Japanese Missile and Guided Munitions Projects
The aim of tactical missiles, specifically guided munitions, is to increase accuracy. It takes a considerable amount of conventional bombs or torpedoes to strike a ship and inflict enough damage to cripple or sink the vessel. Likewise, anti-aircraft cannons have to put a significant amount of shells into the air to bring down a single plane. Another benefit of using missiles is the measure of protection afforded to the user by way of range. A fighter combating bombers has to attack at such a range that his weapons are effective and therefore within range of the defensive armament of the target. The fighter also has to contend with escorting fighters before he even has a chance to press home an attack on the bomber. The same is true of attacking ships. To improve accuracy, a torpedo or dive – bomber has to be close enough to the ship to ensure a hit. Of course, this also puts the aircraft in the uncomfortable position of being within range of the many anti-aircraft cannons and machine guns carried by the ship, as well as attack by fighters providing cover for the vessel. Guided munitions eliminate some or all of these problems.
Without doubt, the undisputed leader in World War 2 missile development was Germany. Missiles such as the Fieseler Fi 103 (the V-l), EMW A4 (better known as the V-2), Ruhrstahl-Kramer X-l Fritz X and the Hen – schel Hs 293A were used operationally with a measure of success. This was just the tip of the iceberg. Many more designs came close to seeing service or were in the latter stages of testing at the war’s end. Such weapons included the EMW C2 Wasserfall, Rhein – metall-Borsig Rheintochter, Henschel Hs 117 Schmetterling, Ruhrsahl-Kramer X-4 and many more. The US was not lacking in missile and guided munition technology of its own. Operational weapons included the ASM-N-2 Bat, GB-l/GB-4 and the VB-1 AZON (AZimuth ONly). Projects included ‘Little Joe’ (intended as a ship-borne missile to combat kamikazes), the McDonnell LBD-1 Gargoyle and the JB series of missiles. Other Allies, such as the British and the Russians, would not spend nearly as much resources on the subject as did the Germans and Americans. The British would squander the potential of the Brakemine surface-to-air missile and stall the Fairey Stooge while the Russians would only test and reject the promising Korolev Type 212A (built in 1937), waiting until the close of World War 2 to revive its missile development work. In some cases the Soviets used the fruits of German labour as their basis, for example, developing the R-l/SS-1 Scunner from the V-2 missile and the Type lOCh from the V-l flying bomb.
An example of the greater accuracy of missiles and guided munitions can be seen in the 27 December 27 1944 mission flown by the US to attack the Pyinmana rail bridge in Burma. Nine VB-1 AZON guided bombs were enough to destroy a bridge that for two years previously had failed to be hit by thousands of conventional bombs. Likewise, the Germans were able to successfully attack shipping targets using the Henschel Hs293A and Fritz-X using less aircraft and with a higher hit and kill ratio than if the same attacks had been made using conventional bombs and torpedoes.
With these benefits in mind, it is not surprising that Japan also devoted considerable effort to producing such weapons themselves (while Japan did receive some German missile technology, it is unknown how much of it found its way into the IJA and UN missile programs). Both the IJA and UN funded the development of missiles as a means to both combat the bombers that tormented the homeland and to attack Allied shipping.