Dive bomber

A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target simplifies the bomb's trajectory and allows the pilot to keep visual contact throughout the bomb run. This allows attacks on point targets and ships, which were difficult to attack with conventional level bombers, even en masse. Dive bombing was especially effective against vehicles when integrated into early instances of Blitzkrieg.

After World War II, the rise of precision-guided munitions and improved anti-aircraft defences—both fixed gunnery positions and fighter interception—led to a fundamental change in dive bombing. New weapons, such as rockets, allowed for better accuracy from smaller dive angles and from greater distances. They could be fitted to almost any aircraft, including fighters, improving their effectiveness without the inherent vulnerabilities of dive bombers, which needed air superiority to operate effectively.

A dive bomber dives at a steep angle, normally between 45 and 60 degrees or even up to a near vertical dive of 80 degrees with the Junkers Ju 87, and thus requires an abrupt pull-up after dropping its bombs. This puts great strains on both the pilot and aircraft. It demands an aircraft of strong construction, with some means to slow its dive. This limited the class to light bomber designs with ordnance loads in the range of 1,000 lb (450 kg) although there were larger examples.

The most famous examples are the Junkers Ju 87 Stuka (short for Sturzkampfflugzeug, dive fighter), which was widely used during the opening stages of World War II often accompanied with the screaming sound of its sirens, the Aichi D3A "Val" dive bomber, which sank more Allied warships during the war than any other Axis aircraft, and the Douglas SBD Dauntless, which sank more Japanese shipping than any other allied aircraft type. The SBD Dauntless helped win the Battle of Midway, was instrumental in the victory at the Battle of the Coral Sea, and fought in every US battle involving carrier aircraft.

An alternative technique, glide-bombing, allowed the use of heavier aircraft, which faced far greater difficulties in recovering from near-vertical approaches, though it required greater use of sophisticated bombsights and aiming techniques, by a specialised member of aircrews, namely a bombardier/bomb aimer. The crews of multi-engined dive-bombers, such as variants of the Junkers Ju 88 and Petlyakov Pe-2, frequently used this technique. The heaviest aircraft to have dive-bombing included in its design and development, the twin engine Heinkel He 177, also utilised a glide-bombing approach; the requirement that the He 177 be able to dive/glide-bomb delayed its development and impaired its overall performance.

Dive bombing was most widely used before and during World War II; its use declined during the war, when its vulnerability to enemy fighters became apparent. In the post-war era, this role was replaced with a combination of improved and automated bombsights, larger weapons and even nuclear warheads that greatly reduced the need for accuracy, and finally by precision guided weapons as they became available in the 1960s. Most tactical aircraft today allow bombing in shallow dives to keep the target visible, but true dive bombers have not been a part of military forces since the start of the jet age.

When released from an aircraft, a bomb carries with it the aircraft's trajectory. In the case of a bomber flying horizontally, the bomb will initially only be travelling forward. This forward motion is opposed by the drag of the air, so the forward motion decreases over time. Additionally, gravity causes the bomb to accelerate after it is dropped. The combination of these two forces, drag and gravity, results in a complex pseudo-parabolic trajectory.

The distance that the bomb moves forward while it falls is known as its range. If the range for a given set of conditions is calculated, simple trigonometry can be used to find the angle between the aircraft and the target. By setting the bombsight to this "range angle", the aircraft can time the drop of its bombs at the instant when the target is lined up in the sight. This was only effective for "area bombing", however, since the path of the bomb is only roughly estimated. Large formations could drop bombs on an area hoping to hit a specific target, but there was no guarantee of success, and huge areas around the target would also be hit. The advantage to this approach, however, was that it is easy to build such an aircraft and fly it at high altitude, keeping it out of range of ground-based defences.