One of the conditions for accepting the Sukhoi Su-7B into service in 1961 was the requirement for Sukhoi to develop an all-weather variant capable of precision air strikes. Preliminary investigations with S-28 and S-32 aircraft revealed that the basic Su-7 design was too small to contain all the avionics required for the mission. OKB-794 (later known as Leninets) was tasked with developing an advanced nav/attack system, codenamed Puma, which would be at the core of the new aircraft. That same year, the United States proposal for their new all-weather strike fighter would be the TFX. The resulting F-111 would introduce a variable-geometry wing for greatly increased payload, range, and low-level penetration capabilities.
In 1962–1963, Sukhoi initially set out to build an aircraft without the complexity of moving wings like the F-111. It designed and built a mockup of S-6, a delta wing aircraft powered by two Tumansky R-21turbojet engines and with a crew of two in a tandem arrangement. The mockup was inspected but no further work was ordered due to lack of progress on the Puma hardware.
In 1964, Sukhoi started work on S-58M. The aircraft was supposed to represent a modification of the Sukhoi Su-15 interceptor (factory designation S-58). In the meantime, revised Soviet Air Force requirements called for a low-altitude strike aircraft with STOL capability. A key feature was the ability to cruise at supersonic speeds at low altitude for extended periods of time in order to traverse enemy air defenses. To achieve this, the design included two Tumansky R-27 afterburning turbojets for cruise and four Rybinsk RD-36-35 turbojets for STOL performance. Side-by-side seating for the crew was implemented since the large Orion radar antennas required a large frontal cross-section. To test the six-engine scheme, the first Su-15 prototype was converted into S-58VD flying laboratory which operated in 1966–1969.
The aircraft was officially sanctioned on 24 August 1965 under the internal codename T-6. The first prototype, T-6-1, was completed in May 1967 and flew on 2 July with Vladimir Ilyushin at the controls. The initial flights were performed without the four lift jets, which were installed in October 1967. At the same time, R-27s were replaced with Lyulka AL-21Fs. STOL tests confirmed the data from S-58VD that short-field performance was achieved at the cost of significant loss of flight distance as the lift engines occupied space normally reserved for fuel, loss of under-fuselage hardpoints, and instability during transition from STOL to conventional flight. So the six-engine approach was abandoned.
By 1967, the F-111 had entered service and demonstrated the practical advantages and solutions to the technical problems of a swing-wing design. On 7 August 1968, the OKB was officially tasked with investigating a variable geometry wing for the T-6. The resulting T-6-2I first flew on 17 January 1970 with Ilyushin at the controls. The subsequent government trials lasted until 1974, dictated by the complexity of the on-board systems. The day or night and all-weather capability was achieved – for the first time in Soviet tactical attack aircraft – thanks to the Puma nav/attack system consisting of two Orion-A superimposed radar scanners for nav/attack, a dedicated Relyefterrain clearance radar to provide automatic control of flights at low and extremely low altitudes, and an Orbita-10-58 onboard computer. The crew was equipped with ZvezdaK-36Dejection seats, allowing them to bail out at any altitude and flight speed, including during takeoff and landing. The resulting design with a range of 3,000 kilometers (1,900 mi) and payload of 8,000 kilograms (18,000 lb) was slightly smaller and shorter ranged than the F-111.
Ten fatal accidents occurred during Su-24 development, killing thirteen Sukhoi and Soviet Air Forcetest pilots, and more than 5 crashes per year were occurring at average after that 
A Russian Su-24M in flight, 2009
The first production aircraft flew on 31 December 1971 with V.T. Vylomov at the controls, and on 4 February 1975, T-6 was formally accepted into service as the Su-24. About 1,400 Su-24s were produced.
