Alternative A1 Tank Specification

ITTL the General Staff wanted a heavier gun capable of bunker busting as well as firing H.E. for infantry support. Therefore instead of one main turret mounting a 3pdr (47mm) gun and four subsidiary turrets mounting 0.303 Vickers machine guns the tank was fitted with a single turret mounting one 3-inch (76mm gun) with a coaxial Vickers MG with a 3 man crew (commander, gunner and driver) plus a driver and radio operator in the hull. The latter also operated the hull mounted Vickers MG. The gun was an adaptation of the 3-inch anti-aircraft gun used by the British Army in large numbers in World War One.

The British Army later adapted its 3.7-inch AA gun into the 32-pdr anti-tank gun. Would the same be possible with the 3-inch? AFAIK there were hundreds of them in storage in the 1920s.
 
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This is going to be a timeline where the Government spends 5 times more on Vote 9 of the Army Estimates between 1924-25 and 1933-34. IOTL the annual gross spending was £3 million and the annual net spending was £2.3 million. These miniscule sums were spent on:
  • Establishments for Research, Experiment and Design upon which about £700,000 was spent every year in this period.
  • Inspection of Warlike Stores upon which about £450,000 was spent every year in this period.
  • Warlike Stores upon which about £1.9 million was spent every year in this period.
  • Miscellaneous Charges, which were the Subsidy to Ordnance Factories and Rewards to Inventors. About £80,000 was spent anually
Warlike Stores included:
  1. Guns & Carriages
  2. Gun Ammunition
  3. Small Arms
  4. Small Arm Ammunition
  5. Horse Transport Vehicles
  6. Motor Transport Vehicles (Wheeled)
  7. Motor Transport Vehicles (Tracked and Half Tracked).
  8. Anti-Gas Equipment
  9. Searchlight, Signal and Bridging Equipment
  10. Miscellaneous Warlike Stores
Vote 9, Head C, Subhead 7 Motor Transport Vehicles (Tracked and Half Tracked) included: Tanks and other mobile machines on continuous or half-tracks, e.g. artillery dragons, tracked infantry transport and self-propelled mountings for artillery, are included in MT (Tracked and half-tracked). An annual average of £450,000 was spend on them between 1924-25 and 1933-34.
 
Therefore ITTL 5 A1 tank chassis would have been built. I can't decide between the following:

Scenario 1 - One prototype and 4 production tanks would have been built.

Scenario 2 - 5 different prototypes would have been built to the same specification. The intention was that the production vehicle would be a new design built using the experience gained from the prototypes.

Scenario 3 - 5 identical chassis would be built. 2 would be gun tanks, with different armaments, one would be a recovery vehicle, one would be a Royal Engineers tank and another would be completed as a Super Birch Gun to compliment the "ordinary" Birch Gun, which used the chassis of the A2 Medium Tank.
 
Therefore ITTL 5 A1 tank chassis would have been built. I can't decide between the following:

Scenario 1 - One prototype and 4 production tanks would have been built.

Scenario 2 - 5 different prototypes would have been built to the same specification. The intention was that the production vehicle would be a new design built using the experience gained from the prototypes.

Scenario 3 - 5 identical chassis would be built. 2 would be gun tanks, with different armaments, one would be a recovery vehicle, one would be a Royal Engineers tank and another would be completed as a Super Birch Gun to compliment the "ordinary" Birch Gun, which used the chassis of the A2 Medium Tank.
Instead of putting it on the British Army Sanity thread I'll continue this...
 
In this TL HM Treasury was persuaded to spend £15 million extra a year on the British Army in the 1919-20 to 1939-40 financial years. Most of this money was spent on Vote 9 of the Army Estimates. That is Warlike Stores. The actual net expenditure IOTL on Vote 9 was as follows:

1914-15 £1,578,000
1919-20 £18,797,000
1920-21 £4,394,000
1921-22 £2,707,000
1922-23 £2,821,700
1923-24 £2,559,100
1924-25 £2,647,500
1925-26 £2,743,300
1926-27 £2,345,000
1927-28 £2,310,000
1928-29 £2,442,000
1929-30 £2,538,000
1930-31 £1,918,000
1931-32 £2,211,000
1932-33 £2,000,000
1933-34 £2,437,000
1934-35 £3,004,000
1935-36 £5,115,000
1936-37 £11,474,000 This is after supplementary estimates. The original estimate was £7,185,000
1937-38 £15,880,000 Plus £13,000,000 issued from the Consolidated Fund increasing the total to £26,880,000
1938-39 £27,242,000 Plus £14,000,000 issued from the Consolidated Fund increasing the total to £41,242,000
1939-40 £8,661,000 Plus £48,000,000 issued from the Consolidated Fund increasing the total to £56,661,000

For the years 1919-20 to about 1924-25 the information in the Army Estimates was presented in a different way. Therefore they might not be strictly comparable to 1914-15 and 1925-26 onwards.

However, it can clearly be seen that with the extra £15 million the Army can quintuple its expenditure on Warlike Stores between 1921-22 and 1934-35. The next year it can be trebled and in 1936-37 it can be doubled.

Vote 9 was divided into the following headings:
A Establishments for Research, Experiment and Design
B Inspection of Warlike Stores
C Warlike Stores, which was divided into the following sub-heads:
1 Guns & Carriages
2 Gun Ammunition
3 Small Arms
4 Small Arm Ammunition
Total Guns, Small Arms and Ammunition
5 Horse Transport Vehicles
6 Motor Transport Vehicles (Wheeled)
7 MT Vehicles (Tracked and Half Tracked)
Total Transport Vehicles
8 Anti-Gas Equipment
9 Searchlight, Signal and Bridging Equipment
10 Miscellaneous Warlike Stores​
D Miscellaneous Charges
E Machine Tools, &c., for manufacture of warlike stores other than at the Royal Ordnance Factories - This was not added until the Supplementary Estimate for 1936-37
Heads A to E were then added together to produce the Gross Estimate​
F Appropriations in Aid
The above were deducted from the Gross Estimate to produce the Net Estimate​

Therefore Vote 9 included R&D of weapons as well as their production.
 
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What about the engine - it is 1924?
To recapitulate (if that is the right word) and I feel like capitulating after today.
Therefore ITTL 5 A1 tank chassis would have been built. I can't decide between the following:
  • Scenario 1 - One prototype and 4 production tanks would have been built.
  • Scenario 2 - 5 different prototypes would have been built to the same specification. The intention was that the production vehicle would be a new design built using the experience gained from the prototypes.
  • Scenario 3 - 5 identical chassis would be built. 2 would be gun tanks, with different armaments, one would be a recovery vehicle, one would be a Royal Engineers tank and another would be completed as a Super Birch Gun to compliment the "ordinary" Birch Gun, which used the chassis of the A2 Medium Tank.
Scenarios 1 and 3 would use the OTL engine.

Scenario 2 - The M-G Ordnance issued Specification A1 and asked for firms to tender designs. Once received the designs were evaluated. Then five prototypes were ordered for competitive evaluation. That is one prototype of each of the five most promising designs. That is one from ROF Woolwich, one from Armstrong, one from Vickers and two others. The manufacturers could put whatever engine they wanted to in the tank.

The tank built by Vickers would be the OTL Vickers Independent and it would have used the OTL engine. Your guess is as good as mine for the others. I'm open to suggestions provided they fit in with what I have written so far.
 
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I think the 3" 20cwt gun would be total overkill for a 1920s tank, the 13pounder 9cwt is possible without going too big. My idea is simply specify that all tanks use the Hotchkiss 40 calibre 6pounder naval quick firing gun in a 3 man turret with geared elevation not balanced free elevation. This was the gun used by the Rhomboid Male tanks. This forces the tank designers to use a bigger turret ring and external mantlet, when the Hotchkiss 6pounder is replaced with later 6 pounders or 75/76mm guns there is more room to fit them.
 
Specification A2 Medium Tank Mks I and II plus their derivatives
Depending upon which source is read either 160 or 200 A2 Medium Mk I and II tanks were built by ROF Woolwich and Vickers IOTL.

ITTL the equivalent reference books would say either 800 or 1,000. Plus Woolwich was busy with other work ITTL so it transferred the work to Leeds. According to Wikipaedia the Leeds factory was first opened as a munitions factory in December 1915, as National Filling Factory No. 1 (Barnbow) and IOTL was then reopened as an ROF January 1936.

