Tank
With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper considerations to comfort and ergonomics, are an important factor in the combat effectiveness of a tank, as it limits fatigue and speeds up individual actions.
Ace (military)
The term "tank ace" is occasionally applied to tank crew. For instance, Sydney Radley-Walters' obituary published in "The Globe and Mail" in 2015 described him as the "best Canadian front-line tank ace" of World War II. Robert Kershaw in his book "Tank Men" refers to a "Tank Ace" being the minority of tank commanders that accounted for the most amount of destroyed enemy armour, saying it is roughly analogous with flying ace. Soviet tankers with over five kills, such as Dmitry Lavrinenko and Zinovy Kolobanov, have also been referred to as "tank aces".