The Soviet Union employed the Yakovlev Yak-25, an interceptor and reconnaissance aircraft with a swept wing design and powered by turbojet engines.
This aircraft was manufactured by Yakovlev, a renowned aircraft manufacturer.
The Yak-25 played a crucial role in the Soviet Union’s military operations, serving as an effective means of intercepting enemy aircraft and gathering valuable reconnaissance information.
Its advanced features and capabilities made it a significant asset for the Soviet Union during its operational lifespan.
The Yak-25 was developed in response to the requirement for an Interceptor aircraft with extended range capabilities to safeguard the northern and eastern regions of the Soviet Union.
The directive for a twin-engine, two-seater jet fighter and a corresponding reconnaissance aircraft was put forth by Joseph Stalin on 6 August 1951.
The impetus for the creation of the Yak-25 stemmed from the need to defend the vast expanse of the USSR’s northern and eastern territories.
To meet this requirement, a specification was issued by Joseph Stalin on 6 August 1951, calling for the development of a twin-engine, two-seater jet fighter and a reconnaissance aircraft.
The Yak-25 was the result of this directive, designed to provide long-range Interceptor capabilities to protect the Soviet Union’s borders.
In order to safeguard the northern and eastern regions of the Soviet Union, a need arose for an Interceptor aircraft with extended range capabilities.
To meet this requirement, Joseph Stalin issued a directive on 6 August 1951, calling for the development of a twin-engine, two-seater jet fighter and a corresponding reconnaissance aircraft.
The Yak-25 was developed in response to this specification, designed to provide the necessary long-range Interceptor capabilities to protect the vast expanse of the USSR’s northern and eastern territories. Yak-120 In 1951, Yakovlev initiated the development of a twin-engine patrol interceptor, known as the Yak-120, under the guidance of the design bureau.
This project was granted official authorization through a directive issued by the Council of Ministers on 10 August of the same year.
Diverging from the conventional Yakovlev designs, the Yak-120 featured slender, mid-set wings that were inclined at a 45-degree angle and incorporated large two-section flaps.
To enhance its directional stability, a ventral fin was affixed beneath the swept cruciform tail.
The aircraft was propelled by two Mikulin AM-5 turbojets, which were mounted in nacelles directly attached to the undersurface of the wing.
In order to enhance its endurance capabilities, the design of the aircraft focused on maximizing fuel capacity.
This was achieved by incorporating a bicycle undercarriage with a single-wheel nose unit and a two-wheel main unit.
To further support stability, outrigger struts were installed beneath the wingtips.
Additionally, the Yak-120 was specifically configured to accommodate a conformal drop tank positioned on the centreline of the fuselage.
This strategic placement of the drop tank served the purpose of extending the aircraft’s endurance by providing supplementary fuel capacity.
The nose of the aircraft was equipped with an RP-6 Sokol radar, which was enclosed by a bullet-shaped glass fibre radome.
The radar had the capability to detect four engine bombers at a distance of 25 km and fighters at a distance of 16 km.
The aircraft had a crew of two, consisting of a pilot and a radar intercept operator, who were seated in tandem below a shared aft-sliding canopy.
The radar intercept operator was responsible for target searching and assisted the pilot in guiding the aircraft towards the target in unfavourable weather conditions.
Additionally, the operator was able to fly the aircraft when required due to the aircraft’s dual controls, which helped to reduce pilot fatigue on lengthy missions.
The aircraft’s windshield was fixed and included a 105-millimeter (4.1 in)-thick bulletproof glass panel.
The rest of the aircraft was protected by 10-millimeter (0.39 in) all-round armour plates.
This ensured that the crew was well-protected during combat missions.
The combination of the radar and armour plates made the aircraft a formidable opponent in the air.
The aircraft’s design was well-suited for its intended purpose, which was to engage in combat and provide support to ground troops.
The Sokol radar and the dual controls were particularly useful in ensuring that the aircraft could operate effectively in unfavourable weather conditions and during lengthy missions.
The Centre fuselage of the aircraft housed two 37 mm NL-37L cannon, which were positioned at a low level on either side.
Typically, each cannon carried a supply of 50 rounds, although the ammunition boxes had the capacity to hold twice as much.
Additionally, the wings of the aircraft had the capability to accommodate two 212-millimeter (8.3 in) ARS-212 unguided rockets.
The aircraft’s avionics were designed to enable navigation and interception of targets under all weather conditions, up to its service ceiling.
In addition to the radar, the aircraft was equipped with an SRO-1 IFF transponder, an RSIU-3 Klyon VHF radio, and an AP-28 autopilot.
