HHM-18 Oshosi
| HHM-18 Oshosi | |
|---|---|
 HHM-18 Oshosi with ammunition options. | |
| Type | Self-propelled artillery |
| Place of origin |  Carthage |
| Service history | |
| In service | 2013-present |
| Used by | Carthage |
| Production history | |
| Designer | Army Vehicle Research Center |
| Designed | 2007-2012 |
| Manufacturer | Cooperative Defense Industries |
| Unit cost | $9 million (FY2014) |
| Produced | 2011-present |
| No. built | 820 |
| Specifications | |
| Weight | 68.4 t (75.4 short tons) |
| Length | 15.34 m (50.3 ft) (gun forward) 8.18 m (26.8 ft) (hull only) |
| Width | 3.80 m (12.5 ft) 3.85 m (12.6 ft) (w/skirts) |
| Height | 2.97 m (9.7 ft) (max) 2.47 m (8.1 ft) (min) |
| Crew | 3 (commander, gunner, driver) |
| Breech | Automatic interrupted screw |
| Elevation | -4° to +70° |
| Traverse | 360° |
| Rate of fire | Max: 6 rpm Sustained: 4 rpm |
| Muzzle velocity | Max: 960 m/s (3,100 ft/s) |
| Maximum firing range | Conventional: 56 km (35 mi) RAP: 75 km (47 mi) |
| Armor | Modular composite armor |
Main armament | 210 mm L/52 CCA-375 rifled gun |
Secondary armament | 1 × CRA-334 15.5 mm autocannon (RWS) |
| Engine | Danel Group VTX-12-1200B V-12 turbocharged diesel engine 1,200 kW (1,600 hp) |
| Power/weight | 23.4 kW/tonne (30.7 hp/tonne) |
| Transmission | North Iberian RAT-40-16B series hybrid drive (1,600 kW (2,100 hp)) |
| Suspension | Active in-arm hydropneumatic |
| Ground clearance | Variable 0.1-0.6 m (3.9-23.6 in) |
| Fuel capacity | 1,200 l (320 US gal) |
Operational range | 550 km (340 mi) |
| Speed | Road: 80 km/h (50 mph) Off road: 60 km/h (37 mph) |
Steering system | Electric |
The HHM-18 Oshosi (Yoruba: Ọ̀ṣọ́ọ̀sì) is a Carthaginian 210 mm self-propelled gun developed by and for use in the Carthaginian Army. It was developed to replace the SPG-68, the previous generation of self-propelled field gun, as the primary heavy gun at the corps level. The HHM-18 is the most powerful conventional artillery system in use by the Carthaginian Army, capable of firing conventional shells over 56 kilometers (35 mi) at a rate of up six rounds per minute. The HHM-18 is based on the Heavy Brigade Armored Fighting Vehicle (HB-AFV) chassis and as a result shares a significant number of its automotive and protective components with other common vehicles such as the HTA-02 Jaguar II tank and the HIV-06 Eryx infantry fighting vehicle. Unlike the preceding SPG-68, the HHM-18 is fully enclosed and has a fully automated loading system, sharply reducing crew requirements from the twelve men required with the SPG-68 to just three men in the HHM-18, all enclosed in a protected crew pod in the hull.
Development began in the mid-2000s as a second replacement for the SPG-68 after the prototype SPG-85 was cancelled in the 1980s. Development proceeded concurrently with the 155 mm HHM-09 Bowman self-propelled gun which was also based on the HB-AFV chassis derived from the HTA-02 Jaguar II. Low-rate production began in 2011 and the HHM-18 was formally introduced in 2013. Production continues as of 2017 and at current rates of production, the HHM-18 is expected to replace all remaining SPG-68s in the active and reserve forces by 2026 and all SPG-68s in the militia by 2032.
History
The HHM-18 is Oshosi was developed as the replacement to the SPG-68 210 mm self-propelled gun, first introduced in 1969. The SPG-68 was the first self-propelled 210 mm artillery piece in the Carthaginian arsenal and was introduced as an army-level heavy support gun built on the chassis of the T-64 Elephant main battle tank. While the SPG-68 was a significant improvement over earlier towed pieces in terms of mobility, it was an open-topped vehicle that required a crew of twelve men to operate, most of which were carried in an accompanying vehicle that also transported the majority of the ammunition load. The manual loading process limited the practical rate of fire and resulted in long setup and breakdown times, rendering SPG-68 batteries vulnerable to counter-battery fire.
