Ram Tank

Thanks VP, from Canuckland! :p Here's a question for a tank expert (if you know any around here) The Canadian "Ram" site says that it would be difficult for a Ram to be up-gunned to the 75 or 77mm gun because the turret ring is only 60", however the Aussie "Sentinal" originally had only a 54" ring, but was later enlarged. What was the turret ring on the modified "Sentinal", and what was the size of the turret ring on the Cromwell & Comet? Thanks

 

Cromwell's ring diameter was c.57 Inches, dunno for Comet?

It's not strictly a question of ring diameter (though it's an easy thing to pick up on for many British AFVs and their sponson-less shapes as an initial flaw in the design concept) there's the question of ring strength too. The Sentinel hull was a famously strong casting, perhaps that also had some bearing on the strength of the ring and the relative stresses it could tolerate. It's said to have withstood 20% more than a 17pdr's recoil force when set up with 2X25pdrs 'with ease'.
Obviously the ring is only one factor though, size & shape of turret and hull, suspension strength, overall width etc. all come into play when up-gunning.
Like everything else, it's always more complex than it seems at first.


I think the Sentinal had to have a new turret for the 17 pounder though. Was it an actual original 17 pounder or was it the more compact re-designed version? (the 77mm)

 

Something here on the Sentinel!

The Sentinel's best feature was not the gun, but the turret ring. It was bigger than on any other Commonwealth tank, so it could be upgunned quite easily.

This meant that while it started with a 2pdr (a fairly effective pre/early war weapon) it could be upgraded to the comparatively monstrous 17pdr, or the 25 pdr if needs be. Due to the lack of available 17pdrs, the tank was proven by mounting two 25pdrs and firing them simultaneously.

There are only 4 surviving examples of the Sentinel, one in Bovington, which was shipped there for trials during WW2, another recently rebuilt to running condition at the School of Armour in Puckapunyal, Victoria.This vehicle is the mascot of the Royal Australian Armoured Corp.(RAAC) There is a 25pdr armed vehicle in the Australian War Memorial and the last vehicle is a shell in poor condition at a privately owned museum in Victoria again.

In an effort to further improve the firepower of the Australian produced tanks a turret was developed and mounted on one of the earlier development vehicles to assess the vehicle's ability to mount the foremost allied anti-tank gun of the day - the British 17 pounder (76 mm, 3 in). This was achieved by mounting two 25 pounder gun-howitzers which when fired together would significantly exceed the recoil of a 17 pounder; it was later fitted with a 17 pounder and after successful gunnery trials the 17 pounder was selected for the AC4 design.

 

Cromwell's ring diameter was c.57 Inches, dunno for Comet?

It's not strictly a question of ring diameter (though it's an easy thing to pick up on for many British AFVs and their sponson-less shapes as an initial flaw in the design concept) there's the question of ring strength too. The Sentinel hull was a famously strong casting, perhaps that also had some bearing on the strength of the ring and the relative stresses it could tolerate. It's said to have withstood 20% more than a 17pdr's recoil force when set up with 2X25pdrs 'with ease'.
Obviously the ring is only one factor though, size & shape of turret and hull, suspension strength, overall width etc. all come into play when up-gunning.
Like everything else, it's always more complex than it seems at first.


Trials, Tests and Experiments for the Sentinel MK's
25 pounder field gun/howitzer armed test vehicle
The 25 pounder armed test vehicle was used to trial the 25 pounder as a tank armament for the AC3 design. Proofing tests were held on the 29th of June 1942 in a prototype turret mounted on development hull E2 by a 137cm (54 inch) turret ring. Gunnery trials were held shortly after on the 27th of July. The tests were successful and the AC3 was ordered to be produced immediately after AC1 production had finished.
Double 25 pounder field gun/howitzer armed test vehicle
The twin 25 pounder armed tank was a test vehicle only. As a 17 pounder was not available at the time two 25 pounders were fitted into a turret mounted on the development hull E1 by a 163cm (64 inch) turret ring. The intent was to test the recoil system and turret ring by significantly exceeding the recoil force of a single 17 pounder anti-tank gun. The pair of 25 pounders fired together produced approximately 120% of the recoil force of a single 17 pounder anti-tank gun. The tank survived and was subsequently armed with a 17 pounder.
17 pounder anti-tank gun armed test vehicle
The 17 pounder anti-tank gun armed test vehicle used to test the armament for the AC4 design. The design for an experimental 17 pounder armed version of the AC had started back in February 1942. Development hull E1 was mounted with a 17 pounder anti-tank gun in a turret with a 163cm (64 inch) turret ring. Firing trials in January 1943 were successful and the weapon was selected for the AC4 design.
Suspension test vehicle
One hull was modified to test a different suspension system of five large road wheels with three track return rollers. Each road wheel had a vertical volute spring semi-recessed into the hull, similar to "Christie" suspension. Probably inspired by the suspension of the British "Crusader" Cruiser tank that had been imported to assist with the design and development of the Australian Cruisers. The concept was not adopted for production.
Armour Basis - Armour Basis for AC1, AC3 and AC4. The armour basis here is defined as providing protection equivalent to a vertical plate of the specified thickness. So if the armour is sloped so as to present an angled face to an incoming projectile it can be of a reduced thickness and still provide the same level of protection.
65mm (2 1/2 inch) Hull Front
45mm (1 3/4 inch) Hull sides and rear
23mm (7/8 inch) Hull top
16mm (5/8 inch) Hull floor
65mm (2 1/2 inch) Turret all round
25mm (1 inch) Turret roof
Initially the specification called for 50mm (2 inches) of armour which was considered proof at close range against anti-tank guns of performance similar to that of the 2 pounder. Experience against German tank and anti-tank guns proved that this was inadequate and the specification was raised first to 65mm (2 1/2 inches) and then 75mm (3 inches) although the second increase seems to have been ignored.
Australian Zirconium-Alloy Cast Armour specification
Brinell Hardness: 230-240.
Izod Impact Strength: 20ft/lb rising through production to 52ft/lb.
Ultimate Tensile Strength: 756MPa (49 T/sq inch). Purposely kept low to reduce spalling.
This armour was developed specifically for the Australian Cruiser Tank, it's formulation was based on the Australian Bullet Proof Plate armour as used for Australian built Universal Carriers, the Dingo scout car, and other projects. Unlike armour produced in other countries the Australian cast armour contained no nickel as there was no source for this in Australia. Similar to British IT90 cast armour it was slightly softer but much tougher, resulting in less spalling from hits. When an AC1 turret was compared against a specially imported M4 turret the armour proved at least as good the American armour if not better.

