Bomber aircraft are military airplanes optimized to deliver large volumes of bombs, missiles, mines, etc., to targets. While they may have a capability to fight other airplanes, that detracts from their mission of attacking a surface target.
Throughout the history of aviation, bombers have changed constantly to meet current military requirements. While a Second World War bomber attacking the heartland of Germany needed considerable defensive armor and armament to survive attack by fighters, modern bombers carry no defensive guns, but extensive electronic warfare systems to defeat or hide from enemy radar.
At one time, it was quite routine to speak of bombers as light, medium, or heavy, reflecting both their weight and payload. Their weight would, in turn, define the size of runways they would need, and usually their range.
Current bombers all would qualify as "heavy" by past standards. With air refueling, all have intercontinental range, and can carry large bombloads.
Under strategic arms limitation agreements, Russia has agreed not to operate the Tu-22M at intercontinental ranges, and the U.S. has agreed not to equip the B-1 with nuclear weapons. Russia has leased several navalized versions of the Tu-22M to India.
- Russia: Tu-160 BLACKJACK, Tu-22M BACKFIRE. While the Tu-95 BEAR still is operational, it is not clear that any are assigned to strategic nuclear missions.
- United States: B-1 Lancer, B-2 Spirit, B-52
Second World War
Before precision-guided munitions, bombers had several ways to attack, and often were designed around the attack mode. Most modern fighter-bombers can attack with
In dive bombing, the carrying aircraft aims itself, at a steep angle (e.g., 70 degrees), at the target, and releases the bomb when the it is clear the trajectory of the aircraft will take the bomb into the target. The bomber then pulls out of that trajectory by climbing, turning, or both. A pullout puts substantial centripetal force on the crew.
The invention of dive bombing is generally credited to the United States Navy, and, more specifically, a Marine aviator, Lawson H.M. Henderson, during fighting in Haiti in 1919. The Navy standardized on it as a technique in 1928.  It was a rejection of the horizontal bombing technique preferred by the Army Air Corps.
The Navy thought first in terms of attacking moving ships, probably in combination with torpedo bombers making low-level horizontal runs. Attackers coming from two radically different directions confused the defense. Even when the ideal synchronization of the two types of attacks failed, the Battle of Midway serves as sacrificial evidence of the defense problem: the torpedo bombers arrived first, and attacked independently. Virtually all were shot down and none scored a hit, but the carriers' defensive fighter patrols were engaging them at low level when the dive bombers arrived. While there was antiaircraft fire against the dive bombers, the fighters could not get to them in time to have any effect.
Marine Aviation also believed that dive bombing was more accurate for close air support, especially if one remembers there was no electronic assistance to finding the target or guiding the bomb.
Land-based Army aircraft could use large, multi-engine aircraft that carried multiple bombs. Carrier-based aircraft might be able to carry only a single bomb, so could not rely on the pattern of bombs from a medium-altitude horizontal drop.
German observers were impressed with the technique, and Ernst Udet insisted on buying two U.S. aircraft for evaluation. The Germans later developed their own dive bomber for close air support and battlefield air interdiction, the Ju-87 Stuka. Hitler, subsequently, insisted that all German bombers be able to dive-bomb, which is one of the reasons Germany never deployed a heavy bomber -- only light and medium bombers, as well as fighter-bombers, are agile enough for dive-bombing,
Purpose-built dive bombers normally had dive brakes or other aerodynamic controls to slow the dive and give the pilot more aiming time. They also needed a bomb release that released the bomb on an even steeper dive than the aircraft, so the bomb would clear the propeller arc.
Modern dive bombing
With electronic bombsights, pure dive bombing reached the limits of its effectiveness. The U.S. Navy F-18 Hornet and U.S. Air Force F-16 Fighting Falcon could precisely fly a course toward the target, but, eventually, the aircraft, with its power and control surfaces, became more accurate than an unguided gravity bomb that had minimum stabilization.
In some cases, [[[precision-guided munition]]s (PGM) may be delivered in a dive, but they also are dropped from horizontal flight. The guidance aboard the PGM takes the weapon to a level of accuracy impossible for pure dive bombing.
While air-dropped torpedoes are no longer used for anti-surface warfare, and were indeed nearly futile in the Second World War unless part of a coordinated attack that distracted air defenses, a torpedo bomber was optimized for low-altitude flight. Using unguided torpedoes, it had to fly a straight-line course against the target, so that the torpedo would not have any lateral component of its flight path. The torpedo had to be dropped low enough and slow enough so that it would not break up on contact with water.
Survivable flight profiles for nuclear weapon delivery
Given the massive effects of a nuclear weapon, for the aircraft delivering it to survive, it must be outside the blast and fireball. Starting at Hiroshima and Nagasaki, the bombs were dropped from horizontal bombers, which then took a radical, 158 degree diving turn away from their flight path. The bombs, once dropped, deployed parachutes to slow their drop rate and give the bomber more time to escape.
Parachute-retarded bombing from bigh altitude continued, but more powerful air defense introduced low-altitude "laydown" modes, where the delivery aircraft would drop the bomb, which would be parachute-retarded, and rugged enough to survive landing. The bomb, on the ground, might have additional timing delay.
Aircraft more agile than heavy bombers had additional techniques. Officially called the "low altitude bombing technique" (LABS), a fighter-bomber, approaching its target at high speed, would, near the release point, start climbing into an inside loop. At the point of the flight path where the aircraft was closest to the target, the aircraft would release the bomb, then roll over and dive.
The bomb would continue in a parabolic trajectory toward the target, which could be a considerable distance away if the bomb was released at high speed or had a rocket booster to give it additional energy, or if, once the bomb started descending toward its target, deployed a parachute.
- Weider History Group, Curtiss SB2C Helldiver: The Last Dive Bomber