Escort fighter The escort fighter was a World War II concept for a fighter aircraft designed to escort bomber s to and from their targets . An escort fighter needed range long enough to reach the target , loiter over it for the duration of the raid to defend the bombers , and return . A number of twin - engined heavy fighter s with high fuel capacity were designed for escort duties before World War II . Such heavy fighters largely failed in their intended escort role during the war , as they were outmaneuvered by more agile single - engined fighters . As the war progressed , longer - range fighter designs and the use of drop tanks allowed single - engined fighters to perform escort duties . Use in the Luftwaffe . During the Battle of Britain , the Luftwaffe used Messerschmitt Bf 109 s and Bf 110 s based in France as escort fighter - bombers . Although flying from relatively close airfields in France , the Bf 109 was operating at the extreme of its range and unable to remain for long with the bombers if it was to have fuel to return , while the Bf 110 , specifically designed for the escort role , had inferior performance and was easily outperformed by the Royal Air Force Supermarine Spitfire s and Hawker Hurricane s . Flying with the Heinkel He 111 and Junkers Ju 88 medium bombers , they would drop their light bomb - loads and — for a brief period — fight off the British fighters . U . S . Army Air Forces ' operations . The U . S . Army Air Forces ' precision strategic bombing campaign against German industries was only possible during the day . At first , this was not seen as an issue ; the Forces ' Boeing B - 17 Flying Fortress and Consolidated B - 24 Liberator bombers , were the most heavily armed in history . Close formations of them were planned , creating a crossfire of . 50 caliber machine - guns that would fend off the enemy with no need for a fighter escort . The plan was quickly undermined . Hitting a fast - moving fighter with guns in a turret proved extremely difficult ; hitting a slow - moving bomber from a fighter with a gunsight was much easier . USAAF bomber losses gradually increased , and experimental " gunships " like the YB - 40 did nothing to reduce them . It was not until the introduction of the Lockheed P - 38 Lightning and Republic P - 47 Thunderbolt fighters that the bombing raids could claim a measure of success . Able to carry large Lockheed - designed drop tanks , the fighters were able to escort the bombers for much of their missions . The first Allied fighters over Berlin were 55th Fighter Group P - 38s on March 3 , 1944 . When the Merlin - powered North American P - 51 Mustang was introduced , with a laminar - flow wing for efficiency , the final escort fighter development of the war was complete . Cold War . The successes of the P - 47N and P - 51 gave the impression that the escort fighter was a concept worth continuing after the end of the war . The high fuel use of early jet engines made such aircraft difficult to design , and a number of experimental designs were tried that used mixed power , typically a turboprop and jet , but these failed to meet performance requirements . A new concept , the XF - 85 Goblin microfighter , planned to act as a parasite fighter for the Convair B - 36 , was tested with a B - 29 Superfortress and found to be utterly impossible to use operationally . Later the FICON project attempted a similar solution , docking jet fighter s with heavy bombers via a trapeze mechanism or their wingtips . Whilst projects for dedicated escort fighters such as the XF - 85 Goblin came to nothing , the advancement of technology and the nature of warfare of the wars being fought allowed the role of fighter escort to gradually merge with fighter types , so the term fell out of use . In Korea , the F - 80 Shooting Star and later the F - 86 Sabre escorted B - 29 heavy bombers and F - 84 Thunderjet strike fighter s . Although the XB - 70 Valkyrie , North American Aviation ' s Mach 3 bomber , was intended to be immune to enemy attack due to its speed , NAA very briefly proposed the XF - 108 Rapier interceptor for the escort role . With the development of guided missiles , particularly surface - to - air missile s , plans for dedicated escort fighters designed to escort nuclear bombers gradually faded from the scene . Missile technology meant that interceptors would rarely engage bombers directly , if ever , and the escorts could do little against missiles . As of bombers themselves , the advancement of land and submarine - based ballistic missiles relegated them to a lower importance — they became just a single element of the nuclear triad . Furthermore , with the concept of mutally assured destruction high on the political agenda throughout the Cold War , a nuclear exchange became ever less likely , leaving existing fighter designs more than adequate for their protection in the wars being fought . In Vietnam for instance , F - 4 Phantom II s and sometimes F - 8 Crusader s escorted the American bombers such as B - 52 Stratofortress es and F - 105 Thunderchief s . In some cases the missions of F - 4 were " mixed " , when some F - 4 were equipped with bombs , and some F - 4 acted as escorts ( similar cases occurred with F - 8 ) . Modern era . The advent of the air superiority fighter , such as the F - 15 Eagle , meant that bombers and attack aircraft would be protected by fighters flying far afield and ahead of them , engaging distant enemy air units , rather than by direct escorts staying in sight nearby . The development of the multirole fighter , such as F / A - 18 , also decreased the need for escorts , as the aircraft on air strike mission became capable of effective self - defense .