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The 2S14 "Zhalo-S" (2С14 «Жало-С») was a Soviet experimental 85 mm-caliber battalion-level self-propelled anti-tank gun. Designed by the Gorky-based Burevestnik Central Scientific Research Institute (led by V. E. Serebryaniy), the 2S14 is based on the BTR-70 armored personnel carrier.

History
After the end of World War II, in 1948, the Ministry of Defence of the Soviet Union formulated requirements for future tank guns and anti-tank guns of the Soviet Army. For anti-tank guns, the requirements included an increase in muzzle velocity and in effective range. In response to such requirements the 100 mm T-12 (also known as the MT-12) was designed and accepted for service in 1960. However, further work on the design and development of ammunition was considered impractical, as in the late 1950s the Soviet leadership assigned the duty of combating enemy tanks to anti-tank missile systems rather than traditional guns.

With tanks of enemy armed forces possessing increasing levels of protection against HEAT shells, there was again a need to resume work on improving the armor-piercing capabilities of sub-caliber armor-piercing shells, prompting a resumption of work on anti-tank guns. The 3rd Central Research Institute of the Ministry of Defense proposed to have anti-tank guns serving alongside anti-tank missile systems in 1964, when development of a new weapons system for the Rocket Forces of the USSR was underway. Work on a new generation of anti-tank guns began in 1969-1970, with the 100 mm "Norov" self-propelled anti-tank gun meant for regimental use and the 125 mm Sprut anti-tank gun for regimental use. For battalions, 85 mm light anti-tank guns, in both towed and self-propelled versions would be used. This led to the creation of the 2S14.

Design work on the Zhalo-S was given to the Burevestnik Central Scientific Research Institute, who was at the same time working on a towed variant, the 2A55 Zhalo-B. It built a mock-up model of the gun under the designation KM-33, and developed and tested new ammunition for both the 2A55 and the Zhalo-S.

The prototype vehicle of the Zhalo-S was completed in 1975 and passed factory tests before being sent for testing at the Rzhevsky Artillery Range and the proving grounds in Kubinka. By 1980, the Zhalo-S had completed the entire test cycle, the results of which were assessed as positive, but was not adopted due to how the 85 mm gun became ineffective against newer tanks. Furthermore, the rather small caliber of 85 mm meant that the gun was not suitable for using guided munitions, which were actively developed for other larger-caliber weapon systems.

Description
The 2S14 Zhalo-S was built on the BTR-70 armored personnel carrier chassis, with a turret mounting a 85 mm 2A62 gun, which had identical ballistic characteristics and ammunition to the towed 2A55 anti-tank gun. The 2A62 was equipped with a muzzle brake with an efficiency up to 75-80%, capable of firing 20-25 shells per minute. The 2A62 used armor-piercing composite-rigid (APCR) shells, which were exclusive to the gun. The APCR shell had a penetration capability 1.5 times lower than that from a 125 mm D-81 gun. A periscopic sight was provided for aiming the gun, with an R-173 radio station provided for communications.

Comparison with other similar vehicles
Work on high-maneuverability wheeled anti-tank guns began in the USSR long before the invention of the Zhalo-S, such as the 76 mm KSP-76 built upon a GAZ-63 truck chassis, which was not adopted into service due to insufficient mobility. Compared to the KSP-76 the 2S14 Zhalo-S had a number of advantages, such as a turreted main gun, a higher-speed chassis, a better rate-of-fire and armor penetration. This made the Zhalo-S better suited to fight against light armored vehicles and self-propelled artillery. However, there were also disadvantages. The caliber of 85 mm meant that guided munitions were impossible to develop at that time, and the penetration capability was insufficient to penetrate tanks such as the American M1 Abrams and the British FV4034. Later, the USSR Ministry of Defence returned to wheeled self-propelled guns, starting work on what would eventually became the Sprut-K. The Sprut-K was supposed to have the same ballistic performance and ammunition as the 2A46 125 mm gun, mounted atop a BTR-90 chassis. However, the Sprut-K was also not adopted, making the place of lightweight high-mobility self-propelled anti-tank guns hitherto vacant in the Russian Armed Forces.

Compared to foreign counterparts, such as the French AMX-10 RC and the Brazilian EE-9 Cascavel, the 2S14 Zhalo-S lacked the reconnaissance capabilities of the two. Later on, as more countries turned their eyes to wheeled anti-tank vehicles, a separate class of vehicles sometimes known as "wheeled tanks" began to appear, an example of which is the M1128 Mobile Gun System.

= Su-17 starts here = The Su-17 (izdeliye S32)....

