I-400 Japanese SuperSub.

1946, ten months after the end of World War II, an explosion rocked the Pacific off the coast of Hawaii. The United States had just destroyed one of Japan's most advanced weapons systems. I was vigilant when I was able to look through the periscope. It was a rebound to believe me. Instead of a late attack on the defeated Japanese, the sinking of this top-secret submarine was a preventative measure for the impending Cold War. a brazen decision by the Americans to keep the submarine out of the hands of the Soviets. The plan worked and the gun remained untouched in the background. of the ocean for six decades until a team of underwater explorers from the University of Hawaii located its remains.

The discovery prompted a new examination of the forgotten super submarine. You could basically strike anywhere in the world, this was a global weapons system, a system that defied conventional design and combined the tactical advantages of sea and sky as the United States raced to build nuclear bombs and Germany experimented with powerful rockets. , Japan hoped that its secret weapon would change the course of the war 1941 six months before the attack on Pearl Harbor the imperial Japanese navy dominated the Pacific the Japanese attack in December 1941 because they see it as a window of opportunity Japan temporarily has the largest navy powerful of the Pacific, let's take advantage of the fact that the Japanese plan was simply to hit hard and unbalance the Americans.

They believed that this would force an American withdrawal, leaving Japan as the only superpower in the region. The architect of Japan's peaceful strategy was Admiral Harvard-educated Isuruku Yamamoto, Yamamoto had mixed feelings. Regarding the campaign, in terms of his own personal views, he was very much against a war with the United States that he considered essentially unwinnable, but at the same time, as commander-in-chief of the combined fleet, he felt that he had to devise some kind of strategy to make a Japanese war in the United States a viable proposition, but no one realizes more than he does how badly everything can go right, and his gambler's instinct tells him that the odds will have to be very high to win. he wants some ability to, say, bring the war to America's national waters, he really shocked the American population by some bold gesture.

His gesture, the bombing of Pearl Harbor, the attack sank five battleships, three destroyers and several small ships, but the Japanese did not time their mission well because on December 7th. the three American aircraft carriers were at sea and out of danger Japan also misjudged the United States' willingness to counterattack one day after Pearl Harbor the United States declared war on Japan The fight was on both nations were fighting for an advantage the United States put in The operation of its industry and its manpower relied on it aimed to overwhelm the Japanese with superior numbers, but for Japan the challenge was different knowing that it would soon be surpassed in personnel and weapons.

Admiral Yamamoto needed more surgical strikes in the months after Pearl Harbor as he strategized how to bring the war across the Pacific to the United States. From 5,400 miles away, he observed the success of the German submarines. The deadly Nazi submarines that attacked ships in the Atlantic from February to May 1942. The submarines sank 348 ships, preventing millions of tons of American supplies from reaching Europe. The ships were torpedoed within sight of New York City and Boston. If German U-boats could terrorize the East Coast of the US, could Japanese U-boats do the same in the West to find out?

Yamamoto ordered a series of test missions. He sent a submarine to fire projectiles at a refinery in California. It did not cause much damage but it did raise fears of a Japanese invasion throughout the Pacific. The search is underway for the submarine that brought the water to American soil in high altitude. sea ​​the marauder opened against oil refineries near santa barbara beach a A piece of projectile manufactured in Tokyo caused little damage, but it was the first fired in this war against our own shores. The next day, coastal artillery brigades fired on what they thought were enemy aircraft.

The cannons fired into the shadows. No sighting was confirmed, but the panicked American reaction meant to Yamamoto that his instincts were correct. If he could attack the Americans at home, he could make them think twice about an all-out war with Japan to instill such fear that he would need more firepower than a few small submarines could offer. an aircraft carrier and a fleet of bombers would be ideal, but with the United States on high alert no aircraft carrier could sneak up on the west coast. Yamamoto needed something unexpected, his solution was a super weapon that combined the firepower of an aircraft carrier with the stealth of a submarine.

