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FH-70

Towed howitzer

FH-70 howitzer

The FH-70 was jointly developed by 3 members of NATO, and was the first operational towed artillery piece to employ an auxiliary power unit

 
 
Country of origin United Kingdom, West Germany and Italy
Entered service 1980
Crew 8 men
Armament
Gun bore 155 mm
Barrel length 39 calibers
Projectile weight (HE) 43.5 kg
Maximum range of fire 24 - 30 km
Maximum rate of fire 6 rpm
Sustained rate of fire 2 rpm
Elevation range - 5 to + 7 degrees
Traverse range 56 degrees
Dimensions and weight
Weight 9.6 t
Length (in travelling order) 9.8 m
Length (in combat order) 12.43 m
Width (in travelling order 2.58 m
Width (in combat order) 7.5 m
Auxiliary power unit
Engine Volkswagen 1.8-liter diesel
Engine power 71 hp
Maximum road speed 16 km/h
Road range 20 km
Mobility
Towing vehicle 6x6 truck
Road towing speed 100 km/h
Cross-country towing speed ~ 50 km/h
Emplacement 2 minutes
Displacement 2 minutes

 

   The FH-70 is a towed 155 mm howitzer developed by an international consortium, which included Vickers Ltd in the UK, OTO Melara in Italy, and Rheinmetall GmbH in West Germany. It was also manufactured in all three of these nations during its decade-long production run, and it was also produced in substantial quantity in Japan.

   The FH-70 program began in 1962, when a need for a new and common NATO field howitzer was identified, and was initially a joint effort between the United States, the United Kingdom, and West Germany. Intending for the new weapon to be in service by 1970, the effort was dubbed FH-70 ("Field Howitzer for 1970"), the future weapon was to replace the M114 155 mm howitzers used by the US and West Germany, and the UK's BL 5.5-inch (140 mm) Medium Gun; both were holdovers from World War 2, and they lacked common ammunition.

   The objectives of the program were highly ambitious, to say the least, and included a very high towing speed, requirement for a range of 24 km with conventional ammunition, 30 km with rocket-assisted ammunition, the ability to fire 3 rounds in only 15 seconds, 6 rounds/minute with burst fire, a sustained rate of fire of 3 rounds/minute, and compatibility with all existing and projected NATO 155 mm ammunition. By far the most unusual requirement --- and one with far-reaching implications for future artillery development --- was that the FH-70 was to have an Auxiliary Power Unit (APU), which would not only provide hydraulic pressure and electrical power, but also provide power directly to the wheels themselves, allowing the gun crew to literally drive it as a vehicle (though only for short distances).

   However, as has been the case with many international weapon programs, disagreements soon arose between members of the consortium over what features the FH-70 was to have. Two issues that proved irreconcilable were that the US military demanded a gun that was significantly lighter, in order to make it more easily transported by helicopters, and refused to acquire a weapon fitted with an APU. As a result, the US broke away from the FH-70 program in the 1965, and began developing an indigenous alternative in 1969, which in time became the M198.

   The consortium to produce the FH-70 was officially formed in 1964, minus US participation, and work began on the prototypes in 1964. The development of the FH-70 proceeded slowly, and testing of fully-functional prototypes didn't begin until 1969. However, the program received a much-needed boost in 1970, when Italy joined the consortium, pledging to share 25% of the expenses (the UK held another 25%, and West Germany held 50%). Though even with the addition of Italian support, testing and evaluation weren't deemed complete until 1976. Deliveries of production FH-70s began in 1978, with Initial Operational Capacity (IOC) being achieved later in the same year. Though 1978 is often the date cited that the FH-70 first became operational, it did not achieve full operational status with any of its users until 1980. Moreover, as outlined further below, a litany of problems surfaced in active service that prevented the FH-70 from achieving its full operability for several years.

