Interceptor aircraft
However, dramatic improvements in both ground-based and airborne radar gave greater flexibility to existing fighters and few later designs were conceived as dedicated day interceptors.
In the early Cold War era the combination of jet-powered bombers and nuclear weapons created air force demand for highly capable interceptors; it is in regards to this period that the term is perhaps most recognized and used.
Cold War-era interceptors became increasingly distinct from their air superiority counterparts, with the former often sacrificing range, endurance, and maneuverability for speed, rate of climb, and armament dedicated to attacking large strategic bombers.
Through the 1960s and 1970s, the rapid improvements in design led to most air-superiority and multirole fighters, such as the Grumman F-14 Tomcat and McDonnell Douglas F-15 Eagle, having the performance to take on the point defense interception role, and the strategic threat moved from bombers to intercontinental ballistic missiles (ICBMs).
Visual and acoustic detection from the ground had a range of only a few miles, which meant that an interceptor would have insufficient time to climb to altitude before the bombers reached their targets.
The invention of radar made possible early, long-range detection of aircraft on the order of 100 miles (160 km), both day and night and in all weather.
Large attacks could so confuse the defense's ability to communicate with pilots that the classic method of manual ground controlled interception was increasingly seen as inadequate.
Air forces increasingly turned to much larger interceptor designs, with enough fuel for longer endurance, leaving the point-defense role to the missiles.
In the 1950s and 1960’s during the Cold War, a strong interceptor force was crucial for the opposing superpowers as it was the best means to defend against an unexpected nuclear attack by strategic bombers.
At the end of the 1960s, a nuclear attack became unstoppable with the introduction of ballistic missiles capable of approaching from outside the atmosphere at speeds as high as 3 to 4 miles per second (5 to 7 km/s).
However, pure interceptors fare poorly in fighter-to-fighter combat against the same "less capable" designs due to limited maneuverability especially at low altitudes and speeds.
At the end of Second World War, the Luftwaffe's most critical requirement was for interceptors as the Commonwealth and American air forces pounded German targets night and day.
As the bombing effort grew, notably in early 1944, the Luftwaffe introduced a rocket-powered design, the Messerschmitt Me 163 Komet, in the very-short-range interceptor role.
Following the Emergency Fighter Program, the Germans developed even odder designs, such as the Bachem Ba 349 Natter, which launched vertically and thus eliminated the need for an airbase.
In general all these initial German designs proved difficult to operate, often becoming death traps for their pilots,[7] and had little effect on the bombing raids.
This led fighter prototypes emphasizing acceleration and operational ceiling, with a sacrifice on the loiter time, essentially limiting them to point defense role.
Designs that depended solely on jet engines achieved more success with the F-104 Starfighter (initial A version) and the English Electric Lightning.
As capabilities continued to improve – especially through the widespread introduction of the jet engine and the adoption of high speed, low level flight profiles, the time available between detection and interception dropped.
During the Cold War in times of heightened tensions, quick reaction alert (QRA) aircraft were kept piloted, fully fueled and armed, with the engines running at idle on the runway ready to take off.
Both aircraft were successful during World War II in standard fighter roles, not specifically assigned to point defense against bombers.
Presently, the F-22 is the USA's latest combat aircraft that serves in part as an interceptor due to its Mach 2+ speed as well as supercruise capabilities, however it was designed primarily as a stealth air superiority fighter.
Like the USAF's F-15, the USN's F-14 was also designed primarily as an air superiority (fighter-to-fighter combat) and F-14s served the interceptor role until it received upgrades in the 1990s for ground attack.
The British Royal Air Force operated a supersonic day fighter, the English Electric Lightning, alongside the Gloster Javelin in the subsonic night/all-weather role.
The UK operated its own, highly adapted version of the McDonnell Douglas F-4 Phantom as its primary interceptor from the mid-1970s, with the air defence variant (ADV) of the Panavia Tornado being introduced in the 1980s.
Initially designed in the early 1960s to counter US-built B-58 Hustler bombers, F-105 Thunderchief fighter-bombers and Lockheed U-2 reconnaissance planes, it still retains the ability to 'sprint' at Mach 2+ speeds, and later versions can carry medium-range PL-12/SD-10 MRAAM missiles for interception purposes.
