Yokosuka Ohka[Oka] Japanese Flying Bomb

Yokosuka Ohka [Oka] Japanese Flying Bomb

Ohka Launch




3vu BW Yokosuka Ohka

The Oka Suicide Flying Bomb

Yokosuka Ohka I-13In the course of the Pacific War, the Japanese lost practically all of its warships and aircraft. They also lost two key commanders, Admiral Yamamoto and his successor Admiral Koga.

In late 1943, proposals were made by Japanese Naval Fighter Pilots for special suicide attacks against the United States Naval Forces to stem the might that was falling upon them. These men were concerned over the inferiority of Japanese Naval and Army strength and they had started to consider suicidal-crash dive tactics with their aircraft to counter growing United States Military strength.

Naval Ensign Ohta, the designer of the OKA bomb, was one of these men. Their idea was originally refused but as the war grew worse for Japan, support grew for Kamikaze Operations.

Captain Jyo, Commander of the Japanese Aircraft carrier "Chiyoda," stated after the Battle of the Philippine Sea in June 1944, "No longer can we hope to sink the numerically I superior enemy carriers through ordinary attack methods. I urge the use of special attack units to crash dive their aircraft and I ask to be placed in command of them."

The "Chiyoda" was later sunk and so the honor to command the Special Attack Group (Kamikaze Corps) fell upon Admiral Takijiro Ohnishi. In October 1944, he took command of the Japanese First Air Fleet in the Philippines. The first organized Kamikaze operations began with volunteers from the 201st Japanese Naval Air Group. This unit was based at Clark Field, 50 miles north of Manila, Philippine Is. The first attacks were made with conventional Zero Fighter Aircraft with 500 Kilogram bombs attached below the aircraft. When the special suicide attacks began in the Philippine lslands, there was for Okinawa another sort of Kamikaze aircraft whose origin lay in events of the preceding year.Yokosuka Ohka I - 13

Many of the Japanese Admirals on the General Staff did not believe the time for such extreme tactics for Kamikaze was at hand. When the Marianas Islands fell, one after the other and each defeat became increasingly worse for Japan, Kamikaze attack plans were put into effect as the only solution.

During the summer of 1944, a Japanese Naval Officer Ensign Mitsuo Ota was given permission to draw up plans for a special Kamikaze attack aircraft. Ensign Ota was a Naval Aircraft Transport pilot with little engineering background, however, he applied for and received assistance from the aviation research department of Tokyo University. When the drawings were completed, they were submitted to Yokosuku Naval Depot for approval. The Navy Command approved Ota's design in late 1944 and this aircraft was afterward named "OKA" which is "Cherry Blossom" in Japanese.

The OKA was kept very secret, even within high naval circles. Japanese Captain Motoharu Okamura was given command to train the elite pilots of the "OKA Bomb." His attack base was located at Kamiike Air Base just northeast of Tokyo.

Yokosuka Ohka Warhead

The OKA Bomb was a small wooden and metal constructed aircraft. It had room pilot and the nose warhead contained 2645 pounds of explosives. The OKA was usually carried under the belly of a twin engine "Betty" Bomber, although other types of twin engine Japanese bombers could be used with modifications. It was attached and partially hung in the bomb bay by one mounting lug and slings fastened under the wing and empennage.

The OKA was generally launched 25-50 miles from target. lts range was determined by the altitude at which it could be released. As air-to-air fighting progressed, two additional rocket motors were fitted, one under each wing, to enable the OKA to pull away from prowling Navy Hellcat Fighters. These rocket units could be fixed singly or simultaneously at the Kamikaze pilot's discretion. The OKA had a conventional pilot stick and rudder bar arrangement.

The pilot had at his disposal a selector switch for firing the propulsion rocket charges pull type arming handle for the nose bomb base fuse, a compass, an altimeter, airspeed indicator, rocket temp. gauge and an inclinometer. All control surfaces were dynamically balanced to eliminate flutter at the high speeds the OKA operated. The nose warhead had five fuses, one in the nose and four in the base. The nose fuse was straight impact fuse and was vane armed. Two of the base fuses were straight impact and the other two were of the "all way" type. All four of the base fuses were armed manually by the pilots from the cockpit.'