   The key identification features of the FH-70 are a 2-wheel carriage, 2 trailing wheels at the bottom of long struts at the back end of the trailing arms, two spades also located at the back end of the trailing arms, two small round headlamps on the front of the carriage, two large hydropneumatic struts on the wedge-shaped breechblock assembly, and a muzzle brake with two pronounced baffles. When travelling, the gun tube is traversed 180 degrees and overhangs the trailing arms atop an "A"-shaped bracket, and the crew sometimes drives the FH-70 like a vehicle from two positions in the front topside of the carriage. In its firing position, the trails are spread-apart, the tube is traversed forward, and the main wheels are elevated, allowing the soleplate to rest atop the ground.

   The tube is carried on a gun cradle, which is in turn carried by slides. Also carried on the gun cradle is the recoil system, which includes a buffer, a high-angle cut-off gear, and a recuperator. The main firing system is mechanical, and carried by one of the cradle trunnions.

   The carriage has a lightweight construction, and consists of a saddle, a soleplate, split trails, self-digging spades, main wheels, and trail wheels. A detachable APU is also usually fitted to the weapon. The gun carriage of the FH-70 has two wheels and a split trail, with spades and small wheels at the ends of the trails. The saddle sits on top of a roller race, containing the elevating and traversing gear and the gun layer’s seat, and these in turn are set atop the main body of the cradle. Large hydropneumatic struts connect the carriage to the trailing arms, which are part of the hydraulic system used to raise and lower the wheels, and also double as shock dampeners; this allows the carriage to be lowered directly onto the ground, to rest atop its soleplate.

   The carriage wheels are hydraulically suspended on swinging arms, and cushioned by hydraulic accumulators; a similar system is used for the trailing wheels. The trailing wheels may thus also be steered, raised, and lowered. The hydraulics used to power these systems are controlled from the driver's position and may be operated regardless of the weapon's placement or orientation.

   The sighting system is mounted on the left side of the saddle, and includes a quadrant elevation scale and leveling bubbles, a periscopic dial sight, and a direct fire telescope; the scales, graticules and bubbles, are all self-illuminating. A low-light sight for direct fire may also be fitted if required. The sight carrier includes transducers for azimuth and elevation. An optional Digital Display Unit (DDU) further aids the laying of the gun; the German and Italian armed forces have outfitted their FH-70s with DDUs, but the British armed forces did not.

   The standard crew for the FH-70 is 8, though it is possible to operate with a crew of only 4 (albeit with much slower operations).

   The tube is autogrettaged and 39 calibers long, and fitted with a single-baffle muzzle brake with a 32% efficiency. The tube life of the FH-70 is 2 500 Equivalent Full Charges (EFC), at which point the tube must be removed and replaced.

   The elevation assembly is carried on the trunnions. It consists of a cradle with a variable-length hydropneumatic recoil system, which reduces the length of the recoil stroke in order to prevent the breech from striking the ground; the maximum recoil length is 1.4 m.

   The loading system is semi-automatic, and consists of a loading tray and an automatic tube loader, which operate at any elevation or traversal. The breech is initially opened by hand, but ammunition, propellant charges, and primers are normally loaded automatically. The breechblock is semi-automatic, and slides upward when opened. As the FH-70 is loaded, a second shell is placed on the loading tray, which is automatically loaded after the first shell is fired, and the breech is re-opened. When the breechblock is in full recoil after firing, the breech is automatically opened by a cam, and the spent propellant casing is ejected as the next round is lifted to the breech for manual ramming. The entire loading sequence spans just 5 seconds.

   These allow for a continuous rate of fire of 2 rounds/minute, rapid fire over a short duration at up to 6 rounds/minute, or a burst fire of 3 rounds in 13 seconds. A fully-automatic system with a flick rammer was also offered for the FH-70, which allowed for firing 3 rounds in only 8 seconds.

