The Yakovlev Yak-25 was a

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

military aircraft, an early turbojet-powered fighter aircraft designed by the

Yakovlev The Joint-stock company, JSC A.S. Yakovlev Design Bureau () is a Russian aircraft designer and manufacturer (design office prefix Yak). Its head office is in Aeroport District, Northern Administrative Okrug, Moscow. It is a subsidiary of Yakovle ...

OKB. The designation was later reused for a different interceptor design. Tasked by the Council of Ministers in a directive issued on 11 March 1947, with producing a straight winged fighter similar to the earlier Yak-19, but powered by a Rolls-Royce Derwent V, OKB-115 swiftly produced the Yak-25, which blazed several trails as the first Soviet fighter with a fully pressurised cockpit, air conditioning, jettisonable canopy, and hydraulic airbrakes on the fuselage amongst other innovations.Gunston, 1997

Development

The Yak-25 closely followed the Yak-19 in layout if not in detail. The straight wings, though similar in planform, were fractionally larger and much thinner (9% t/c throughout), using laminar flow sections. The CAHI flaps were also hydraulically powered. The vertical tail unit differed from the Yak-19 in being swept back at 40° on the leading edge, while the horizontal tail was swept back at 35 degrees.Gunston, 1997 The Derwent V engine was attached to the rear of the centre fuselage in a manner similar to the Yak-19. Though the fuselage had a different non-circular cross-section from the Yak-19, a similar double bulkhead directly behind the wing allowed the rear fuselage to be completely removed, giving access to the engine for removal or maintenance. The undercarriage was very similar to the Yak-19.Gunston, 1997 The cockpit was very similar to the earlier Yakovlev jets, though the Yak-25 was pressurized using an air-cycle system based on engine bleed. The single aft-sliding canopy was powered. The bulletproof front windscreen was 57 mm thick, while 8 mm of armor protected the pilot from behind. The ejection seat was an improvement over the Yak-19, with a longer stroke gun, and leg restraints. Armament was also improved, with three NR-23 cannon, each with 75 rounds.Gunston, 1997

Testing

The Yak-25-I was given the callsign "yellow 15", and had a number "2" painted on the airbrake rudder. It was flown in factory testing by Anokhin between 31 October 1947 and 3 July 1948.Gunston, 1997 Flight tests followed quickly, and showed that the Yak-25 was easy to fly, and had exceptional performance and maneuverability for a straight-wing aircraft. Unfortunately it soon became clear that the laminar flow section used for the tail unit was totally unsuitable, with extremely severe buffeting setting in at 500 km/h (310 mph). Test pilot L.L. Selyakov reporting that the buffeting was so bad that he was thrown about in the cockpit, banging his head on the canopy, and the needles fell off all the flight instruments. The tailplane section was changed with much improved results. Worse yet, both its rivals, the

Lavochkin La-15 The Lavochkin La-15 (Sokol plant, Plant 21 product code Izdeliye 52, USAF reporting name Type 21, NATO reporting name Fantail), was an early Soviet Union, Soviet Fighter aircraft, jet fighter and a contemporary of the Mikoyan-Gurevich MiG-15 whic ...

and rival swept-wing

MiG-15 The Mikoyan-Gurevich MiG-15 (; USAF/DoD designation: Type 14; NATO reporting name: Fagot) is a jet fighter aircraft developed by Mikoyan-Gurevich for the Soviet Union. The MiG-15 was one of the first successful jet fighters to incorporate s ...

had superior performance, with the MiG-15 selected for mass production and the La-15 produced in relatively small numbers (235). Yakovlev was never again to build a single-engine fighter superior to the rival aircraft coming from OKB Mikoyan-Gurevich, though neither was OKB Lavochkin. Development was halted, but two of the prototypes were used for test and development purposes.Gunston, 1997 The Yak-25 never received an ASCC reporting name or USAF type number despite being known to the west at the time.Gunston, 1997

Experimental work

Further development, replacing the straight wing with one of 35° sweepback, was undertaken as the Yak-30.Gunston, 1997

Yak-25E

The Yak-25E (Eksperimentalnyi) was a Yak-25-II specially modified to be towed by a

Tupolev Tu-4 The Tupolev Tu-4 (; NATO reporting name: Bull) is a piston-engined Soviet Union, Soviet strategic bomber that served the Soviet Air Force from the late 1940s to the mid-1960s. The aircraft was a copy of the American Boeing B-29 Superfortress, ha ...

strategic bomber. This came in response to a proposal by the headquarters of Long Range Aviation, calling for a method of towing short-range jet fighters, code-named ''Burlaki'' (barge hauler).Gunston, 1997 Production aircraft would have used Klimov RD-500 engines. At the same time, the U.S. Air Force was experimenting with a similar system, known as Project Tom-Tom. The U.S system would have employed either a specially modified F-84 or an XF-85 Goblin parasite aircraft. Early attempts differed by attaching two fighters to the bomber's wingtips. Later plans called for a

parasite aircraft A parasite aircraft is a component of a composite aircraft which is carried aloft and air launched by a larger carrier aircraft or mother ship to support the primary mission of the carrier. The carrier craft may or may not be able to later recove ...

to be stowed internally within the belly of a B-36.

Specifications (Yak-25 c/n 115001)

References

Bibliography

* Gordon, Yefim. "Early Soviet Jet Fighters". Hinkley: Midland. 2002. * * Green, William & Swanborough, Gordon. "The Complete Book of Fighters". London: Salamander Books. 1994. * Gunston, Bill. ''The Osprey Encyclopedia of Russian Aircraft 1875-1995''. London: Osprey, 1995. . * Gunston, Bill. ''Yakovlev Aircraft since 1924''. London, UK: Putnam Aeronautical Books, 1997. . {{USAF/DoD reporting names Yak-025 1947 1940s Soviet fighter aircraft Abandoned military aircraft projects of the Soviet Union Single-engined jet aircraft Mid-wing aircraft Aircraft first flown in 1947 Aircraft with retractable tricycle landing gear