“Christie’s ‘Tank Tsardom’: From the Revolution to the World Revolutionary War”
Christie’s M1928 tank design crosses an obstacle in the trials conducted by the US Army.
The tank has had a long history in the UASR, with some of the first major confrontations between modern tanks taking place between White British-supplied Vickers 6 Tons, and Red M1928s, and Soviet-supplied T-26’s and BT-7’s. In a great number of battles, especially those in Toledo, Chicago and Baltimore, large groups of White and Red tanks would directly clash, giving a valuable signal to the future influence of tank-versus-tank engagements. During the Civil War and after it, American engineer J. Walter Christie dominated the American tank development, masterminding the conversion of the River Rouge complex into a massive tank factory. Despite not being much of an ideological communist, his friendly relationship with Patton and with the pre-revolution bona-fides of selling his M1928 design to the Soviet Union, Christie enjoyed the support of the Army.
Christie’s support for fast-moving, lightly armoured infantry tanks meshed well with the WFRA’s expectation of having to fight on large, wide-open plains such as the Russian Steppe or Great Plains. Christie’s innovations to his original design would result in the T-3 ‘Pecos Bill’ tank, the first versions of which would be rushed into production during the civil war. Later variants would include a 37mm autocannon or a 45mm anti-tank gun, radios in every tank, a wider, more spacious hull, thicker armour and a five-man crew, and would be produced in both the USAR and the USSR, forming the mainstay of their cavalry. From his experience with the River Rouge factory, Christie would optimise the design for production, introducing a heavy use of castings and the common Caterpillar V12 diesel engine.
In the summer and fall of 1935, the WFRA conducted a series of tests and large scale military exercises to develop and refine the Unified Military Doctrine. Representatives from the Soviet, Mexican and Chilean militaries were involved. A Soviet tank brigade joined exercises in the American southwest and central plains. An American tank brigade joined its RKKA comrades on manoeuvres in Ukraine. Beyond being a symbol of socialist fraternity, the joint exercises would shape doctrine and tank design for the years to come.
The WFRA followed very similar tables of organisation as it had in the Civil War. The primary fighting unit was the triangular infantry division, with a motorised logistical tail. These infantry divisions were organised into three-division rifle corps, supported by a tank brigade and other assets. In the corps level manoeuvres, the rising stars of the American and Soviet officer corps would develop the tactics of tank exploitation and tank defence.
Testing revealed a number of deficiencies in the tank arm, some organisational and some technical. The old M1925 mediums and the Soviet T-26s were no longer adequate for the infantry support role. The proliferation of 12.7mm heavy machine guns had given the modern infantry division plenty of firepower against these lightly armoured tanks, and it was likely that other states would adopt large calibre machine guns and anti-tank rifles in high numbers.
These weapons posed similar threats to the T-3 serving in the “cavalry tank” role. While sufficiently well armoured against frontal attacks from high calibre rifle rounds, the T-3 was still vulnerable to penetration by them in the side and rear arcs. Additionally, the 45mm was found to be less than ideal for high-explosive work. The 118 gram bursting charge and resulting fragmentation of the UO-243 shell did not produce enough shrapnel to satisfactorily knock out artillery emplacements or infantry positions.
Following these trials, the military soviet of the Tank Arm produced two operational requirements. The first, OR-36MT, was for an improved medium tank, capable of succeeding the T-3 in the cavalry and exploitation role, while also providing improved anti-tank and infantry support capabilities. OR-36MT specified a mass of 20 to 25 tonnes, three metre trench crossing capability, a road speed of not less than 50 km/hr, comprehensive protection against large calibre machine guns as well as frontal arc protection against modern anti-tank artillery. OR-36MT would be serve in the expanded tank corps to support army-level offensive operations
The second requirement, OR-36HT, would serve in breakthrough tank brigades in the support of the rifle corps in the offensive. This operational requirement specified comprehensive protection against infantry support weapons, as well as a three-man turret capable of mounting at least a 75mm gun, though the Defence Secretariat preferred the development of a 90mm. Additional requirements included cross-country speed and range sufficient to aid in exploitation operations into the rear area. Compared to the infantry/cavalry tank divide of many other countries, including the UK, OR-36HT would be better protected and more mobile.