   New ammunition was developed for the FH-70, in accordance with the Quadrilateral Ballistics Agreement between US, UK, Germany and Italy. The intention was to maximize ammunition commonality between these nations, and the specifications settled-upon were those of the volume, mass, and general ballistics of the US-made M549 RAP-HE round. With a total mass of 43.5 kg and an 11.3 kg HE fill, the M549 still has the largest explosive charge of any RAP-HE round.

   Although the FH-70 was not adopted by the US military, US ammunition can still be fired from it, though the variations in the sizes of US primers has resulted in some feeding problems.

   A range of common ammunition was developed for the FH-70, which were developed to increase the maximum range and lethality of NATO's 155 mm artillery. The primary three rounds for the FH-70 are the L15A1 HE round, a thin-walled 43.5 kg projectile with a 11.3 kg explosive charge; the DM 105 Base Ejection Smoke projectile, which splits into four smoke candles on descent, producing a dense smoke cloud over a wide area in 30 seconds; and the DM 106 Illumination round, which spawns a parachute flare on descent with an illumination power of 2.1 million candelas for 60 seconds.

   The FH-70 may also fire extended-range projectiles, such as the US Army's M549A1 RAP-HE round and the RB30 Extended Range Base Bleed (ERBB), both of which have a range of 30 km when fired from a 155 mm/L39 weapon. The US Army's laser-guided M712 Copperhead Cannon-Launched Guided Projectile (CLGP) round is also compatible with the FH-70.

   A triple-cartridge propellant charge system is used in the FH-70; i.e., three cartridges are normally loaded behind the projectile. There are three different propellant cartridges for the FH-70, with different charge levels. "Cartridge 1" provides charges 1 and 2; "Cartridge 2" is used for charges 3 through 7, and "Cartridge 3" is used for charge 8. With a maximum charge, the FH-70 will fire an L15 HE round out to its maximum range of 24.7 km.

   The propellant charges are ignited by percussion primers, and the FH-70 automatically reloads the lock with a primer every time the breech is opened, from a magazine containing 11 primers.

   BAE Land Systems has also developed the BIS 14 propellant cartridge for the FH-70, which allow the weapon to fire an extended-range projectile out to as far as 31 km (namely, one BIS 14 cartridge provides "Zone 8" power).

   The FH-70 is technically not a vehicle, but it does have a limited ability to move like one, as the APU doubles as an engine. The APU is located inside an overhanging cab in the front of the carriage, with two seats on top on the left and right for a driver and another crew member. The APU is a Volkswagen Model 127 1.8-liter diesel motor, with 4 cylinders in a "boxer" configuration. It is air-cooled, spark-ignited, and produces up to 71 hp at 80 rpm. The fuel tank has a capacity of 55 liters.

   When using the APU, the FH-70 may be unhitched, positioned, and ready to fight in less than 2 minutes. If a target is to be engaged outside the weapon's traversal range once in its firing position, the trailing wheels may be lowered to the ground and the spades and trails raised, allowing the entire weapon to be quickly swiveled in the required direction. Once the target is within the traversal range, the wheels are raised (dropping the trails back onto the ground) and the spades are lowered; when the weapon is fired, the recoil from the first shot will embed the spades into the ground.

   When propelled by the APU, the FH-70 is capable of achieving 16 km/h on a road or other hard surface, and climbing a 34% gradient, and fording a depth of 0.75 m. While being towed, the FH-70 can ford a depth of 1.5 m.

   The main wheels have brakes, which can be controlled from the driver's position on the carriage, or from a prime mover towing the weapon. The steering system allows the carriage wheels to be turned up to 60 degrees to either side, and when the trails are spread, can turn these wheels through 90 degrees.

   The APU also drives a hydraulic pump, which is used to elevate, depress, and traverse the weapon, and to raise and lower the carriage to transition it between its travelling and firing positions. The FH-70's hydraulics may also be operated by a hand pump if its APU is removed or inactive, though this will obviously not provide propulsion or electrical power.

   An alternate APU was developed by ARIS S.P.a. in Italy, but it is unclear if it was ever operationally used on any FH-70s.

