On 24th January 1961, the USSR Air Forces received the Su-7B fighter-bomber into service. At the insistence of the military, the Government's resolution making the aircraft operational also assigned the design bureau the task of developing a new all-weather version to enable destruction of small targets. The document laid the foundations for the effort of the P.O. Sukhoi Design Bureau to develop the Su-24.
The very first studies undertaken at the New Projects Department of the Sukhoi Design Bureau in 1961-62 under code names S-28 and S-32 made it obvious that it was not possible to do the job by upgrading the original Su-7B, seeing that the extent of the equipment to be installed on board the aircraft was far in excess of available space on the Su-7. A major problem in developing the new plane was to design the aiming and navigation system (ANS) to give the pilot as much automatic control over all major flight and tactical deployment procedures as possible. This Herculean task was given to Design Bureau OKB-794 (later known as Leninets SPA), with Ye.A. Zazorin appointed as chief designer of the system. The system itself became known under a code name of Puma.
In 1962, the Design Bureau began designing a radically new aeroplane, referred to as S-6. The aeroplane had a standard aerodynamic configuration with a thin tapered wing featuring moderate sweepback, with two R21F-300 type engines developed by N.G. Metsvarishvili, and lateral variable air intakes with horizontal airbrake. The crew of two (pilot and navigator/weapon systems officer) were seated in the cockpit in tandem, one behind the other. 1963 saw S-6 conceptual design and a full-scale mock-up produced. An Air Forces commission reviewed the materials and the mock-up, but further work on the project was suspended in connection with a lack of noticeable progress in the development of the Puma ANS.
Starting 1964, the work to produce an attack aircraft at the Sukhoi Design Bureau was continued under a new code name, T-58M, to stand for a version of the Su-15 plane (factory code T-58). The Air Forces adjusted their performance requirements (PR) for the plane to position it now as a low-altitude attack aircraft with a shortened takeoff and landing run (STOL), a major requirement of the military being the ability to sustain a long supersonic flight at a low altitude to penetrate hostile airspace. As the studies progressed, the design concept gradually became more focused. For example, in the summer of 1965, given an increased cross dimension of the Orion sighting station antenna in the nose section of the fuselage, it was decided to introduce a new solution for the cockpit layout, with the crew seated side by side. The powerplant consisted of two R-27F-300 type turbojet thrusters with afterburning developed by the Design Bureau of S.K. Tumansky, and four RD36-35 type lift booster engines by the Design Bureau of P.A. Kolesov for STOL performance.
To try out the combined powerplant and lift-engine-boosted STOL design, the first Su-15 prototype aircraft (T58D-1) was used by the Design Bureau to build a flying laboratory, T-58VD, which was tested between 1966 and 1969, with the flights carried out by the design bureau’s test pilot Ye.S. Solovyov.
Officially, the go-ahead for the development of the aircraft was given by a decree of the government of 24th August 1965. The Design Bureau assigned to the project the working name of T-6. In March 1966, the conceptual design and mock-up were approved, with detailed design completed at the end of 1966. Two prototypes were built concurrently: one for flight testing and the other for structural testing. The first flying prototype, T6-1, was completed in May 1967. On 29th June, it was brought to the FRI airfield and the very next day saw the design bureau’s chief test pilot V.S. Ilyushin perform the first airfield run. On 1st July, a meeting of the FRI advisory board gave the green light for the factory tests to begin. Just next day, 2nd July 1967, V.S. Ilyushin performed the plane's first flight. The urgency of the testing was due to the fact that T6-1 was entered for participation in the Domodedovo air display scheduled for 9th July. But on 4th July, the second test flight resulted in an accident: the left hinged canopy panel was torn off while the plane was in the air. The flight was brought to a successful conclusion, V.S. Ilyushin landing the T6-1 on the airfield. The plane's canopy design was immediately reengineered, with the next flight taking place the following day, but the T6-1's participation in pageant was cancelled. As a result, a presentation of the aircraft to western observers failed to take place in 1967.
