Sukhoi Su-24

History

The Su-24 emerged from an early 1960s specification for a new attack bomber to replace the Ilyushin Il-28 and Yakovlev Yak-28. The specification, issued in 1964, called for an all-weather aircraft capable of supersonic speed at low level, with a very high standard of navigational and bombing accuracy. Furthermore, Soviet Frontial Aviation commanders were well aware that their existing combat aircraft suffered a tactically crippling combination of long take-off distance and short range. As a result the specification demanded excellent short-field performance.

Sukhoi, like rival Mikoyan-Gurevich (which was more or less simultaneously developing an air combat fighter aircraft that was to become the MiG-23), initially considered the possibility of lift jets to reduce take-off distance. Their first prototype, the T-6-1, which first flew in 1967, had a delta wing with lift engines in the fuselage, similar to the T-58VD 'Flagon-B', but this proved to have disastrously poor handling. A modified version, the T-6-2, had no lift jets, but down turned wingtips and slotted flaps. This bore a strong resemblance to the British BAC TSR.2. While the T-6-2 proved more workable, its low wing loading gave it a punishing low-level ride.

A better solution was variable geometry, also being applied to the roughly contemporary Sukhoi Su-17 and Mikoyan-Gurevich 23-11. The second Sukhoi prototype was fitted with a variable wing, redesignated T-6-2IG. This first flew in 1970, and proved to be successful enough to merit production, initially under a cover designation of Su-15M (this designation, mistranslated by Western analysts, led the aircraft to be incorrectly identified as Su-19 until 1981).

The production Su-24 (NATO reporting name 'Fencer-A') first flew in December 1971 entered service in 1974. It was not clearly photographed by NATO intelligence until a regiment was deployed to East Germany five years later, and the apparent capability of the 'Fencer' led to considerable panic among Western analysts, similar to that surrounding the MiG-25 'Foxbat.' As the most sophisticated combat aircraft in Soviet service to date, the Su-24 experienced teething problems, but proved to be popular with its crews. Although known as 'Fencer' in the west, Russian crews have nicknamed it Chemodahn (suitcase) because of its load-carrying ability and versatility.

The Su-24 evolved through several early variations, each earning separate NATO reporting names (although all were apparently designated the same in Soviet service). Development of a substantially upgraded version, the Su-24M (NATO reporting name 'Fencer-D'), began as the original aircraft was entering service, entering production in 1978. The Su-24M finally entered service in 1983. Two specialized versions, the Su-24MR ('Fencer-E') reconnaissance variant and the Su-24MP ('Fencer-F') ELINT gatherer, were developed from the Su-24M.

An export version of the Su-24M, the Su-24MK (K for kommercheskiy, commercial), has been sold to several foreign customers. Ten were sold to Algeria, 15 to Libya, and 12 to Syria. A total of 32-33 Su-24MKs were sold to the Islamic Republic of Iran Air Force and to Iraq, but sources differ on the specific numbers. Russian sources claim that nine were sold to Iran and 24 to Iraq, all of which are now under Iranian control. Iran claims it purchased 14 and gained 16-18 ex-Iraqi aircraft that fled to escape destruction in the 1991 Gulf War.

The Soviets used some Su-24s in Afghanistan in 1984, and the 'Fencer' saw combat service again in the Chechen conflicts of the 1990s. Its bombing accuracy in the latter conflict has been criticized, because while the Su-24 apparently performed within its original design parameters, there were large numbers of civilian casualties and collateral damage.

About 1,200 Su-24s were produced. Substantial numbers of Ex-Soviet Su-24s remain in service with Azerbaijan, Belarus, Kazakhstan, Russia, and Ukraine. Roughly 577 are currently operational with Russian forces, split 447 with the Russian Air Force and 130 with the Russian Navy.

Although a formidable warplane in its day (albeit not quite as much so as initially believed by the West), the 'Fencer' is likely to be replaced by the Su-27IB/Su-32FN/Su-34 or other more advanced aircraft as Russian finances permit.

Description

The Su-24 is aerodynamically similar to the contemporary MiG-23 'Flogger,' although it is substantially larger. It 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 km/h (143 mph), even lower than the Su-17 despite substantially greater take-off weight. Its high wing loading provides a stable low-level ride and minimal gust response, but reportedly makes the aircraft somewhat difficult to fly. The Su-24 can be unforgiving under some circumstances.

