YAK-36/38 'Forger' & Yak-141 - Russia's forgotten Harrier jump jet rivals.

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  1. AJSINGH

    AJSINGH Senior Member Senior Member

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    The Yakovlev Yak-38 (Russian: Як-38, NATO reporting name: Forger) was Soviet Naval Aviation's first and only operational VTOL strike fighter aircraft.

    Design and development
    The first drawings showed a supersonic aircraft strongly influenced by Hawker P.1154 in study in the United Kingdom but with two R27-300 engines. Supersonic performances would have implied many difficulties of development, and it was decided to initially develop a relatively simple aircraft limited to Mach 0.95. Although the Yak-38 and Yak-38M were developed from the land-based Yakovlev Yak-36, the aircraft had almost nothing in common.
    The Prototype VM-01 was finished on April 14, 1970. Though outwardly similar to the British Harrier Jump Jet, it followed a completely different configuration. Apart from having a vectorable engine in the rear used for flight, two smaller, less powerful engines were housed in the front portion of the aircraft and used purely for take-off and landing. (The Harrier uses only one engine, vectoring its thrust through four nozzles.) The aircraft used a similar layout to the German experimental VTOL strike fighter, the VFW VAK 191B, which began development in 1961, and the contemporary Dassault Mirage IIIV.


    A diagram showing the lift forces on a Yak-38 in VTOL mode
    The Yak 36 was sent for tests in May and June 1970. Mikhail Deksbakh carried out the first flight of the VM-02 in conventional mode on January 15, 1971. The VM-03 made its first flight in short takeoff mode on May 25, 1971. Sea trials aboard the aircraft carrier ("aviation cruiser") Kiev were observed in 1975. 231 Yak-38 aircraft were produced, including 38 two-seat trainers (Yak-38U). These were based on the four Kiev class aircraft carriers.
    The Yak-38 used a hands-free landing system. The aircraft could negotiate a telemetry/telecommand link with a computer system in the aircraft carrier which would allow it to be guided onto the deck with no interaction from the pilot.

