interceptor
On 6 September, 1976, the fate of the MiG-25P interceptor was significantly influenced. On that day, a pilot serving with a Russian Far East-deployed ADF air regiment, Senior Lieutenant V. Belenko, defected to Japan in his MiG-25P which he landed at the Hakodate airport (on the island of Hokkaido), thus revealing the top secret plane to western experts. Despite the plane having been returned to the USSR quickly, the American experts had enough time to turn it inside out so as to study the MiG’s design and systems. This resulted in the Council of Ministers’ order issued as soon as on the fourth day to take urgent steps to upgrade the aircraft’s weapons suite. The order provided for development of the MiG-25PD (MiG-25-40D intercept complex) intended to be expeditiously put into series production to replace the MiG-25P, as well as for retrofitting all existing planes of the type in accordance with the new requirements.
The new weapons suite was to hit faster targets at higher altitudes, feature greater detection and tracking range, ground-attack capability as well as the dogfight capability. It was also supposed to provide the aircraft with a better anti-jamming protection and the surprise attack capability due to the employment of the IR sensor as a passive detection means. The new weapons suite was derived from that of the MiG-23ML fighter and comprised the Saphhire-25 (N005) radar derived from the Saphire-23ML (N003) radar,
TP-26Sh1 infrared sensor and upgraded R-40DR and R-40DT radar and IR homing AAMs with their homers ‘borrowed’ from the R-24R radar and R-24T heatseeker homing missiles, as well as R-60 (R-60M) short-range air-to-air missiles. The plane was powered by R15BD-300 enhanced life-span engines featuring newer accessory gearboxes with generators to provide power supply to the Sapphire-25 radar. The aircraft was also fitted with a modified SAU-155PD automatic control system. Some of the communications equipment was also replaced. There was a provision made for mounting a 5,300-litre underbelly drop tank, which would increase the range up to the 2,400 km.
In 1977, at the Gorky-based aircraft plant production of three aircraft, namely, #305, 306, 307, was started under the MiG-25PD programme. The first of them was taken on its maiden flight on 19 November, 1977 by test-pilot V.E. Menitsky with the testing of the other two following in 1978. Besides, the MiG-25P served as a base for deriving in 1977 of a LL-1104 flying lab to develop the SAU-155PD automatic control system, modernised targeting system and other systems. Phase B of the joint official testing was being held during September 1978 – February 1979 with the whole MiG-25-40D intercept complex being included into the inventory in 1980. The MiG-25PD series manufacture at the Gorky plant (Sokol NGAZ nowadays) had been underway since 1978 till 1984 resulting in the total of 150 plus aircraft, some of which were exported to Iraq (20), Syria (30, 6 PU) and Algeria (17). The export versions mounted the Smerch-A2 radar which ensured the firing of the R-60M missile.
MiG-25PDS (product 84DS)
This designation was issued to the MiG-25Ps retrofitted at aircraft repair plants to meet the MiG-25PD standard. The modernisation consisted in replacing the RP-25 Smerch radar by the S-25 Sapphire-25 radar, R15B-300 engines by R-15BD-300 ones as well as of some over equipment, and in making the plane able to fire the R-40DR radar- and R-40DT IR-homing air-to-air missiles as well as R-60 missiles. The first two aircraft were re-equipped at the Air Force repair plant in 1978 with their official testing held during March-June 1979. The retrofitting of all the MiG-25P’s into the MiG-25PDS version was completed in 1983.
MiG-25PDSL
In 1982, one of the MiG-25PDS (reg. #7011) was fitted with ECM equipment to provide individual and collective protection from enemy radar- and IR-homing air-to-air and air-to ground missiles. The equipment comprised the Beryoza-LE radar warning receiver (RWR), Geranium ECM system and KDS-155 flare dispenser. The flight testing was completed in 1983. Later, another aircraft was converted for the same purpose. It was designated MiG-25PDSL (reg. #94). It was equipped with the Beryoza-LM RWR, Gardenia-1FU active ECM system mounted in the external pod, as well as chaff and flare dispenser. Its flight testing commenced in 1985.
MiG-25PDM
This was the programme aimed at upgrading the MiG-25PD interceptor through replacement of the Sapphire-25 radar by the Sukhoi Su-27’s RLPK-27 radar or MiG-29’s RLPK-29UM radar and some other avionics by newer units. The preliminary design was ready in 1985.
In air force of Russia the MiG-25P are replaced with an airplane of new generation the MiG-31.
Configuration and design. The aircraft features the regular aerodynamic configuration and is an all-metal high-wing monoplane with a trapezoid wing, twin tails, all-moving empennage, retractable tricycle landing gear and two engines mounted in the rear of the airframe. The primary materials used in designing the airframe are VNS-2, VNS-4 and VNS-5 steel alloys making up 80% of the airframe, titanium alloys (8%) and D-19T heat-resistant aluminium alloy.
The semi-monocoque fuselage has no maintenance breaks with its main load-carrying compartment is the integral fuel tank. The airframe is divided into the following bays: front bay (up to frame 1), cockpit (between frames 1 and 2), aft-cockpit bay (between frames 2 and 3), side-mounted air intakes (between frames 2-6), fuel tanks’ bay (between 3 and 12), tail bay (between frames 12 and 14) and tail cone (behind frame 14)/ The fuselage nose section mounts the radar antenna cone casing covering radar and IR seeker units. The pressurised cockpit is fitted with the canopy whose hinged part is opened rightwards. The cockpit transparency is made of heat-resistant glass 20 mm (windscreen) and 12 mm (hinged part) thick.