To facilitate automatic landing in adverse weather conditions, the Yak aircraft featured a Materik Instrument Landing System, which allowed for precise approach and touchdown.
The aircraft’s avionics systems were further enhanced by the inclusion of the Pozitron-1 system, which likely served as a command link system.
The Yakovlev aircraft was equipped with various de-icing systems to ensure optimal performance in cold weather conditions.
The wings, tail unit, and air intakes were equipped with hot air de-icing, while the engines’ foreign object damage protection screens and intake centre-bodies were de-iced electrically.
These de-icing systems allowed the Yak to operate in regions with a cold climate and remain at colder altitudes for extended periods of time.
Despite its complex avionics and heavy components, the Yakovlev aircraft featured a lightweight airframe for a twin-engined fighter.
This was achieved through a design that focused on reducing the structural weight to the minimum necessary.
By employing innovative design techniques, Yakovlev was able to create an aircraft that maintained its structural integrity while minimizing unnecessary weight.
Yakovlev produced two prototypes and a static test mock-up during the development of the aircraft.
The first prototype took its maiden flight on 19 June 1952, with Yakovlev test pilot Valentin Volkov at the controls.
The manufacturer’s testing of the aircraft continued until November, ensuring that all necessary evaluations and assessments were conducted to guarantee its performance and reliability.
The Yak-120 demonstrated exceptional performance in meeting the specific operational requirements of the Air Force, with the exception of speed and range.
Its endurance of 3 hours and 45 minutes without a drop tank (or 4 hours and 15 minutes with a tank) and a range of 2,800 km on internal fuel at an altitude of 12,000 m enabled it to conduct long-range patrols.
Despite being smaller and lighter, it outperformed its competitor, the Lavochkin La-200B.
However, the aircraft faced a setback in its path to state acceptance trials due to delays in the development of the RP-6 radar.
Consequently, the RP-1 Izumrood radar was temporarily installed in early December as a substitute.
To assess the performance of the Yak-120 with the RP-1 radar, testing was conducted at the Scientific Research Institute of the Air Force (NII VVS) between May and June 1953.
The results of these tests were predominantly positive, leading to the authorization of the aircraft for production under the service designation Yak-25.
The specifications derived from the NII VVS test results were officially approved for the Yak-25 through a Council of Ministers directive on 8 September.
In summary, the Yak-120 proved to be a highly capable aircraft that met the Air Force’s operational requirements in various aspects, except for speed and range.
Its endurance and range allowed for extended long-range patrols, surpassing the performance of its competitor.
However, delays in the development of the RP-6 radar prevented the aircraft from undergoing state acceptance trials.
As a temporary solution, the RP-1 Izumrood radar was utilized, and after successful testing at the NII VVS, the Yak-25 was authorized for production based on the specifications derived from these tests.
Production and the Yak-25M The production of Yak-25s took place at Factory No. 292 in Saratov, and the first aircraft was completed in September 1954.
These aircraft were equipped with the RP-1D radar, although only a few were built according to the original specifications.
This was due to the fact that the RP-6 radar had already been fully developed by the end of 1953.
As a result, in April 1954, a Yak-120 prototype with the RP-6 radar successfully completed its state acceptance trials.
Subsequently, on 13 May, the Council of Ministers approved the production of a modified version known as the Yak-25M.
The Yak-25M incorporated various changes in addition to the radar upgrade.
The AM-5A Srs 1 turbojets were replaced with RD-5A (AM-5A) Srs 2 engines, which had the same rating.
Furthermore, the wheelbase was extended by moving the nose gear unit 33 cm forward.
This adjustment aimed to enhance the aircraft’s directional stability during takeoff and landing.
Additionally, the cannons were equipped with muzzle brakes.
A total of 406 Yak-25Ms were manufactured at the Saratov factory, and deliveries commenced in January 1955.
RAF RPF ELINT flights conducted from October 1956 revealed that the Yak-25M had been put into service.
However, it was observed that ground-based radars had poor height-finding capabilities, rendering interception ineffective above 35,000 feet.
Despite this limitation, the Yak-25M played a significant role in the aviation industry during its operational period.
Further Yak-120 developments In September of 1953, the Yak-120’s state acceptance trials for its first stage were completed.
Following this, the second prototype of the Yak-120 was re-engined with the new Mikulin AM-9A turbojet, which was an improved version of the AM-5.
The aircraft was also equipped with rocket pods for 57-millimeter ARS-57 Skvorets folding-fin aircraft rockets, which were intended to be used against enemy bomber formations.
