were considered easy to fly and popular among the crews. Quite common were engine breakdowns, mostly due to the low engine position when on the ground, which demanded clean airfields, but thanks to twin-engine arrangement, few such failures were fatal.

Their withdrawal started in 1963. The last Yak-25 interceptors were retired by 1967; the 'Mandrake' reconnaissance version soldiered on in various roles through the late 1970s. Like many other PVO interceptors of the Cold War era, the Yak-25M was not exported to the Warsaw Pact or other nations.

There was also another aircraft named Yak-25 - a light fighter prototype of 1947. After it lost a competition with the MiG-15 and Lavochkin La-15, the first Yak-25 program was abandoned and the designation Yak-25 was re-used for a new interceptor. See Yakovlev Yak-25 (1947) for the description of that aircraft.

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