Dive bomber
A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy. This type of aircraft was most heavily used before and during World War II; its use fell into decline shortly afterwards.
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Technique
Diving (nearly) vertically at the target, in the same direction the bombs will take, the aircraft will release the bombs very close to the target at high speed. This allows a dive bomber to accurately place bombs on relatively small and/or moving targets with relative ease. Additionally, no complicated precision bombsight is needed for targeting.
Dive bombers were widely used to attack high value targets such as ships and bridges. This also had the advantage of attacking ships at a weak spot; armour was the heaviest near the waterline and thin or nonexistent on the deck. In addition, dive bombing allowed relatively small airplanes carrying limited bombload to inflict disproportionately heavy damage.
On the negative side, optimizing an airplane for near-vertical dives came at the expense of performance. In addition, a dive bomber was extremely vulnerable to ground fire as it dived towards its target. Dive brakes were employed on many designs. These created drag which slowed the aircraft somewhat in order to increase accuracy. These were almost exclusive to dive bombers, though the air brakes fitted to modern aircraft are often of a similar design.
History
World War I and inter-war period
The first recorded use of dive bombing was an ad-hoc solution by British Royal Air Force pilots during World War I. In 1917 and 1918, they practiced the technique at the Orford Ness Bombing Range, but the aircraft of the day were generally too frail to be able to withstand the acceleration generated when pulling out of the dive after releasing the bombload.
The first combat dive bombing attack took place in early 1919 when United States Marine Corps pilot Lt. L. H. Sanderson mounted a carbine barrel in front of the windshield of his Curtiss JN-4 (an unarmed training craft) as an improvised bombsight that was lined up with the long axis of his plane, loaded a bomb in a canvas bag that was attached to the plane's belly, and launched a single-handed raid in support of a USMC unit that had been trapped by Haitian Cacos rebels. Sanderson's "Jenny" almost disintegrated when he pulled it into a steep climb after releasing his ordnance, but the bomb had hit its target precisely and the raids were repeated. During 1920 Sanderson familiarized aviators of USMC units at the Atlantic coast with the dive bombing technique[1]. Dive bombing was also used during the United States occupation of Nicaragua.
As planes grew in strength and load capability, the technique became more valuable. By the early 1930s, the technique was clearly favored in tactical doctrine, notably against targets that would otherwise be too small to hit with level bombers. While the United States Army Air Corps concentrated on mass attacks by very large bombers, the Navy ordered the first custom dive bomber aircraft, the Curtiss F8C Hell-Diver biplane (not to be confused with the SB2C Helldiver).
Generally, dive bombing was a technique preferred by naval air forces. Their aircraft often had to operate from small airfields or ships, which limited their size. They, in turn, had to attack small, often moving targets, such as ships. The combination of small bombload and need for accuracy made dive bombing techniques more attractive than other alternatives.
World War II
The only major force not to deploy a dedicated dive bomber were the inventors of the tactic, the British. The Royal Navy attempted to introduce their own on several occasions, but were never able to do so due to various reasons, not the least of which was political interference by the RAF. They only produced hybrid aircraft: the Blackburn Skua, a dive bomber/fighter that was used for a short time and in small numbers, and the Fairey Barracuda, a dive bomber/torpedo bomber.
European theater
In the early 1930s, Ernst Udet visited the U.S. and was able to purchase four F8Cs and ship them to Germany, where they caused a minor revolution. The dive bombing technique would allow a much smaller Luftwaffe to operate effectively in the tactical role. Soon they had sent out contracts for their own dive bomber designs, resulting in the gull-winged Junkers Ju 87 Stuka (a contraction of Sturzkampfflugzeug, literally "dive-combat-air-plane").
For its day, the Stuka was the most advanced dive bomber in the world. Using it as "aerial artillery" solved a major problem in the concept of Blitzkrieg—how to attack dug-in defensive positions. Normally this would require slow-moving artillery to be used, making the fast moving armored forces wait for it to catch up.
This was proven to great effect during the invasion of Poland and the Low Countries. In one particular example, the British Expeditionary Force set up strong defensive positions on the west bank of the Oise River just in front of the rapidly advancing German armor. Attacks by Stukas quickly broke the defense, and combat engineers were able to force a crossing long before the artillery arrived. Another important example was the massive aerial attacks in 13 May 1940 against strong French defense positions at Sedan in the Battle of France, which allowed the German forces a fast and (for the Allies) unexpected breakthrough through the French lines, eventually leading to the German advance to the Channel and the cutting off of large parts of the Allied army.
Despite its success in the French campaign, the Stuka soon showed its weaknesses in the Battle of Britain where great numbers of Stukas were lost due to its inappropriate use as a tactical bomber.
The Ju-87 Stuka was the only widely used dedicated tactical dive bomber to be used against both naval and land targets, particularly in the anti-armor role in case of the land use. Stukas also had 20mm cannon mounted on the wheel spats for use against tanks as well as their bombload. However, with the loss of air superiority they became vulnerable to the Red Army Air Force fighters and beginning from 1943 begun conversion to the more conventional cannon attack tactics.
Pacific theater
The Japanese also spent considerable effort on dive bombers, for the same reason as the U.S. Navy—to allow it to strike ships. They started the war with one of the best designs, the Japanese Navy-flown Aichi D3A Val, but this design also quickly became outdated, partly as it had fixed main landing gear, just as the Stuka did. They later introduced the much better Yokosuka D4Y Suisei, but at a time when their industry was already unable to supply them in any numbers. In contrast, the U.S. fielded the Douglas SBD Dauntless which was similar to the D3A in performance, but later replaced it with the faster, more complex Curtiss SB2C Helldiver. Both were provided in large numbers.
The most famous example of successful naval dive-bombing attacks took place in the Battle of Midway in June 1942 when American Dauntlesses scored fatal hits on three separate first-line Japanese aircraft carriers within a six minute timespan.
Decline
After the war, the dive bomber class quickly disappeared. Anti-aircraft warfare had improved as had the speed and effectiveness of fighter aircraft against the vulnerable, slow-flying dive bombers. At the same time the quality of various computing bombsights allowed for much better accuracy from smaller dive angles, and the sights could be fitted to almost any plane, especially fighter aircraft, much improving the effectiveness of ground-attack aircraft. Although the aircraft could still "dive" on their targets to some degree, they were no longer optimized for steep diving attacks at the expense of other capabilities as the dive bombers of old. As these same aircraft were capable of many other missions as well, they were no longer considered to be dive bombers.
Today, smart bombs are used for precision bombing. Bombs can be dropped many miles from the target at high altitudes, placing the aircraft at little risk. The bomb then guides itself onto the target through a number of means. These include laser designation, onboard GPS, radar, infrared, television guidance, and inertial wind-correction. Bombsights continue to supply several "toss bombing" modes, a sort of reverse dive bombing where an aircraft releases its bomb while steeply pulling up from low level. Shallow, 45° or less dive bombing attacks are still used to deliver unguided, or gravity, bombs when they are employed.
References
- ↑ Nowarra Heinz J: Gezielter Sturz. Die Geschichte der Sturzkampfbomber aus aller Welt. p. 8. Motorbuch Verlag Stuttgart 1982. ISBN 3-87943-844-7
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