If it could be built, his machine would rewrite the rules of war. The concept of putting an aircraft on a submarine was not new, but conventional submarines of the time were only capable of carrying a small aircraft for reconnaissance and targeting. yamamoto wanted sublaunched aircraft. that could be used as an offensive weapon, not just a scout, he ordered another test mission, this time a small submarine-launched plane dropped incendiary bombs on Oregon in hopes of starting a wildfire that the fire couldn't detect, but just as that the Santa Barbara mission confirmed that a submarine could breach American coastal defenses and attack unsuspecting civilian populations in order to reach its destination and launch an air attack undiscovered, undetected, would give the Japanese an advantage that no other navy or air force had during the war, Yamamoto ordered his engineers.

To design a fleet of submarine aircraft carriers capable of sailing undetected across the Pacific launching squadrons of high-tech bombers to attack West Coast cities and then disappear without a trace, the admiral even hoped his submarines could reach the coast this one I hoped to terrify. United States with attacks on New York City and possibly even Washington DC, so here you have all the potential for attacks in the coastal area where of course a large proportion of the US population is constant. That's right, New York City, for example, a dense concentration of population. and if you're attacking with a few dozen aircraft as in the original plans, perhaps you could go for important communications and indeed iconic targets.

The admiral named the submarine i-400 and declared it top secret, but it remained to be determined whether Japanese engineers could realize Yamamoto's ambitious vision. His window for success was small. In America, the United States had accelerated its own work. into a super weapon that could change the course of the war. The effort was codenamed Project Manhattan. It was headed by Robert Oppenheimer, professor of physics at UC. Berkeley. Oppenheimer brought together the country's best engineers and physicists, challenging them to overcome enormous complexities. techniques of splitting the atom and creating an atomic bomb. The Americans worked at a breakneck pace fearing that the Germans and Japanese were advancing. its own nuclear bombs, meanwhile, the Japanese

supersub

marine ran into obstacles in Tokyo, naval architects struggled to find a design that could meet all of Yamamoto's needs.

You're going to need a very large and impressive submarine. In fact, you're going to have to do it. In fact, as far as submarine design was concerned, the standard submarine at the time was cigar-shaped with a cylindrical hull up to 300 feet long, but no one knew whether that conventional design would be able to support heavy support and three aircraft. Of attack. You're going to need a very large hangar that starts there, goes through the superstructure and ends there. What are you doing with the navigation area here? You have to move it to the side of the ship and also up. that is much bigger, they contain very large aircraft that are not long enough so you are flying much longer off deck and therefore need a much larger submarine if this is a transformation in the whole concept of the submarine when we assemble these pieces.

We will end up with a scale submarine model that is almost the same as a full-size submarine, which is 10 times longer than it is wide. Dr. Harold Vincent is an ocean engineer at the University of Rhode Island and has questions about the practicality of the The design of this tube represents the watertight hanger, the three planes, and the bombs the plane carried, so we'll seal the end of the hanger here , so let's see what happens when we place it. Okay, oh boy, that tilts with that on top. The lid size is larger on the sinks, so they had to come up with some other method to be able to fit a heavy hangar with all those planes high above the water, adding the hangar to a conventional submarine was clearly not the answer.

The next seemingly obvious approach would have been to increase the size of the center cylinder to lower the center of gravity. Well, a single large cylinder would be extremely heavy, it would have to have very thick walls to withstand the seat pressure up to 300 or 330 feet to keep this part above the surface of the submarine totally stable, it was simply impossible to have this traditional ribbon design. submarine at the other end and then we can take it. The Japanese came up with an innovative alternative, so now we'll try it. This twin-bore design is now quite stable, so it now writes itself instead of just leaning over a two-cylinder hull, it gave the giant submarine the width needed to support the extra weight, so you have these two cylinders that They are wider and stronger than the two cylinders. a center ship of course lent to greater stability, we can absolutely see that it is much flatter and more stable clearly with the biggest design problem solved.

