Author Topic: A21 Infantry Support Tank - A British StuG Story  (Read 2958 times)

Offline apophenia

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A21 Infantry Support Tank - A British StuG Story
« on: April 02, 2020, 08:58:37 AM »
This sprang out of a simple notion for an early-WW2 British StuG analogue. But do any of my backstories stay terse? Nooo ...

So, with the promise of a captive audience incarcerated by 'social distancing', I have given free reign to my natural verbosity  >:D
_____________________________

Alaric Tank: Born of the Franco-British Bilateral Defence Coordination Committee

Both Britain and French were naturally threatened by the German remilitarization of the Rhineland in early March 1936. Hilter claimed this move to be, in part, a response to the Franco-Soviet Treaty of Mutual Assistance signed a week earlier. After German troops moved into the Rhineland, the Popular Front government in France sought out reassurances from their British ally.

Léon Blum's 1936 Popular Front government assigned the role of maintaining the military alliance with Great Britain to Minister of State (and former PM) Camille Chautemps. [1] To that end, a commission was established in early 1937 aimed at encouraging defence production coordination between the two nations. This working commission would become the Comité de coordination de la défense bilatérale franco-britannique or FB-CCDB.

'Every Time!': Asking for Assured Assistance While Manouevring for Advantage

Chautemps' British opposite (appointed in May 1937) was the Permanent Under-Secretary of State for Foreign Affairs, Sir Robert Vansittart. [2] Both men would spend much of their time managing the natural competitiveness of representative of their militaries and the excessive industrial proprietariness. The recent nationalization of much of French strategic industrial firms also served to unsettle British company representatives. Nevertheless, the need for cooperation was apparent to both sides and some progress was made.

The British Army was most intrigued by the performance of the '7.5 French' cartridge which had been introduced in 1929. [3] Also of interested was the Hispano-Suiza HS 404 20 mm auto-cannon. British authorities also suggested joint development of a medium artillery piece - as replacements for British 127 mm BL 60-pounders and the various aging French 105 mm howitzers and guns. In this, the British were supremely confident in the capabilities of their pending BL 4.5 inch medium field gun. This 114 mm gun, it was argued, would have superior range to the German 10.5 and 15 cm pieces.

For their part, the French were interested in the performance of the British Army's recently-adopted Ordnance QF 2-pounder anti-tank gun (although less so in its complex carriage). Samples of another Vickers design, the QF 3.7-inch AA gun, were also requested. This was primarily for comparisons between the characteristics - both shells and pieces - of Vickers'  gun and the proposed adaptation of 90 mm naval guns from Établissements Schneider for the DCA (Défense contre les aéronefs) regiments. [4] The ultimate goal was a common heavy AA calibre - either the French 90 mm or British '94 mm' depending upon the outcome of comparative trials.

'Every Time!': Asking for Assured Assistance While Manouevring for Advantage

Most of the posturing at FB-CCDB meetings amounted to little more than thinly-disguised industrial espionage. The concept of adopting common munitions calibres was a good one but neither side was willing to simply accept earlier decisions by their ally. In the end, the French stuck with lower-performing 47 mm tank/anti-tank guns and 105 mm field guns. And the British went it alone with their 94 mm anti-aircraft guns and 114 mm medium field guns.

The armoured forces of each nation had little interest in their opposites - both sides believing their own approach to be correct ones. However, representatives of the Royal Armoured Corps were interested in French technical developments. To that end, samples of the new Somua S35 and the Char B tank were requested for review. It was quickly concluded that the forthcoming Matilda II would be the equal or superior of the S35. However, the potential of the older Char B as an infantry support vehicle was appreciated. It was decided - primarily in the interest of maintaining relations between allies - that the RAC would field an 'anglicized' version of the Char B bis.

(To be continued ...)
____________________________________

[1] Chautemps was a member of the centre-left Parti radical while Léon Blum headed the socialist party SFIO.

[2] Vansittart had also been  Principal Private Secretary to PM Baldwin. However, Sir Robert strongly disagreed with disarmament plans of both Baldwin and the in-coming Premier, Neville Chamberlain. It has been suggested that the latter used an appointment to the FB-CCDB to sideline Vansittart.

[3] Of particular interest was the 'heavy ball' Balle 1929D with its boat-tailed spitzer bullet for the drum-magazined Mle 1931F machine gun.

[4] The French were acknowledging the inherent limitations of their Canon anti-aérien de 75mm modèles 1932 and 1938 guns. In the end, the DCA would take on the Schneider guns as their canon de 90 mm modèle 39S.
"Like a hog dance; Like a pig dare; Mind warp deceptor wan ..."

Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #1 on: April 02, 2020, 09:01:49 AM »
Late 1930s British Tank Developments - From 'Shelled Area' to 'Infantry Support'

With war-clouds looming, the British Army's Mechanisation Board began the concept design for a new infantry support tank capable of dealing with WWI-like trench warfare conditions. This design would emerge as the A20 Shelled Area Infantry Tank, prototypes of which would be built in Belfast by Harland and Wolff. However, the General Staff favoured the interim introduction of an 'anglicized' Char B to fill in until delivery of the A20. Accordingly, Dr. H.E. Merritt, Director of Tank Design at the Royal Arsenal, Woolwich, was detailed to the Mechanisation Board to oversee the modification of the Char B design for British service.

