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Cold War British Prototypes

SPARTAN 105 mm SPG

United Kingdom (1958) Self-Propelled Gun – None built

Spartan began as a design study at the Royal Military College of Science, Shrivenham for a Weapon and Fighting Vehicle Design involving the Officers on the group as well as members of the Technical Staff Course. The project was for the design of a close support artillery weapon that would be able to take part in the 1958 Tactical Battle in Nuclear War doctrine.

The UK was both at the forefront and also, paradoxically, a late bloomer in the Self Propelled Artillery (SPG) game, with the first platforms being the Mk.I Gun Carriers in World War 1. These were built as a result of the tank making its debut on the battlefield and the sudden realization that conventional horse-drawn artillery could be left lagging behind a more mobile army. The first of these was ready on March 3rd, 1917, participating in a Tank Trials Day. Fifty vehicles were ordered by the Army, to be produced by Kitson & Co. While the thought process was in the right area, they were still hindered by their ungainly design and never used in anger.

Various other systems were experimented with and, running alongside, the UK also built a series of vehicles called Dragons (a name taken from the simplification of ‘Drag Gun’) but these were no more than mechanical mules. What was needed was an all in one system, which was solved by the Birch Gun.

The Birch Gun, named after General Sir Noel Birch, who was Master General of Ordnance at the time, was a coupling of an 18 pdr gun (83.3 mm) with a Vickers Medium Mk. II chassis by the Royal Arsenal. This produced what could be argued as the first modern SPG, with a front-mounted engine, rotating gun turret, a crew that could travel with the weapon, and good cross country performance. Birch Guns were used in the Experimental Mechanized Force maneuvers of 1928 but by 1931 they had all been removed from service. This revolutionary design, which put the army decades ahead of its rivals, went the same way as anything that was new, innovative, or remotely useful to the army; precisely nowhere, as they chose not to use it. This inability or unwillingness to adapt or welcome new concepts would stymie the British Army until the present day where they still have the same issue.

By 1939, the UK realized it was inevitably going to be embroiled in another war with Germany and her allies. Hitler’s rise to power and the swift annexation of Czechoslovakia followed by the invasion of Poland led the UK to try and rapidly get the next generation of military vehicles into service as it was clear that mechanized mobility had been key to Germany’s success so far. Unfortunately, lessons learned with the Birch gun were not replicated and throughout most of the Second World War, the UK’s mobile self-propelled guns were lacking compared to both her opponents and her Allies.

Post-war, the UK began to reinvest in the concept of mobile artillery and, with new threats looming in the shape of Soviet Russia, new doctrines and tactics had to be accounted for in the design work. Several different vehicles and concepts were initialized. The FV304 and FV305 were to be built on the FV300 chassis armed with 25 pdr (88 mm) and 5.5 inch (139.7 mm) guns. Work stopped with only partial construction on the first and early layout work completed on the latter.

FV3802 and FV3805 were another two programs. FV 3802 was to be armed with the 25 pdr. while FV3805 was to have the 5.5 inch gun. Both were mounted on modified Centurion chassis in rear large casemates. Two prototypes were made (P1 and P2), although neither were accepted for service.

SPARTAN

The introduction of tactical nuclear weapons (one must remember that, at this point in history, the consensus all round was that the next war would be nuclear without a doubt) left the army in need of new tactics based around mobility, counter-attack, and survival in an irradiated wasteland that would be the conflict zone. To avoid offering a nuclear strike target, the artillery had to be able to concentrate its effort by increased range, rate of fire, and lethality whilst having good mobility to remain dispersed and yet stay in contact. Protection also had to be altered. Open topped vehicles were unsuitable for this type of warfare and therefore protection had to be ensured to protect from flash burns, secondary blast effects as well as conventional threats.

The designers decided that heavy and conventional artillery would be required to break through the surviving enemy defenses, larger long-range field guns would be situated further back from where it’s believed tactical nuclear weapons would be used, and so they settled on the mobile medium range of SPG. Each vehicle would need to be amphibious without preparation (to prevent crew being irradiated), highly mobile with long endurance, and carry enough supplies to allow logistics trains to be reformed behind them.

Spartan was to be built of relatively thin welded steel armor stiffened with support braces with priority given to extra room for supplies and the large volume of ammunition that was expected. This increased internal volume also helped with buoyancy. In order to get the high arc of fire required to effectively ‘lob’ shells over ridgelines and areas in which enemy forces may be hiding, the gun was positioned as high above the vehicle floor as possible to allow for a lower breech drop. To achieve this, the gun cradle was to be suspended from two beams arched across the roof.