Initially, the T6-1 was flight tested without the lift booster engines installed. These were fitted in the aeroplane during the engineering follow-up in October 1967, the R-27 type engines being at the same time replaced with regular AL-21F turbojets with afterburning developed by the Design Bureau of A.M. Lyulka. Following this the plane was tested as a STOL aircraft between November 1967 and January 1968. The testing findings confirmed the data obtained earlier in the course of testing the T-58VD. The improved takeoff and landing characteristics (TOLC) in no way compensated for the aeroplane's shortened range. This was due to the impaired fuel performance as a result of the weight of the lift engines. The other drawbacks of "lifters" included:
- hazardous impact of the exhaust gases on the plane’s structural members and landing gear,
- the impossibility of suspending external stores and ordnance from the bottom of the fuselage.
- the aeroplane's pronounced overbalancing in the forward-aft axis upon their activation.
The faults of the concept obviously overshadowing its advantages, it was necessary to look for alternative solutions to improve TOLC.
Starting mid-1967, the Design Bureau began to look into the option of engineering the T-6 with variable sweep wings. Officially, the efforts to develop the new plane got underway following a decree of the government of 7th August 1968, with the PR for the aeroplane finalised by the Air Forces as an addendum to the 1965 requirements. The T-6 detailed design revision was completed in 1968-69, with two prototypes built by the autumn of 1969. The first flying prototype of the T6-2I aeroplane was moved to the Design Bureau's flight test and development base (FT&DB) at FRI on 10th November 1969. The first flight was performed by V.S. Ilyushin on 17th January 1970. The T-6 official tests took as long as four years: from January 1970 to July 1974. Such a long test period was due to the great complexity and newness of the tasks facing the Design Bureau and the military in the course of refining the aircraft.
The T-6 became the USSR's first attack aeroplane of the tactical air arm to be deployed day or night in all weathers. This was achieved thanks to the Puma ANS consisting of two Orion-A superimposed radar scanners for nav/attack and a dedicated Relyef terrain clearance radar to provide automatic control of flights at low and extremely low altitudes. The ANS incorporated an Orbita-10-58 onboard computer, the armaments including Kh-23 and Kh-28 type air-to-ground guided missiles, together with R-55 type air-to-air guided missiles. A distinctive feature of the T-6 design was the use of a variable geometry shoulder wing, which gave the aeroplane acceptable TOLC and superior APC in various flight modes. Another major design feature of the aeroplane was the extensive use of long-length machined panels. For the first time in two-seat planes of this class the Soviet aviation industry saw a side-by-side crew accommodation arrangement and a standardized type of K-36D ejection seat, allowing the pilots to bail out at any altitude and flight speed, including during takeoff and landing.
A decree of the government of 4th February 1975 included the T-6 plane in the Armed Forces inventory under the designation of Su-24, at the same time authorising development of upgraded versions to improve its combat capabilities. Series production of the T-6 (Su-24) was started in 1971 by pooling the resources of two aircraft plants: The Far Eastern factory named after Yury Gagarin at Komsomolsk-on-Amur (director – V.Ye. Kopylov) and the Novosibirsk plant named after V.P. Chkalov (director – G.A. Vanag). The Komsomolsk-on-Amur plant assembled the fuselage tail units, fins and wing panels, and the Novosibirsk facility made the nose and mid- sections of the fuselage together with the centre wing section, and carried out the final assembly. The first series production plane took off the ground in Novosibirsk on 31st December 1971, flown by the factory's leading test pilot, V.T. Vylomov. Deliveries to the Air Forces started in 1973, with the first production aircraft assigned to the 4th airborne personnel combat training and transition training centre (APCT&TTC) of the Air Forces (town of Voronezh), with the 3rd bomber regiment stationed at the Chernyakhovsk aerodrome (Baltic MD) becoming the first combat unit to be equipped with the Su-24. Service testing of the Su-24 was conducted in two stages: Stage 1, from May 1975 through August 1976, used the resources of the 3rd bomber regiment, Stage 2, from January 1981 through March 1982, those of the bomber regiment of the Transcaucasian MD. Production of the Su-24 continued till 1983; later the plant was converted to make new versions.