From the outset, it had been decided to import Char B track system and advanced hydraulic suspension units directly from France. This was partially in the spirit of the FB-CCDB but also a practical consideration considering the small numbers involved in an interim purchase. Whitehall also insisted that the armoured body itself be entirely constructed in the UK from British plate. Since Harland and Wolff were engaged with the A20, work on the British Char B - now designated A21 - was assigned to W.G. Allen & Sons, boiler-makers at Tipton in Staffordshire, but with armour experience dating from WWI.

Reports from trials with the loaned Char B1s were rather critical. Some issues were moot. The AMX1 one-man turret was judged exceedingly impractical. However, since the General Staff required a rooftop unditching beam, British vehicles would be turretless in any case. The Renault 6-cylinder petrol engine was reliable enough but Whitehall had already dictated that a British-made engine be used. Most troublesome was the Chaize Naeder hydrostatic system - essential in the Char B for traverse in azimuth (since the gun itself had only 1 degree of traverse for 'fine-tuning'). Fortunately, the General Staff had requested that the main gun be raised to increase ground clearance and allow for manual traverse on the 'anglicized' Char B.

The dictate of a British-made engine was further complicated when the General Staff expressed preference for a diesel engine. Dr. Merritt judged a diesel impractical within the time constraints (no powerful-enough British diesel then existing which was suitable for tank use). Instead, the British Char B would be powered by the Bedford Twin-Six - a new horizontally-opposed petrol engine developing 325 hp at 2,200 rpm. Transmission would be a a Meadows 4-speed and reverse crash gearbox with control via a Merritt-Brown system - also built by David Brown Ltd. but designed by Henry Edward Merritt himself.

The resulting design was initially dubbed A21 Accordance but this nomenclature was amended to A21 Tank, Infantry Support, Mk I, Alaric IA before the first prototype was rolled out in the early Summer of 1938. The Alaric IA was armed with an Elswick QF 12-pounder 12 cwt gun - a 3-inch former naval piece. Although close in calibre to the Char B's French gun (76.2 mm versus 75 mm), the 12 cwt gun had a much longer barrel - 40 calibres (ten feet) versus the Char B1 gun's stumpy 17.1 calibres. In service, this reasonably high-velocity gun was given the short-form of '3-inch-40'. Fortunately, the Bedford Twin-Six proved shorter than the Renault engine which allowed the fighting compartment to be slightly lengthened. With the large '3-inch-40' mounted, every inch counted.

Top An Alaric IA of the Dorset coastal defence force in late June 1940. A3802 'Alexander' was a crew trainer based at the Armoured Fighting Vehicles School, Bovington, but has been 'gunned up' and deployed south to West Bexington on the Dorset coast.

Note the portside hull door and more upright driver's hood unique to the Alaric IA. Distinct features of this particular vehicle are the muzzle brake fitted to the main gun (presumably a piece which had been under test at the Lulworth Gunnery School prior to being fitted) and a commander's turret taken from an obsolete light tank.

Developments and Evolution of the A21 Infantry Support Tank

Changes in British Infantry Support Tank policy were dictated by slow progress on the A20 and urged on by the 'Sudeten crisis' of the summer of 1938. This prompted an order for increased production of the 'interim' A21 Alaric. [1] Since supplies of '3-inch-40' guns were limited, [2] a new main armament would be needed. This resulted in a proliferation of proposed new sub-types of the A21 Tank, Infantry Support. The Alaric IB was to have a heavier 12-pounder gun but never reached the hardware stage. [3] The Alaric II was armed with a QF 13-pounder 9 cwt - an anti-aircraft gun pulled back out of retirement. The Mk II made it to the prototype stage (based on an incomplete Alaric IA hull) but it was decided to deploy available QF 13-pounder 9 cwt guns as reserve AA artillery instead. A related project, the Alaric IIA was to use a hybrid 3-inch gun-howitzer but this 'tube' never appeared. [4]

The follow-on development which did reach production was the so-called 'Expeditionary Alaric'. The production model Alaric IV was armed with a 'French 75' gun. The latter were chosen specifically for commonality with the French allies but the guns themselves were sourced from the United States. As affairs 'heated up' in Europe, the Americans made clear through 'back channels' that their military was willing to part with some of its older equipment. This included stocks of 75 mm field guns - both French-made M1897A2 and US-made M1897A4 models. All of these ex-USA guns had non-updated and rather worn carriages but that was not a concern for use in Infantry Support Tanks. Accordingly, the American guns were lightly refurnished and adapted for vehicle use.

A major advantage of the '75' was its fixed ammunition. The British 12-pounder guns all had separate casings and projectiles requiring a 'holder' to keep them together for loading. The move to the '75' greatly simplified the job of the Alaric's loader. But overall, Alaric IV gun performance reduced compared with the Alaric IA. The L/40 '3-inch-40' had a muzzle velocity of 2,210 ft/s and a rate of fire of 15-20 rounds per minute. By comparison the L/36 75 mm had a muzzle velocity of only 1,600 ft/s but, with its 'fixed' ammunition had a potentially higher rate of fire. HE shell weight was similar - 12.9 lbs for the '3-inch-40' and 12 lbs exactly for the 'French gun'. So, the '75' was a compromise but one softened by its availability in fairly large numbers.

Bottom 'Expeditionary Alaric' - a 75 mm '3-inch-40'-armed Alaric IV of the 4th Royal Tank Regiment, British Expeditiary Force. One of 18 Alaric IIs deployed to France in May 1940, A3844 'Alcuin' was knocked out in a divebomber attack outside of Mercatel during the Battle of Arras. (The crew abandoned their vehicle after setting it alight and joined the retreat on foot before being captured south of Duisans.)

