The RAF's variants of the Lockheed Martin C-130J Hercules family are designated as the Hercules C4 in stretched-fuselage configuration and the Hercules C5 in short-fuselage form. In total, 24 aircraft across both versions are in service with squadrons based at RAF Brize Norton. The C4 and C5 have now completely replaced the earlier C-130K, or Hercules C1 and C3, models. In C-130J form the Hercules is a very different beast, with four Allison AE2100D3 turboprops driving advanced propellers, and a modern 'glass' cockpit incorporating advanced avionics such as head-up displays and provision for the use of night vision goggles. However, its primary role remains the same: tactical air transport in support of British forces, carrying cargo or troops. Other tasks include strategic transport and support of special forces.