Much of the Western panic surrounding the 'Fencer' was based on the assumption that the Su-24 had efficient turbofan engines, which would have given it substantially greater range. In fact, it had two Saturn/Lyulka AL-21F-3A afterburning turbojet engines with 109.8 kN (24,700 lbf) thrust each. These engines give excellent performance, but have inherently higher fuel consumption than a turbofan. In compensation, the simple, well-proven AL-21F presumably gave fewer problems than the troublesome Pratt & Whitney TF-30 turbofans of the USAF F-111 and US Navy F-14 Tomcat.

The Su-24 has side-mounted intakes, unlike the nose intake of the Su-17. In early 'Fencer-A' aircraft these intakes had variable ramps, allowing a maximum speed of 2,320 km/h (1,440 mph), Mach 2.18, at altitude and a ceiling of some 17,500 m (57,400 ft). Because the Su-24 is used almost exclusively for low-level missions, the actuators for the variable intakes were deleted to reduce weight and maintenance. This has no effect on low-level performance, but absolute maximum speed and altitude are cut to a modest Mach 1.35 and 11,000 m (36,100 ft). The earliest 'Fencer-A' had a box-like rear fuselage, which was shortly changed in production to a rear exhaust shroud more closely shaped around the engines in order 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 tailfin. The revised aircraft were dubbed 'Fencer-B' by NATO, but did not merit a new Soviet designation.

The Su-24 seats two, a pilot and a weapon systems officer, in side-by-side cockpit (similar to the F-111). The avionics were the most sophisticated in Soviet use, with the USSR's first integrated, and computerized nav/attack system. The early Su-24s carried separate attack and terrain-avoidance radars, along with a Doppler navigation set.

The Su-24's fixed armament is a single fast-firing GSh-6-23 cannon with 500 rounds of ammunition, mounted in the fuselage underside. Unlike the MiG-27's external cannon gondola, the 'Fencer' installation of this weapon covers the gun with an eyelid shutter when not in use. There are eight external hardpoints (two under the inner wing glove, two swiveling pylons under the outer wing, and four on the fuselage) for a maximum warload of 8,000 kg (17,600 lb), including various nuclear weapons. Two or four R-60 (NATO AA-8 'Aphid') infrared missiles are usually carried for self-defense.

Initial 'Fencers' had sparse ECM equipment, with many 'Fencer-A' and 'Fencer-B' 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 antennae 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 '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 tailfin.

The Su-24 has often been compared to the American F-111, but despite being close to the F-111 in size, it never matched the USAF aircraft's range or load-carrying ability. Its true capabilities are closer to those of the smaller Panavia Tornado, although its less-efficient engines make the 'Fencer's' range somewhat shorter.

Variants

• Su-24M ('Fencer-D'): An upgraded 'Fencer' began development in the mid-1970s and entered service around 1983, has a 0.76 m (30 in) longer fuselage section forward of the cockpit, adding a retractable inflight refueling probe, and a reshaped, shorter radome for the new 'Orion-A' attack radar. It can be identified by the single nose probe in place of the three-part probe of earlier aircraft. The new radar was coupled with a Relyef terrain-following radar coupled with SAU-6M1 automatic flight control system, allowing automatic ("hands-off") low-level flight. A new PNS-24M inertial navigation system and digital computer were also added. A Kaira 24 laser designator/TV system (similar to the American Pave Tack) was fitted in a bulge in the port side of the lower fuselage for compatibility with guided weapons, including laser-guided bombs and TV-guided bombs, and Kh-14 (AS-12 'Kegler') and Kh-59 (AS-13 'Kingbolt') missiles, as well as unguided bombs and rockets. The new systems led to a reduction in internal fuel amounting to 85 litres (22.4 US gallons).

• Su-24MK ('Fencer-D'): Export versions of the Su-24M (although a few do serve with CIS regiments), basically similar to Su-24M, but with moderately downgraded avionics. Some also lack the refueling probe.

• Su-24MR ('Fencer-E'): Dedicated tactical recce variant, which first flew in September 1980 and entered service in 1985. It 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.

• Su-24MP ('Fencer-F'): Dedicated ELINT variant, intended to replace the Yak-28PP 'Brewer-E'. It first flew in December 1979. The Su-24MP has additional antennae for intelligence-gathering sensors, omitting the laser/TV fairing, but retaining the cannon and provision for up to four R-60 (AA-8) missiles for self-defense. Only a small number (12-20) were produced.

Specifications (Su-24M)

General characteristics