In evidence are the more sloped driver's hood of the Alaric IV (and IIA). This is a standard vehicle but 'Alcuin' has had a French-style camouflage stripe added as well as unofficial, WWI-style 'tactical' markings near her nose. A small RAC pennant flies from a wireless antenna.

Importing US surplus stocks of 75 mm ammunition continued until the outbreak of war. However, production of 75 mm ammunition was already underway in Britain prior to September 1939. One indirect result of that was the development of the 'domestic' Alaric V with its '3-inch-36' gun. The latter was another hybrid born of necessity. The best of the ex-US '75s' had been installed in Alaric IIAs. However, many of the older M1897A2 and M1897A4 tubes were found to be quite worn. [5] Rather than boring out and lining already elderly weapons, it was concluded that minimal work would be required to get the '75' to chamber and fire the slightly larger British 3-inch projectile. Accordingly, the British-made 75 mm casing was adjusted to accept the fractionally larger 3-inch shell. [6] Initially, the Alaric V was to be a limited production training model. As events unfolded, the Alaric V trainer with its '3-inch-36' gun would become an essential component of Home Defence after Dunkirk.

(To be continued ...)
_______________________________

[1] BTW: There was a RW A21 project. It was to have been a developed A20E2 Shelled Area Infantry Tank but Harland and Wolff's A21 was passed over in favour of the A22 Churchill.

[2] The QF 12-pounder 12 cwt guns were also in demand for shore defence installations.

[3] The QF 12-pounder 18 cwt was another ex-naval gun which, in the end. While a potentially hard-hitting gun, a separate shell and cartridge made it extremely impractical for tank use.

[4] The proposed 3-inch gun was based on the pending Ordnance QF 25-pounder piece. The modifications consisted of breech and barrel liners reducing the bore down from 88 mm to 76.2 mm (essentially the same mods use to create the Mk II's QF 13-pounder 9 cwt during WWI).

[5] Indeed, this wear would have been one of the reasons why such guns had not been selected for the US Army upgrade prorammes.

[6] There was only .0472 of an inch difference between 'French' and British projectiles. This could be accommodated by a slight enlargement of the cartridge's copper driving band. In metric measures, the French (and American) 75×350 mm R round became a 76.2x350 mm R for the '3-inch-36' gun.
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Offline GTX_Admin

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #2 on: April 03, 2020, 03:01:11 AM »
Interesting
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Offline tankmodeler

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #3 on: April 03, 2020, 05:44:59 AM »
Very cool. One might imagine that if the A21 served in combat for more than a few months (as the French Char Bs only did) the Brits might have seen their way clear to deal with the CharB's second largest flaw after the 1-man turret, the huge radiator weak points on the hull sides. Offset armoured covers over the grilles permitting air ingress, but not shells would seem an obvious improvement on the design. As would some sort of commander's cupola permitting better lateral (at least) visibility for the commander, if not the driver. A slightly raised superstructure area to permit the fitting of a radio in each tank and the cylindrical cupola from a Matilda II, mught be a good Mk V design?

Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #4 on: April 03, 2020, 12:04:35 PM »
Cheers folks.

tankmodeler: Agreed that the AMX turrets were dreadful. The AMX4 was meant to be an improvement - it was enlarged just enough for a second crewman to squeeze his shoulders inside the turret in an emergency. Était-ce ergonomique?  :P

On the radiators, I've read conflicting reports. Some sources say that they were successfully targeted by German 3.7 cm Pak 36s. Others claim that the louvres offered protection equivalent to 60 mm of armour plate. But which version is correct?

With the RW Char B, there was sufficient room inside to have a corridor running along the starboard side of the engine. Presumably, any crew member attending to that engine would have to crouch. Why they didn't lower the ceiling a smidge and mount those two radiators on the roof is anyone's guess.

Another curiosity is the appareil Naeder at the stern which was almost as long the Renault engine. So, first chance I got, that hydrostatic system got junked. My British HO12 engine would need to be mounted fairly high up to meet its new transmission. I had a vague notion that this boxer engine could sit above a fuel tank ... not sure if that's ever been done or even if it would be practical.  ???
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Offline tankmodeler

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #5 on: April 04, 2020, 03:20:04 AM »
On the radiators, I've read conflicting reports. Some sources say that they were successfully targeted by German 3.7 cm Pak 36s. Others claim that the louvres offered protection equivalent to 60 mm of armour plate. But which version is correct?
I've seen a number of dead Char Bs with holes in the louvres. The louvre itself was relatively thick, but there was a reasonable path from it through to the radiator for splinters and high velocity remnants making the radiators quite vulnerable.

Quote
Another curiosity is the appareil Naeder at the stern which was almost as long the Renault engine. So, first chance I got, that hydrostatic system got junked. My British HO12 engine would need to be mounted fairly high up to meet its new transmission. I had a vague notion that this boxer engine could sit above a fuel tank ... not sure if that's ever been done or even if it would be practical.  ???
If the breech can be raised up enough that you can junk the French precision tranny, that is a key improvement, for sure. Using the later German experience, if you can manage +-15 deg traverse from the longitudinal axis, you are probably viable as a panzerjaeger.

By junking the tranny and simplifying the rear end you probably gain at least the capability to repackage things to bring the radiator trunking inboard and put the intake and exhaust up on the engine deck even if the radiators themselves are in about the same place in the sponsons.