Yokosuka Ohka CockpitA post and ring sight was mounted on the OKA for aiding the pilot in aiming the OKA at its target. There is no landing gear and the OKA was moved on a special dolly when on the ground. It had a wing span of sixteen feet and five inches and a length of twenty feet. Its loaded weight was 4,718 pounds. It had three Type 4, MK 1, Model 20 solid fuel rocket motors mounted in the tail. The prototype OKA Bomb was completed in September 1944. Flight testing began on October 23, 1944, using a number of OKAs constructed at the Yokosuka Naval Air Depot. The first prototype was a pilot less OKA 11. It was launched from a Mitsubishi G4M "Betty" Bomber, high above Sagami Bay near Tokyo, at an altitude of 13,000 feet. The test trials were successfully completed and production was increased by adding two additional plants into producing the OKA bomb: Fuji Hikok and Chigasaki-seisakusho.

The OKA MXY-7 was built as a Training Glider for pilot training. lt differed from the armed OKA 11 primarily in having no rocket powered motor or warhead. A large skid was fitted beneath the fuselage and a smaller one beneath each wing for landing. In order to simulate combat load conditions of the OKA 11, water ballast tanks were fitted at the front and rear of the cockpit. For landing the water was discharged, thereby reducing the weight considerably.

The testing of the prototype OKA MXY-7 Training Glider was carried out by a Japanese Naval Man-Pilot Officer Nagoro at Hykurigaharu Air Base. On October 31, 1944, after the test was completed, he reported the flight handling characteristics were very good. Later the water ballast tanks were deleted as being unnecessary. A total of forty-five OKA MXY-7's were built. One example can be seen today in the Air Force Museum at Dayton, Ohio; however, the skid has been removed to make it appear as an OKA 11.

The OKA pilot would ride in the mother bomber until the target area was approached. He would then climb through the bomb bay of the mother plane into the cockpit of the OKA.

When the enemy position had been made known to the pilot, he would then signal his readiness to the bomber crew. He would pull the release handle and would be on his way in his missile of destruction. Once the release handle was pulled it became a one-way trip for the pilot. American propaganda during the war stated that the Japanese pilots were locked in their cockpit. This was not true. The pilot would glide the OKA toward the remaining distance to the target area, whereupon after selecting the target would ignite all three rocket motors and crash dive into the target at over 600 miles per hour. Needless to say it was very hard to down this aircraft once the Kamikaze aircraft was in the air under its own power.

When the OKA bomb became known it was labeled as the "BAKA BOMB" or "Fool Bomb" and this name prevails to this day

.Yokosuka Ohka I - 18

It took a little over six months to train a pilot for the OKA Special Attack Mission. These men were carefully selected from throughout the Navy Air Force and all were well qualified.

With the invasion of Okinawa, Japan knew the crushing might of the United States Navy had to be stopped. Fifty OKA 11's were selected to meet this challenge and on the first day of the Okinawa Invasion, four United States carriers were hit and damaged. The U.S.S. Enterprise, Yorktown, Intrepid, and Franklin by OKA Suicide Flying Bombs.

On March 21, 1945, United States carriers were again sighted just south of Kyushu. Japanese Admiral Ugaki, 5th Air Fleet Commander, took this opportunity for using OKA 11's from Kanoya Air Base.

Yokosuka OhkaFighter aircraft protection was assigned but it was felt more fighter aircraft would be needed to protect the slow and vulnerable G4M "Betty" Bomber mother aircraft. The Japanese Navy was well aware of the capabilities of the U.S. Navy's very fine Grumman F6F "Hellcat" fighters.

