The F-111 was developed in the 1960s by the USAF as a fighter plane with Mach 2.5 speed at altitude and March 1.2 speed at low level, a combat radius of 1,200 km half of which is at low level and at supersonic speed, and with an internal weapons bay. The first F-111A was rolled out in 1964 and first flew on 21 December. The F-111 is an imposing craft: it is of exceptional size and weight, being 22 metres in length and with an empty weight of 21 tons and max takeoff weight of 45 tons. The F-111A could carry 50 bombs of 340 kg or 26 bombs of 450 kg, a load similar to that of the B-52. It had an exceptional range with max internal fuel over 2,750 km and ordnance capacity of over 7,000 kg.