The Su-24 has a shoulder-mounted variable geometry wing outboard of a relatively small fixed wing glove, swept at 69°. The wing has four sweep settings: 16° for take-off and landing, 35° and 45° for cruise at different altitudes, and 69° for minimum aspect ratio and wing area in low-level dashes. The variable geometry wing provides excellent STOL performance, allowing a landing speed of 230 kilometers per hour (140 mph), even lower than the Sukhoi Su-17 despite substantially greater take-off weight. Its high wing loading provides a stable low-level ride and minimal gust response.
In early Su-24 ("Fencer A" according to NATO) aircraft these intakes had variable ramps, allowing a maximum speed of 2,320 kilometers per hour (1,440 mph), Mach 2.18, at altitude and a ceiling of 17,500 meters (57,400 ft). Because the Su-24 is used almost exclusively for low-level missions, the actuators for the variable intakes were removed to reduce weight and maintenance. This has no effect on low-level performance, but absolute maximum speed and altitude are cut to Mach 1.35 and 11,000 meters (36,000 ft).[unreliable source?] The earliest Su-24 had a box-like rear fuselage, which was soon changed in production to a rear exhaust shroud more closely shaped around the engines to reduce drag. The revised aircraft also gained three side-by-side antenna fairings in the nose, a repositioned braking chute, and a new ram-air inlet at the base of the tail fin. The revised aircraft were dubbed "Fencer-B" by NATO, but did not merit a new Soviet designation.
A Su-24 in flight (2009).
The Su-24's fixed armament is a single fast-firing GSh-6-23cannon with 500 rounds of ammunition, mounted in the fuselage underside. The gun is covered with an eyelid shutter when not in use. Two or four R-60 (NATO AA-8 'Aphid')infrared missiles are usually carried for self-defence by the Su-24M/24MK.
Initial Su-24s had basic electronic countermeasures (ECM) equipment, with many Su-24s limited to the old Sirena radar-warning receiver with no integral jamming system. Later-production Su-24s had more comprehensive radar warning, missile-launch warning, and active ECM equipment, with triangular antennas on the sides of the intakes and the tip of the vertical fin. This earned the NATO designation "Fencer-C", although again it did not have a separate Soviet designation. Some "Fencer-C" and later Su-24M (NATO "Fencer-D") have large wing fence/pylons on the wing glove portion with integral chaff/flare dispensers; others have such launchers scabbed onto either side of the tail fin.
In August 1999 Tajikistan protested over an alleged strike involving four UzAF Su-24s against Islamist militants in areas close to two mountain villages in the Jirgatol District that, despite not producing human casualties, killed some 100 head of livestock and set ablaze several crop fields. Tashkent denied the accusations.
Su-24s were used in combat during the Second Chechen War performing bombing and reconnaissance missions. Up to four were lost, one due to hostile fire: on 4 October 1999, a Su-24 was shot down by a SAM while searching for the crash site of a downed Su-25. The pilot was killed while the navigator was taken prisoner.
2008 Russo-Georgian War
In August 2008, a low intensity conflict in the breakaway Georgian regions of Samachablo and Abkhazia, escalated into the 2008 South Ossetia war. Russian Su-24s flew bombing and reconnaissance sorties over Georgia. Russia admitted that three of its Su-25 strike aircraft and one Tu-22M3 long-range bomber were lost. Moscow Defence Brief provided a higher estimate, saying that Russian Air Force total losses during the war were one Tu-22M3 long-range bomber, one Su-24M Fencer fighter-bomber, one Su-24MR Fencer E reconnaissance plane and four Su-25 attack planes. Anton Lavrov listed one Su-25SM, two Su-25BM, two Su-24M and one Tu-22M3 lost.