The special attack group consisted of sixteen OKA and eighteen mother planes. The flight leader was Naval Commander Goro Naraka. One of the Kamikaze pilots remarked on this sortie: "We are sixteen warriors manning our aircraft. May our death be as sudden as the shattering of crystal." Only thirty Japanese fighters were available to provide fighter escort protection and with this news, the chance for success in this mission became doubtful. The attack was launched regardless and at 4 p.m. at a point sixty miles short of the sighted U.S. fleet, fifty Grumman FGF "Hellcats" attacked the OKA bomber force and destroyed the entire group before the deadly OKA bombs could be released.

In November 1944, the world's largest aircraft carrier at the time, the gigantic Shinano, left Yokosuka Bay during the darkness of night to transport fifty OKA bombs to the philippine islands. But, as it got under way it was spotted and tracked by a U.S. Naval Submarine and sunk on November 29, 1944, off the Japanese mainland. Thus, the projected use of the OKA in the Philippines was precluded.

Special OKA groups of the 721st and 722nd squadrons were based at Kanoya, Miyazaki, Oita, Atsuki and Kamatsu Air Base. The chief targets for the OKA special attack group lay chiefly at Okinawa and the surrounding waters. Early Kamikaze pilots were replaced by new ones, who in turn were replaced by still newer pilots. Some Cherry Blossoms had fallen but there were still more to come.Yokosuka Ohka I - 18

The initial landings on Okinawa were met with little enemy opposition, but the fighting became fierce as U. S. forces went to the interior of the island One of the big surprises to U. S. Technical Air lntelligence men was the capture of six new Japanese OKA." Bombs in caves near Kadena Airfield. These OKA bombs came as a complete surprise to U. S. forces. These special attack aircraft had only arrived from Japan a few weeks before the invasion. They were assembled and were ready for use when U. S. Naval fighters hit the airfield and destroyed their mother aircraft.

The Kamikaze Special Attack Corps derived their name after the typhoon which frustrated the Mongolian invasion of Japan in 1280.

The man who was given responsibility for the formation of the Kamikaze Corps was Vice Admiral Ohnishi. The success of his organization is attributable to the bond of feeling and purpose which existed between he and his men. The watchword of the Kamikaze was "We die for the great cause of our country." The pilots did not consider they were committing suicide but rather were only doing their job as pilots by inflicting the greatest possible damage upon the enemy.

To the Kamikaze pilot, their greatest concern seemed always to have been to make sure that they would hit the target. By comparison, their death to them was a matter of very minor importance. This can be summed up as-There is an old Japanese proverb: "Life is as the weight of a feather compared to one's duty."

The Kamikaze attacks shocked the world primarily because of their certain death-self destruction aspects. The Kamikaze inflicted more casualties to the U.S. Fleet off the Okinawa shore than did the bloody hand-to-hand fighting to the invading troops in the long battle ashore.

The Kamikaze attacks also did tremendous damage to U.S. ships but it failed to produce the desired results which the Japanese hoped for.

It is perhaps hard for the Western mind to accept this idea - a man determined to die in order that he might destroy us in battle.

One of the earliest lessons one learns in battle is that courage is a very common human quality. Evidence of this can be seen from U. S. Navy Torpedo Squadron B at the Battle of Midway in June !942, where all aircraft and pilots were lost save one pilot.

But there was a fundamental difference in the heroism of Japanese and U. S. flyers. The Japanese resolutely closed all avenues of hope and escape; the American never did. To the Western mind there must always be that last slim chance of survival, that, though a lot of other men may die, you yourself, somehow, someway, will make it back.