    Operational history
    The majority of Yak-36M initial production deliveries were to the 279 OKShAP (Otdelnyi Korabelnyi Shturmovoi Aviatsionnyi Polk, Independent Shipboard Attack Air Regiment) initially based at Saki, the AV-MF’s training centre in Crimea. Pilots for this unit were drawn from the Yakovlev OKB and the LII at Zhukovskii, as well as from the AV-MF. Established as early as December 1973, the 279 OKShAP of the Black Sea Fleet made use of a dummy Kiev class aircraft carrier deck, and also operated a pair of MiG-21UMs (and, briefly, Ka-25s) for training. The first AV-MF squadron embarked on Kiev in July 1976. On the conclusion of acceptance tests for the Yak-36M initial series in August 1976 (Kiev was underway in the Atlantic at this point), the aircraft was formally accepted by the AV-MF in October, under the new designation Yak-38.
    On its arrival in Murmansk, the 279 OKShAP was transferred to the Northern Fleet, with subsequent flying operations mainly being conducted from Severomorsk-3. The 299 IIAP (Issledovatlesko-Instruktorskiy Aviatsionnyi Polk, Research and Instructor Air Regiment) had been formed as a training unit at Saki in September 1976 to replace the previous unit within the Black Sea Fleet.
    The February 1978 entry into service of Minsk, the second Kiev class ship, was accompanied by a further series of Yak-38 shipboard trials, beginning in April 1978, and with the emphasis now placed on developing procedure for STOL operations. The passage of Minsk out of the Black Sea in February 1979 was duly followed by a major exercise involving the first two ships of the Project 1143 class in the Mediterranean. On this occasion, five aircraft from each vessel conducted formation exercises in proximity to NATO observers.
    The Yak-38’s limited useful payload was always its Achilles’ heel, but the high ambient temperatures that had been encountered in the Black Sea during the summer 1976 trials frequently prevented the aircraft from carrying any external stores at all, despite a reduced fuel load. Similar problems were then encountered when Minsk sailed off the coast of West Africa and then in the Indian Ocean; in these instances the lift jets proved unwilling to start under hot and humid conditions. (An oxygen-boosting intake system[clarification needed] helped alleviate the problem, and was installed from September 1979 during routine overhauls.) In July 1979, Minsk arrived in the Sea of Japan, where the vessel was home-ported at Strelok Bay, the Yak-38 component of its air wing thereafter being provided by the 311 OKShAP subordinate to the Pacific Fleet. The 311 OKShAP was the second AV-MF Yak-38 unit, and had been established in March 1976.
    During its first few years of ship-borne operations the Yak-38 was not cleared to make rolling take-offs and run-on landings, leading some Western observers[who?] to believe that the fundamentals of its propulsion design restricted the type to VTOL operations.[citation needed] In fact, shipboard short take-off trials had begun by December 1979, while experiments with run-on landings followed onboard Minsk between September 1980 and February 1981. V/STOL operations were made easier by the addition of a refined automatic flight-control system, linked to a thumb switch on the pilot’s stick. Rolling take-offs were conducted with the lift engines deflected aft, the main engine nozzles being rotated automatically from 60° to 25° during the take-off run, before being slowly returned to the horizontal as the lift engines were shut down.
    The Kiev class ships normally embarked a total of 12 single-seat Yak-38s, supplemented by two or three two-seat Yak-38Us, as part of an independent aviation regiment that also included two squadrons of (mainly anti-submarine warfare) helicopters. Of the seven landing pads available on the deck of each of the Project 1143s, all but one could accommodate the Yak-38.
    During April and May 1980 four Yak-38s and four AV-MF pilots were deployed to Afghanistan as part of a 50-day trial codenamed Romb-1, although the ‘hot and high’ conditions prevented any meaningful combat missions from being undertaken – in total, 12 combat sorties were made, but only two 100 kg (220 lb) bombs could be carried. In the event, any involvement would have been further limited by the ‘near-operational’ nature of the Romb-1 deployment (which also involved the first and third prototype Su-25s). The aircraft involved were not intended to be subject to combat, but rather tested under conditions that simulated the battlefield to a high degree. Despite their official non-operational nature, aircraft involved in the Romb trials could be requested to undertake combat sorties by local divisional commanders, on an ad hoc basis. The Yak-38s and prototype Su-25s operated out of a specially prepared air base near Shindand. Even with a much-reduced fuel and weapons load, the Yak-38 proved incapable of operating during the hot daylight hours (after around 0500 hrs).
    In September 1982, Novorossiysk - the third Kiev class vessel - was commissioned. By now the V/STOL technique had been well practised, and the resulting increase in the Yak-38’s overall performance and capability was exploited during the passage of Novorossiysk from Severomorsk to join the Pacific Fleet. In a maritime context, the Yak-38 was not limited to the decks of the Kiev class. In September 1983, AV-MF pilots operated from the civilian ‘Ro-Ro’ vessel Agostinio Neto, and NII-VVS pilots conducted further tests from another ‘Ro-Ro’, Nikolai Cherkasov. In both cases, use was made of a heat-resistant landing platform; further land-based trials tested the practicality of dispersed landing platforms, in a similar concept to the RAF’s Harrier operations in West Germany.
    Variants