History and design
Shortly after the Su-7 fighter-bomber was put into service, the Sukhoi Design Bureau was ordered to develop a deep modernization program for the aircraft in the early 1960s. The program would be aimed primarily at updating on-board avionics and the takeoff/landing performance characteristics. The concept of variable-geometry wings - something gaining wider attention at that time - was adopted as well. The program was to be led by Sukhoi's head designer, Nikolay Zyrin.

The first prototype of the program was designated the Su-7IG (internally known as the S-22I), essentially a serial-production Su-7BM with new wings and a few modifications to the fuselage. The Su-7IG first took off, with Vladimir Ilyushin at the controls on August 2, 1966. It was later publicly demonstrated to the public at the air parade in Domodedovo in July 1967. Tests revealed that the new configuration has improved both the take-off/landing characteristics and the range and endurance of the aircraft. The aircraft was ordered into serial production in 1969 by a joint resolution of the Central Committee of the Communist Party of the Soviet Union and the Council of Ministers. The design of the Su-7IG was modified further, eventually with enough difference to justify the S-32 internal designation. The S-32 first took off on July 1, 1969, with Yevgeny Kukushev at the controls.

Serial production of the Su-17 started at the Yuri Gagarin Aviation Factory (now KnAAPO) in 1969. The 523rd Aviation Regiment, of the Far East Military Okrug, was the first unit to receive the Su-17. The Su-17 was produced until 1990, at a total of 2867 units produced.

The Su-17 largely resembles its predecessor, the Su-7, with weight-saving measures added at the cost of combat survivability, an example of which is the removal of armored protection for the pilot.

The prototype S-22I differed little from the Su-7 except for the wing, being essentially a technology demonstrator for the variable-geometry wing. It was later lost in an accident.

Following the S-22I, two pre-production prototypes were constructed, designated the S32-1 and the S32-2, respectively. The two aircraft mounted updated avionics, and replaced the older AP-28I-2 autopilot with the newer SAU-22 automatic control system.

The next series of prototypes were the Su-7-85, with 85 indicating the batch number, continued from that of the Su-7. The batch of ten aircraft incorporated a completely redesigned fuselage, a streamlined cockpit (similar to that of the Su-7U), extra and more accessible maintenance hatches, and an upwards-opening canopy. The front of the cockpit was protected with a windshield and two electrically heated side windows. The first three aircraft of the 86th batch that followed further incorporated clear windshields with warm air blown at it, taken from the 9th stage of the engine compressor. However, this new windshield was dropped in favor of the more traditional glazed windshield following tests by the 4th Combat Use and Retraining of Air Force Personnel Center in Lipetsk.

The Su-7-85 was equipped with a modified KS4-S32 ejection seat, capable of safely ejecting the pilot at speeds above 140-170 km/h in the event of an accident.

The fuel system of the Su-17 was modified from that of the Su-7 as well - fuel was now stored in three lightweight tanks, with provisions for up to four disposable auxiliary tanks each with 600 litres of capacity (itself used on the Su-7B), or two PTB-1150 tanks with 1150 litres each, mounted on "wet" pylons underneath the fuselage.

The wing was largely unmodified from that mounted on the S-22I prototype. The stationary part of the wing being half as long as the rotating part. With wings at maximum sweep, the Su-17 would look virtually identical to the Su-7. A slide-out flap was installed on the stationary part of the wing, while a slat, a rotating flap and aileron are mounted on the rotating part. The sweep angle of the wing could be configured between 30° and 63°. The horizontal and vertical tails are swept at 55°.

Flight control was assisted by non-reversing hydraulic boosters, the BU-220DL2 and -220DP2 for the left and right ailerons, the BU-250L and -250P for the stabilizers and the BU-250DRP for the rudder. The flight control systems are spring loaded to provide a feedback force on the stick and the rudder pedals.

There are three independent hydraulic systems installed on the Su-17 - an actuating system and two booster systems, each with its own hydraulic pump. The actuating hydraulic system was responsible for adjusting the sweep angle of the wing, deploying/retracting the landing gear, the flaps and slats, adjusting the intake ramps, the flight control mechanisms used by the SAU-22 autopilot, and the steering front wheel. The booster systems are responsible for controlling the flight surfaces. Both systems operate in parallel to ensure safe operation in the event of one of them failing. The remaining operational system would still provide power to all the flight surfaces, albeit at half the power. The Nr 1 booster system also feeds the GM-40 hydraulic motor driving the rotary parts of the wing. All hydraulic systems are fed with the AMG-10 hydraulic fluid, with a standard operating pressure of 215 kgf/cm2 for the booster systems and 210 for the actuating system.

A pneumatic system with a 150kgf/cm2 pressure operates the normal and emergency brakes on the landing gear as well as the emergency landing gear/flaps deployment system, and was responsible for charging the two NR-30 cannons mounted on the aircraft, pressurizing the cockpit, opening/closing the canopy and pressurizing the hydraulic fluid tanks.