In 1935, Christie, as a member of the Detroit Arsenal, would turn his eye to designing a better-armoured yet still mobile medium tank for the WFRA. By 1937, a prototype was ready, using Christie’s favoured suspension design and with relatively light armour. However Christie conflicted with his co-designers on the tank over the level of armour to be mounted, and the suspension type. Due to the bulkiness of the Christie suspension and the corresponding lack of effective levels of armour on the sides of the tank (the original design’s sides being easily penetrated anti-tank rifles), his opponents, unofficially lead by engineer Preston Tucker, would accuse Christie of attempting to make the T-3 all over again, and of a domineering attitude towards other engineers. Christie’s detractors said that he believed himself to be the ‘Tank Tsar,’ and claimed their plans for the T-4 and the Arsenal’s tank division were more consistent with the ongoing transformation of the UASR’s economy towards socialism.
In the end, Christie’s suspension was removed from the tank and replaced with torsion bars. This perceived snub from the Defence Secretariat would cause a rupture in Christie’s design team, and cause J. Walter himself to turn his attentions to future projects. The revisions required along with the new suspension resulted in an increase in the thickness of the vehicles armour and the repositioning of the turret to the middle of the tank, from the front. This also allowed the driver and radioman/hull machine gunner’s hatches to be moved to a better-protected position, off of the upper glacis and onto the roof. While the T-4’s turret was relatively well-armoured, the smaller 57mm L/52 AT-57-S2 high velocity gun, based off of a more compact version of the ZiS-2 AT gun, the ZiS-4, was unable to provide the highly effective fire support that larger calibre cannons were able to. While some advocated waiting for the planned compact 76mm gun to be developed, Christie believed the 220 gram bursting charge of its HE shell to be a sufficient improvement over the 45mm gun from its predecessor. The cavalry-focused WFRA brass did not consider this problem to be especially significant, as they believed that the tanks’ machine guns would be sufficient for infantry support.
The AT-57 series excelled in the anti-tank role, and its adoption as the primary infantry anti-tank artillery was an added boon. Shared ammunition between the anti-tank artillery and the tank arm simplified logistics. It was markedly superior to the 5cm KwK 37 adopted by the German Panzertruppen for the Panzer III, capable of penetrating 90mm of RHA at 500 metres compared to just 56mm for the German gun. However, it suffered from weak high explosive and shrapnel shells, and a lack of accuracy at long range. The Wehrmacht compensated for the weakness of the 5 cm gun by arming just over a third of its Panzer IIIs with the 7.5 cm KwK 37 howitzer, though this weapon lacked enough muzzle velocity for use with APHE ammunition, in contrast with American infantry support guns.
The one area where Christie and his rivals agreed was the need for good protection along the frontal arc. While Christie believed that obstacles like anti-tank guns should be bypassed rather than engaged, engagements with other tanks could not be decided by mobility alone. The cast hull of the T-4 would utilise sloped upper and lower glacis. The 45 mm thick upper glacis used a novel face-hardening technique to improve effective protection. With the 54 degree slope, the plate had a line of sight thickness of 76mm, offering excellent protection against the British 6-pounder except at point-black range. The turret front was 85 mm thick, with an overlapping 50mm mantlet giving additional protection to the gun breach.
T-4BU mod. 1942, a 76mm gun retrofit
—
J. Walter Christie’s immense personal prestige at the Detroit Arsenal effectively left the T-4 “John Henry” orphaned once the initial requirements were completed. At the Arsenal, design work turned towards T-7 series light tank and its derivatives as mass production began, with further development of the T-4 design passed on to Eric L. Buford’s* team at the Birmingham Machine Works in New Afrika.