Yokosuka Ohka 3vu ColorYokosuka Ohka Drawing



Yokosuka OhkaThe Yokosuka MXY-7 Ohka, "cherry blossom", H was a purpose-built, rocket powered human-guided anti-shipping kamikaze attack plane[1] employed by Japan towards the end of World War II. The United States gave the aircraft the name Baka (Japanese for "fool" or "idiot").
It was a manned flying bomb that was usually carried underneath a Mitsubishi G4M "Betty", Yokosuka P1Y Ginga "Frances" (guided Type 22) or planned Nakajima G8N Renzan "Rita" (transport type 43A/B) bombers to within range of its target; on release, the pilot would first glide toward the target and when close enough he would fire the Ohka's rocket engine and guide the missile towards the ship that he intended to destroy. The final approach was almost unstoppable (especially for the type 11) because the aircraft gained tremendous speed. Later versions were designed to be launched from coastal air bases and caves, and even from submarines equipped with aircraft catapults, although none was actually used in this way. It appears that the operational record of Ohkas includes three ships sunk or damaged beyond repair and three other ships with significant damage. Seven US ships were damaged or sunk by Ohkas throughout the war.
Conceived by Ensign Mitsuo Ohta of the 405th Kokutai, and aided by students of the Aeronautical Research Institute at the University of Tokyo, Ohta submitted his plans to the Yokosuka research facility. The Imperial Japanese Navy decided the idea had merit and Yokosuka engineers of the First Naval Air Technical Bureau (Kugisho) created formal blueprints for what was to be the MXY7. The only variant which saw service was the Type 11, and was powered by three Type 4 Mark 1 Model 20 rockets. 150 were built at Yokosuka, and another 700 were built at the Kasumigaura Naval Air Arsenal.
The Ohka pilots, members of the Jinrai Butai (Thunder Gods Corps), are honored in Japan at Ohka Park in Kashima City, the Ohka Monument in Kanoya City, the Kamakura Ohka Monument at Kench?-ji Kamakura, and the Yasukuni Shrine in Tokyo.


The only operational Ohka was the Type 11. Essentially a 2,646 lb bomb with wooden wings powered by three Type 4 Model 1 Mark 20 solid-fuel rocket motors, the Type 11 achieved great speed but with limited range. This was problematic, as it required the slow, heavily-laden mother aircraft to approach within 23 mi of the target, making them very vulnerable to defending fighters. There was one experimental variant of the Type 11, the Type 21, which had thin steel wings manufactured by Nakajima.
The Type 22 was designed to overcome the short standoff distance problem by using a Campini-type thermojet engine, the Tsu-11. This engine was successfully tested, and 50 Ohkas were built at Yokosuka to accept this engine. The Type 22 was to be launched by the more agile P1Y3 version of the Navy's Ginga bomber, necessitating a shorter wing span and much smaller 1,320 lb warhead. None appear to have been used operationally, and only three of the experimental Tsu-11s engines were known to be produced.
The Type 33, was a larger version of the Type 22 powered by an Ishikawajima Ne-20 turbojet with a 1,760 lb warhead. The mothership was to be the Renzan. The Type 33 was cancelled due to the likelihood that the Renzan would not be available.
Other unbuilt planned types were the Type 43A to be launched from submarines, and the 43B, a catapult/rocket assisted version, also with folding wings so that it could be hidden in caves. Two trainer versions were also under development for this version, the two-seat K-1 and the K-1 Kai, the former being a glider, and the latter fitted with a single rocket motor. In place of the warhead, a second seat was installed for the student pilot.
Finally, the Type 53 would also use the Ne-20 turbojet, but was to be towed like a glider and released near its target.


Yokosuka Ohka Cutaway

Yokosuka Ohka in Museum
Yokosuka Ohka in MuseumYokosuka Ohka in Museum
Yokosuka Ohka in Museum
These images are were taken at Smithsoniam Air and Space Musem.



Length: 20 ft 0 in
Wingspan: 16 ft 8 in
Height: 3 ft 11 in
Wing area: 65 ft²
Loaded weight: 4,720 lb
Powerplant: 3× rocket motors , 587 lbf each

Maximum speed: 500 mph
Range: 23 mi
Wing loading: 72 lb/ft²
Thrust/weight: 0.38
Dive speed (3×Rocket motors Full-Boost): 650 mph

1,200 kg (2,646 lb) Ammonal warhead

U.S.S. Bunker Hill