Paul

Offline robunos

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #6 on: April 04, 2020, 04:56:16 AM »

Interesting stuff !! 
Apposite, too, as A, I'm currently building the Matchbox Char B for a GB on another Forum, and B, I've been working on some Early / Mid-War British AFV Whiffery myself . . . more in due course . . .


cheers,
Robin.
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Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #7 on: April 04, 2020, 06:23:10 AM »
Paul: Many thanks for those details! I hadn't thought of leaving the radiators where they were and just moving the trunking. Good thinking  :smiley:

Robin: Cheers. Hopefully, the next post provides some more grist for your mill ...

Alaric VI - A21 meets A12 'Matilda Senior'

Obviously, the calamitous fall of France ended the supply of French-made suspension parts for the Alaric programme. By June 1940, Dr. Merritt had already issued specifications for a replacement design - the A22 Infantry Tank (which would also eclipse the now-obsolete A20). But, as German troops lined the English Channel, the A22 was at least a year away from production. With an invasion threat building, it was critical that partially-completed Alarics be finished. An ad hoc solution was fitting Alaric hulls with the suspension of the pending A12 Infantry Tank - the so-called 'Matilda Senior'. The A12 was a Matilda I replacement but with an astonishingly thick armour. The result was a mass of 25 tons - just 2.5 tons short of the Alaric. Work began at once on adapting the A12's coil-spring suspension to the larger A21 hull.

Fortunately, production of the A12 suspension was well ahead of anticipated delivery to the tank's complex and largely cast hulls. Beyond the usual drive sprocket and idler, the suspension for the 'Matilda Senior' consisted of five paired bogie assemblies and a forward 'jockey wheel' which came into contact with the ground only when the bogie wheels were under load. Although the Alaric hull was longer than the A12, there was not sufficient space to install an additional bogie pair. Instead, a rear jockey wheel was added to each side. This 'fix' got Alaric assembly rolling again but the A12 suspension was somewhat overtaxed by the Support Tank's greater weight. In light of the times, this compromise was considered fully acceptable.

Top An Alaric VI prototype fitted with A12 'Matilda Senior' suspension units. This vehicle was part of the Dorset coastal defence force based at Lulworth in July 1940. The tank was actually assigned to the 52nd Training Regiment, Armoured Fighting Vehicles School - specifically, the Gunnery School at Lulworth, close to the Dorset coast.

The Alaric VI prototype's commander was A/Maj E.F. Offord (a South African who was an Assistant Instructor at the Gunnery School). Here, Acting Major Offord sits in his commander's hatch with access to a pintle-mounted Lewis gun. Since arriving at Lulworth, this Alaric VI has been fitted with an experimental 'pepper-pot' muzzle brake (likely to trial the effects of large numbers of firings).

Note the truncated, Alaric IIA-style cooling louvres (explaining why the tank's rooftop cooling 'mushroom' is fixed in the fully-open position). This prototype has a non-standard wireless arrangement and is also missing its lower suspension-covering skirts. For security reasons, the individual vehicle number has been painted out (although why that was thought necessary is unclear). It seems that this tank never received an individual vehicle name (which was not that strange for a prototype).

Into Active Service - the Operational Alaric VIA Infantry Support Tank

Two Alaric VI prototype conversions [1] were completed and both suffered cooling problems. The production model Alaric VIA introduced enlarged hull-side cooling louvres to address the issue. The extended louvres helped but - especially in Summer months - it was not unusual to see Alaric VIAs with their hull-top cooling 'mushrooms' gaping. Other than its suspension and cooling 'mods', the VIA was indistinguishable from the preceding Alaric V.

A total of 32 Alaric VIAs were completed and all were issued to the 141st Battalion, RAC (making up three squadrons of this newly-formed unit). [2] The Alaric VIA did what was required of it during the Summer of 1940. As feared, the under-strength suspension proved to be the Achille's heel of the  Alaric VIAs. Within a year, the type had been withdrawn from active service (other than some retained for crew training at Bovington).

Bottom An Alaric VIA of the 141st Bn, RAC, near Folkestone, Kent, in August 1940. This is a near-new vehicle. Note the Alaric VIA's enlarged cooling louvres and full lower skirts. A3864 has been fitted with a fixed machine gun shield armed with a Lewis gun.

(To be continued ...)

_______________________________

[1] The first Alaric VI prototype conversion was made to an Alaric I - one of the original French Char B1s supplied as demonstrators. In May 1940, this vehicle had suffered a failure of its Naeder hydrostatic system and was awaiting a replacement from France. (The other three Alaric Is went overseas with the British Expeditionary Force as support vehicles for the Alaric IA force. All three deployed Alaric Is were lost in France.) In June 1940, the remaining Alaric I had been stripped of its suspension in order to complete another Alaric IIA hull.

[2] 141 Bn formed as the 7th Battalion, Buffs (Royal East Kent Regiment) which was to be assigned to the 209th Independent Infantry Brigade (Home). Instead, the nascent unit was transferred to the Royal Armoured Corps. Members of 141 Regt wore The Buffs' cap badge on their black RAC berets (as did all such transformed former infantry regiments).
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Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #8 on: April 06, 2020, 02:35:36 AM »
An Adversarial Relationship - DTD/MEE and the A23 Adversary

Other than some experimental conversion test-beds, the Alaric VIA was the end of the line for the Char B-based A21 series. However, it is also worth mention one further vehicle type - albeit, one with only a conceptual relationship to the A21. When seeking out suspension units with which to complete the unfinished Alaric V hulls, brief consideration was given to the vertical volute spring suspension (VVSS) of the then-experimental American M2 Medium Tank.