Buford had studied engineering at Tuskegee University after serving as an infantryman and tank driver during the Great War. Prior to the Revolution, Buford had managed to find work in the harshly competitive climate of the “Big Three” automakers in Detroit, bouncing between Ford and Chrysler working under men less talented than he. His experience in the iterative improvement of truck and passenger car models, gained improving designs credited to his white coworkers, proved invaluable in the ongoing development of the T-4.
The Birmingham Machine Works and the attached EDB-481 had been established as a model enterprise for industrial development of the Deep South. The new complex was a natural complement to Birmingham’s steel industry, and as part of urban renewal projects reshaped the city into a centre of cutting-edge science.
Though originally intended to be a locomotive and automotive plant, total mobilisation and the massive demand for armoured fighting vehicles resulted in the Birmingham Machine Works coming online as a tank and artillery plant.
The T-4B was running up against a number of design shortcomings, and those had only gotten worse in the harsh battlefield conditions in Russia. Beginning in December 1940, Buford’s team worked around the clock to overcome deficiencies in the transmission and final drive. The T-4 had adopted an at the time novel dual-epicyclic steering system, in which the motive power from the engine is transferred to an independently geared final drive on each track. Steering is accomplished by reducing the gear ratio on one track, reducing its speed and causing the tank to turn that direction. Since this causes a fixed turning radius at each gear, this system is augmented with a clutch-and-brake system for tighter turns.
While more efficient than the clutch-and-brake system used on its predecessor, transmissions require incredible manufacturing precision, and with a tank weighing twenty-eight tonnes driven by a nearly 500 hp engine, the incredible stresses caused unacceptably high failure rates. Buford’s team identified a dozen design flaws in the transmission system alone, and more in the tracks and running gear.
Additionally, the tank’s production was proving more costly than anticipated. Buford was stuck between the Scylla and Charybdis of D.C. demanding a tank that was more reliable and less prone to catastrophic damage in combat, which would also require fewer man-hours of work to produce.
Buford’s iterative improvements succeeded . New tanks and replacement parts were more reliable, and the T-4C model reduced overall labour requirements by almost twenty-five percent. Buford’s design team, still largely working in Christie’s shadow, also developed a new turret to upgun the tank with the AT-76-M1, giving the tank sufficient firepower to engage Nashorn tanks from the flanks while also greatly improving burst-charge mass on HE shells. The new turret would first be fit on the T-4CU model, as well as on the up-armoured T-4D series.
The success of the upgunned “John Henry” program would result in the XT-9 medium tank project to be sent to Birmingham, while Christie’s own XT-18 project proved to be years away from realisation.
Christie wished to make the same leap ahead of existing tank technology with the XT-18 as had been made with the T-4: to create a tank with firepower and frontal protection on the same scale as a heavy tank while still maintaining the mobility of a medium tank. Intelligence reports on the German’s VK 45 series of prototypes, speculated to be adopted as PzKpfw V, as well as the Ford/Todt Entwicklung project competing against it, had convinced the Stapel2 to fund Christie’s ambitions.
But in the interim, it was also clear that the T-4 would be reaching the limits of upgradability in the coming years. Upgunning and uparmoring the chassis in later marks had compromised the reliability and cross-country performance of the tank.
The XT-9 project was a much more conservative one, aiming to use as much existing technologies and tooling to produce an improved medium tank. It would be armed with the same 90mm high velocity cannon that had been intended for the T-5 heavy tank before program delays forced a downgrade to the AT-76-M1. Tracks, road wheels and other suspension components would be reutilized, but the hull would be designed from scratch for the new operational requirements.