The fighting compartment housed a five-man detachment consisting of the commander, two loaders, gunner and driver, and 210 rounds of ammunition. Charges, fuses, and other requirements were kept in sponsons to either side. Large rear watertight doors to the back could be opened to assist in loading shells, which were gravity fed to assist the loader in battle. Other than being airtight with an overpressure system to prevent gas biological and nuclear agents from entering the vehicle, the armor itself* would stop harmful gamma rays while a plastic spall liner would protect against fast neutrons. All the optical devices had polarizing filters to prevent blindness from nuclear flash.

*While the original authors quote the armor would be adequate, correspondence between the author and a nuclear physicist confirmed suspicions that such material would offer no protection against the level of gamma radiation likely to be received.

Automotive power was provided by a turbo-blown, supercharged 400bhp Foden FD12 compression ignition engine which could run on fuels ranging from Diesel, Avtur, Kerosene, and MT 80. Sufficient fuel was carried to allow for a 24-hour operational day and the power and speed allowed it to keep up with other MBTs at an average combat speed of 15 mph (24 km/h). A Merritt Brown gearbox and disc brakes were fitted for the final transmission. The entire powerpack could be extracted via the rear doors on a pull-out roller sheet due to the gun and seat etc. being mounted from the ceiling.

The suspension was via 12 road wheels in 6 pairs on either side via hydraulically adjusted torsion bars allowing the vehicle to lower itself to the ground to provide a stable firing platform.

Firepower

The gun was designed to replace the 25 pounder field gun and the 4.2 inch mortar in service. At a high angle, it was to engage targets between 1500 yards and 17,500 yards (1.4 km to 16 km) with a rate of fire of eight rounds a minute and new ammunition giving a marked performance upgrade over the 25 Pdr. The gun itself was a twelve-foot long (3.6 meter) monobloc non-autofrettaged barrel.

Autofrettage is a process by which the barrel is produced from a smaller caliber one by increasing the pressure on the inside of the barrel past its elastic limit. This enlarges the inner diameter of the barrel by pushing the inner layers of the barrel outwards, thus increasing the density as well. This gives a higher density barrel with better strength, lifetime, and safety. Made from a single forging of high-quality steel with a yield of 55 tons per square inch the gun was fitted with a fume extractor to assist with drawing fumes from the main compartment.

The gun was built to handle UK 105 mm HE and HESH bagged charges. However, an adaption existed to fit a replaceable liner and breach block that would allow it to use the US 155 mm rounds if required, this procedure taking about 2 hours. The new HE round was torpex based with a 60/30/10 mic fo RDX/TNT/AL mixture and an explosive filler of 6.6 lbs (3 kg) offering 250% more effective explosive volume over the older 25 pdr round. The horizontal sliding breech block was fitted with a semi-automatic gear for opening and closing the breach.

An automatic tube loading device with a tube magazine was incorporated for use when the British ammunition was fired. The ring-type cradle had parallel extension members at the rear to take anti-rotational slides for the block. The gun rammer was provided by compressed air in the engine compartment.

Sighting arrangements for the gun consisted of a conventional rocking bar sight and a long-necked dial sight. Laying for elevation was by means of a quadrant elevation bubble clinometer. A separate anti-tank periscope sight was mounted outside the cupola roof to avoid the effects of heat shimmer on the barrel.

Conclusion

The Spartan project certainly identified an area of light Self Propelled Artillery that was required for the MOD and the factors identified were already being used in several Russian developments despite there being no common communication between the developers. To add credence to this, a few years later, the F.V.433 Abbot began development which is remarkably similar in many ways to Spartan and may well have taken inspiration from the preceding project.

The SPARTAN had a very curious profile for a Self Propelled Gun. However, it was designed around the perceived needs of a war during which tactical nuclear weapons would be used. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

Sources

SPARTAN: Royal Military College of Science.
Discussions with Lucian Stan regarding radiation penetration

Specifications

Dimensions 6.22 x 3.1 x 2.82 m (20ft5in x 10ft2in x 9ft3in)
Armament 105 mm Howitzer, with 210 rounds and 300 charges
Time to action 60 seconds
Crew 6
Propulsion Foden FD 12 multifuel 400 BHP at 2400 rpm
Speed 48 km/h (30 mph)
Range 645 km (400 mi)
Traverse Power assisted
Elevation From -5° to +75°
Gun Range 16 km (17,500 yards)
Total production None built

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