At this time IOTL the RTC had the 1st (Depot) Battalion and the 2nd to 5th Battalions. The intention was that each of the 5 regular infantry divisions in the UK should have a tank battalion.

However, ITTL that didn't mean that the regular RTC was expanded into 5 depot and 20 operational battalions. Instead 16 RTC battalions were formed in the Territorial Army. This might have been by converting the 16 Yeomanry regiments that kept their horses IOTL (some of which became part of the 1st Cavalry Division and then 10th Armoured Division in World War II IOTL) or some of the Yeomany regiments that were converted to artillery IOTL were converted to tanks and the 16 RA brigades that were disbanded to make way for them were disbanded.

Five times as many were sent to India for trials and the Australian Army also acquired 5 times as many Vickers Mediums. Hopefully building so many tanks reduced the unit cost so that the Governments of Australia and India could afford to buy 5 times as many. If not the War Office would have paid for the extra vehicles.

Some of the early Dragon tracked artillery tractors were based on the Vickers Medium tank. Five times as many of them were built ITTL.

Finally the Birch Gun used the chassis of the Vickers Medium Tank. ITTL 35 were built instead of 7, but instead of one prototype and 6 production vehicles there were 3 prototypes and 32 production vehicles. The latter equipped 2 RA field regiments. Each regiment had 2 batteries and there were 8 guns to a battery so the total strength was 16 guns.

ITTL the Royal Artillery used its share of the extra £15 million to start conversion of its 18pdr gun into the 18/25pdr howitzers forward by 10 years. This is why the ROF Woolwich was too busy to build any A2 Medium Tanks. This also brought the reorganisation of the field artillery from brigades with four batteries each into regiments with two double-strength batteries forward by 10 years also. It also allowed all 35 Birch Guns to be fitted with the 18/25pdr weapon.
 
I think the 3" 20cwt gun would be total overkill for a 1920s tank, the 13pounder 9cwt is possible without going too big. My idea is simply specify that all tanks use the Hotchkiss 40 calibre 6pounder naval quick firing gun in a 3 man turret with geared elevation not balanced free elevation. This was the gun used by the Rhomboid Male tanks. This forces the tank designers to use a bigger turret ring and external mantlet, when the Hotchkiss 6pounder is replaced with later 6 pounders or 75/76mm guns there is more room to fit them.
It depends upon what it's wanted for. If its for infantry support then something like the 3" 20cwt gun might be wanted for bunker busting.

In any case in this TL it's more tanks rather than better tanks until the second half of the 1930s.
 
Specifications A6 and A7
Following on five times as many prototypes of the A3 and A5 were built. A4 is a different story, but a separate post for that.

All other things being equal 15 A6 prototypes and 15 Medium Tank Mk III production vehicles (enough to form a squadron) and 15 A7 prototypes were built.

Five times as many prototypes of the A6 and A7 gun tanks were not required. Therefore the extra hulls were used for derivatives. There would have been at least one prototype each of the SPG intended to replace the Birch Gun, an ARV and some RE vehicles like AVREs and AVLBs. There might even be a Kangeroo APC version.

However, at £16,000 a copy the Medium Mk III could not be built in quantity even with the enlarged equipment budgets of my TL. That is unless one of you can make it cheaper to produce, but even if the price is halved then the production is only increased to 30.

On the subject of the Royal Engineers they were forming 3 tank battalions of their own at the end of the Great War which would have been equipped with modified Heavy Tanks. I haven't done the research in depth, but I think they were reduced to a single field company that was retained for R&D work. AFAIK this was the field engineer company attached to the Experimental Armoured Force and its successors.
 
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It depends upon what it's wanted for. If its for infantry support then something like the 3" 20cwt gun might be wanted for bunker busting.

For bunker busting a lower velocity gun with a bigger bursting charge might be better. An 18 pounder or even a 4.5" howitzer might be best
 
For bunker busting a lower velocity gun with a bigger bursting charge might be better. An 18 pounder or even a 4.5" howitzer might be best
ITTL they start converting 18pdrs into 18/25pdrs 10 years earlier. Would that do? I'm putting them into the TTL Birch Guns.
 
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