The Yak-120M was then designated to begin its state acceptance trials in September of 1954, with a modified RP-6 known as the Sokol-M to be added.
However, due to the late delivery of the engines and lack of radar, the aircraft was not completed until the end of 1954.
As a result, the aircraft was instead equipped with a standard RP-6.
In November, the first stage of the state acceptance trials was postponed until January of 1955, with the standard RP-6 and no FFARs.
By March of that year, the aircraft was planned to be ready for the second stage, with the Sokol-M and FFARs.
The same directive that changed the schedule also specified that the 190-millimeter TRS-190 rocket be used as alternate armament.
To allow for the increased weight of the rockets, lighter 23-millimeter Nudelman-Rikhter NR-23 cannons replaced the N-37Ls.
In summary, the Yak-120 underwent several modifications and trials during the 1950s.
The second prototype was re-engined with the new Mikulin AM-9A turbojet and equipped with rocket pods for 57-millimeter ARS-57 Skvorets folding-fin aircraft rockets.
The Yak-120M was designated to begin its state acceptance trials in September of 1954, but due to delays, the aircraft was not completed until the end of 1954.
The aircraft was then equipped with a standard RP-6 and underwent several trials with different armaments, including the 190-millimeter TRS-190 rocket and lighter 23-millimeter Nudelman-Rikhter NR-23 cannons.
The Yak-120M underwent state acceptance trials in two stages, with the first stage being completed on schedule in January 1955 and the second stage concluding in late April of the same year.
However, the aircraft’s performance fell slightly short of the operational requirements, and the Sokol-M was not completed.
Additionally, the need for supersonic interceptors led to the abandonment of the Yak-120M.
As a result, the prototype was repurposed as a testbed for RD-9F engines and redesignated as the Yak-120MF.
In the following years, several Yak-25Ms were refitted as testbeds for air-to-air missile armament in 1955 and 1956.
Yak-125, Yak-25R, Yak-25MR The Yak-125, a prototype of a tactical reconnaissance aircraft, was developed alongside the Yak-120.
To accommodate two AKAFU automatic tilting camera mounts placed side by side, the radar was removed and the nose was slightly extended.
These mounts were equipped with AFA-33/100M, AFA-33/75M, or AFA-33/50M vertical photographic cameras.
Additionally, a flexible oblique camera mount with an AFA-33/75M or AFA-22/50M camera was positioned at the front to cover the port and starboard areas.
During take-off and landing, the ports were safeguarded by hinged doors, and the reconnaissance systems operator in the rear cockpit controlled both the ports and cameras.
The twin cannons of the Yak-120 were substituted with a single NR-23 cannon, which held 80 rounds and was located on the starboard side of the fuselage.
Furthermore, the Yak-125 had an increased internal fuel capacity of 3,925 litres (863 imp gal).
In August 1952, the prototype of the aircraft was completed and subsequently took its maiden flight on 26th August, with Volkov serving as the pilot.
Following this, the manufacturer flight tests were successfully conducted in October 1953.
The state acceptance trials, on the other hand, were carried out between December 1953 and February 1954.
Notably, the Yak-125 showcased superior performance compared to the production models of Ilyushin Il-28R and Mikoyan-Gurevich MiG-15bisR.
However, the state commission recommended certain modifications due to visibility limitations faced by the pilot and reconnaissance systems operator.
These limitations were attributed to the longer nose in the case of the former and the small ventral window for the latter.
Consequently, the commission directed the construction of a small pre-production batch for service trials.
The Yak-125 underwent a redesign of its forward fuselage as a result of comments from the state commission.
This redesign involved moving the reconnaissance systems operator to a compartment in the nose, where oblique and vertical cameras were installed in front of the seat.
Additional cameras were also placed in the centre fuselage, while the rest of the aircraft remained unchanged.
The modified version of the aircraft was given the name Yak-25R.
A directive from the Council of Ministers on March 10, 1955, followed by an order from the Ministry of Aircraft Production the next day, tasked Yakovlev and Factory No. 292 in Saratov with building ten pre-production aircraft.
However, due to the Yak-25R’s obsolescence, Yakovlev’s later supersonic reconnaissance aircraft, which was ready for testing, and the introduction of the Il-28R as the main reconnaissance aircraft of the Soviet Air Forces, the Yak-25R did not enter production.
In September 1954, Yakovlev received a directive from the Council of Ministers and an order from the Ministry of Aircraft Production to create a speedy maritime reconnaissance version of the Yak-25, known as the Yak-25MR.
The purpose of this aircraft was to meet the needs of Soviet Naval Aviation for a reconnaissance plane that could match or surpass the performance of the Yak-25.
