AHC: each nation's best possible tank for 1941
- Thread starter tomo pauk
- Start date
I've always been fornd of the 'JagdChurchill' - erstwhile with a good 3in installed, later a more refined version, armed with 17 pdr.
Firstly I am presuming that this RamIII is in the late 1941 prototype class.
But secondly I would question why the 75mm gun should be the American one? A British ROF 75mm barrelled 6 pounder was ready to go and used the same mounting as the 6 pounder.
The smallest practical weapon of this calibre would be a modernised 13 pounder 9 CWT gun (1008 Imp pounds or 457 KGs) orginally used as a truck mounted AA gun in WW1.
Breech recoil was 24" in 1916 but there have been 2 generations of improvements so this recoil is going to be less than 12" by the late 30s making its installation in a turret much less an issue and also the weight might be less than 1000 odd pounds.
I pick this weapon as it can fire a 12.5 pound 3" HE shell a usefull distance and also can fire a similiar size APC round at over 2000 ft per second and was used in Ground fire support role by British units operating in Italy in 1918.
I think that the confusion comes from the fact that the Breech of the 6 pounder was similiar in size to the 75mm allowing the weapon to effectively become a 'drop in' replacement without redesigning/requiring much work for the turret cradle etc.
Vickers had produced and sold hundreds of a 75mm AA gun the Model 1931 used by Finland, Romania, Latvia and the Chinese. It was used by the Romanians as an emergency AT gun and provided the basis of a proper AT Gun the TAC 43 Reşiţa 75mm. It had a 495mm shell case fired a 6.5kg 14 pound shell at 2500 fps and was the basis of the Vickers 75mmHV tank gun. Infamously the designers of the Cromwell tank Turret didnt talk to the designers of the gun and it wouldnt fit because of the strange British obsession with internal mantlets.
While a tank with the 75mmHV is not going to be available till 1943 all the elements of a really good tank were there it just needed someone to bring them together. Unfortunately seperate groups were designing turrets, engine/transmission, hull and guns, If only the Army had said to Vickers heres what we want get on with it.
The Fastmongrel MarkI Heavy Cruiser tank
30 tons
All welded construction
Minimum armour 3 inch hull frontal 4 inch turret
45 degree sloped glacis
Belly armour under crew able to stand up to latest German AT Mine
Armour bolts to fit applique armour
Horstman or Vertical Volute style suspension, suspension units should be easily replaceable in the field
20 inch wide tracks
Meteor engine plus Merrit Brown transmission
Space for 5 crew but lose the co driver if necassary
75mm HV gun plus 55 rounds stowage
Minimum speed 25mph
Minimum range 100 miles
None of the above spec is Unobtanium, it was either was available or produceable by Dec 31st 1941 and Vickers had in the Valentine produced one of if not the most reliable tanks of WWII. There is reasonable evidence that the first Soviet armoured vehicle into Berlin was a Valentine MkIX not bad seeing the last Valentines they received were shipped March 1944.
While a tank with the 75mmHV is not going to be available till 1943 all the elements of a really good tank were there it just needed someone to bring them together. Unfortunately seperate groups were designing turrets, engine/transmission, hull and guns, If only the Army had said to Vickers heres what we want get on with it.
The Fastmongrel MarkI Heavy Cruiser tank
30 tons
All welded construction
Minimum armour 3 inch hull frontal 4 inch turret
45 degree sloped glacis
Belly armour under crew able to stand up to latest German AT Mine
Armour bolts to fit applique armour
Horstman or Vertical Volute style suspension, suspension units should be easily replaceable in the field
20 inch wide tracks
Meteor engine plus Merrit Brown transmission
Space for 5 crew but lose the co driver if necassary
75mm HV gun plus 55 rounds stowage
Minimum speed 25mph
Minimum range 100 miles
None of the above spec is Unobtanium, it was either was available or produceable by Dec 31st 1941 and Vickers had in the Valentine produced one of if not the most reliable tanks of WWII. There is reasonable evidence that the first Soviet armoured vehicle into Berlin was a Valentine MkIX not bad seeing the last Valentines they received were shipped March 1944.
