The US aviation industry produced three great fighter designs to equip its burgeoning army air force during World War 2, and of this trio, Republic's P-47 Thunderbolt was easily the heaviest. Powered, crucially, by a turbocharged Pratt & Whitney R-2800 Double Wasp radial engine that produced 2000 hp, the first production fighters reached the 56th FG in June 1942, and six months later the group joined the Eight Air Force in Britain. The arrival of the first P-47Cs in mid-1943 addressed the problem of the aircraft's short combat radius, as this model could be fitted with an external tank. Slowly, as combat tactics evolved in units like the 56th and 78th FGs, pilots learnt how best to fly the Thunderbolt in order to effectively counter the more nimble Luftwaffe fighters.