    Yak-36M "Forger"
    The initial pre-production version, differing slightly from the Yak-38. It weighed only 6,650 kg (14,660 lb) compared to the Yak-38's 7,370 kg (16,250 lb) and the engines were slightly less powerful.
    Yak-38 "Forger-A"
    The Yak-38 was the first production model, it first flew on January 15, 1971, and entered service with the Soviet Naval Aviation on August 11, 1976. A total of 143 Yak-38s were produced.
    Yak-38M "Forger-A"
    The Yak-38M was an upgraded version of the Yak-38, the main difference being the new Tumansky R-28V-300 and two Rybinsk RD-38 engines. The maximum take off weight in VTOL was increased from 10 × 300 kg (660 lb) to 11 × 300 kg (660 lb) (or 12,000 kg/26,450 lb in short takeoff mode). The air intakes were slightly widened and the pylons under wings were reinforced to carry a ton of armament. Yak-38M begin entered service with the Soviet Naval Aviation after June 1985, a total of 50 Yak-38M were produced.
    Yak-38U "Forger-B"
    Two-seat training version for the Soviet Naval Aviation, this version differed from the basic aircraft in having an enlarged fuselage to accommodate a two-seater cockpit. The Yak-38U entered service on November 15, 1978, a total of 38 Yak-38U have been produced with the 38th aircraft being delivered in 1981.
    [edit]Unbuilt projects
    Yak-36P (or Yak-36MF)
    Intended supersonic follow-on to the attack-optimised Yak-36M, adding AI radar, medium-range AAMs and advanced navigation equipment. A third RD-36-35 lift jet was also added to cope with increased take-off weight.
    Yak-36-70F
    1970 project for supersonic light fighter with a pair of afterburning (hence ‘F’ suffix) lift/cruise engines, lift engines deleted, variable intakes, bicycle undercarriage.
    Yak-36A
    Project for version with R-49V lift/cruise engine and two lift engines; one fuselage completed for tests under Tu-16.
    Yak-36O
    Refined version of Yak-36M with 15,000 kgf (33,100 lbf) thrust Type 55 (or subsequently R-61V) engine in redesigned fuselage.
    Yak-38L (Yak-38I?)
    AL-21F lift/cruise engine replacing R-27V-300.
    Yak-38MP
    Yak-38M fitted with a weapons system derived from that of the MiG-29 and including N019 radar and advanced nav/attack suite.
    Yak-39
    Multi-role fighter/attack aircraft project dating from 1983, employing one R-28V-300 and two RD-48 engines, PRNK-39 avionics kompleks; S-41D multi-mode radar, larger wing, increased fuel capacity and expanded weapons options based around Shkval or Kaira PGM designation systems.


    Specifications (Yakovlev Yak-38M)
    General characteristics
    Crew: One
    Length: 16.37 m (50 ft 1 in)
    Wingspan: 7.32 m (24 ft 0 in)
    Height: 4.25 m (14 ft 5 in)
    Wing area: 18.5 m² (199 ft²)
    Empty weight: 7,385 kg (16,281 lb)
    Loaded weight: kg (lb)
    Max takeoff weight: 11,300 kg (28,700 lb)
    Powerplant: 1 x Tumansky R-28 V-300 turbojet, 66.7 kN (15,000 lbf)
    Powerplant: 2× Rybinsk RD-38 turbojets, 31.9 kN (7,870 lbf>) each
    Performance
    Maximum speed: 1 280 km/h (795 mph)
    Range: 1,300 km (807 miles)
    Service ceiling: 11,000 m (36,089 ft)
    Rate of climb: 4,500 m/min (14,760 ft/min)
    Wing loading: kg/m² (lb/ft²)
    Thrust/weight: 1+
     