Construction plans were drawn up for the new monster submarine, the i-400 went into production in January 1943. Yamamoto needed it fast the Japanese were losing ground in the Pacific the previous June Yamamoto had ordered a surprise attack on the American fleet in the Midway Island in hopes of sinking the aircraft carriers it had lost at Pearl Harbor, but the Americans had cracked the Japanese naval code and saw the attack coming and were able to lay an ambush of their own in three days of fierce fighting. American bombers sank four Yamamoto aircraft carriers. It was a devastating defeat for Japan.

Its aircraft carrier fleet was decimated and thousands of soldiers were killed. The I-400s were now. Even more vital, but with a severe shortage of steel and labor in Japan, Yamamoto was only able to get 18 of the giant submarines into operation and work on the first i-400 was underway. The Japanese navy began to develop the secret bomber that would be transported in the watertight hangar on the deck of the submarine, the plane was called seyran, as its name suggests, the plane would suddenly appear as a fog carried by a submarine that would surface once to approach a target by moving like a ninja, which is how sayron came to be called. the only living member of the elite saeran squadron in an annual shinto ceremony honors his lost comrades still remembers the thrill of being part of the top secret project i think not many people knew about ceyron, even in the

japanese

navy many repeated tests and experiments were done in Top secret With a top speed of more than 200 miles per hour and the ability to carry a 1,700-pound bomb, the newly designed Saeran would be an intimidating warplane, but Japanese aircraft designers first had to solve some technical puzzles, though the i-400 was wider than any other submarine of its time, the aircraft hangar was only 11 feet in diameter here is the i-400 hangar that this aircraft must fit into and here we have a front view on the same screen uh you know the fuselage will fit in there but uh gosh you have the wings you have the tailplanes and it doesn't exactly fit to accommodate the tight spaces the

japanese

designed wings are very similar to the grumman hellcat.

Powerful carrier-based fighter in US arsenal to minimize Hellcat profile for below-deck storage. The wings rotated 90 degrees and folded back against the fuselage. The Seyran went even further. It had a tail fin that folded to reduce height when we do. That all fits together very, very well, but there was still one major problem that Japanese designers had to solve before the ceyrons could be released. They had to warm up their engines, a process that took up to 20 minutes, starting the engines in the hangar with the boat. submerged would have exposed the crew to deadly carbon monoxide fumes, butWarming up the engines on the surface meant exposing the submarine to radar and air attack once again.

Engineers needed an innovative solution at a small airport in Connecticut. Former Air Force gunner Craig Mcburney knows all about it. the problems of warming up an engine before takeoff this is his pet project a rare 28 cylinder corsair engine it is larger than the ceyron engine but shares similar characteristics well we have a clear propeller as is the case with many WWII era aircraft World War that starts the engine The cold is a risky and complicated matter. Now is when we start using bad words. The problem is the viscosity of the cold engine oil. You can see how thick the oil is because it hasn't been heated and you know how critical tolerances are. inside the aircraft engine, how tight they are and how small the passages are, it would really make an exciting difference trying to pump that heavy thick oil through an aircraft engine, heating the oil makes a noticeable difference as as that is cold we heat it to approximately 60 or 70 degrees centigrade, which is 140 or 160 degrees fahrenheit, it is the same oil that was just heated with the preheater almost wow, look at that water poured, what a difference, yes, and you can imagine how important What would it be like to have a hot engine? much faster, especially in a combat situation, Mcburney uses an external tank to preheat the oil inside this container.

We have the main engine oil tank here to feed the engine oil. Then we have also installed our own pre-oil tank with a heater on. and with the preheater onIf we can raise the temperature a little bit, we can increase the temperature about 120 degrees, so we need to open this valve and we will open the engine oil tank valve and the hot oil can be pumped out directly. in the cold engine, clear support, the results are easy to see, well, I tell you that it is an incredible temperature, it is almost at takeoff temperature, an amazing difference, can you imagine in a combat situation?

Mcburney's heating method was the same one that Japanese engineers used for seirans. In reality, it is borrowed from a German design with the engine oil preheated, the plane could roll out of the hangar onto the launch ramp, the engine started, the wings, tail and horizontal stabilizers were deployed and locked in position, the floats were set and the Seyron was launched into the air. I would train very hard trying to shorten the time it takes to launch even by one second the first plane is launched the objective is to launch the three planes as fast as we can to get back on the seyrons the engineers designed a hydraulic crane to launch the planes from the sea and hoisted onto the deck with all design issues resolved, it looked like the Japanese would be the first to bring their super weapon to war, but then in April 1943, the i-400 program suffered the Japanese navy .