Libyan Air Force
Libya received five Su-24MK and one Su-24MR from the Soviet Union in 1989. This was one of the last deliveries by the USSR to Libya before the end of the Cold War. One Su-24MK and one Su-24MR may have been transferred to the Syrian Arab Air Force. At the beginning of 2011, the Libyan Air Force was ordered to attack rebel positions and opposition rallies. The Libyan Air Force was limited to a composite force of some MiG-23 (due to be retired, according to plans) and Su-22 and few units of flyable MiG-21, Su-24 and Mirage F1ED fighter-bombers, supported by Soko G-2 Galeb and Aero L-39 Albatros armed trainers. The largest part of the former fleet was in disrepair or stored in not flyable condition. On 5 March 2011, at the beginning of the 2011 Libyan civil war, rebels shot down a Libyan Air Force Su-24MK during fighting around Ra's Lanuf with a ZU-23-2 anti-aircraft gun. Both crew members died. A BBC reporter was on the scene soon after the event and filmed an aircraft part at the crash site showing the emblem of the 1124 Squadron, flying the Su-24MK.
Syrian Civil War
Starting in November 2012, 18 months after the beginning of the Syrian Civil War and four months after the beginning of air raids by fixed-wing SyAAF aircraft, Su-24 bombers were filmed attacking rebel positions. The SAF suffered its first Su-24 loss, an upgraded MK2 version, to an Igla surface-to-air missile on 28 November 2012 near the town of Darat Izza in the Aleppo Governorate. One of the crew members, Col. Ziad Daud Ali, was injured and filmed being taken to a rebel field hospital.
Syrian Su-24s have reportedly also been involved in near-encounters with NATO warplanes. The first of such incidents occurred in early September 2013, when Syrian Su-24s of the 819th Squadron (launched from Tiyas Military Airbase) flew low over the Merranean and approached the 14-mile air exclusion zone surrounding the British airbase in Akrotiri, Cyprus. The jets turned back before reaching the area due to two RAFEurofighter Typhoons being scrambled to intercept them. Turkey also sent two F-16s. The Fencers were possibly testing the air defenses of the base (and their reaction time) in preparation for a possible military strike by the U.S, the United Kingdom and France in the aftermath of the chemical weapons attack in Ghouta, Damascus allegedly committed by the Syrian government.
On 23 September 2014, a Syrian Su-24 was shot down by an Israeli Air Defense CommandMIM-104D Patriot missile near Quneitra, after it had flown 800 meters (2,600 ft) into Israeli controlled airspace over the occupied Golan Heights. The missile hit the aircraft when it already re-entered into the Syrian air space. Both crew members ejected safely and landed in Syrian territory.
On 18 March 2018, a SyAAF Su-24 was shot down by rebels in East Qalamoun, East of Damascus province; it fell into territory controlled by Syrian government forces.
The long-range striking power of the Russian aerospace forces in the region comes from the twelve Su-24M2 bombers that Russia sent to its base in Latakia, Syria. On 24 November 2015, a Russian Su-24M was shot down by a flight of two Turkish F-16s near the Turkey–Syrian border. The two crew ejected before the plane crashed in Syrian territory. Russia claimed that the jet had not left Syrian airspace while Turkey claimed that the jet entered their airspace and was warned 10–12 times before being shot down.
A deputy commander in a Syrian Turkmen brigade claimed that his personnel shot and killed the crew while they were descending in their parachutes, while some Turkish officials subsequently stated that the crew was still alive. The weapon systems officer was rescued by Russian forces but the pilot was killed by rebels, along with a Russian marine involved in a helicopter rescue attempt. Russian president Vladimir Putin warned Turkey of serious consequences. To increase safety during aerial operations in the region, Russian fighter jets would escort bombers, S-400SAM systems were deployed in Syria and a Russian cruiser was stationed off the coast to protect Russian aircraft. Following the incident, Russia announced that Su-24s in Syria had been armed with air-to-air missiles on operational sorties.
On 2 July 2014, one Ukrainian Air Force Su-24 was damaged by a MANPADS fired by pro-Russian forces. One of the engines was damaged but the crew managed to return to base and land. During landing a new fire started but it was extinguished by the ground crew. Initially identified as a Su-25, on 20 August 2014 a Ukrainian Su-24M was shot down by pro-Russian forces in the Lugansk region and confirmed by Ukrainian authorities who reported that the crew members ejected safely and were recovered. On 21 August 2014, the downed plane was identified as a Su-24M.