   The FH-70 is light enough to be sling-loaded under a heavy-lift helicopter such as the CH-47 Chinook, CH-53 Sea Stallion, or Super Frelon.

   The operational service of the FH-70 began in 1980 with the UK, but despite a prolonged development that had taken more than twice as long as planned, inadequate pre-service testing left numerous problems undetected until the weapon entered service. Many of these problems were caused by the manner in which the weapon was operated, and were solved by simply changing training practices and re-writing the field manuals. However, other issues proved much more difficult to resolve. In particular, the FH-70 proved much more susceptible to malfunctions from dust contamination in the field, whose operating conditions were not accurately simulated in testing, and the rough handling typical of NATO exercises (and by extension, combat) revealed that the structural integrity of the FH-70's trails was inadequate for towing. To mitigate these problems, the FH-70 fleet ultimately had to be sent back to the factory for modifications and reconstruction, a process which began in 1987. There were also numerous additional unforeseen problems pertaining to ammunition handling, which were serious enough that this alone reduced the system's overall reliability level to just 51% --- low enough that West Germany seriously considered abandoning their share of the program. There were also additional problems that didn't become apparent until the FH-70 entered service, for which no complete solution was ever found; notably, the APU, hydraulics, and the digital sight carrier all had inadequate protection from the elements, and were dangerously exposed to possible sources of combat damage, such as shrapnel and shell splinters.

   Though despite its long and troubled development, the FH-70 has defied the odds and become a success, with 1 007 examples produced from 1977 to 1989. A total of 397 were acquired by the UK (67), West Germany (150), and Italy (162), with Norway and the Netherlands each eventually acquiring 15. Malaysia became the first non-NATO customer, acquiring 15 ex-UK weapons, with Oman acquiring another 15 as well, while Morocco acquired 30, and in later years Estonia purchased 32. The largest export customer of the FH-70 is Saudi Arabia, with 72 examples, while an unpublished number of FH-70s were also acquired by Lebanon.

   Perhaps the biggest surprise is that the largest user of the FH-70 is Japan, with some 460 (more than the combined active inventory of all other current users combined!), and that aside from an initial import of 20 FH-70s, the remainder were all built locally under license by Japan Steel Works. With the exception of Japan's FH-70s, it is probable that these howitzers will continue to proliferate in the foreseeable future, particularly as they are retired from service with their primary users. Japanese production ended in 1997.

   The FH-70's production is complete, and while it was still available for further production into the early 2000s, it is unlikely that and could or would be produced today. According to Forecast International, the unit cost of an FH-70 in 2002 was US$594,000.

 

Variants

 

   FH-70: Basic production model.

   FH 155-1: Alternate designation for the FH-70, which is also used by the Bundeswehr.

   L121: British designation for British Army FH-70s. No L121s have ever used a DDU gunnery computer in operational service, but are otherwise almost identical to their foreign counterparts.

   SP-70: Self-propelled howitzer employing the ordnance of the FH-70, mounted in an original turret atop a modified Leopard 1 MBT chassis. Did not enter production or service.

   Type 99: Self-propelled howitzer manufactured for the JGSDF by Mitsubishi. This vehicle has a heavily-modified Type 89 IFV hull, topped with an original turret, and is armed with a longer 52-caliber version of the FH-70. In service only with Japan.

   Palmaria: Self-propelled howitzer manufactured by OTO Melara in Italy, for export. It is armed with the ordnance from the FH-70, in a turret based on that of the SP-70, mounted atop an OF-40 MBT hull. Palmarias are operated by Libya and Nigeria.

   TAM VCA: Argentinean self-propelled howitzer, consisting of a modified TAM light tank chassis topped with a complete Palmaria turret. Used only by Argentina.

   FH-70s were also offered with 46-caliber and 52-caliber barrels, but it does not appear that any operational weapons were given these upgrades.

 

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