Escort fighter
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 fighters with high fuel capacity were designed for escort duties prior to the outbreak of World War II.
First experimented with in WWI, the U.S.-designed XF-85 Goblin would emerge as the last dedicated parasite fighter design and was abandoned in 1949 due to technical issues as well as the advent of practical aerial refueling.
[10] Prototype aircraft were built – Armstrong Whitworth F.K.6, Sopwith L.R.T.Tr and Vickers F.B.11 – all three put gunners into nacelles to provide wide fields of fire.
Luftwaffe strategy was based mostly on daytime tactical bombing and put significant effort into the escort fighter concept before the outbreak of World War II.
At the time of its introduction, the Bf 110 had been among the fastest production aircraft ever built, but as had occurred with the schnellbomber designs, by the start of the conflict, its performance lead had been seriously eroded.
[18] From that point onwards, the Bf 110 was mostly withdrawn from the escort role, in part because so many had been lost that sufficient numbers could no longer be fielded in the short term; when it did return, it was largely used as a light bomber,[19][20] and night fighter instead.
On 30 November 1936, Director of Staff Duties Sholto Douglas made this position formal, stating "the bombers should be able to look after themselves without the addition of an escort of fighters."
Production allocation followed this rule, capping the number of fighters delivered to front-line use with the British Expeditionary Force and sending the rest to UK formations.
[22][page range too broad] The concept of daytime raids quickly ended after the disastrous air battle of the Heligoland Bight, in which a force of 22 Wellingtons lost 12 aircraft to German fighters as they attacked warships in harbour.
[22][page range too broad] During the preparations for the Big Week offensive, the USAAF asked the RAF to consider how to carry out daytime bombing with Spitfire escorts.
In spite of this demonstration, Fighter Command was slow to consider such adaptations and was not until well after Pointblank was concluded that final sign-off was given, at which point they saw no need for such conversions.
Unlike earlier twin-engine designs like the Bf 110, the Lightning proved to be competitive with the German fighters it faced, permitting it to be easily adapted to the escort role through the use of drop tanks.
[35][36] Finally, the extremely high efficiency of the laminar-flow wing on the Merlin-powered North American P-51 Mustang gave it unparalleled range even on internal fuel, and with external tanks, it could cover most of Europe.
A new concept, the McDonnell XF-85 Goblin microfighter, planned to act as a parasite fighter for the Convair B-36 Peacemaker strategic bomber, was tested with a Boeing B-29 Superfortress and found to be utterly impossible to use operationally.
[39][40] The subsequent FICON project attempted a similar solution, docking jet fighters with heavy bombers via a trapeze mechanism or their wingtips.
During the Korean War, the Lockheed F-80 Shooting Star and later the North American F-86 Sabre escorted B-29 heavy bombers and Republic F-84 Thunderjet strike fighters.
At the same time, the advancement of land and submarine-based ballistic missiles relegated bombers to a lower importance – they became just a single element of the nuclear triad in the US, and largely ignored entirely in the USSR.
The development of the multirole fighter, such as McDonnell Douglas F/A-18 Hornet, also decreased the need for escorts, as the aircraft on air strike mission became capable of effectively defending themselves.
[47] During the 2010s, the US Air Force was in the early stages of developing a new fighter intended to operate as an escort for the next generation Northrop Grumman B-21 Raider strategic bomber.