Russian encounters with NATO forces
A Russian Sukhoi Su-24 attack aircraft flies over USS Donald Cook.
In late May 2015, a pair of Russian Su-24s made a low pass over the USS Ross in the Black Sea. In April 2016, several Russian Su-24s flew within 30 metres of another American ship, the destroyer Donald Cook in the Baltic Sea. The incidents occurred over two days, with the planes making passes by the Donald Cook while it was in international waters. In November 2018, two armed Russian Su-24s flew low over the Belgian frigateGodetia. At the time of the incident, the Godetia was in use as the command ship of NATO’s northern mine-sweeping fleet.
Saudi-led intervention in Yemen
In March 2015, Sudanese President Omar al-Bashir committed Sudan to join the Saudi Arabian-led intervention in Yemen against the Houthis. Part of the military effort was the commitment of up to four recently acquired Sudanese Air Force Su-24s to the Saudi King Khalid Air Base where they were depicted. Sudanese Armed Forces did not specify the type of mission the Su-24s conducted. Integrating few Soviet made combat jets with Air Forces using modern Western models (F-15s, F-16s, F/A-18s, Tornadoes, Typhoons) during an active military campaign would represent a first in the world which would require extensive communication integration or leaving the Soviet made jets operating on a different mission plan, not integrated with the rest of the campaign. Air defense units, like Saudi MIM-104 Patriot batteries, would either need to stand down, taking the risk of not monitoring for incoming threats or some very specific orders to avoid shooting down friendlies.
On 28 March 2015, during Operation Decisive Storm, Houthi forces claimed they shot down a Sudanese Air Force Su-24. Houthis published photos of an allegedly captured Sudanese pilot and metal parts claiming it as the aircraft wreckage.
In the first hours of the invasion, the Ukrainian Air Force used at least two Su-24Ms during the Battle of Antonov Airport against Russian Airborne Forces which had been inserted in the airport by helicopters. On 27 February, one Ukrainian Su-24 was lost near Bucha, Kyiv Oblast. The pilots, Commander Ruslan Aleksandrovich Belous and Commander Roman Aleksandrovich Dovhalyuk, died, and were awarded with the Order of Bohdan Khmelnytsky. Another bomber was reported lost on 3 April, when a video emerged showing the crash site with the remains of a blue-coloured AL-21 engine employed by the Su-24. On 10 April, another Ukrainian Su-24 was destroyed by Russian forces in Izyum. On 19 May, a Su-24 from the 7th Tactical Aviation Brigade was lost near Pylove. The pilot Lt. Colonel Igor Khamar and the navigator Major Ilya Negar, died.
An early project in the gestation of the Su-24, like a meld of the Su-7 and Su-15.
The initial prototype with cropped delta wings and 4 RD-36-35 lift engines in the fuselage.
T6-2I / T6-3I / T6-4I
Prototypes for the variable geometry Su-24 production aircraft.
The first production version, the armaments include Kh-23 and Kh-28 type air-to-ground guided missiles, together with R-55 type air-to-air guided missiles. Manufactured 1971–1983.
Work on upgrading the Su-24 was started in 1971, and included the addition of inflight refueling and expansion of attack capabilities with even more payload options. T-6M-8 prototype first flew on 29 June 1977, and the first production Su-24M flew on 20 June 1979. The aircraft was accepted into service in 1983. Su-24M has a 0.76 m (30 in) longer fuselage section forward of the cockpit, adding a retractable refueling probe, and a reshaped, shorter radome for the attack radar. It can be identified by the single nose probe in place of the three-part probe of earlier aircraft. A new PNS-24Minertial navigation system and digital computer were also added. A Kaira-24laser designator/TV-optical quantum system (similar to the American Pave Tack) was fitted in a bulge in the port side of the lower fuselage, as well as Tekon track and search system (in pod), for compatibility with guided weapons, including 500 and 1,500kg laser-guided bombs and TV-guided bombs, and laser/TV-guided missiles Kh-25 and Kh-29L/T, anti-radar missiles Kh-58 and Kh-14 (AS-12 'Kegler') and Kh-59 (AS-13 'Kingbolt')/Kh-59M TV-target seeker guided missiles. The new systems led to a reduction in internal fuel amounting to 85 l (22.4 US gal). Su-24M was manufactured in 1981–1993.
