T52, the Sherman with a Ball Turret. "In early 1942, the US Ordnance Department and Army Ground Forces laid out requirements for a new self-propelled anti-aircraft gun based on the M4 Sherman.
It was to be armed with an automatic 40 mm cannon, and two .50 caliber machine guns.
They were fitted inside a strange ball-like turret that was separated into two main parts. The lower part sat in the Sherman’s turret ring, and controlled the turret’s lateral movement.
The upper part sat within this and pivoted up and down on a trunnion for the turret’s vertical movement. During its evaluations at the Aberdeen Proving Ground, the T52 was found to be unsatisfactory".
I'm just transcribing what I just read on Facebook:
How effective was the sandbag on a Sherman?
The most common argument made about why these sandbags were added were mostly around the idea that these sandbags were a great protection against Panzerfaust or Raketenpanzerbüchse 54 "Panzerschrek"
However here's something that many people missed when trying to reason this; these sandbags were little to no effect when it comes to stopping these rounds. In fact both the Panzerfaust and Panzerschrek requires about 1 meter of air gap to substantially reduce the penetrating capability of the warhead, which effectively not only render a sideskirt useless, but also made the idea of adding sandbags a moot point as well...
All you did is providing a false sense of security while you overburdening your vehicle with extra weight which significantly shortening your tank suspension lifespan.
In this top view see the radial engine of a Sherman tank during routine maintenance. "The radial was used due to its high horsepower and being air cooled".