Untitled Document
Untitled Document

jp bombers

Japanese naval bombers and torpedo planes

The Empire of the Rising Sun entered war against the great world powers in the belief that victory was ensured by virtue of its strong navy and an aviation which could boast state-of-the-art strike aircraft, excellent fighter planes, and military pilots who had accumulated ten years of experience fighting in China and Indochina. The Japanese started the war for a number of reasons: raw materials in Southeast Asia that the rapidly growing Japanese industry so desperately required; wounded pride in the wake of public humiliation by the Americans, who had initiated a political and economic blockade against Japan; and, not least, Japans certainty in a swift victory in a limited war against the United States and Britain. Up till the start of World War II, Japan had never lost a war, and its recent successes in localized wars, first against China in 1894, then against Russia in 1904-1905 and Manchuria in 1931, seemed to convince the Japanese leaders that it was possible to make a quick and decisive strike against a great power and then dictate the conditions of a peace treaty.

Led by the Minister of War and leader of the Nationalistic War Party General Tojo (Prime Minister and Foreign Minister from October 1941), the proponents of war had been planning a blitz in Malaya, Burma, the Dutch East Indies, New Guinea and the Bismarck Archipelago. To neutralize American and British bases in the area it was necessary to occupy the Philippines, Guam, Wake and Singapore. Admiral Yamamoto Isoroku, Commander in Chief of the Combined Imperial Fleet, opposed the war, understanding that in a protracted military campaign against the United States, Japan was fated to lose since its economy was not nearly as powerful as that of the US, and it would not be able to replace lost ships and aircraft as quickly as the Americans could. And, what is more important, it would not be able to replace the losses of its experienced military pilots and sailors. But adhering to what he felt was his duty, Yamamoto proposed the only solution which could at least postpone a military catastrophe if not avert it: to destroy the enemy fleet at its home base. Just as the Russian Pacific Fleet had been attacked and destroyed at Port Arthur in 1904, so the American Pacific fleet was to be destroyed at Pearl Harbor on December 7, 1941.

D3A1 is taking off from an aircraft carrier with a 250-kg bomb.
B5N2s from Akagi are carrying their 800-kg bombs to Pearl Harbor.

This mission was to be accomplished by 135 D3A1 dive bombers, 144 B5N2 torpedo bombers and a number of escort A6M2 Zero fighter planes from six heavy aircraft carriers (the Akagi, Kaga, Soryu, Hiryu, Zuikaku and Shokaku) of a naval strike force under Vice-Admiral Nagumo Tuity. At 6:15 on that memorable day at a distance of 275 miles from the target, the first wave of attackers rose into the air: 51 D3A1s carrying 250-kg anti-armor high-explosive bombs, 49 B5N2s carrying 800-kg anti-armor bombs (406-mm major-caliber shells with stabilizer fins attached), and 40 B5N2 torpedo planes accompanied by 43 Zero fighters. The torpedoes were fitted with plywood stabilizers so that they could be used in the shallow waters of the harbor. 45 minutes later the second wave took off: 80 D3A1s and 54 B5N2s carrying three 250-kg bombs each and escorted by 36 Zeroes. When the first wave attacked American ships in the harbor, the Japanese encountered almost no resistance. The D3A1 dive-bombers contributed most to the success of this attack (torpedo planes scored 30% of hits and B5N2 conventional bombers 27%). D3A1 bombers in the second wave continued to pound the ships while the B5N2 bombers attacked the air bases with the help of the fighters, which were machine-gunning American aircraft on the ground.

B5N2 bombers from Zuikaku in the sky over Hikam Field air base, Oahu island.
A wave of strike Aichi D3A1 dive bombers taking off

The concentrated attacks of the 353 Japanese aircraft were a complete success: all 8 battleships and a number of other ships in the harbor were sunk or severely damaged; out of 390 American planes stationed on the island only 43 survived while the Japanese lost only 29 of their aircraft - 15 dive-bombers, 5 torpedo bombers and 9 fighters - and only 7 of these were shot down by American fighters. However American aircraft carriers were not destroyed (they were out in the ocean), and because of Nagumo's reluctance to send the third wave of the attackers out of fear for the safety of his ships, American military infrastructure (docks, repair shops, fuel depots, airfields) remained largely intact, a circumstance that allowed the American fleet to recover quickly and strike back against Japanese warships and even against Japanese homeland islands within a mere four months.

