The Tiger I represented a new approach that emphasised firepower and armour at the expense of mobility. Design studies for a new heavy tank had been started in the late 1930s, without any production planning. The real impetus for the Tiger was provided by the quality of the Soviet T-34. Although the general design and layout were broadly similar to the previous medium tank the Panzer IV, the Tiger weighed more than twice as much. This was due to its substantially thicker armour, the larger main gun, and the consequently greater volume of fuel and ammunition storage, larger engine, and more solidly-built transmission and suspension.
The Tiger I had frontal hull armour 100 mm thick and frontal turret armour of 110 mm, as opposed to the 80 mm frontal hull and 50 mm frontal turret armour of contemporary models of the Panzer IV. It also had 80 mm thick armour on the sides and rear. The top and bottom armour was 25 mm thick; later, the turret roof was thickened to 40 mm. Armour plates were mostly flat, with interlocking construction. The armour joints were of high quality, being stepped and welded rather than riveted.
The rear of the tank held an engine room flanked by two floodable rear compartments each containing a fuel tank, radiator, and fans. The petrol (gasoline) engine was a 21-litre 12-cylinder Maybach HL 210 P45 with 650 PS (641 hp, 478 kW). Although a good engine, it was inadequate for the vehicle. From the 250th Tiger it was replaced by the uprated HL 230 P45 (23 litres) of 700 PS (690 hp, 515 kW). The engine was in V-form, with two cylinder banks at 60 degrees. An inertial starter was mounted on its right side, driven via chain gears through a port in the rear wall. The engine could be lifted out through a hatch on the hull roof.
The internal layout was typical of German tanks. Forward was an open crew compartment, with the driver and radio-operator seated at the front, either side of the gearbox. Behind them the turret floor was surrounded by panels forming a continuous level surface. This helped the loader to retrieve the ammunition, which was mostly stowed above the tracks. Two men were seated in the turret; the gunner to the left of the gun, and the commander behind him. There was also a folding seat for the loader. The turret had a full circular floor and 157 cm headroom.
The gun breech and firing mechanism were derived from the famous German “88” dual purpose flak gun. The 88 mm Kwk 36 L/56 gun was the variant chosen for the Tiger and was, along with the Tiger II’s 88 mm Kwk 43 L/71, one of the most effective and feared tank guns of WW2. The Tiger’s gun had a very flat trajectory and extremely accurate Zeiss TZF 9b sights. Tigers were reported to have knocked out enemy tanks at ranges greater than a mile (1,600 m), although most WW2 engagements were fought at much closer range.
The Tiger was first used in action in September 1942 near Leningrad. Under pressure from Hitler the tank was put into action months earlier than planned and many early models proved to be mechanically fragile. In its first action on 23 September 1942, many of the first Tigers broke down. Others were knocked out by dug-in Soviet anti-tank guns. One tank was captured largely intact, which gave the Soviets a chance to study the tank and prepare a response. In the Tiger’s first actions in North Africa, the tank was able to dominate Allied tanks in the wide-open terrain. However, mechanical failures meant that there were rarely more than a few in action. In a replay of the Leningrad experience, at least one Tiger was knocked out by towed British six-pounder antitank guns.
The Tiger’s armour and firepower, however, were feared by all its opponents. In tactical defence, its poor mobility was less of an issue. Whereas Panthers were the more serious threat to Allied tanks, Tigers had a bigger psychological effect on opposing crews, causing a “Tiger phobia”. Allied tankers would sometimes evade rather than confront a Tiger, even a tank that only looked like one, such as the Panzer IV with turret skirts applied. In the Normandy campaign, it could take four to five Shermans to knock out a single Tiger tank by maneuvering to its weaker flank or rear armour; the Soviet T-34s fared similarly against the German tanks, as had the German PzIII earlier against the Soviet heavy tanks.
An accepted Allied tactic was to engage the Tiger as a group, one attracting the attention of the Tiger crew while the others attacked the sides or rear of the vehicle. Since the ammunition and fuel were stored in the sponsons, a side penetration often resulted in a kill. This was, however, a risky tactic, and often resulted in the loss of several Allied vehicles. It took a great deal of tactical skill to eliminate a Tiger.