The reason for interest in the M2 suspension sprang from plans to build a new cruiser tank in Canada to British standards but based upon the M2 hull. For study purposes, an incomplete set of M2 drivetrain components was procured from the US Army's Rock Island Arsenal in late 1939. After examination by the Mechanisation Experimental Establishment (MEE) at Farnborough, the trial components were turned over to Dr. Merritt's Design Department at the Royal Arsenal, Woolwich. Although rejected as insufficiently strong for the Alaric, the VVSS units prompted the detail design of a lighter-weight future Tank, Infantry Support (a concept already being advanced by the Mechanisation Board).

As a 'clean sheet' design, the new vehicle could better represent the vision of the Mechanisation Board. This meant an 'assault focus' - defined as being well-armoured enough for head-on attacks against dug in positions including bunkers. The fighting compartment was designed around the '3-inch-36' gun. The gunner was ideally placed on the portside of the gun (with the vehicle's driver located on the vehicle's starboard side). Suspension units would be common with those of the forthcoming Canadian-made cruiser tank but propulsion would be by the Mechanisation Board's preferred high-speed diesel engine. Indeed, the diesel powerplant was one of the reasons that the vehicle's size could be greatly reduced compared with the Alaric series.

The engine chosen for what became the A23 Mk II Adversary, [1] was a 420 hp HLW D.4-5M 4-cylinder high-speed diesel. This prototype engine was made by the Hawthorn-Leslie-Werkspoor Diesel Engine Works (HLW Diesel) division of R. and W. Hawthorn, Leslie and Company of St. Peter's, Newcastle-upon-Tyne. The form of the engine was unusual for diesel engines of its time. In layout, the D.4-5M was a compact V-6 engine with cylinder rows arranged in a 30° Vee. On the centreline between the two banks of cylinders were an air compressor (in front) on centreline and, a scavenger pump (towards the rear). The end result was a very tall engine but one that was otherwise quite compact. [2]

The Adversary began as a cooperative project between the Woolwich Design Department and W.G. Allen & Sons. However, prototype construction was actually undertaken in works rented from another Tipton engineering firm, Horseley Bridge and Thomas Piggott. Considering the times, work proceeded quite quickly with the armed prototype A23 Mk II running under its own power by early September 1940. Problems were revealed immediately with the powerplant. [3] Since both David Brown transaxle and HLW Diesel engine were effectively prototypes themselves, teething troubles were expected. However, such were the exigencies of the Summer of 1940 that little engineering effort could be spared to work out the bugs. The prototype Adversary would later be used to test the 2.24 inch tank gun [4] but no further A23 Mk IIs would be built.

Our American Cousins - The US Grant Infantry Support Tank

After work on the A23 Mk II Adversary was abandoned, design attention turned to an Alaric replacement based directly on pending US M3 Medium Tank hull. Since the story of the Grant tank and its infantry support variant are well-known, they won't be described in detail here. The Grant Infantry Support Tank (GIST) was created specifically to address British requirements for an A21 Alaric replacement. Due to its urgency, the GIST was little more than a turretless Grant. However, that proved not to a major disadvantage since GISTs were generally operated in mixed formations with turreted Grants.

Bottom Grant Infantry Support Tank, 3rd Tank Regiment, Battle of Gazala, Cyrenaica, 27 May 1941. T20046 was a Pullman Standard-built GIST of the 3rd Tank Regiment during the Battle of Gazala. This GIST was abandoned when it hit a landmine at Bur el Harma on 27 May 1941.

Although the lack of a rotating turret could be critical, tactically, the GIST did have some major advantages in desert fighting. Obviously its profile was lower than that of the turreted Grant. The resulting weight reduction meant less ground pressure, giving the GIST superior mobility on dry, loose sand. More important still was simple availability. In the absense of any other infantry support tank, the Grant Infantry Support Tank proved vital to the Western Desert war.

(To be continued ...)

____________________________

[1] The unbuilt A23 Mk I was unrelated to the Adversary, being a projected lightened version of A21 Alaric VI. Quite rightly, the latter type was judged to be past its time for further development. Funds set aside for the aborted Mk I were reallocated towards the entirely different A23 Mk II Adversary.

[2] Two potential engine candidates were rejected - both lengthier inline diesels. One was the 420 hp 'Economy' inline 4-cylinder high-speed diesel submitted by William Doxford and Son (with a central scavenge pump dividing pairs of cylinders). The other was a more developed 6-cylinder diesel by North British Diesel Engine Works (NBDEW) - the LB-6M or 'Long Bore 6-cylinder, Military' -  based on a simplified cylinder design by engineer, J.C.M. MacLagan. In part, British Army technical people found difficulties in dealing with engine making firms with exclusively maritime backgrounds.

[3] Wags at Bovington would joke that the Adversary's diesel engine provided its own smokescreen - whether required or not.

[4] The 2.24 inch gun was another adaptation of ex-US M1897A2/M1897A4 tubes. In this case, worn barrels were bored out and a liner inserted. This liner and a 2 foot barrel extension were bored to 57 mm to take a new 'wildcat' round - necking down the US 75 mm casing to accept a driving band for a projectile from the pending Ordnance QF 6-pounder anti-tank gun.
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Offline robunos

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #9 on: April 06, 2020, 05:53:20 AM »
Again, good stuff, and another mention of my town . . .   ;D
I've read somewhere,but of course can't find it now, that some M3s were operated without their top turrets, to allow them to fit it into LSTs, so I'm thinking the Sicily campaign . . .


cheers,
Robin.
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Offline buzzbomb

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #10 on: April 06, 2020, 05:30:05 PM »
Hmmm, very good reading

Remember this build by Claymore on his take on a Lee based support vehicle
http://beyondthesprues.com/Forum/index.php?topic=6719.0

Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #11 on: April 07, 2020, 04:05:01 AM »
robunos: Very interesting to hear about those Sicily campaign M3s sans-turrets! Not too surprising, I suppose, but its amazing how often this happens in whiffery. (Even when I come up with something I regard as truly radical, invariably, Jon quickly comes up with a RW example that's even stranger!)