The lower part of the slanted frame mounts ejection seat and nosewheel strut fixtures. The KM-1M ejection seat is effective at any altitude at a minimal speed of 130 km/h. The pressurised and heat-proof upper part of the aft-cockpit bay houses various avionics systems while the lower part houses the nosewheel well.
The fuel tanks’ bay is the main airframe structural element carrying the loading of the wing, empennage and landing gear. It is made of VNS-2, VNS-4, VNS-5 and SN-3 steels through the argon welding. Inside the bay, there are six fuel tanks: tanks 1and 2 between frames 3 and 6, tank 3 between frames 6 and 7, tanks 4 and 5 between frames 7 and 11, tank 6 between frames 11 and 12. The area between frames 6 and 9 houses main landing gear wells with the gear strut fixtures being mounted on frame 8/ The airframe rear section houses the bays holding the engines, gearboxes and stabiliser actuators. To mount and maintain engines, there have been hatches between frames 9 and 13 provided for. The engine nacelles’ lower surfaces mount ventral fins and two spoilers. The fuselage spine fairing near the nozzles turns smoothly into the drag chute container.
The aircraft features side-mounted horizontal-ramp scoop-type rectangular variable air intakes. The lower part of the air intakes is made as a door which can take three positions. Three boundary layer suction channels are situated on the airframe surface above the air intakes. There are boundary layer drain slots between the air intake sides and airframe sides to drain the air into the engine compartment.
The tapered wing has a leading edge sweep angle of 42.5 degrees in the root and 41 degrees in the tip with the trailing edge sweep angle of 9.5 degrees, dihedral of -5 degrees and setting angle of 2 degrees. The wing airfoil is 3.7% thick in the root and 4.76% thick in the tip. The main elements of the wing are three longerons and two auxiliary beams. There are integral fuel tanks inside the wing with two cells housed by each wing panel. Each wing panel is attached to the airframe by five fixtures. The trailing edge mounts ailerons and flaps. The leading edge slats are detachable for the ease of access to the hydraulic and fuel systems’ pipelines. The wingtips carry antiflutter loads. The air-to-air missile launch pylons are mounted under the wing, two at each wing panel. There are fences mounted on the upper surface of each wing panel right above the pylons.
The empennage is all-moving and differentially-deflectable to control the banking. The stabiliser’s leading edge has a sweep angle of 50.3 degrees. The stabiliser’s deflection angle is 32/-13 degrees during take-off and landing and 12.5/-5 degrees in flight at s max speed.
The aircraft is fitted with two rudder-equipped tails and underbelly fins. The fins’ leading edge sweep angle is 54 degrees while the tails are outwardly canted at 8 degrees. The tails are of three-spar design. Their rudders deflect at +/-25 degrees.
The landing gear is retractable, and tricycle-type. The nosewheel strut is fitted with two KT-112 700-by-200 mm breaking wheels and a mudguard and retracts forward. The main struts fitted with KT-111 1,300-by-360 mm breaking wheels are fixed to the airframe and retract in it. The aircraft is equipped with a drag chute of two 50 sq.m canopies. The left ventral fin houses a extendable probe that extends during the landing and touches the runway, thus activating the automatic drag chute deployment.
Powerplant. It comprises two R-15BD-300 engines with a thrust of 11,200-kgf in afterburner. 17,470 litres of the T-6 avgas are carried in six fuselage and four wing tanks. A 5,280-litre drop tank could be mounted under the fuselage. The aircraft systems include the main and auxiliary hydraulic systems, pneumatic system, power supply system, air conditioning system, fire suppressant system, etc.
Avionics. The MiG-25PD sighting system comprises the Sapphire-25 radar, AVM-25 computer and TP-23 IR
seeker. The aircraft also carries the Lazur-M radio command system.
The Polyot-1I navigation suite incorporates the RSBN-6s short-range radio navigation system, SKV-2N attitude and heading reference system and SVS-PN-5 air data computer system, ARK-10 radio compass, RV-4 and RV-18 radio altimeters, MPR-56P marker receiver, SO-63B transponder and SAU-155P autopilot and flight director automatic control system.
Communication between the crew and ground control as well as between the crew and other aircraft is performed via the R-832M VHF radio and R-864 short-wave radio.
Weapons suite. It comprises missiles only, which are attached to four underwing hardpoints and include the R-40RD or R-40TD medium-range air-to-air missiles as well as R-60M short-range air-to-air missiles. The missiles can be carried in the following configurations: 2 R-40RDs and two R-40TDs; 4 R-40RDs; 2 R-40RD and 4 R-60Ms.
References and Credits:
- Aviatsia i Kosmonavtika №8. 1999
- History and aircraft of Mikoyan design bureau / «Wings of Russia», 1999, CD-ROM /
- Aerospase Herald №4. 1999
- «Fighters» / V.Il’in, M.Levin, 1997 /
- MiG-25PD / «Sky Corner» /
- Mig-25 / Su-27 Flanker in life and in game (A.Shukaylo) /
References and Credits:
- Aviatsia i Kosmonavtika №8. 1999
- History and aircraft of Mikoyan design bureau / «Wings of Russia», 1999, CD-ROM /
- Aerospase Herald №4. 1999
- «Fighters» / V.Il’in, M.Levin, 1997 /
- MiG-25PD / «Sky Corner» /
- Mig-25 / Su-27 Flanker in life and in game /