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  3. AJSINGH

    AJSINGH Senior Member Senior Member

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    Yakovlev Yak-141
    The Yakovlev Yak-41 (NATO reporting name Freestyle) is a supersonic VTOL fighter aircraft from the Soviet Union. It did not enter production.
    Design and development
    Yakovlev always believed the Yak-38 to be an interim aircraft, developed to gain experience designing and developing military VTOL aircraft. Even before the Yak-38's introduction, the Soviet Navy desired a more comprehensive aircraft, with greater capabilities than the Yak-38 offered. The result was a design contract offered to Yakovlev in 1975 without any competition. The requirement was for an aircraft with only one mission: air defense of the fleet. Unlike the Yak-38, this aircraft was to have sustained supersonic speed. Maneuverability, radar and weapons loads were expected to be similar to those of current front-line fighters. For the Soviet Navy this aircraft was to be their next generation VTOL fighter. For Yakovlev the aircraft was viewed as a way of returning to designing Soviet fighter aircraft.[1]
    Because of the importance and complexity of the project Yakovlev assigned a large portion of his OKB to the development of the new VTOL fighter, which the OKB called "Product 48", and the military designated Yak-41. The program had no fewer than ten chief engineers working simultaneously. Over fifty designs were studied. One key problem was designing an aircraft with both vectoring thrust and an afterburner, which was essential for sustained supersonic speeds. A twin engine design was considered, but abandoned as the loss of an engine on landing would result in an immediate roll to the side. Eventually it was decided that the best arrangement was a single vectoring nozzle located just behind the center of gravity, as well as dedicated vertical thrust jets positioned just behind the cockpit. A considerable amount of time was spent in the development of a flat, rectangular nozzle similar to that later employed on the American F-22 Raptor. Such a nozzle proved well-suited for the changes in configuration needed for both thrust vectoring and supersonic flight, and allowed for a thin, shallow tail. Ultimately, a circular nozzle was used, located between twin booms supporting the twin-finned tail.[1]
    The final design bore a strong resemblance to other contemporary fighters such as the MiG-25 and American F-15 Eagle. Parts that were to be subjected to excessive heat from the engines during landing were manufactured of titanium, and no less than 26% of the overall aircraft was to be manufactured of graphite or composite material. Because of heat build-up, hovering was restricted to no more than 2 1/2 minutes.[1]
    All three engines were controlled through an interlinked digital system, which was capable of controlling both engine start-up as well as modulating the thrust of all three engines during landing and hovering flight. Twin tandem reaction control jets were positioned at the wingtips, while a swiveling yaw jet was positioned under the nose.[1]
    The cockpit was pressurized and air-conditioned. The small canopy was bulletproof in front. It hinged to the right, but because of a long dorsal spine it had no rear vision. The ejection seat was automatically armed as soon as the engine duct was rotated past 30 degrees with an airspeed of less than 300 km/h (186 mph). The instrumentation in the prototypes was simple and similar to that planned for the earlier Yak-36M. The production version was to have been fitted with an extensive avionics and weapons suite including doppler radar, laser-TV ranging and aiming, as well as a heads-up multifunction display (HUD) which worked in connection with a helmet-mounted missile aiming system as found on the Mikoyan MiG-29. This system allows the pilot to lock onto an enemy aircraft by turning his head as far as 80 degrees from front.[1]
    The undercarriage was tricycle, and equipped with the latest multi-disc, anti-skid brakes. The steerable nose wheel retracted to the rear, while the main gear retracted forward.[1]
    The top mounted wing was similar to that used on the Yakovlev Yak-36, though the outer panel swept back, and could be folded up for shipboard storage. The main engine was served by four side-mounted ducts as well as a row of large louvers along the upper surface to allow air to enter the engine during full power hovering. This engine was the R-79V-300, a two-shaft augmented turbofan with a bypass ratio of 1. Maximum thrust was 14,000 kg (30,864 lb). The rear nozzle could rotate from 0 degrees to 95 degrees for VTOL landing and hovering. The two lift engines were the RD-41 design, a simple single-shaft engine made mostly of titanium. Each had a thrust of 4,100 kg (9,040 lb). The engines were installed behind the cockpit at an angle of 85 degrees. Like the Yak-38, the engines received their air through eight spring-operated dorsal flaps, and the exhaust exited through a belly opening covered by two ventral doors.
    Testing
