There is a What If campaign starting over on Armorama. Based on the discussion here on an all-cast Churchill built by the Australians instead of the Sentinel, here's my backstory:
What If the Australians had decided to emulate the Churchill when they made their indigenous tank and not use components from the Sherman/Lee.
The Australian Cast Churchill w/ 87mm gun
With supplies of tanks from the UK being almost nonexistant, the Australians decided, like the other Dominions, to design their own tank to suit their purposes. Without an indigenous armour plate industry, cast homgeneous armour was seen as the way to go. The existing cruiser and infantry tanks had numerous shortcomings, but the Brits were making this new tank, the Churchill, and it looked very promising.
With the exception that the manufacturing method changed from welded plate to casting, the Churchill's hull and running gear were kept much as they were. Yes, shot traps were eliminated along with the side doors, but you could definitely tell it was a Churchill. The turret, though, was a different thing. The Aussies had had enough of the 2 pdr in the desert and knew it was useless as an infantry support weapon and nearly useless as an antitank weapon. They needed something better, but were not tooling up to make any of the larger AT guns themselves. What they were making was the 25 pdr. It had a very useful AT performance and was more than perfect for infantry support, the task they expected to use their tanks for most.
Having access to 25 pdrs and ammo, they took the initiative when putting the 25 pdr into their home-made Churchill and lengthened the 25 pdr's tube a little, adding about 24" to the length and taking full advantage of the slightly increased muzzle velocity to increase the armour penetration power of the 25 pdr's AP rounds while not sacrificing the performance or, more importantly, the interchangeability with the artillery rounds. The new recoil mechanism needed for the turret mount could easily absorb the higher recoil, but the increase in velocity and bore pressure wasn't enough to compromise the existing 25 pdr ammo.
To fit this much larger gun required a new turret. The Aussies took advantage of necessity and changed the turret design to eliminate the vertical sides and large flat front face of the Churchill turret. The new turret tapered toward the front and the sides were angled away from the vertical to increase both internal room and penetration resistance. The Commander's and Loaders hatches were mover further apart to clear the larger breech of the new tank gun and the loader actually found himself with a fair amount of room in which to load the larger ammunition. The rate of fire of the new tank gun was nearly as high as that of the artillery piece it was derived from.
Cast Churchills were supplied with 75 rounds of what was called 87mm ammo to distinguish the new fixed tank ammo from the separate-loading 25 pdr artillery ammo, but the shells were interchangeable with the artillery peices. 87mm AP rounds were the equivalent of the standard 25 pdr AP shot married to the super-charge filled casing and the HE round was the equivalent of the 25 pdr's HE round married to a casing filled with the artillery Charge 1. There being no need for extended range for the tank gun, fixed cartridges with different charges were not procured.
Late in the war, the Austrialian ordnance industry developed an APCBC round, but given the poor quality of the Japanese armour, this was not proceeded with.
While officially designated the Churchill Mk XX, they were universally called Winnies to distinguish them from the standard Churchills.
Several variants of the Winnie were built or prototyped. There was the Churchilll XXI, with an experimental attempt to fit a 17 pdr in a modified Winnie turret. The Winnie AVRE, a Churchill XX connerted to jungle AVRE configuration. The Churchill XXII, fitted with an American Flamethrower instead of the main gun which served in the jungle battles. And finally the Winnie ARK, which, like it's Churchill bretheren, was used to cross small rivers and streams.
The Winnie served faithfully until replaced by the Centurion although several Winnie AVREs and ARKs survived to serve in Vietnam until 1969 when they were finally clapped out and withdrawn.
My model will be an old Tamiya Churchill converted to a cast hull with a new turret and a main gun made from a lengthened Tamiya 25 PDR tube with muzzle brake.
Also, here's my start on the 25 pdr Churchill:
Still in the box:
[img width= height=]http://gallery3.kitmaker.net/data/28970/Start6.JPG[/img]
Next, the chopped and sectioned waiting to dry before getting a new shape.
[img width= height=]http://gallery3.kitmaker.net/data/28970/IMG_0489.JPG[/img]
[img width= height=]http://gallery3.kitmaker.net/data/28970/IMG_04871.JPG[/img]
[img width= height=]http://gallery3.kitmaker.net/data/28970/IMG_04881.JPG[/img]
[img width= height=]http://gallery3.kitmaker.net/data/28970/IMG_04862.JPG[/img]
So she's well underway!
Paul
