Bombs were the primary strike weapon of aircraft. They were usually iron containers of high explosive with an aerodynamic form to reduce drag and improve accuracy. However, there was increasing variety in the kinds of bombs carried by strike aircraft as the war progressed.
Light bombers
typically carried a single bomb weighing up to half a ton, though some
could carry a number of smaller bombs. Medium and heavy bombers could carry
several large or many small bombs in their bomb bays, with a total
weight of up to two tons for a medium bomber and as much as 20 tons for
the heaviest bombers flying at short range and low altitude. By the end
of the war, some fighter aircraft
were also capable
of carrying up to a ton of bombs.
General-purpose or demolition bombs had thin metal
walls, a large explosive charge, and a contact fuse that detonated the
bomb as soon as it hit
something. Such weapons were effective against soft targets, which
included unarmored ships,
infantry in the open, and most
civilian
installations.
Armor-piercing bombs had thick steel cases, a relatively small explosive charge, and a delayed fuse that did not detonate the explosive until a few tenths of a second after the bomb hit a solid surface. This gave time for the bomb to penetrate before detonating. AP bombs were useful against armored ships, bunkers, concrete runways, and other hard targets.
Incendiary bombs were filled with a flammable material in place of explosive. Early incendiaries were filled with oil, gasoline, magnesium, or thermite, but it was discovered during the Battle of Britain that such weapons were fairly easy to deal with in isolation if firefighters were close at hand. Incendiaries were therefore typically dropped together with demolition bombs, which smashed structures into kindling while suppressing firefighting efforts. Both sides indulged in the practice of dropping demolition bombs into areas already on fire from incendiary attack, which produced heavy casualties among firefighters. In many cases, this was done simply because the fires were convenient aiming points during night bombing missions.
The Americans discovered that a mixture of napthalenic and palmitic acids (fatty acids similar to those present in soap) could be added to gasoline to turn it into a gel that adhered to whatever it hit and burned longer than plain gasoline. The resulting incendiary mixture, napalm, was highly effective and remained in widespread use until late in the 20th century, when precision bombing technology and increased concern for collateral damage cast incendiaries into disfavor.
Practically all the bombs used in the Second World War were what are now called gravity bombs. They had no active guidance mechanism, and bombardiers were trained to steer the aircraft towards the target and release the bomb at just the right moment so that its free fall trajectory took it into the target. This was not a very accurate procedure, even with sophisticated computing bomb sights such as the American Norden bomb sight, which both steered the aircraft towards the target and computed the exact moment of release. Dive bombing was developed in part to improve the accuracy of bombing. Because the bomb was released on a trajectory much closer to that of the aircraft itself, range error (error along the flight path) was greatly reduced.
The Germans experimented with radio-guided bombs with some success. The Japanese Kamikazes were, in some sense, guided bombs. The only non-gravity bombs used extensively by the Allies in the Pacific were parafrag bombs, which proved highly effective against aircraft revetments.
Another specialized
form of antishipping attack was skip bombing. This was conducted at low
level by aircraft equipped with multiple forward-firing machine guns.
The aircraft would saturate the target with machine gun fire as it
approached to suppress antiaircraft
fire, then drop its bombs, which were equipped with delayed fuses. When
the bombs were dropped at the correct speed and altitude, they would
skip along the surface of the water and hit the target ship at the
waterline, then sink below the surface to explode seconds later with
the same devastating effect as a torpedo
or mine. This tactic was first
employed at the Battle of the Bismarck
Sea, where the Japanese assumed that aircraft approaching at low
level were going to drop torpedoes. The ships turned into the attack,
which left them highly vulnerable to skip bombing.
Bombs were not particularly effective against heavily armored ships, because these moving targets had to be attacked from relatively low altitude, where the bombs did not develop sufficient velocity to penetrate thick deck armor. As a result, aerial torpedoes were developed. Naval architects responded by developing antitorpedo systems for warships. These theoretically could allow a battleship to continue operating after one or more torpedo hits, but in practice the systems did not seem to work well. North Carolina had its forward turret disabled off Guadalcanal by a torpedo hit it should have shrugged off, and Yamato was never quite the same after a torpedo hit at the forward edge of its armor belt. The catch was that torpedo planes had to make a low, slow glide towards the target to ensure a clean drop, which left them vulnerable to fighters and antiaircraft fire.
Almost all combat aircraft carried machine guns or light cannon, which were the principal weapons of fighters. Fighter aircraft sometimes attacked soft ground targets with these weapons (strafing), and, as the war progressed, medium bombers were often equipped with impressive numbers of machine guns to turn them into potent strafers. Experiments with heavier cannon (up to 3" or 75mm) in medium bombers were less successful because of the heavy recoil and low rate of fire.
Unguided rockets proved to be
an effective alternative to heavy
cannon, and, because they had no recoil, they could be mounted on light
bombers and fighters. A small aircraft could carry six 5" rockets under
its wings, giving it firepower equivalent to a destroyer broadside.
These rockets were quite inaccurate, but when several were fired at
once, they were able to saturated the target area. In principle, the
rockets could be equipped with shaped-charge
warheads for use against
hard targets, but this apparently was not attempted until after the war.
References
The Pacific War Online Encyclopedia (c) 2007-2008 by Kent G. Budge. Index