Again, good stuff, and another mention of my town . . .

Cheers Robin. So, how are things in Rock Island?  ;D

buzzbomb: Thanks for bringing up Claymore's M3 'Stonewall' FSV ... I'd completely forgotten that brilliant build. (It reminded me of some of the postwar Bundeswehr's twin-barrelled 'casement tank' prototypes.)

In his backstory, Claymore mentions the Brits later replacing 75s with 6-pounders in their 'Stonewalls'. I thought a variation on that theme might be to keep one of the 75s for support fire and replace the other with a 6-pounder (or US 57 mm Gun M1 derivative) for anti-tank use.

Next in my series is a bit of a toss-off based on the Grant hull ...
______________________________________________________

While the first Grant Infantry Support Tanks went into battle in the Western Desert, another Grant derivative was being finalized in Canada. Then known as the M.3 Cruiser Tank, this design would enter service as the Tank, Cruiser, Ram in early 1942. Ram makers, Montreal Locomotive Works (MLW), were also anxious to produce an 'assault' version armed with the Grant's 75 mm gun - M.3 Cruiser Infantry Support Tank. This would emerge as the 'Canadian Ram Assault' concept.

The Canadian Interdepartmental Tank Committee had been able to call upon the British Tank Mission for assistance. Much of this help was contributed by armour casting specialist L.E. Carr. Canadian authorities now called upon Carr to design a one-piece casting for the upper hull of the 'Canadian Ram Assault' (the riveted lower hull and running gear being identical to the US-built M3 Grant). This hull design was duly conceived but, in the meantime, the British Tank Mission had concluded that Ted Carr's skills were better employed designing cast turrets in the US. [1]

Despite the loss of Ted Carr's abilities, MLW pressed on with their assault tank concept. This included the preparation of a full-sized, running mockup based on a Grant hull. Intended to demonstrate their machine's ergonomics, representative of the Canadian Army were very impressed. [2] The 'Ram Assault' concept was judged well in advance of anything currently in Commonwealth service. However, it quickly became apparent that the smaller hull castings for the Ram tanks would represent a major challenge for Canadian industry. Accordingly, MLW were ordered to focus on producing the Tank, Cruiser, Ram as quickly as possible.

Below The 'Ram Assault' concept mockup. The upper hull was cast in concrete, the 'cannon' was wood. [3]

MLW was not prepared to completely abandon its 'Ram Assault' concept. To get around the casting limitations, a flat-plate upper hull was designed in-house. This was to go along with the planned M3A6 'rivet-hull Ram' ... but that variant never appeared. In the end, both the 'rivet-hull Ram' and the 'Ram Assault' concept faded away.

(To be continued ...)
______________________________

[1] Ted Carr had been with the Mechanisation Board where he was involved with the cast turret for the A12 Matilda infantry tank. Carr also designed the 'British' turret for the Grant while in the US

[2] By contrast, the Department of Munitions and Supply was furious that MLW had used a government asset (in the form of the M3 hull) without explicit permission. Departmental ire eased somewhat when MLW demonstrated that their mockup upper hull was easily removed and the M3 lower hull restored for use.

[3] MLW was postulating an L/48 development of the US M3 75 mm gun (which could be viewed as a direct decendant of the M1897 'French 75'). Unfortunately, such a weapon simply did not exist.
"Like a hog dance; Like a pig dare; Mind warp deceptor wan ..."

Offline robunos

  • Can't afford the top wing of his biplanes...
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #12 on: April 07, 2020, 04:47:19 AM »
robunos: Very interesting to hear about those Sicily campaign M3s sans-turrets! Not too surprising, I suppose, but its amazing how often this happens in whiffery. (Even when I come up with something I regard as truly radical, invariably, Jon quickly comes up with a RW example that's even stranger!)


Stand Fast on that ! I was mistaken ! It wasn't M3 gun tanks, they'd all been shipped off to Burma, and replaced with Shermans. Rather it was sime Grant Scorpion flail tanks, used during Operation Husky . . .
Again, good stuff, and another mention of my town . . .
Cheers Robin. So, how are things in Rock Island?  ;D

Probably a damn sight better than in Tipton at the moment ! Another 'Police Incident' tonight . . .


https://www.birminghammail.co.uk/black-country/police-ambulance-crews-descend-tipton-18053628


I never would have thought that the 'pharmaceutical' business could be so hazardous . . .


cheers,
Robin.
By the pricking of my thumbs, Something Whiff-y this way comes . . .

Offline GTX_Admin

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #13 on: April 08, 2020, 02:45:16 AM »
Ram Assault' concept.

I thought this was a RAM assault... ;)

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Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #14 on: April 09, 2020, 04:23:57 AM »
I thought this was a RAM assault...

 ;D

Robin: Well, things do seem to be 'lively' in the Black Country!  BTW, I came across a mention of the RW Horseley Bridge & Thomas Piggott providing armour bodies for Standard Beaverette armoured cars in 1941. So, their involvement in my whif scenario isn't entirely fanciful...