The prototype was a modified 6 pounder breech (the extractor cam was different and caused a lot of trouble at first the straight walled case needed a bigger pull to extract than the tapered 6 pounder) fitted to a 6 pounder barrel forging that had been taken from the production line and fitted with a 75mm liner and machined to suit. The recoil system was also revalved to work with the 75mm ammo.
It would be impossible to simply bore out a 6 pounder to fit the 75mm ammo the 6 pounder chamber is longer, tapered not straight and the rifling drive bands are further forward. The only dimension the two types of ammo shared was the diameter of the base of the case and overal length was similar due to the shorter 6 pounder shell.
Production ROF 75mm guns were new manufacture with a different shape of gun barrel and a muzzle brake. The barrel was slightly thicker at the breech end and didnt have a 2nd taper section approx 1/3 down the barrel. The gun mantlet and mounting also had to be replaced when swapping from 6 pounder to 75mm to allow for the slightly fatter breech section plus ammo racking and gun sight. Also the 6 pounder (apart from very late production) had been a free floating gun elevated by the gunner using a shoulder pad the 75mm was a geared elevation. The internet sometimes claims it was a straight swap but there was considerable work to do even small stuff like the commanders sighting vane had to be changed plus re zeroing the gun and probably a lot more that I dont know about.
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Valid point my dear yazuli,
I contemplated installing a ROF QF 75mm but could never figure out when it entered production.
The other question was which sub-contractor would supply CPR's Angus Shop with guns, radios, etc.????????
During WW2 Canada gradually shifted from building British pattern equipment to America designed equipment.
A 75mm gun with similar external dimensions to the existing 6 pounder would be an easy decision. The new mantlet could bolt to the existing Ram turret casting. New sights and elevation mechanism are best installed early on the production line.
I did not realize that the Royal Ordance Quick Firing 75mm was ready for production in 1941. Does anyone have a precise date?
OTL supports yazuli, because post-war the Dutch Army re-armed a batch of Rams with ROF QF 75mm guns.
I contemplated installing a ROF QF 75mm but could never figure out when it entered production.
The other question was which sub-contractor would supply CPR's Angus Shop with guns, radios, etc.????????
During WW2 Canada gradually shifted from building British pattern equipment to America designed equipment.
A 75mm gun with similar external dimensions to the existing 6 pounder would be an easy decision. The new mantlet could bolt to the existing Ram turret casting. New sights and elevation mechanism are best installed early on the production line.
I did not realize that the Royal Ordance Quick Firing 75mm was ready for production in 1941. Does anyone have a precise date?
OTL supports yazuli, because post-war the Dutch Army re-armed a batch of Rams with ROF QF 75mm guns.
What is the weight of the Model 31 75mm (Gun and Breech etc - not the full mounting?
Its the 2nd thing I am concerned about with regards to the Mk 1 'Mongrel' Universal Tank design
The other is Meteor engines werer they being developed and built in 41?
Thats why I suggested the land use RR Kestral
In terms of British tanks, the 75mm was somewhat expensive to supply and slightly limited the amount of ammunition carried by the tank in question. I don't know if it would fit, but the Molin's six pounder used by the navy and coastal command was a very capable weapon with APCBC and HE rounds available and in production. Slapped into a larger tank like a Churchill or even the TOG would allow a formidable level of firepower to be brought into action without enlarging the logistical boot print to much. I don't remember if it would fit easily though.
I had always thought that the 75mm was a completely new weapon - I was not aware that the existing 6 pounder breech was leveraged for this gun!
So it was effectively an existing 6 pounder AT gun with a new 75mm barrel?
I think that while the 75mm prototype was a modified 6 pounder the changes needed for the production version meant only a small parts commonality and it could be called a new gun.
What I can say with some certainty.
Barrel externally and internally different but a barrel is a barrel no matter what the bore.
Breech block externally the same but changes to the extractor cam and springs plus it might have been changed to allow the shorter fatter case to eject properly not 100% sure on that one, there were a lot of ejection problems early on.