XT-9 would require frontal protection against both 7.5 cm PaK 40 and the 8.8 cm KwK 36 at 500 metres, and weigh less than 35 tonnes. This daunting requirement was assisted, ironically, by the evacuation of the Kharkov Komintern Locomotive Factory before the city’s fall. As plant machinery evacuated to Nizhny Tagil to be joined with the Dzerzhinsky works, much of the engineering staff and design materials were relocated abroad to continue development out of the range of German bombing.
True to Aleksandr Morozov’s dictum that “armouring air is expensive,” the team at Birmingham worked to radically reduce the size of the tank’s armour profile. Though wider than its predecessor, the hull of the XT-9 was able to be greatly shortened thanks to the adoption of a transverse mounting of the 600 hp V12 diesel engine. Buford’s next victim was the bow machine gun and the assistant driver/radio operator stationed there. Reducing the crew to four men and redistributing radio operation duties to the loader’s station allowed a major reduction in the size of the fighting compartment without harming crew ergonomics.
The space once occupied by the assistant driver would instead house a fuel cell and the reserve ammunition rack. The low volatile diesel fuel would prevent the highly volatile powder from conflagrating in the event of a penetration, and the thickness and slope of the frontal armour would make this portion of the tank the most heavily protected. With the upper glacis 90mm thick in the eventual production variant, angled at 64 degrees, the line-of-sight thickness alone would be 200mm, to say nothing of the potential for ricochets.
T-9 prototype during field testing.
As the design evolved to its final form, the 1800 mm turret ring shifted rearward to a more central location in the hull, and the driver’s cabin shifted backwards, removing the vulnerable cupola in the glacis. The test type, delivered in May 1942, froze the basic design arrangement. The new tank would heavily resemble its estranged brother, Morozov’s T-44 tank. Notable differences are the wider turret, roomier interior, and prominent fully-rotating commander’s cupola, armed with a high-elevation .57 calibre heavy machine gun, capable of fire from under armour.
Internally, the test type continued to suffer from a number of reliability problems. While most of the engineering problems with a rear transmission had seemingly been resolved on its predecessor, the additional engineering complexity of the transverse mounting had caused the old demon to return. Additionally, the redesign of the engine to mount more of the components to the side of the block to reduce overall height introduced considerable delays.
Nonetheless, work was forced to proceed at a breakneck pace throughout 1942. The first encounters with German PzKpfw 50 Jaguars during the summer campaign of 1942 influenced the decision to move for mass production beginning in fall 1942, and accept the teething penalties in the interim until an improved model could be developed. This rush affected not just the tank automotively, but also its armament.
The first model of the T-9 was produced without the single-plane gun stabiliser that had made its predecessor deadly at firing on the move, and would not be included until the T-9A model several months later. The AT-90-D42 would prove to be an excellent all-purpose tank gun, and the 932g bursting charge of its HE shell was incredibly effective against enemy infantry and field fortifications, but the early AP shot suffered from shattering and poorer performance than anticipated. By the time a new AP shot was fielded in mass with improved muzzle velocity and metallurgy to repliably defeat the highly sloped 80mm upper front plate of the Jaguar, the Germans had already switched to producing new marks with thicker frontal armour and the fearsome 8.8cm KwK 43 gun, and most American tankers would have to rely upon precious APCR subcalibre munitions to reliably defeat the fearsome cats of the Wehrmacht throughout the war.
- “Experimental Design Bureau”, a calque of the Russian “opytnoye konstruktorskoye byuro ”, and likewise a system of state-run research and development institutions, often associated with larger industrial institutions but not focused on proprietary development.
- Pronounced “stah-pel”, a metonym for the Secretariat for Defense, similar to how “the Pentagon” metaphorically refers to the whole institution of the Defense Department. It refers to the skyscraper building constructed in the mid-30s in Foggy Bottom in D.C., whose trefoil shape around a central core is meant to evoke rifles stacked point-to-point by soldiers in the field, referred to in the WFRA by a German loanword.
*[WPA]: Works Progress Administration *[NBI]: National Bureau of Investigation
Bình luận
0