In the late 1970s, the Carthage Defense Forces were reorganized into a series of military districts and the army level of organization was abolished. SPG-68 batteries were reallocated as corps guns and the more tactical nature of their work further exacerbated their vulnerabilities. In 1981, the Army started a program to replace the SPG-68, dubbed the Future Corps Artillery System (FCAS). FCAS envisioned a new vehicle equipped with a semi-automatic loading system that could reduce the crew to ten men and improve mobility through the use of the newer MBT-74 Rhinoceros chassis.
Four FCAS pilots were produced by 1983 and entered testing and evaluation under the provisional designation of SPG-85 but the program was cancelled in 1984 as protection and mobility standards were further increased. The existing MBT-74 chassis was not believed to be capable of meeting the greater protection and mobility requirements without significant overhauls to the suspension and powerpack while the semi-automatic loading system left a significant proportion of the crew vulnerable to counter-battery fire. These problems made the program a target for elimination in the austere budget environment of the 1980s.
The SPG-68 remained in service until in the mid-2000s, when the HTA-02 Jaguar II program and accompanying Heavy Brigade Armored Fighting Vehicle chassis created the opportunity to start a new replacement program. the HB-AFV chassis was larger and could support more protection than the MBT-74 chassis, while developments in autoloader technology were expected to allow for a much greater crew reduction than originally proposed in the SPG-85. As the Armored Brigade Modernization Program already included a new 155 mm self-propelled howitzer, it was expected that significant commonalities in design could be achieved.
The new Corps Artillery Modernization Program (CAMP) developed a vehicle using the same HB-AFV platform and the same general method of operation as the 155 mm HHM-09, including a full autoloader that reduced the crew complement to three and allowed for greater onboard ammunition storage. A new liquid-cooled gun enabled a significantly higher rate of fire and a modern fire control system resulted in improved accuracy. The first pilot vehicles, provisionally designated XHM-18, entered testing in late 2008 and were evaluated at the Scleras Gunnery Range and Mangaize Proving Grounds before entering field testing at the Bourem Training Center. Low-rate production was approved in 2011 and the first production units were delivered in early 2012 under the final HHM-18 Oshosi designation.
As of 2017 the HHM-18 Oshosi and HHM-19 Ogun are both in production to replace the remaining SPG-68 guns in service. Both are produced at the Kumasi Tank Plant alongside the HIV-06 Eryx infantry fighting vehicle.
General characteristics
Protection
The HHM-18's crew is situated in a protected crew pod in the hull, between the front-mounted engine and the weapon system compartment to the rear. The crew are completely isolated from the ammunition and propellant charges by an armored bulkhead which ensures crew survivability in the event of an ammunition cook-off or propellant deflagration. The forward hull armor is designed to protect the engine and crew from enemy fire up to and including 40 mm autocannons and is composed of an array of spaced plates with an outer layer of pin armor for improved protection against shaped charges. When equipped, the track skirts provide the same level of protection from the side and the ammunition compartment bulkhead provides protection from the rear. The weapon system compartment is protected from 25 mm cannon fire all around.
Due to the significant threat of counter-battery fire, the Oshosi has improved roof protection against shell fragments, cluster bomblets, as well as artillery- and air-delivered explosively-formed penetrator submunitions. This protection is known to include an array of spaced plates and is believed to include additional layers of undisclosed materials. The two hatches to the crew compartment are also heavily armored and are equipped with torsion springs and an electric motor to ease operation by the crew.
Like other Carthaginian armored fighting vehicles, the HHM-18 is normally covered by the Moonlight camouflage netting system which reduces the vehicle's visibility in the visible light and infrared spectra. The vehicle is equipped with laser warning sensors to detect the use of laser rangefinders and laser designators against the vehicle. The sensors trigger an automatic alarm and alert the crew to the direction of the laser and can be set to automatically trigger the vehicle's smoke dispensers to disrupt weapon seekers. The Oshosi is not normally fitted with an active protection system but can be equipped with the same EAH-538 short-range APS as other front line combat vehicles.
Armament
The primary armament of the HHM-18 is the 210 mm L/52 CCA-375 rifled gun. The CCA-375 is manufactured from conventional high-strength steel and layered with a chrome liner to reduce fouling and maintain barrel life. Like the CCA-373 in the HHM-09 Bowman, the CCA-375 has an integrated midwall liquid cooling layer which circulates a mixture of ethyl gylcol and water to sustain higher rates of fire. The gun is fed using an autoloader system composed of two closed-loop conveyors in the hull feeding a central shuttle, which feeds the round into the loading tray. A separate loader moves modular propellant charges from the bustle magazine into the gun after the shell has been rammed. This system enables loading at any angle and combined with the barrel cooling system is capable of a maximum rate of fire of six rounds per minute and a sustained rate of fire of four rounds per minute.