A devastating loss American code breakers discovered that Admiral Yamamoto was planning an inspection trip to the Solomon Islands. American fighters intercepted and shot down his plane, killing the man behind the attack on Pearl Harbor. It was such a crushing blow to the Japanese navy that it was a complete A month before Yamamoto's death was even announced to the navy, much less the Japanese public, without the backing of the powerful admiral, the i-400 program quickly went to the back burner. Japan's priority list, before the submarines were completed, the order was reduced from 18 to 9. another year and a half before the first of Yamamoto's i-400s reached sea in December 1944, the first i -400 was finally commissioned a few months later a second submarine, the i-401, was ready to sail.

The super submarine carried three dive bombing runs in a 65-foot-long hangar, an 85-foot ramp, and a catapult. steam launched the planes into action even in rough seas. Not only was the i-400 the longest submarine in the ocean at 400 feet, it was also the most heavily armed. On the aft deck was a giant 140-millimeter cannon, one of the largest ever mounted on a submarine, four anti-aircraft guns defended against air attack and the submarine also had eight torpedo tubes in the bow, the man appointed to lead the i- The 400 program was Tasunosuke Arizumi Izumi had been in charge of the submarine attack on Pearl Harbor the i-400 crews were chosen from among the elite of the navy and were treated very well the hallway was full of cans of food and other basic foodstuffs that you couldn't even look at the floor, I was never unhappy with the food, for example, even We had expensive food like Cow Town and lots of fancy things.

Morale among the crews was strong, but the Japanese high command was not so jubilant in the three years since the i-400. The project began, the situation in the Pacific had changed, the United States now dominated the region and the original mission of the submarines to bomb American cities and instill fear of a Japanese invasion was outdated, they simply did not have enough firepower and each submarine carried three planes. In each plane carrying only one bomb per flight they could cause little real damage in comparison, Nazi bombers dropped an average of 330 bombs per night for 57 nights during the Blitz of London and yet the British did not give up with a conventional bombing raid on American cities. out of the question the Japanese needed another mission for the i-400s, they considered all options as the Japanese were becoming frantic by any means to inflict more pain on the United States in an effort again to slow our advance or get us to negotiate. a part.

The Japanese considered using germs against American cities. This was discussed and the obvious means of transporting them would have been by submarine-launched aircraft from the I-400 from other submarines. In the spring of 1945, Vice Admiral Jisoburu Ozawa proposed a controversial top-secret plan. He suggested using the Saerans to launch biological weapons on the west coast of the US. Such an attack could kill thousands of people and create panic throughout the United States. Japan's biological weapons program was not new under the command of A military doctor named Shiro Ishii, a secret team had been experimenting on the Chinese since the 1930s, plague-infested fleas bred in his laboratory had been released into Chinese villages, infected prisoners with anthrax and cholera, and injected diseases. venereal to men and women.

Up to 200,000 Chinese died as a result of these horrific experiments, the Japanese military was working hard on this in Manchuria under quite dire circumstances and certainly the Japanese navy appears to have been interested in the use of anthrax in bombs and the more radical elements within the military o the navy would advocate for such a Well, I would say an insane plan. There was little doubt that biological weapons dropped on an American city could cause enormous casualties and therefore panic among the American population much more effectively than conventional bombs, but a month later cooler heads prevailed, General Yoshido Umezu of the imperial army. canceled the operation and declared that germ warfare against the United States would escalate to a war against all of humanity with a biological attack off the table the Japanese high command found a new mission for the i-400s an attack on a key strategic target the Panama Canal was absolutely crucial to the transfer of naval forces from the Atlantic into the Pacific Ocean, so the Japanese wanted to attack it, of course, and we understood that any logical military scenario would want to attack the Panama Canal if Japan could eliminate the canal that bring. stopping ship traffic and forcing the Allies to use the much longer route around Cape Horn.

