How A Simple Design Flaw Destroyed an Aircraft Carrier during WW-II

Time in History: The Battle of the Philippine Sea, World War II.

TAIHO (IJN TAIHO), by meaning "Grand Phoenix" was an aircraft carrier of The Imperial Japanese Navy (IJN) with an armored flight deck deployed during World War II. The IJN had high expectations for their so-called 'Magnificent Phoenix'. But as Taiho launched her planes on the morning of June 19, 1944, one of the six torpedoes from the U.S. Navy submarine USS Albacore struck the ship which after seven hours blew up and sank!

Taiho took 1,650 sailors and dozens of aircraft as she went down. Five hundred sailors survived. It was an irrecoverable blow to Japan’s fleet at this stage of the war and occurred during her first combat mission, only three months after her commissioning. - Taiho blew up because of a major design flaw.

As a matter of engineering, Taiho shouldn’t have gone down like this, as the carrier was designed to be more heavily armored and protected than her predecessors.

Taiho was unusual for a Japanese carrier when she first launched on April 7, 1943, as she was the first of the Imperial Japanese Navy’s flattops to feature an armored flight deck. Previous decks were made of wooden planks, which saved weight and made for a more-stable design. The downside, obviously, was that bombs could more easily penetrate wooden decks.

To the IJN’s horror during the 1942 Battle of Midway, a 1,000-pound bomb dropped by a U.S. Navy SBD Dauntless dive bomber penetrated the deck of the carrier Kaga — one of several bombs which fatally ignited fuel and gas inside the ship. Kaga was one of four Japanese carriers destroyed during the battle.

Battle of Midway was not the impetus for the heavily-armored, 855-foot-long and 37,000-ton Taiho. The IJN first established the carrier’s requirements in 1939, three years before the battle, and put down her hull in 1941, although this lengthy period may have been because of changing requirements as Japan monitored the United Kingdom’s wartime carrier operations.

It’s worth noting that the Royal Navy preferred armored-deck carriers given the need to operate in the Mediterranean, where ships were vulnerable to swarms of attack planes operating from nearby land bases, unlike the Pacific where the distances were much more far flung — or so the Japanese and American navies believed at the time.

Either way, Taiho would be more advanced — and beautiful — than any Japanese carrier to that point, and in theory capable with her steel flight deck of withstanding greater punishment while launching up to 84 aircraft. However, by 1944 the IJN trimmed down her compliment to 77 planes — 27 fighters, 27 dive bombers, 16 torpedo bombers and three reconnaissance planes.

Taiho was also heavy, with a higher proportion of her weight to armor than every Japanese carrier except the Shinano, a converted battleship — originally a Yamato-class super-battleship — sunk by U.S. torpedoes in November 1944. Taiho also had the first island bridge as opposed to a mere conning tower.

Design Flaws

In a major design flaw, Taiho's aviation fuel storage facilities were not fully encompassed by the main belt and torpedo protection system.

Taiho was so heavy, she sat low in the water, and her bottom most hangar deck was almost at the waterline.

The lift wells, where aircraft traveled to and from the hangar deck to the flight deck on elevators, actually sat below the waterline at their lowest point.

The torpedo that hit Taiho exploded abreast the forward lift, immediately alongside the forward aviation fuel storage containers. The deck of the elevator pit – directly above the forward gasoline tank – was ruptured. The shock of the explosion had split a joint in the armour above the forward avgas tank. The AvGas tanks themselves were also ruptured, spilling avgas into the surrounding voids. A small fire was contained by inrushing seawater as Taiho did not immediately reduce her speed of 27 knots in a bid to escape the submarine threat. 

The forward lift well quickly filled with a volatile mix of seawater, fuel oil and aviation fuel. That mixture emitted vapors, which then spread throughout the carrier after the damage control team opened all of Taiho‘s hatches and flipped on the ventilation systems. It was a terrible mistake. It allowed the heavy fuel-air mixture to spread throughout the ship.

Six and a half hours after being torpedoed, the inevitable spark happened and, Taiho — like a bomb — exploded!.

Source: warisboring | Credits: NationalInterest, ArmouredCarriers

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