___________________________________

Ad Hoc Infantry Support Tanks in the Western Desert

No A21 series vehicles were ever sent to North Africa. Instead, a range of locally-converted vehicles saw service in the Western Desert The first dedicated tracked artillery support vehicles were conversions of captured Italian vehicles performed at Helwan. Most conversions were simply recovered Carro Armato M11/39 or M13/40 tanks with turrets removed and, in some cases, hull roofs cut away for cooler interiors and quicker dismounts. All such vehicles received the generic designation of Self-Propelled Artillery (SPA).

Some M11/39s retained or were given armaments to back up recce tank units. These were styled as Self-Propelled Artillery - Gun (SPA-G) and, with their Italian origin, perhaps inevitably were dubbed 'Spag Bols'. [1] Generally, the M11/39's 37 mm Vickers-Terni L/40 main gun failed to impress. Where possible, this gun was replaced by a 47 mm cannone da 47/32 AT gun taken from knocked-out M13/40 turrets. In a few cases, Ordnance ML 3-inch mortars were fitted or captured light field artillery.

Top A SPA-G of 'C' Squadron (the 'Kelly Gang') of the 6th Australian Division Cavalry Regiment. 'Kalbarri' (after the Western Australian town?) is armed with a 65 mm infantry gun - the cannone da 65/17 modello 13. This vehicle has been fitted with a large angle-iron rack to hold ammunition cases and string hessian netting from. Although not mounted here, hessian nets had the added advantage of providing a patch of shade fore the vehicle and its crew.

'Kalbarri' is clearly marked with white kangaroos for recognition. This vehicle has likely been freshly delivered from the depot - otherwise she would be festooned personal gear (whereas only the essential billy for brew-ups is in evidence).

With the appearance of the Afrika Korps, many of the British tanks in the Western Desert were outclassed. Both the A9 and A10 Cruiser tanks fell into that unfortunate category. While many A10s had to soldier on regardless, most of the surviving A9s were converted into support vehicles - both gun tractors and anti-aircraft tanks. With its offset driver's position, the A10 hull was better-suited for armed Self-Propelled Artillery - Gun conversions. A host of different guns types were mounted. Most Cruiser SPA-Gs were armed with Ordnance QF 18-pounder Mk 4s but captured 75 mm cannone da 75/32 modello 37 field guns were not unusual.

Bottom An A10 Cruiser SPA-G conversion of an unidentified unit. This vehicle is unusual in mounting a capture German 5 cm Pak 38 (L/60) anti-tank gun. Any opportunity was taken to 'return' shells to their former owners but comparatively few of the German 50 mm guns were ever captured in the Western Desert.

This unidentified A10 Cruiser SPA-G has been provided with a tubular camouflage netting rack over its engine (although, at this point, it seemed to be acting primarily as an airing cupboard).

_________________________________

[1] The 'Spag Bol' became the 'Spag Bog' which devolved into 'Bog' and then down into plain 'Dunny'.
"Like a hog dance; Like a pig dare; Mind warp deceptor wan ..."

Offline buzzbomb

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #15 on: April 09, 2020, 07:41:34 AM »
The fact you put a kettle on that Valentine SPG, which I must add, I really like, ticked some boxes.
Great detail work on the images

Offline GTX_Admin

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #16 on: April 10, 2020, 02:23:14 AM »
 :smiley:
All hail the God of Frustration!!!

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But you can make the Bastard work for it.

Offline apophenia

  • Patterns? What patterns?
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #17 on: April 11, 2020, 11:51:14 AM »
Thanks folks. More to come (once current distractions are pounded flat) ...

buzzbomb: The A10 got a shiny new kettle. For the Aussie billy, I went with well-scorched from many a brew-up  :D
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Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #18 on: April 13, 2020, 10:31:36 AM »
And to finish off, a pair of Commonwealth assault tank prototypes ...

The 'Assault Ram' concept was replaced by the 'Sexton 75'. Like the 25-pounder SP, tracked, Sexton, this assault tank had an open-topped fighting compartment. By comparison, the gun carrier's hull was shallower but its spaced-armour front plating was both thicker and better-sloped to deflect AP shot. Officially known as the 75 mm Gun Carrier, Ram Mk.X, the assault tank was generally referred to as the 'AT Sexton' or just the 'Sexton 75'. As the names suggest, the main armament was the Ordnance QF 75 mm - itself a bored-out QF 6-pounder of the type which had armed the Canadian Ram Mk.II tank.

Developments overtook the 75 mm Gun Carrier, Ram Mk.X. The spaced armour of its front plating was adequate for European battlefield conditions in 1942 but woefully vulnerable by late 1943. Attempts to interest US authorities in the vehicle type had failed. Most vehicles were completed in Gun Tractor Sexton Mk.XA form and used to tow BL 7.2-inch howitzers or BL 5.5-inch guns. As gun tractors, the Sexton XAs did useful work. Consideration was given to a Sexton Mk.XI development to act as ammunition limbers but hull priority was given to the production of 25-pounder SPs and Grizzly tanks. In any case, the US were now developing turreted tank destroyers on a similar chassis.

Work on heavier assault tanks continued in Britain. The Self-Propelled OQF 17-pounder, Churchill Mk.XX began as a refinement of the 3-inch Gun Carrier armed with an Ordnance QF 3-inch 20 cwt gun. In place of that heavy, former anti-aircraft gun, another 76 mm tube was substituted - that of the Ordnance Quick-Firing 17-pounder anti-tank gun. However, the design of this new 17-pdr Gun Carrier changed over time. First, the blocky crew section of the 3-inch Gun Carrier was replaced with a thick, cast casement. Then a modest hull redesign was undertaken.