Next modernization of Su-24M introduced in 2000 with the "Sukhoi" program and in 1999 with the "Gefest" program. The modernized planes are equipped with new equipment and systems. As a result, they get new capabilities and improved combat efficiency, including new navigation system (SVP-24), new weapons control system, new HUD (ILS-31, like in Su-27SM or KAI-24) and expanding list of usable munitions (Kh-31A/P, Kh-59MK, KAB-500S). The last batch of the Sukhoi was delivered to the Russian VVS in 2009. Modernization continues with the program "Gefest". All frontline bombers Su-24 in the Central Military District received new sighting and navigation systems SVP-24 in 2013.
Export version of the Su-24M with downgraded avionics and weapons capabilities. First flight 30 May 1987 as T-6MK, 17 May 1988 as Su-24MK. Manufactured 1988–1992, sold to Algeria, Iraq, Libya, and Syria. Many Iraqi examples were evacuated to Iran.
Dedicated tactical reconnaissance variant. First flight 25 July 1980 as T-6MR-26, 13 April 1983 as Su-24MR. Entered service in 1983. Su-24MR retains much of the Su-24M's navigation suite, including the terrain-following radar, but deletes the Orion-A attack radar, the laser/TV system, and the cannon in favor of two panoramic camera installations, 'Aist-M' ('Stork') TV camera, RDS-BO 'Shtik' ('Bayonet') side-looking airborne radar (SLAR), and 'Zima' ('Winter') infrared reconnaissance system. Other sensors are carried in pod form. Manufactured 1983–1993. It is also being modernized.
Dedicated electronic signals intelligence (ELINT) variant, intended to replace the Yak-28PP 'Brewer-E'. First flight 14 March 1980 as T-6MP-25, 7 April 1983 as Su-24MP. The Su-24MP has additional antennas for intelligence-gathering sensors and radar jamming, omitting the laser/TV fairing, but retaining the cannon and provision for up to four R-60 (AA-8) missiles for self-defense. Only 10 were built.
Islamic Republic of Iran Air Force – 30 Su-24MKs were in service as of January 2013. 24 Iraqi examples were evacuated to Iran during the 1991 Gulf War and were put in service with the IRIAF. Iran possibly purchased other Su-24s from Russia or other former Soviet States. Iran tested domestically produced anti-radar missiles carried by Su-24 aircraft in September 2011, the IRIAF's Deputy Commander, General Mohammad Alavi said, according to IRIB TV1.
Syrian Arab Air Force – 22 received. 20 Su-24MKs from the Soviet Union starting in 1987, one Su-24MK and one Su-24MR from Libya. 20 were in service in January 2013. All the Su-24MKs have been upgraded to Su-24MK2 standard, between 2009 and 2013. The contract for that was signed in 2009 and the upgrade started in 2010.
On 10 April 2011 an Islamic Republic of Iran Air Force Su-24MK crashed close to Khavaran village near the city of Sarvestan, about 80 km east of Shiraz in the southern province of Fars.
On 30 October 2012, a Russian Air Force Su-24M crashed in Chelyabinsk Oblast, Russia. During the flight the nose cone fractured. After attempting an emergency landing, the crew of two flew to open territory and safely ejected. A regional government website stated that emergency was the result of aircraft control system failure. Flights of Su-24 were suspended at the Shagol base.