The State acceptance trials for the Yak-25MR were set to begin in February 1955. Yak-125B
Yakovlev was assigned the task of developing a high-speed nuclear bomber based on the Yak-125 design, known as the Yak-125B.
This directive came from a special joint order issued by the Central Committee of the Communist Party and the Council of Ministers.
The primary objective of the Yak-125B was to penetrate enemy air defenses and carry out nuclear strikes on strategic targets located in the enemy’s rear.
The aircraft had a two-member crew, with the navigator also serving as the bombardier.
The navigator’s compartment was situated in the extreme nose of the aircraft.
The nuclear bomb was stored in a bomb bay near the center of gravity, resulting in the nose unit of the undercarriage being equipped with twin wheels of similar size to the main unit, which was positioned just behind the bomb bay.
This particular configuration was later adopted for Yakovlev’s tactical bombers, including the Yak-28.
Notably, the Yak-125B was the first Yakovlev aircraft to incorporate a 360-degree ground mapping and bomb-aiming radar called the RMM-2 Rubidiy.
This radar system was housed in a radome directly beneath the cockpit.
The Yak-125B commenced flight testing in 1955, and the production version was intended to be designated as the Yak-25B.
However, it never progressed to the production stage due to becoming outdated, as Yakovlev focused on testing a more advanced supersonic nuclear bomber, the Yak-26. Yak-25RV The Yak-25RV, also known as ‘Mandrake’, was a reconnaissance aircraft developed in 1959 as a derivative of the Yak-25.
It featured a new, longer wing with a span of 23.4 meters and a total area of 55 square meters, which was more than twice the size of the Yak-25M interceptor.
The fuselage was equipped with camera and sensor packs, and some versions may have retained one cannon.
Despite its low wing loading, the Yak-25RV’s altitude performance was subpar due to engine problems at high altitudes, excessive vibration, and primitive equipment that imposed high workloads for the crews.
Nevertheless, the Soviet Air Force kept the Yak-25RV in service until 1974, and a few were used in the late 1970s for monitoring radioactive contamination with specialized sensors, designated as Yak-25RRV.
However, efforts to develop the ‘Mandrake’ as a high-altitude interceptor in 1971 (Yak-25PA) were unsuccessful.
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 interception practice, while the Yak-25RV-II was a remote-piloted drone. Yak-26 The derivative Yak-26 was developed as a bomber, but only nine were built. The Yak-25 made its debut at Tushino Airfield in July 1955, where it was showcased to the public.
Initially designated as Flashlight, it was later renamed Flashlight-A when the Yak-26 and Yak-27 were introduced.
From 1955 onwards, air defence units began to be equipped with these aircraft.
The Yak-25 was highly regarded for its user-friendly nature and was well-liked by the crews operating them.
However, engine breakdowns were a common occurrence, primarily due to the low positioning of the engines when the aircraft was on the ground.
This necessitated the need for clean airfields.
Nevertheless, the twin-engine configuration of the Yak-25 minimized the number of fatal failures.
The inclusion of twin engines and a radar intercept operator on board instilled greater confidence in pilots during long missions conducted in the remote northern and eastern regions of the Soviet Union.
In 1955, a total of 108 pilots and 95 ground crew members successfully completed conversion training on the Yak-25M at the Savasleyka PVO Training and Methodical Center.
Despite its capabilities, the Yak-25 had a limited service ceiling, rendering it unable to intercept the American RB-47 Stratojet, which frequently conducted reconnaissance missions over Soviet territory.
The process of phasing out the Yak-25 began in 1963, with the last interceptors being retired by 1967.
However, the ‘Mandrake’ reconnaissance variant continued to serve in various capacities until the late 1970s.
Similar to other PVO interceptors of the Cold War era, the Yak-25M was not exported to any nations within the Warsaw Pact or elsewhere. Variants Yak-25 First production version equipped with the RP-1D “Izumrud” radar. 67 aircraft built. Yak-25B Projected production version of Yak-125 tactical nuclear bomber prototype. Yak-25M Basic production version with some minor improvements, upgraded AM-5A engines and new RP-6 “Sokol” radar. 406 aircraft built. Yak-25MG Some Yak-25M aircraft refitted with the ‘Gorizont-1’ system to allow them to be flown (via autopilot) by ground stations for ground control interception missions. According to aviation historian Yefim Gordon, this designation was used for Yak-25Ms upgraded to the newer Granat radar later in their careers. Yak-25RV (“high-altitude reconnaissance”) High-altitude reconnaissance version with new wing and camera and sensor packs in the fuselage.