The Design Bureau started development work to upgrade the baseline plane as early as at the beginning of the '70s, with a pilot project to retrofit it with flight refuelling capability developed as early as 1971. Later on, the modernisation effort focused on improving the combat capabilities by installing new attack equipment and expanding the weapons array by adding laser and TV guided weapons: guided missiles (Kh-25, Kh-29L/T, Kh-58 and R-60) and 500 and 1,500kg guided bombs. The Design Bureau in 1973 produced a conceptual design to equip the T-6 with the Kaira TV-optical quantum system and Tekon track and search system (in pod) for Kh-59/Kh-59M missiles with TV target seekers. The new version differed from the original design in having an elongated nose section to the fuselage. The Design Bureau designated the work under code name T-6M. There were several prototype planes built on the Su-24 platform to try out the design of individual items of equipment. The aerodynamics prototype T6M-8 made its maiden flight on 29th June 1977, and the first of the two pre-production planes made its first flight at the plant in Novosibirsk on 17th December 1977 with the plant's test crew, pilot V.T. Vylomov and navigator A.N. Kosarev, at the controls. The official testing of the new version took place from December 1976 through May 1981. A decree of the government of 22th June 1983 put the plane into service under the name Su-24M. According to experts, the combat effectiveness of the Su-24M was 1.5-2 higher than that of the Su-24.
The first series production Su-24M was flight tested on 20th June 1979 by the factory's test pilot V.T. Vylomov and test navigator G.V. Gridusov. Production of the Su-24M was set up in Novosibirsk, with the same work division of tasks as before with the Komsomolsk-on-Amur plant. Later on, due to the high workload of the Gagarin plant connected with the setting up of production of the Su-27, an order of the ministry released it from the obligation to deliver assemblies for the Su-24 starting in 1980. From then on, the production of all the assemblies in question was set up in Novosibirsk. The first series Su-24Ms were delivered to the USSR Air Forces in June 1981, the pilots of the 4th CEC (Voronezh) being the first to fly them. Service testing of the plane was conducted in 1985-86. The Su-24M was in production till 1993.
In 1986, it was decided to produce a special export version of the Su-24M. The first pre-production plane T-6MK (Su-24MK) was assembled at the Novosibirsk plant on the platform of the Su-24 in spring 1987, its first flight performed on 30th May 1987 by the plant's test crew pilot Ye.N. Rudakas and navigator V.V. Rudakov. The export version differed from the baseline model in the avionics and weapon systems configuration. Production of the plane was launched a year later, with the first series Su-24MK flight tested on 17th May 1988. Between 1988 and 1992, the Su-24MK was exported to Algeria, Libya, Iran, Iraq and Syria.
Work to produce Su-24-based special-purpose variants such as reconnaissance (designation T-58MR) and electronic countermeasures aircraft (designation T-58MP) got under way in the early '70s. Prototype designs were completed in 1973; later on, from 1976, work on both versions was restarted, but the new variant of the plane, the T-6M, was used as the platform. In 1986, committees of the Air Forces reviewed both versions of the plane, with conversion of series T-6Ms into prototypes (designated T-6MR and T-6MP) entering a completion stage at the Novosibirsk plant. The first to undergo flight testing was the prototype of the countermeasures aircraft: on 14th March, the design bureau’s test pilot A.S. Komarov took T6MP-25 off the ground; on 25th July 1980, the design bureau’s test pilot A.A. Ivanov followed with the T6MR-26, the first prototype of the reconnaissance aircraft. The official testing of both variants was conducted at the same time and completed at the same time – in November 1982.
The production run of the Su-24MP was 10 units only, with the first series plane taken into the air at the Novosibirsk plant on 7th April 1983 by the crew of commander I.Ya. Sushko and navigator V.Ya. Glinchikov. The first series Su-24MR was flight tested in Novosibirsk one week later on 13th April 1983 by commander V.T. Vylomov and navigator V.S. Shkuratov. The aeroplane was produced from 1983 to 1993, the machines assigned to separate reconnaissance aviation regiments (SRAR) under army (district) command. The Air Forces’ first Su-24MRs were service tested by pilots of the 4th APCT&TTC in summer 1983, with the first Su-24MRs to be assigned to combat units for tactical employment received by the 47th SGRAR of MMD of Air Forces (Shatalovo), where the new plane was successfully service tested in 1987-88.
The chief designer of the plane between 1965 and 1985 was Ye.S. Felsner, and then, from 1985, work was headed by L.A. Logvinov. The total production of the Su-24 type was about 1,400 planes. The Su-24/Su-24M is currently the only type of modern domestically-produced frontline bomber and forms the backbone of the strike capability of the frontal aviation of the Air Forces of the RF and Ukraine. The Design Bureau has been implementing a joint programme with the Air Forces to upgrade combat aircraft since 1999.