    Yakovlev obtained funding for four prototypes. The first (48-0, with no callsign) was a bare airframe for static and fatigue testing. The second (48-1, callsign "48") was a non-flying powerplant testbed. The third and fourth (48-2 and 48-3, callsigns "75" and "77") were for flight testing. While 48-1 remained unpainted, 48-2 and 48-3 were painted in overall grey, with a black radome and fin cap antennas.[1]
    The first conventional flight, using 48-2, took place at Zhukovskii on 9 March 1987, with chief test pilot Sinitsyn at the controls. He made the first hovering flight on 29 December 1989 flying 48-3, and used the same aircraft to make the first complete transition from vertical to high-speed flight and vertical landing on 13 June 1990. From April 1991, various kinds of rolling take-off and run-on landings were performed on normal runways and also "ski-jump" ramps at the lift jet center at Saky. Throughout testing the aircraft was found to demonstrate excellent combat maneuvers.[1] Chief test pilot Sinitsyn went on to set twelve new world class records, but as the Yak-41 designation was classified, the records were submitted under the fictitious name "Yak-41".[1] As a result, the previously unknown aircraft came to be known in the west as the "Yak-41". In 1992, Yakovlev repainted both flying aircraft in olive/grey camouflage, with the Russian tricolor insignia, and painted a white "141" on both aircraft in place of their previous callsigns, "75" and 77".[1]
    On 26 September 1991, Sinitsyn made the first vertical landing on the Soviet aircraft carrier Admiral Gorshkov (ex-Baku) in 48-2. An hour later, Vladimir A. Yakimov landed 48-3 on the same deck. The pilots would go on to make eight flights from the ship until Yakimov made a hard landing on 5 October. The undercarriage ruptured a fuel tank, causing a serious fire. After almost 30 seconds, Yakimov ejected successfully, and was rescued from the sea. The aircraft was later repaired and placed on display (see "Survivors").[1] That same month the CIS Navy announced that no further funds were available to continue the program. The factory at Smolensk had anticipated this and had not constructed the tooling for production.
    Lockheed-Martin
    Following the announcement by the CIS that it could no longer fund development of the Yak-41M, Yakovlev immediately entered into discussions with several foreign partners who could help fund the program (a tactic they were also pursuing for development of the Yak-130 trainer, which was eventually developed in partnership with Aermacchi of Italy). Lockheed-Martin, which was in the process of developing the X-35 for the U.S. Joint Strike Fighter program, quickly stepped forward, and with their assistance 48-2 was displayed at the Farnborough Airshow in September 1992. Yakovlev announced that they had reached an agreement with Lockheed-Martin for funds of $385 to $400 million for three new prototypes and an additional static test aircraft to test improvements in design and avionics. Planned modifications for the proposed Yak-41M included an increase in STOL weight to 21,500 kg (47,400 lb). One of the prototypes would have been a dual-control trainer. Though no longer flyable, both 48-2 and 48-3 were exhibited at the 1993 Moscow airshow. The partnership began in late 1991, though it was not publicly revealed by Yakovlev until 6 September 1992, and was not revealed by Lockheed-Martin until June 1994.
    Variants
    Yak-41
    The two flying protoypes and ground test article
    Yak-41M
    Proposed production aircraft with large LERX's (leading-edge root extensions) and other improvements, particularly in the avionic suite.
    Yak-43 (a.k.a. Izdeliye 201)
    A proposed development of the Yak-41M 'Freehand' equipped with Kuznetsov NK-321 engines.
    Yak-141
    Designation originally applied to a single Yak-41 for disinformation and propaganda purposes when registering records with the FAI (Fédération Aéronautique Internationale)[2][3] and later for promotional purposes by Yakovlev.
    Specifications (Yak-41)
    General characteristics
    Crew: One: pilot
    Length: 18.36 m (60 ft 2 1/4 in)
    Wingspan: 10.105 m (33 ft 1 1/2 in)
    Height: 5.00 m (16 ft 5 in)
    Wing area: 31.7 m² (341 ft²)
    Empty weight: 11,650 kg (25,683 lb)
    Max takeoff weight: 19,500 kg (42,989 lb)
    Powerplant: 1× MNPK Soyuz R-79V-300 lift/cruise turbofan
    Dry thrust: 108 kN (24,300 lbf)
    Thrust with afterburner: 152 kN (34,170 lbf
    Lift engines: 2x RKBM RD-41 turbojets 41.7 kN (9,300 lbf) thrust each)
    Performance
    Maximum speed: 1,800 km/h (1,118 mph, Mach 1.4+)
    Range: 2,100 km (1,305 mi)
    Ferry range: 3,000 km (1,865 mi)
    Service ceiling: 15,500 m (50,853 ft)
    Rate of climb: 15,000 m/min (49,213 ft/min)
    Armament
    Guns: 1 × 30 mm GSh-301 cannon with 120 rounds
    Hardpoints: 4 underwing and 1 fuselage hardpoints with a capacity of 2,600 kg (5,733 lb) of external stores and provisions to carry combinations of:
    Missiles: R-73 Archer, R-77 Adder or R-27 Alamo air-to-air missiles

    http://en.wikipedia.org/wiki/Yakovlev_Yak-141
     

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