The Su-17 was powered by a modified Lyulka AL-7F1-250 with a slightly uprated thrust of 9600 kgf on afterburners. It was equipped with a compressor actuator with redundancy, and a system for intake adjustment. The aircraft would need to be disassembled into two halves to replace its engine. Jettisonable SPRD-110 RATO boosters are available to facilitate take-off on short runways, providing a momentary thrust of up to 3000 kgf.

On-board electronics are fed by a 28V DC circuit and a 115V, 400Hz single-phase AC circuit, fed by two GS-12T DC generators, an SGO-8TF AC generator and a 20NKBN25 nickel–cadmium battery.

The Su-17 has the ability to carry free-fall nuclear bombs with a BD3-56FNM bomb rack. A special code device would also be installed in the cockpit, mandating a correct code input before the bomb could be armed and released, to prevent unauthorized uses of nuclear weaponry. The aircraft also has a toss bombing capability for nuclear weapon delivery, with which it could approach the target, initiate a steep climb and release the bomb when pointing almost upright, and then activate afterburners to escape the blast radius. A special IAB-500 bomb was made specifically for practicing such a bombing technique.

Su-17M
The Su-17's Lyulka AL-7F engine was replaced with the newer AL-21F with a wet thrust of 8900 kgf, which was uprated further to 11200 kgf with the AL-21F-3, using either the T-1, TS or RT jet fuel.

The Su-17M was fitted with a modified fuselage and wing-sweep mechanism (which omitted the driveshafts). The fuel system comprised of a central rubber tank, three interconnected, pressurized follower tanks that feed into the central tank, plus two additional follower tanks in the stationary parts of the wing. The Su-17M was also fitted with the new SPO-10 Sirena-ZM radar warning receiver and the ARK-15 Tobol radio compass.

The combat payload for the Su-17M was increased to 4 tons with the addition of two extra fuselage hardpoints, providing a total of eight BD3-57M or MT hardpoints for carrying free-fall bombs. MBD3-U6-68 hardpoints are also available for KMGU submunition containers, S-8 or S-25 rocket pods. The Su-17M could also carry the Kh-28 anti-radiation missile, which, used in concert with the Metel-A ELINT pod enables the aircraft to engage surface-to-air radar systems.

Su-17M2
The design of the Su-17M was further modified into what would become the Su-17M2, with three pre-production aircraft used as prototypes. The Su-17M2 incorporated changes numerous enough to justify a reset in batch number.

The on-board avionics received an overhaul - the KN-23 navigation system taken from the MiG-23 was installed, with an IKV inertial attitude indicator, a DISS-7 Doppler velocity sensor, air signal systems, and a V-144 analog computer with its own input panel. With the RSBN-6S Romb-K navigation system and the SAU-22M autopilot, the KN-23 provided the capability of automatically navigating along a route defined by three turning points before heading for the target location. The V-144 stored four sets of coordinates for landing airfields, and made it possible for the aircraft to automatically approach the airfield for landing and descend down to an altitude of 50-60 meters prior to manual landing. The SOD-57M transponder was replaced with the newer SO-69. During its service, the SRO-2M nation-wide transponder was replaced with the newer Parol (Russian for "Password") system. A Fon-1400 laser rangefinder was installed under the inlet cone. The Delta NG missile control system, designed to send command signals to the Kh-23 Grom missile, was integrated into a pod suspended under the wing. The Su-17M2 was fitted with a new ASP-17S gunsight and a PBK-3-17S bombsight.

The nose section of the Su-17M2 was lengthened by 200 mm and the nose intake was slightly narrowed. The fuel system also received a nitrogen pressurizer with a 200 kg capacity increase. Starting from aircraft Nr 03909 a central fuel feed system was also introduced with the installation of the ETsN-45 fuel pump.

The Su-17M2 was also capable of carrying the Kh-25 air-to-ground missiles, fitted with the 24N1 laser seeker. This was first tested by retrofitted Su-7BM's and Su-17M's, designated as the Su-17MKG. The Su-17M2 could carry two such missiles, one each under the wing, mounted on an APU-68U or UM rack. The missiles are guided using a Prozhektor-1 laser-designator pod.

The Su-17M2 also has an unofficial nickname, s borodoy, which means "with a beard", in Russian.

Su-17UM
The Su-17UM was a two-seat trainer variant, introduced in 1976. It differed from the Su-17 in a droop nose inclined at 3° downwards from horizontal, a raised K-36D ejection seat with good front-down visibility, a second cockpit located at where the first fuselage fuel tank would be (which reduces the fuel load to 876 liters), and the removal of the port-side NR-30 cannon. Avionics of the Su-17UM remained unchanged compared to those of the Su-17M2 with the exception of an updated SAU-22MU autopilot.