 

Ok thanks for the info. So the original turret ring was 54" but the enlarged one was 64", which is the same as a Comet.

 

Was this tank used for all Canadian Armored Units? How did it fare against the German Armor?

 

Was this tank used for all Canadian Armored Units? How did it fare against the German Armor?


I dont think either Sentinal or the Ram I/II saw any combat.

The Ram hulls saw some action as APC's, which seems to have been reasonably successfull, though what deductions you make from this I dont know.

Kev

 

I dont think either Sentinal or the Ram I/II saw any combat.

The Ram hulls saw some action as APC's, which seems to have been reasonably successfull, though what deductions you make from this I dont know.

Kev
I read somewhere that the Ram I was originally chosen for the Kangaroo APC role because of the side doors on the hull, which would have been an advantage for the troops leaving the vehicle. Ironically by the time Kangaroo was given the go-ahead the new improved Ram II had appeared. One of the 'improvements' was to dispense with the side doors...

 

I read somewhere that the Ram I was originally chosen for the Kangaroo APC role because of the side doors on the hull, which would have been an advantage for the troops leaving the vehicle. Ironically by the time Kangaroo was given the go-ahead the new improved Ram II had appeared. One of the 'improvements' was to dispense with the side doors...


Maybe, Cant see them being much use mind, Seen how small they are, side doors is probably not quite doing them justice?

Kev

 

Maybe, Cant see them being much use mind, Seen how small they are, side doors is probably not quite doing them justice?

Kev
I can't imagine being an infantryman trying to use those cat-flaps in the heat of battle. Carrying a rifle or Bren, ammo pouches on your belt and with a pack and a shovel on your back. Tight squeeze I reckon.

 

Was this tank used for all Canadian Armored Units? How did it fare against the German Armor?

No it was never used as a gun tank, unfortunately, as the others have said. Ironic, given the fact that it was probably the best Allied tank available in the spring of 1942 (IMHO). The Ram was produced from late 1941, it was used for training Canadian troops, but it should have been sent to Egypt right away. Consider the difference it would have made at "Gazala" (May 1942) where the Allies had the Germans bottled up in the "Cauldron" but the British armour could not contain the Panzers, and they broke out. No other British tank had the 6 pounder gun at this time as far as I am aware, but the 6 pounder field guns were very effective in this battle. I believe that the 57 mm gun was almost as effective anti-armour as the 75 mm at longer ranges, although of course the resident tank experts could probably tell more.... One problem with the Grant tanks that were used, was that unlike the Ram they could not easily use "hull-down", which was even more important in the desert.

 

did any independent companies from america,england,australia,canada etc build their own tanks for evaluation by governments,war offices etc.yours,4th wilts.

 

did any independent companies from america,england,australia,canada etc build their own tanks for evaluation by governments,war offices etc.yours,4th wilts.


Not sure I understand the question. Most Tanks where made by independant companies.

Normally the MOD would issue a loose requirment in the form of a specification and companies are invited to bid for it by either with a design spec or a working example. The MOd then select the supplier(s) they like and they are awarded the contract.

Kev

 

On the Ram tank, I wondered is there any. truth in a once heard urban legend that the sherman was knock off of the Ram, as it's prototype came off the line in early july 1941 and was on the aberdeen proving grounds a by july 18th 41 a full 2 months ahead of the Sherman. Many have pointed out the American assistance in tooling the Montreal Locomotive works to build them. As well as the dissatisaftion with the M3 Grant. I cant imagine the that the US designers werent fully aware of the Canadian design based on the MOD requirements for the new battle tank in 1941.