Tactical bombers are smaller aircraft that operate at shorter range, typically along with troops on the ground. This role is filled by many designs, including those listed below. In modern terms, any combat aircraft that is not a purpose-designed strategic bomber falls into this category.
Ground attack aircraft or "close air support" aircraft are designed to loiter over a battlefield and attack tactical targets, such as tanks, troop concentrations, etc. Examples: Junkers Ju 87 Stuka, Ilyushin Il-2 Shturmovik, A-10 Thunderbolt II, and Sukhoi Su-25 'Frogfoot'.
Fighter-bombers (also called tactical fighters, strike fighters, and attack fighters) are multi-role combat aircraft which can (at least theoretically) be equipped for either air-to-air combat or air-to-ground combat. Many fighter bombers were also designed to engage in aerial combat immediately after attacking ground targets. Modern multi-role combat aircraft are designed to fulfill multiple roles due to budget restrictions as often as they are for versatility. Examples: Chengdu J-10, F-4 Phantom II, F-15E "Strike Eagle", F-16 Fighting Falcon, F/A-18 Hornet, Sukhoi Su-32 'Fullback', Dassault-Breguet Mirage 2000, and the Panavia Tornado.
Bombers evolved at the same time as the fighter aircraft at the start of World War I. The first use of an air-dropped bomb however, was carried out by the Italians in their 1911 war for Libya. In 1912 Bulgarian Air Force pilot Christo Toprakchiev suggested the use of airplanes to drop "bombs" (as grenades were called in the Bulgarian army at this time) on Turkish positions. Captain Simeon Petrov developed the idea and created several prototypes by adapting different types of grenades and increasing their payload. On October 16, 1912, observer Prodan Tarakchiev dropped two of those bombs on the Turkish railway station of Karaagac (near the besieged Edirne) from an Albatros F.II airplane piloted by Radul Milkov.
After a number of tests Petrov created the final design, with improved aerodynamics, an X shaped tail and impact detonator. This version was widely used by the Bulgarian Air Force during the siege of Edrine. Later a copy of the plans was sold to Germany and the bomb, codenamed "Chathaldza" ("Чаталджа") remained in mass production until the end of World War I.
The weight of the bomb was 6 kilograms. On impact it created a crater 4-5 meters wide and about 1 meter deep. The Germans used Zeppelins as bombers since they had the range and capacity to carry a useful bomb load from Germany to England. With advances in aircraft design and equipment, they were joined by larger multi-engined biplane aircraft on both sides for long range strategic bombing especially by night. The majority of bombing was still done by one-engined biplanes with one or two crew-members flying short distances to attack the enemy lines and immediate hinterland.
The world's first four-engined bomber was the Russian Il'ya Muromets created in 1914 and successfully used in World War I. By the end of the First World War the UK had amassed a force of heavy bombers with the sole intent of attacking Germany's industrial heart but the armistice came before it was used.
In the past, bombers were a separate type of aircraft, and often looked dramatically different from other aircraft. This was due largely to the lack of power in aircraft engines, meaning that to carry any reasonable payload, the aircraft had to have multiple engines. The result was a much larger aircraft, one with a reasonable useful load fraction for the role.
With engine power as a major limitation combined with the desire for accuracy and other operational factors, bomber designs tended to be tailored to one particular role. By the start of World War II this included
Bombers have carried armament for defence against enemy aircraft only. They are not intended nor designed to actively engage in combat with other aircraft. The majority have been relatively large and unmaneuverable - although some smaller designs have been used as the basis for specialist fighters such as the night-fighter. Attack aircraft are smaller, faster, and more agile, but when armed for a ground attack mission, less so than a fighter. Attack aircraft may carry air-to-air armament, but typically only infrared-guided weapons (such as the AIM-9) for self-defence.
At the start of the Cold War, bombers were the only means to take the nuclear weapons to the enemy and had the role of deterrence. With the advent of the guided missile, bombers had to turn to different ways to avoid interception. High speed and high altitude flying became a means of evading detection and attack. Some designs such as the English Electric Canberra could fly faster or higher than contemporary fighters. Surface to air missiles threatened high flying aircraft, and bombers moved to high speed low flying to get under air defences. Since the bombs were now "stand off" designs (effectively large guided missiles themselves) they did not have to climb over the targets to drop them but would have fired and turned away to escape the blast. Nuclear strike aircraft were generally finished in bare metal or anti-flash white to avoid any residual effects.
At the same time the need to drop conventional bombs remained in conflicts with a non-nuclear power such as the Vietnam war or Malayan Emergency.
The development of large strategic bombers stagnated in the later part of the Cold War because of spiraling costs and the advent of the intercontinental ballistic missile which was felt to have equal deterrent value while being much more difficult to intercept. The United States Air Force XB-70 Valkyrie program was cancelled for that reason in the early 1960s, and the later B-1B Lancer and B-2 Spirit aircraft entered service only after protracted political and development problems. Their high cost meant that few were built and the 1950s-designed B-52s continued in use into the 21st century. Similarly, the Soviet Union used the intermediate-range Tu-22M 'Backfire'in the 1970s, but their Mach 3 bomber project came to naught. The Mach 2 Tu-160 'Blackjack' was built only in tiny numbers, leaving the earlier Tupolev Tu-16 and Tu-95 'Bear' heavy bombers of 1950s vintage to continue being used into the 21st century. Meanwhile, the British strategic bombing force largely came to an end with the phase-out of the V Bomber force (the last of which left service in 1983. The only other nation that fields a strategic bombing force at present is the People's Republic of China, which has a number of Chinese-built Tu-16 'Badgers'.
In modern air forces, the distinction between bombers, fighter-bombers, and attack aircraft has become blurred. Many attack aircraft, even ones that look like fighters, are optimized to drop bombs, with very little ability to engage in aerial combat. Indeed, the design qualities that make an effective low-level attack aircraft make for a distinctly inferior air superiority fighter, and vice versa. Conversely, many fighter aircraft, such as the F-16, are often used as 'bomb trucks,' despite being designed for aerial combat. Perhaps the one meaningful distinction at present is the question of range: a bomber is generally a long-range aircraft capable of striking targets deep within enemy territory, whereas fighter bombers and attack aircraft are limited to 'theater' missions in and around the immediate area of battlefield combat. Even that distinction is muddied by the availability of aerial refueling, which greatly increases the potential radius of combat operations.
Plans in the U.S. and Russia for successors to the current strategic bomber force remain only paper projects, and political and funding pressures suggest that they are likely to for the foreseeable future. In the U.S., current plans call for the existing USAF bomber fleet to remain in service until the mid-to-late 2020s, with the first possible replacements becoming operational in 2018.