The attack on Pearl Harbor became the most glamorous success for the Aichi D3A1 dive bomber officially named Type 99 Naval Carrier-based bomber Model 11, allied code name Val. In 1940-1941 it successfully operated from land bases in China and Indochina, and until 1943 it remained the only carrier-based dive bomber in the Japanese fleet. In March and April 1942 Vals in just two attacks sunk the British cruisers Cornwell and Dorsetshire (80 attackers, attack lasting 19 minutes, 87% of hits) as well as the aircraft carrier Hermes and the destroyer Vampire (attack lasting 15 minutes, 82% of hits). Vals subsequently also participated in the air attacks that culminated in the sinking of American aircraft carriers Lexington (May 8, 1942, Battle of the Coral Sea), Yorktown (June 4, Battle of Midway) and Hornet (October 26, Battle of Santa Cruz Island; in this battle Japanese dive bombers also damaged the Enterprise - the only remaining American heavy aircraft carrier, as well as the battleship South Dakota and two cruisers).

D3A1 profile and instrument panel

The D3A prototype of the first Japanese carrier-based dive bomber took to the air in January 1938. A low-wing monoplane of simple and robust overall design, it featured elliptical cross-section wings (similar to the German He-70), non-retractable landing gear in fairings and latticed air-brake flaps (similar to the famous German Ju-87 Stuka). During the next year its lateral control issues were resolved and a new Mitsubishi Kensei-43 engine rated at1000 ph installed. As a result, the aircraft now had the same handling characteristics and weapons (2 small-caliber machine guns under the cowling and an additional turret-mounted machine gun in Gunner-radioman position) as naval fighter planes. The wings folded upwards so that the plane would fit into an aircraft carrier lift. Standard bomb load was a 250-kg bomb carried on a turning frame, which made it possible to drop it in a steep dive at 450 km/hr, together with a couple of 60-kg bombs carried on the wings. From December 1939 until August 1942, a total of 470 D3A1s were manufactured. For the most part these aircraft were equipped with a 1070 hp Mitsubishi Kensei-44 engine.

D3A2 with a 250-kg bomb.
B5N2s from Shokaku returning after attacking Pearl Harbor

In May and June 1942, when Vals suffered heavily from American F4F Wildcats and anti-aircraft artillery, it became clear that the D3A1 aircraft no longer met the current requirements for speed and survivability. However, since the dive bomber Yokosuka D4Y chosen to replace it was still being flight tested, the Japanese started production of a modified Type 99 Naval Carrier-Based Bomber Model 22 (Aichi D3A2), equipped with a 1300 hp Mitsubishi Kensei-54 engine and featuring improved aerodynamics and larger fuel tanks. However, the speed increase was only marginal, and the lack of self-sealing capability meant that the fuel caught fire from only a few bullet hits. On April 7, 1943 in a fight against Japanese D3A2s making their debut attack against positions of American marines on the island of Guadalcanal, Junior Lieutenant James Swett, fighting his first air battle, shot down either seven or eight Vals, setting a new American record for the number of enemy aircraft shot down in a single fight. According to Swett's account, only the eighth Japanese aircraft did not flare up from a short burst of fire from his machine guns, which gave the Japanese gunner time to shoot down his F4F-4. This incident clearly demonstrated that the D3A2 was no longer fit for combat, and from the end of 1943 the majority of the 1016 D3A2 aircraft that had been made were transferred to land bases or light aircraft carriers whose decks were too short for the newer D4Y. It was only at the concluding stages of the war that some of these planes were used again, this time in kamikaze attacks.

B5N1 cockpit.
B5N2 profiles

Val's sister aircraft, the Nakajima B5N2 torpedo-bomber, shared initial successes at Pearl Harbor, in the Indian Ocean, at Coral Sea, and at Midway Island. It was B5N2 torpedo bombers that finished off the American aircraft carriers Lexington, Yorktown and Hornet already damaged by Japanese dive bombers. In December 1941 the B5N2 was undoubtedly the best carrier-based torpedo bomber in the world, in every way superior to the American Douglas TBD-1 Devastator, to say nothing of the British Fairey Swordfish and Fairey Albacore bombers. By the beginning of the war, the B5N or Kate, as the Americans preferred to call it, had been in the Navy inventory for four years with all production and operational problems long since resolved. The aircraft was even upgraded once after the start of its production.

B5N2 fighting for Solomon islands, autumn 1942.
B5N2 being tested in the United States after the war. Note radar antennas along the leading edge and at the tail.