The HHM-18 is also capable of multiple-round simultaneous-impact (MRSI) missions, firing a maximum of five shells against a specified target with all shells calculated to arrive at the same time. The gun is also capable of being used in direct-fire situations against attackers and the turret is equipped with both optical and infrared sensors for gun-laying in this mode. The gun is equipped with two radar units, one for shell-tracking purposes to allow the fire control system to self-correct for environmental and other factors, and a second to transmit data to smart shells shortly after launch. In normal operation, gun-laying and self-location functions are handled automatically, enabling the HHM-18 to receive a fire mission while underway and to stop, compute its own fire control data, and begin firing within 30 seconds of receiving orders.
A total of 48 rounds can be carried onboard in the two autoloader conveyors. The transfer shuttle is capable of indexing and rearranging these shells as required within the conveyor system and is responsible for feeding new ammunition into the conveyors during resupply periods. Depending on mission requirements, both conventional and ERFB ammunition is available. The use of an autoloader system required the use of the newer modular charge system rather than the old bagged charges and the use of a laser ignition source eliminates the need to manage separate primers.
For self-defense, the Oshosi is equipped with a remote weapon station normally armed with a CRA-334 15.5 mm chain gun but which may be rearmed with a variety of alternative weapons depending on mission requirements.
Mobility
Like other vehicles based on the Heavy Brigade Armored Fighting Vehicle platform, the Oshosi is powered by a 1,200-kilowatt (1,600 hp) Danel Group VTX-12-1200B V-12 diesel engine connected to a series electric North Iberian RAT-40-16B traction drive. This combination is the same arrangement used in the HTA-02 Jaguar II but rearranged for a front-engine configuration. This powerpack provides the HHM-18 with a power to weight ratio of 23.4 kW/tonne (30.7 hp/tonne) and a maximum road range of 550 kilometers (340 mi), both significant improvements over the SPG-68. The improved power to weight ratio also improves off-road mobility, allowing the HHM-18 to maintain pace with mechanized advances and expanding the range of accessible firing sites.
The Oshosi is designed to rapidly come into and go out of action to improve survivability against counter-battery fire. The gun is capable of engaging targets within 30 seconds of coming to a halt and all of the necessary actions to bring the gun into action are automated or can be carried out from within the vehicle, including computing fire control data and disengaging the travel lock. The vehicle can be brought out of action in less than one minute, allowing it to quickly depart the area after completing its fire mission. All of these factors are designed to significantly improve the availability of corps-level heavy artillery by maximizing the readiness and cutting travel times between sites.
For strategic movement, a maximum of two HHM-18s can fit in the cargo compartment of a RTS-224B Albatross airlifter or one vehicle in an RTS-224A MRTT. The Oshosi can also be moved by rail and by RORO ship, which are the preferred methods of movement across long distances. When transported by train, the armored skirts can be removed to accommodate narrower loading gauges.
Derivatives
While not a derivative, the HHM-18 shares a number of technological similarities with the smaller-caliber 155 mm HHM-09 Bowman self-propelled howitzer. Both are built on the same HB-AFV chassis and use liquid-cooled guns and autoloaders of similar design for higher sustained rates of fire. The Oshosi is also mechanically related to other HB-AFV-derived vehicles, such as the HIV-6 Eryx IFV and the HOM-14 Apollo MLRS.
HHM-19 Ogun
The HHA-19 Ogun (Yoruba: Ògún) is an ammunition carrier vehicle designed to accompany the HHM-18 in the field. The Ogun replaces the Oshosi's turret and autoloader system in the weapon compartment with a large fixed casemate with storage for 72 rounds and an equivalent number of propellant charges. The use of the HHM-18 chassis and powerpack allows the HHA-19 to match the HHM-18's mobility and share spares and logistics.
Like the HHM-18, the HHA-19's ammunition handling systems are automated and the crew can remain in the armored crew pod during reloading operations to protect them from enemy fire. Rounds and charges are transferred by a hydraulic conveyor system through an extendable munition bridge into the rear of the HHM-18's turret, from which the autoloader system can automatically index the new rounds and stow them for use. The maximum transfer rate is ten rounds per minute, allowing for a complete resupply of the HHM-18's ammunition and propellant magazines in under ten minutes.
The HHA-19's own onboard magazines are resupplied via a rear hatch where new rounds are loaded and the automatic transfer system stows them for travel. In the event of a loading system failure, rounds and charges can be manually removed but this is extremely rare due to the significant weight of the 210 mm ammunition.
Operators
- Carthage – 820 vehicles in service, with an additional 7,400 vehicles on order. An additional order to replace militia inventory is expected at a later date.
- Army of Carthage: 820 vehicles in service.