Su-17M3
The Su-17M3 was planned at the same time as the UM trainer. The rear cockpit was replaced with an avionics bay. The fuel capacity was increased by 260kg. Starting from the 38th batch the tailfin was raised with a radiotransparent guide and a fin was added on the underside of the tail to improve high-speed stability. A new KN-23-1 navigation system, the SAU-22M1 autopilot and the RV-15 (A-031) radio altimeter was added. Some aircraft later received an RSDN-10 Skip-2 (A-720) long-range radio navigation system, with its antenna installed on the leading edge of the tailfin. The SARPP-12GM flight recorder was replaced with the newer Tester-UZ recorder, and the SPO-10 radar warning receiver was replaced with the SPO-15A (izdeliye L006L) Beryoza. A Klyon-PS combined laser rangefinder/designator was installed alongside the ASP-17BTs sight. The Su-17M3 could carry an SPS-141 (or the 142-143) Siren or an SPS-141MVG Gvozdika ECM pod. Infrared countermeasures can be deployed via KDS-23 launchers.

The BSPPU fire-control system was also installed in the Su-17M3, which would control SPPU-22-01 gun pods suspended on the wings to automatically stay on target in automatic tracking mode, up to a depression angle of 30°.

Two additional hardpoints were placed under the fuselage, with S-52-8812-300 pylons, on which BD3-57MT or MTA racks would hold APU-68UM's, which in turn would carry Kh-23M or Kh-25 missiles. These hardpoints would also be capable of carrying the Kh-25ML or MR missiles, as well as the Kh-29L, mounted on an AKU-58 catapult-launch rack. Some of the Su-17M3's were modified to the Su-17M3P standard, which would enable them to carry up to four Kh-27PS, two on the wings and two under the fuselage, or two Kh-58 anti-radiation missiles, which could only be carried on the fuselage pylons. A Vyuga-17 (L-086) target designator pod is installed under the fuselage, with its receiver integrated into the aircraft's nose.

The BD3-57MT racks could also hold ordinary ordnance, such as the UB-16, -32 or the B-13L rocket pods, free-fall bombs, KMGU submunition containers, and the SPPU-22-01 gun pods. In a somewhat unconventional manner, the S-52-8307-200 pylons could be mounted on the aircraft, on which the gun pods would be installed in a rearwards-facing manner, pointed downwards at 23°, and fired as the aircraft flies away from ground targets.

The first Su-17M3's were unpainted with the silver color from the anodized duralumin. Later Su-17M3's, as well as all variants that followed, was painted with a green camouflage pattern on the top, and blue on the bottom. This camouflage pattern eventually found its way to all Su-17's in service, and the paint jobs were done at repair plants. The camouflage pattern - the locations of the paint dots - were not standardized, thus each aircraft would have its own "unique" camouflage.

The Su-17M3 would also have a trainer variant designated the Su-17UM3.

Su-17M4
The Su-17M4 differed from the Su-17M3 in the removal of the inlet cone control system, which restricted the maximum allowable flight speed to Mach 1.75. The inlet cone housed the Klyon-54 laser rangefinder.

The avionics again differed significantly from the Su-17M4's predecessors - a new A-312 Radikal NP close- and A-720 Skip-2 long-range navigation systems, an ARK-22 radio compass, an MRP-66 radio beacon receiver, an RV-21 Impuls (A-035) radio altimeter, and the DISS-7 Doppler velocity sensor, air signal systems, the IKV-8 intertial attitude indicator inherited from the Su-17M2. The Vyuga target designator pod could be carried in a BA-58 pod under the fuselage, which would enable the use of the Kh-27PS, -58U or E missiles. Some Su-17M4's were fitted with the IT-23M indicator, which would transmit video from the Tubus-2 seeker on the Kh-29T missile to facilitate target acquisition.

Su-17M4R
The Su-17M4R is a reconnaissance version, with the capability to carry reconnaissance pods dedicated to the Su-17.

The KKR-1 pod carried A-39 and PA-1 daylight cameras, and an AFA UA-47 night camera, which would be used with FP-100 illumination cartridges loaded in KDF-38 containers at night. The KKR-1 was also provided with the SRS-9 Virazh (or the SRS-13 Tangazh on newer versions) ELINT device.

The KKR-1/2 carried the AFA-100 and the PA-1 cameras, a Zima TV camera, and a 429-T Chibis TV station.

The KKR-2A was provided with the AFA A-39 and the AP-402 panoramic cameras, supplemented by the Aist-M TV camera and the Zima infrared camera.

The KKR-2Sh was provided with a side-looking Shtyk-2M radar station.

The KKR-2E housed the Efir-1M NBC monitor system.

In total, around 15 different models of reconnaissance pods were introduced to fulfill different tasks.