During 1969-1970, two prototypes known as “Keiler“, (tusker), were built. These vehicles were designated as ET.01 and ET.02, and were a development of the “Vergolderer Leopard” project, (Golden Leopard), a program started in 1967 and which consisted of improving the capabilities of Leopard 1 tanks in service with the Bundeswehr.Keiler tank was developed between Krauss-Maffei, (main contractor), Porsche, (chassis), and Wegmann, (turret). The two prototypes had the MTU MB-872 engine and its main armament was a smothbore 105mm gun. Its development ended in 1970, although it can be said that they were the seed of the Leopard 2 tank.The first Leopard 2 experimental prototypes looked very similar to what would be the future Leopard 1A4, although the front part of the hull had a wedge shape. These prototypes began their tests in 1972.The roadwheels and tracks of these first prototypes came from the vehicles designed for the MBT/KPz-70 program and the return rollers were the same as in the Leopard 1.This prototype and that of the two previous pictures has installed the 105mm smoothbore gun, which was installed in ten of the turretts prototype built between 1972 and 1974.All prototypes except PT.7, PT.9, PT.15 and PT.17 included the MTU MB-873 Ka-500 water-cooled 12-cylinder twin-turbo multi-fuel engine. This 1,500hp engine was the same used for the MBT/KPz-70 project. The prototypes mentioned above had a slightly modified engine.The engine along with the generator, the gearbox, the air filters and the braking and cooling systems formed a compact group that was designed to be easily replaced in 15 minutes. Gearbox was a Renk HSWL-354/3 model with 4 forward gears and 4 reverse gears.From February 14 to March 19, 1975, four prototypes were tested in Shilo, Canada, at temperatures that reached -45ºC. These prototypes were armed with the 105mm smoothbore gun. Later they would be sent to Yuma, Arizona, where they would withstand temperatures up to + 45ºC.This is one of the prototypes that carried one of the seven turrets armed with the 120mm smoothbore gun. All turrets were designed by Rheinmetall and at the beginning of the program these tanks were designated as Leopard 2K, by “Kanone”. At this time, a variant designated as Leopard 2FK was in development. The variant was armed with the Shillelagh 152mm cannon-launcher.. In 1971 the development of the gun-launcher was ended and the prototypes were simply called Leopard 2.PT.11 prototype in 1972. This prototype had installed the same hydro-pneumatic suspension than MBT/KPz-70 and a 20mm remotely controlled automatic gun. This gun assembly was unique in the whole series of prototypes but was not adopted in the serial models. Suspension was also installed in PT.17 tank and was not selected for the final vehicles either. The main armament is the Rheinmetall 120mm smoothbore gun.This is the PT.14 in 1974. It has installed a turret with a 120mm smoothbore gun and is in the Münster proving ground performing mobility tests. The prototype had incorporated the EMES-13 optical rangefinder, developed by Leitz and AEG-Telefunken companies. The device was small and was designed to be installed also in the Leopard 1 tanks already in service.Here we see the PT.14 T.13 in 1974, which along with 3 more prototypes was sent in summer to carry out troops trials at the Panzertruppenschule 2 located in Münster. The word “Gesperrt” written in the 120mm gun barrel means “do not shoot”, so this prototype did not have the ability to fire.Again, we see the PT.14 T.13 in 1974 with the turret designated as “Spitzmaus Turm” (shrew turret). This turret was built by Wegmann in mid-1973 and weighed 1,500 kg less than the previous ones. It only served for tests since it would not be finally chosen for the series model.PT.17 prototype in 1974. This prototype had the MBT/KPz-70 suspension installed as the PT.11, but unlike that, this model has the 105mm instead of the 120mm smoothbore gun and it lacks the 20mm gun mounting on the turret roof.This is the PT.17 armed on this occasion with the 120mm smoothbore gun. The prototype is loading ammunition during tests carried out in Arizona in May 1975. At that time, temperatures of 43ºC were reached outside and up to 60ºC inside the tank.