Japanese military planners and intelligence experts work together to plot the attack. The plan was more or less like this: this flotilla of submarines would come, four submarines with ten planes. maintaining a proper distance after having traveled a long way across the Pacific, yes, eight thousand miles or so, yes, until they reach their launch point off Ecuador, approximately there, then they surface and launch their planes, six planes as fast as they can and so as to completely surprise the enemy they go in a completely different direction they fly through Colombia the three then turn sharply here yes and then suddenly and perhaps they dive to a low level they go down here towards the canal and hit it at its northern end at the locks here the mission would be extremely dangerous for the i-400 fleet before hitting the canal the submarines would have to navigate through waters swimming with Americans by the summer of 1945 essentially the pacific era an American lake and that meant it would be relatively difficult to get any type of vessel safely into the Panama Canal zone, but the Japanese had an ace up their sleeve, a secret technology that the designers of the i-400 had borrowed from the Germans, a technology that could help them evade the enemy. sonar Sonar works by bouncing sound waves off hard objects like ships, measuring the time it takes for the sound waves to travel to the target and back, the system can calculate its location, but the i-400s, like some German submarines, were equipped With a new A stealthy shell designed to absorb sound waves rather than reflect them, called an anechoic coating, it was made of rubber and asphalt tiles that cushioned the submarines' sonar fingerprints as they glided through the water.

These overlays performed remarkably well and their details are still very high. classified for the i-400 crossing the pacific undetected was only the first step their objectives the cotoon locks in the panama canal were heavily guarded by anti-aircraft guns the ceyrons could reach above the range of the gun but that would make reaching the targets were almost impossible those locks the walls were incredible reinforced concrete structures that at the base were between fifty and sixty feet thick at the top maybe eight ten twelve feet thick the doors themselves may be 90 feet wide they had six seven Eight feet thick steel but at thirteen thousand feet, it would look like just a hair from that kind of altitude.

The challenge of high-altitude bombing is easy to see when a B-29 equipped with a World War II bombing site drops a half-dozen water bombs on a stationary target in California. desert, not a single bomb hits the nearest lines more than 500 feet away for a target the light they tune is blocked anything less than almost a direct hit within a foot or two or three of the target would be a waste of energy given the relatively primitive bomb sites the Japanese were using, their chances of being able to hit a target like that were pretty slim and with only six planes carrying a bomb each, the Japanese knew there was no margin for error. , following Japanese military tradition, the decision was made to turn. the attack on a one way trip the pilots were ordered to become kamikazes at that time almost all Japanese air missions were flown as kamikaze one way missions and the plan was to do the same here, I know it is controversial in some The People are against it, but I think we had no choice at that time.

We knew we probably couldn't hit the target even with multiple bombs. The i-400 crews prepared for the Panama Canal mission, but the window of opportunity for the attack was rapidly closing. In the spring of 1945, the United States was already deciding on possible targets for the atomic bomb. Then the war reached Japanese soil when the Allied forces invaded the island of Okinawa. 82 days of brutal fighting left more than one hundred thousand Japanese soldiers dead and thousands of fighter planes and ships destroyed. Vice Admiral Ozawa realized that a raid on the Panama Canal would be too little, too late, and most American forces would already They were in the Pacific so Ozawa changed the mission of the i-400 once again the new target was Ulithi Atoll a staging area for The huge US fleet preparing to invade Japan was the likely base for the attacking units.

Okinawa and perhaps also those that were to be sent for the final confrontation on the continent. Supplies were probably sent from there as well. In the photo I saw several American planes. The aircraft carriers at the site headquarters ordered us to attack as many of them as possible three and a half years after the i-400s were conceived. The two giant submarines were finally ready to attack. They traveled separately with orders to meet Ulithi where they would join together. by two smaller submarines, once they reached their objective, six seirons would be launched in a kamikaze attack to deepen the surprise.