The hull redesign for the Self-Propelled OQF 17-pounder, Churchill Mk.XX shortened the length but, more importantly, it lowered the forward drive wheels to improve gun traverse without increasing casement height. In theory, the shortened hull better allowed for the long overhang of the 17-pdr barrel and added weight of the new casement. In reality, the Churchill Mk.XX was ill-balanced and overweight - exacerbating the reliability problems faced by tank versions of the Churchill. A pre-production run had been begun but weren't completed as assault tanks. Making use of their heavily-armoured casements, the short hulls were completed as turretless Churchill AVRE SP demolition tanks.

These Churchill AVRE SP demolition tanks were re-armed with Super Petards - breech-loading 11-inch (290 mm) spigot mortars. The Churchill AVRE SP vehicles were finished in time for the D-Day landings but their Super Petard armaments were not. Development of the semi-automatic mortars proved troublesome. Eventually, feed issues with the Super Petards were overcome and low-rate production began. The armed Churchill AVRE SPs joined the 79th Armoured Division in time for Operation Blackcock - the clearing of German troops from Belgium's Roer Triangle - in January of 1945.
"Like a hog dance; Like a pig dare; Mind warp deceptor wan ..."

Offline robunos

  • Can't afford the top wing of his biplanes...
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #19 on: April 13, 2020, 06:46:13 PM »
More excellent concepts . . .   8)
But you've forgotten the most obvious one, mounting the OQF 17-pounder on a Sexton . . . the first 17-pounders in service were mounted on modified 25-pounder carriages, to get them into service quickly, under the code name 'Pheasant', and I'm sure it would be possible to perform the same conversion on a Sexton. See :-

https://weaponsandwarfare.com/2017/07/31/1725-pounder-pheasant-tunisia-1943/


I'm planning on  building a model of this, in due course, as I have a spare Sexton kit available . . .




cheers,
Robin.
By the pricking of my thumbs, Something Whiff-y this way comes . . .

Offline apophenia

  • Patterns? What patterns?
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #20 on: April 14, 2020, 04:10:39 AM »
Yes, you're right Robin. I was thinking that my 'Sexton 75' might be a smidge early for the 17-pdr ... but was more than a little fuzzy on RW IOCs for these guns  :-[

'Pheasant' always sound like a good description of the jump those early 17-pdrs must taken when fired  :o

Clever connection with the Sexton gun mount though  :smiley:  I look forward to seeing your 'Sexton 17-pounder'! What scale will you be building in?
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Offline robunos

  • Can't afford the top wing of his biplanes...
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #21 on: April 14, 2020, 05:41:12 AM »

I was surprised about the in service date for the 17-pounder, too, I thought it didn't enter service until Normandy . . .When I do get around to building this, (it will be a while, I'll be building Lee, Sherman, and Ram variants as a block project), I'll be using the Plastic Soldier Sexton, and I'll replace the 25 pounder barrel, with one from an Armourfast Sherman Firefly. Looking at images of the 'Pheasant', and the Sexton, the gun mounting may need to be raised on the chassis, one, to allow for the increased length of the breech behind the trunnions, and two, to allow sufficient length for the gun to recoil over the engine deck . . . further study is needed . . .   ???


cheers,
Robin.
« Last Edit: April 14, 2020, 05:42:56 AM by robunos »
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Offline apophenia

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #22 on: April 16, 2020, 03:43:38 AM »
Plastic Soldier kits are around 1/100th scale, aren't they (he says while squinting at what he's typing)  :o

On breech clearance, what about a radical re-engining instead? Would a Bedford flat-12 (or similar) fit into an M3/Ram hull?
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Offline robunos

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Re: A21 Infantry Support Tank - A British StuG Story
« Reply #23 on: April 16, 2020, 05:01:46 AM »
Plastic Soldier make wargaming kits in both 15mm scale ( 1/100 to us ), AND 20mm scale ( 1/72 ). They're not the most detailed of kits, but accurate enough, and look like what they're supposed to be . . .   :smiley:
But the best bit, is that you tend to get two or three in one box, with parts to make different versions. With the Sexton kit, you get parts for three models, each of which can made as an early or late production Mark II.
As another example, they do a Valentine tank kit(s), with three models, each of which can be made into a Mark II, Mark III, or Mark IX. This means each individual kit has TWO hull tops, TWO pairs of wheels and tracks, and THREE guns and turrets . . . lots of spare bits for kitbashing . . .   8)
Regarding my model, the scenario is '17-pounders on everything that moves', in order to to go Big Cat hunting, so any changes must be confined to the absolute minimum. We're talking depot-level conversions here. I think it's easier to bolt a spacer under a gun mount, than re-engine a vehicle . . .   ;)


cheers,
Robin.
By the pricking of my thumbs, Something Whiff-y this way comes . . .

Offline apophenia

  • Patterns? What patterns?
Re: A21 Infantry Support Tank - A British StuG Story
« Reply #24 on: April 16, 2020, 08:55:14 AM »
... I think it's easier to bolt a spacer under a gun mount, than re-engine a vehicle...

Yeah, just a smidge  ;D  I love the sound of your approach and these Plastic Soldier kits do sound like total whif-bait  :smiley:
"Like a hog dance; Like a pig dare; Mind warp deceptor wan ..."