Recoil system externally the same but internally many modifications to the valves and a different Oil weight but a recoil system is a recoil system no matter what.
Mounting lots of changes because of the change from free elevation to geared. Also change to the castings because of slight barrel diameter changes.
Mantlet similar but changes for barrel diameter.
Travelling lock completely different the 6 pounder was locked by a roof mounted system that allowed small vertical movements when the tank went over rough ground to stop the gunner getting his shoulder dislocated. The 75mm travelling lock went through about a dozen changes and ended up being a copy of the US Sherman system solidly locking via the elevation quadrant gear.
Firing mechanism iirc the 6 poundr fired via a pistol grip and the 75mm via a foot pedal but there were many many changes so not sure on that.
Muzzle The 6 pounder had a muzzle balancing weight because of the free elevation to relieve the effort needed by the gunner. The gun balanced on the trunnions and a gun in good condition could be depressed or elevated with one finger. The 75mm had a muzzle break which did help to balance the gun and reduce strain on the elevating gear but mainly helped to reduce the greater recoil thrust on the mounting.
Sights The 6 pounder mostly had a 1.9xpower sight with graticules for AP. For firing HE and APDS it had to be converted by the gunner ie firing APDS at 600 yards use iirc the 400 yards mark, HE for 600 yards iirc use the 800 mark. The 75mm sight was a 3xpower sight with scales for HE, Smoke and AP. The 6 pounder sight was lower power because its very difficult to keep the target on sight with the much narrower field of view of a more powerful magnification.
The 75mm was different but very obviously from the same family. Closest I can think was when the Germans modified the 15mm MG151 to the 20mm MG151/20 was it a new gun or a variant.
TLDR err yes and err no
Give the T-34 with a three-man turret and torsion bar suspension and you have the best possible tank for the Soviets right there. It won’t have much impact given the Red Army’s myriad other issues but there it is.
Deleted member 1487
Not in 1941, but as they increase in skill it will. By 1943 it would be hard to match.
Well, even by ‘43 the Soviets, though they had come far, still had major improvements to make in terms of crew skill and the Germans had pretty much closed the gap with the up-gunned Panzer IV and large numbers of PaK-40s to say nothing of the introduction of the Panther (even with all it’s flaws), Tigers, and the associated models of assault guns and tank destroyers. You probably are right that there would be improvement tactically, but I wouldn’t say it would be “hard-to-match”.
Anyone wondering why an External mantlet is better for mounting a larger gun I found 2 good pictures
Cromwell with internal mantlet see the disc just behind the turret front plate thats the trunnion on which the gun swings when elevating
Tiger I with external mantlet the gun trunnion is at the front of the turret front plate a worse position for balance but much more economical of room
Move the trunnion of the 88mm back to the position of the cromwells gun and the 88 would never fit.
Cromwell with internal mantlet see the disc just behind the turret front plate thats the trunnion on which the gun swings when elevating
Tiger I with external mantlet the gun trunnion is at the front of the turret front plate a worse position for balance but much more economical of room
Move the trunnion of the 88mm back to the position of the cromwells gun and the 88 would never fit.
Deleted member 1487
Let's clarify what I mean my 'hard to match', which is having a medium tank in that same weight class that could overall match up to it's combat capabilities technically speaking.
Heavy tanks are a different category and the armor on the T-34 as well as the mobility due to wider tracks and in this scenario torsion bar suspension would leave it superior to the Pz-IV all things considered. Crew training is a separate issue IMHO. The Pz-IV would be more or at least as vulnerable to the Soviet Zis-3 as the T-34M would be to the PAK 40, which wasn't really as widespread as it would be in 1944 by 1943.
Tank for tank the T-34M would outclass the Pz-IV and probably even the M4 Sherman of 1943. Certainly the Tiger would trump the T-34M in the way that the KV-1 trumped anything the Germans had (FLAK 37 excluded) until the Tiger.
Wimble Toot
Banned
September 1941 was when it was first tested. Mass production not til 1943-44.
Typical bureaucracy and mismanagement - intimately connected to the bureaucracy and mismanagement around the gas turbine aero engine.
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