Commander Arizumi orderedThe crew disguised the bombers with American markings, a clear violation of international law. The pilots themselves opposed the planes being painted in American. colors felt it was dishonorable and were ready to die they knew they would not return what they did not know was that their mission once again had little time four days before the i-400 set sail America had successfully exploded the world's first atomic bomb A second bomb was already on its way to Japan to make matters worse Arizumi's mission was plagued with problems on the way to Ulithi One of the smaller submarines was discovered and sunk by an American warship All 140 crew members were later killed in an effort To avoid the enemy ships, Arizumi decided to change his route and they agreed on a meeting point, but the message never reached the other ships, they missed the meeting while the i-400 and i-401 rushed to regroup and renew the attack. radio, the American super weapon had opened the war on August 6, 1945, an American atomic bomb annihilated the city of Hiroshima, killing some 80,000 people.

On August 9, a second bomb decimated Nagasaki, forty thousand dead, and the city was left in ruins for six days. Japan later surrendered to the United States in his radio address to the nation, the emperor never mentioned defeat or surrender, but instead told his people that we have to endure the unbearable and suffer the insult for machinist Paul Whitmer . The double hull design was a particular surprise. Lo and behold, we get to the engine room and there is a door to the next door neighbor's room, what the hell is going on here? Take a look there. There's another set of engines there.

The port and starboard engine rooms we discovered there were two. hulls bolted together with two submarines side by side the Japanese crew remained on board but with six Americans now in command I had a 45 but you had a 45 and I had an extra magazine of bullets in my jacket pocket that's all I had to use it. I would have used it, oh it was, it was very tense, no one trusted anyone, we didn't know what to expect, we could have been outnumbered in the blink of an eye because they were so outnumbered and if they decided to dive into the ship we couldn't go out.

The Americans chained the hatches open to prevent the Japanese from submerging, but as time passed, tensions slowly decreased between the former enemies. They now had the common goal of bringing the submarines back to Tokyo safely. In the engine room, we had to learn to communicate with the Japanese. you know, they had to teach us and we had to teach them, we needed to know some of the words to describe a basic elementary school type communication engine and try to build a relationship and learn its symbols and its words to know what it's called. This is how both submarines returned to Tokyo where the prisoners were released to the Americans.

The next step was to bring the unusual ships home for further study in November 1945. They left Japan for Hawaii. They arrived at Pearl Harbor right after. On New Year's Day 1946, Navy engineers immediately began inspecting and recording every detail of the super submarine design, but by the spring of 1946 a new postwar reality had set in and the i-400s were back in business. to be shrouded in secrecy, this time it was the United States. The states hide them from the Soviet Union. Large aircraft carrying submarines intended for strategic attacks against their enemies are exactly the things the Russians don't want and now it is the cold war that is starting, yes at the beginning of the cold war they were worried that the Russians would demand to inspect the submarines The US Navy made a hasty decision on May 31, 1946, sinking the i-400 off the coast of Pearl Harbor.

Two days later, the i-401 joined it at the bottom of the sea, two powerful weapons that never made it to battle. They never had the chance to truly prove their worth if the question is: Did Operation I-400 decisively change the course of World War II? um, ultimately, no, I don't think so. It would have made things worse in 1942, but not in 1945, and Japan surrendered due to the overwhelming amount of material. U.S. Superiority The U.S. has the will and desire to deploy that overwhelming power. Ultimately, the i-400 arrived too late in the war to make a difference, but while its timing was flawed, its technology stood out.

Ahead of its time, the innovation The design became a model for future Cold War submarines and changed military thinking about how they could be deployed in the 1950s. A new type of American submarine. The Regulus class began patrolling the seas. It bore a striking resemblance to the Japanese super submarine of World War II, although it was launched. missiles, not planes, from its deck-mounted hangar. I don't think anyone had previously considered submarines as a means of attacking enemy cities and we see this idea today in the primary nuclear weapons of the United States, France, Great Britain and even Russia as submarines. launched missiles to attack enemy cities with nuclear warheads, although we hope that their lethal force will never be necessary.

Each of these powerful stealth submarines is a living testament to one of the greatest weapons that ever fought.