On 21 March 2014, a Ukrainian Air Force Su-24M belonging to the 7th Brigade crashed during approach for landing near Starokonstantinov in the Khmelnitsky region, Ukraine. Both crew members ejected safely.
On 13 October 2014, an Algerian Air Force Su-24 crashed during a training flight killing both crew members
On 6 July 2015, a Russian Air Force Su-24 crashed outside of Khabarovsk in Russia's Far East killing one out of two crew members.
On 24 November 2015, a Russian Air Force Su-24 was shot down by a Turkish F-16 near the Turkey-Syria border. Both crew ejected, but the pilot was killed by Turkmen rebels as he parachuted to the ground, while the navigator was rescued.
On 10 October 2017, a Russian Air Force Su-24 crashed during takeoff at Khmeimim Air Base, Latakia province, Syria. Both crew members died in the crash.
On 9 August 2022, a series of explosions occurred at the Saki Air Base in currently occupied Crimea, Ukraine. As a result, at least 1 Su-24 was destroyed, with satellite imagery taken hours before indicating there were at least two others in the immediate vicinity. The Russian Ministry of Defense stated "there had been no attack and no aviation equipment had been damaged."
^Barabanov, M.S.; Lavrov, A.V.; Tseluiko, V.A. (2010). "Russian Air Losses in the Five Day War Against Georgia". In Pukhov, R.N. (ed.). The Tanks of August(PDF). Moscow: Centre for Analysis of Strategies and Technologies. ISBN978-5-9902320-1-3. Retrieved 2019-08-13.
^"Ukrainian Su-24 Back In The Fight And Armed With A Laser-Guided Missile". Thedrive.com. 10 August 2022. Retrieved 2022-08-11. Western sources reported a total fully operational fleet of only 12 of these aircraft before the current conflict. It’s likely that this last number is an underestimation, although only one tactical aviation brigade flew Fencers, both Su-24Ms for strike, and Su-24MR reconnaissance versions, based at Starokostyantyniv. Typically, a pre-war brigade had two squadrons with 10-12 aircraft each, although some brigades had only a single squadron.
^Axe, David (7 April 2022). "Where Are Ukraine's Bombers?". Forbes. There however is evidence the Ukrainians have lost at least one Su-24. On March 30, a video circulated on social media apparently depicting a Ukrainian bomber trailing smoke over Rivne in western Ukraine, purportedly after a Russian fighter intercepted it. At least one of those claimed kills appears to be valid. On or before April 3, someone shot a video depicting the crash site of a Ukrainian Su-24. Its blue camouflage pattern is visible, as are the remains of one of its AL-21 engines
^"Widespread Destruction Seen After Blasts At Russian Base In Crimea". The Drive - The War Zone. 10 August 2022. ..and three more Su-24 Fencers sitting inside revetments were very likely destroyed. Another Su-24 and adjacent structure, along with an additional separate structure, all in this same portion of the base were obliterated, as well. A fifth Su-24 looks to be damaged, too.
^Cordesman, Anthony H.; Nerguizian, Aram (2009), "The North African Military Balance: Force Developments in the Maghreb", Significant issues series, Washington, DC: Center for Strategic and International Studies, vol. 31, no. 2, p. 68, ISBN9780892065523
^Cooper, Tom (2018). Hot Skies Over Yemen, Volume 2: Aerial Warfare Over the South Arabian Peninsula, 1994-2017. Warwick, UK: Helion & Company Publishing. p. VI. ISBN978-1-911628-18-7.
^Ponomarenko, Illia (15 March 2019). "Ukraine's Air Force rebuilds amidst war". Kyiv Post. Kyiv, Ukraine. Retrieved 3 September 2019. These include approximately 37 MiG‑29 and 34 Su‑27 fighters, 14 Su‑24M attack aircraft, 31 Su‑25 close air support aircraft, nine Su‑24MR and three Antonov An‑30 reconnaissance aircraft, 32 L‑39 training planes, and five Ilyushin Il‑76 and three An‑26 military transport aircraft.