155 aircraft built. Yak-25RR (radiation reconnaissance aircraft) Yak-25RV equipped with specialized sensors for monitoring radioactive contamination. Yak-25RRV (high altitude electronic intelligence aircraft) Yak-25RV equipped with specialized SIGINT sensors. Yak-25RV-I Manned target version for unarmed (no live fire) interception practice. Yak-25RV-II Remote-piloted drone for armed (live fire) interception practice. Yak-25PA (balloon interceptor) Balloon interceptor version of the Yak-25RV, probably armed with a single cannon; one built / converted. Yak-25 family prototypes and projects Yak-2AM-11 Reconnaissance and tactical reconnaissance projects powered by 2 x Mikulin AM-11(Tumansky R-11), cancelled as production of Tumansky R-11 allocated to MiG-21. Yak-13 immediate predecessor of Yak-120, not built (re-use of designation from light tourer of 1946). Yak-25K Yak-25M with removed cannon, equipped Yak-25K-5 weapon system consisting of the “Izumrud” radar and four RS-1U (NATO AA-1 “Alkali”) beam-riding missiles on the wings inboard of the engine pods. Small number built. Yak-25K-7L Yak-25K testbed for K-7L missiles. This version did not enter service and the aircraft version was abandoned. Yak-25K-75 Yak-25M testbed for K-75 missiles. This weapon did not enter service and the aircraft version was abandoned. Yak-25K-8 (Yak-25S K-8) Two Yak-25K converted to Yak-25K-8 weapons system testbeds with two K-8 (NATO AA-3 ‘Anab’) missiles. Two Yak-25M aircraft (Yak-25S K-8) were modified for carriage trials of the K-8 missile. Terminated in favor of the upcoming Yak-28P. Yak-25L (flying laboratory) Ejection seat testbed. Yak-25MR (maritime reconnaissance aircraft) Maritime reconnaissance aircraft prototype. Yak-25MSh Prototype of Radio controlled target drone, no production but many were converted to drones after service, but did not have MSh designation. Yak-25R Reconnaissance version with glazed nose for second crewman (navigator) and two cameras. Aircraft armed with 23mm cannon, 10 pre-production aircraft built. Yak-26 Tactical nuclear bomber development, 9 aircraft built. Yak-120M Yak-120 re-engined with Mikulin AM-9A (AM-5 with 0stage added to compressor, can-annular combustion chamber and afterburning and improvements to armament and avionics. Yak-120MF Yak-120M converted to RD-9F engine testbed. Yak-122 Tactical reconnaissance aircraft prototype evolved from the Yak-25 and the Yak2AM-11 project, powered by two RD-9F turbojets. This aircraft was converted into the Yak-27R tactical reconnaissance prototype. Yak-123 prototype for Yak-26 tactical nuclear bomber. Yak-125B OKB designation for Yak-25B tactical nuclear strike aircraft prototype, carrying 1 x (special slung load) Yak-SM-6 Two production Yak-25s modified for testing K-6 AAMs, missile cancelled used for other test tasks. Specifications Yak-25 Crew Two, pilot and radar intercept operator Length 15.665 m (51 ft 4.87 in) Wingspan 10.964 m (35 ft 11.65625 in) Wing area 28.95 m2 (311.62 sq ft) Empty weight 6,210 kg (13,690 lb) Gross weight 9,220 kg (20,326 lb) Powerplant 2 × Mikulin AM-5 (RD-5A) turbojets, 19.6 kN (4,410 lbf) thrust each Performance Maximum speed 1,090 km/h (677 mph, 588 kn) Range 2,700 km (1,677 mi, 1,457 nmi) Service ceiling 12,000 m (39,370 ft) Rate of climb 44 m/s (8,660 ft/min) Armament Guns 2× 37 mm Nudelman NL-37 cannon (50 rounds per gun) Sources Yakovlev Aircraft Since 1924 – Bill Gunston & Yefim Gordon. OKB Yakovlev, A History of the Design Bureau and its Aircraft-Yefim Gordon, Dmitriy Komissarov & Sergey Komissarov. Soviet Aircrafts Illustrated-A.S.Yakovlev. The History of Soviet Aircraft from 1918-Vaclav Nemecek. Soviet AF Fighter Colours 1941-45-Erik Pilaeskii. Soviet Combat Aircraft of the Second World War, Vol 1, Single Engined Fighters-Yefim Gordon and Dmitri Khazanov. Early Soviet Jet Fighters, The1940s and early 50s-Yefim Gordon.
