Ohka
Encyclopedia
The Yokosuka MXY-7 Ohka (櫻花; Shinjitai
Shinjitai
Shinjitai are the forms of kanji used in Japan since the promulgation of the Tōyō Kanji List in 1946. Some of the new forms found in shinjitai are also found in simplified Chinese, but shinjitai is generally not as extensive in the scope of its modification...
: 桜花; "cherry blossom"; Hebon-shiki transcription Ōka) was a purpose-built, rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
powered human-guided anti-shipping kamikaze
Kamikaze
The were suicide attacks by military aviators from the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, designed to destroy as many warships as possible....
attack plane employed by Japan towards the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. United States sailors gave the aircraft the nickname Baka
Baka (fool)
Baka is a frequently used Japanese word meaning "fool; idiot; jerk; dolt; imbecile; foolish; stupid; worthless; absurd; ridiculous; idiotic".-Word:...
(Japanese for "fool" or "idiot").
Design and development
The MXY-7 Navy Suicide Attacker Ohka was a manned flying bombFlying bomb
A flying bomb is a manned or unmanned aerial vehicle or aircraft carrying a large explosive warhead, a precursor to contemporary cruise missiles...
that was usually carried underneath a Mitsubishi G4M
Mitsubishi G4M
The Mitsubishi G4M 一式陸上攻撃機, 一式陸攻 Isshiki rikujō kōgeki ki, Isshikirikkō was the main twin-engine, land-based bomber used by the Imperial Japanese Navy Air Service in World War II. The Allies gave the G4M the reporting name Betty...
2e "Betty" Model 24J bomber
Bomber
A bomber is a military aircraft designed to attack ground and sea targets, by dropping bombs on them, or – in recent years – by launching cruise missiles at them.-Classifications of bombers:...
to within range of its target; on release, the pilot would first glide towards the target and when close enough he would fire the Ohkas three solid-fuel rockets, one at a time or in unison, and fly the missile towards the ship that he intended to destroy.
The design was conceived by Ensign
Ensign (rank)
Ensign is a junior rank of a commissioned officer in the armed forces of some countries, normally in the infantry or navy. As the junior officer in an infantry regiment was traditionally the carrier of the ensign flag, the rank itself acquired the name....
Mitsuo Ohta of the 405th Kokutai
Kokutai
Kokutai is a politically loaded word in the Japanese language, translatable as "sovereign", "national identity; national essence; national character" or "national polity; body politic; national entity; basis for the Emperor's sovereignty; Japanese constitution". "Sovereign" is perhaps the most...
, aided by students of the Aeronautical Research Institute at the University of Tokyo
University of Tokyo
, abbreviated as , is a major research university located in Tokyo, Japan. The University has 10 faculties with a total of around 30,000 students, 2,100 of whom are foreign. Its five campuses are in Hongō, Komaba, Kashiwa, Shirokane and Nakano. It is considered to be the most prestigious university...
. Ohta submitted his plans to the Yokosuka research facility. The Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
decided the idea had merit and Yokosuka engineers
Military engineer
In military science, engineering refers to the practice of designing, building, maintaining and dismantling military works, including offensive, defensive and logistical structures, to shape the physical operating environment in war...
of the Yokosuka Naval Air Technical Arsenal
Yokosuka Naval Air Technical Arsenal
had many names, each depending on the period of its existence, and the circumstances at that time. Many of the names were acronyms that were derived from its military name or designation, which changed from time to time. The arsenal was sometimes known as "Kūgi-shō"...
(Dai-Ichi Kaigun Koku Gijitsusho, or in short Kugisho) created formal blueprints for what was to be the MXY7. The only variant which saw service was the Model 11, and it was powered by three Type 4 Mark 1 Model 20 rockets. 155 Ohka Model 11s were built at Yokosuka, and another 600 were built at the Kasumigaura
Kasumigaura, Ibaraki
is a city located in Ibaraki, Japan. Kasumigaura was formerly a town in Niihari District and became a city on March 28, 2005 after merging with the neighboring town of Chiyoda, also from Niihari District. The city takes its name from the nearby lake, Lake Kasumigaura...
Naval Air Arsenal.
The final approach was almost unstoppable because the aircraft gained high speed (403 miles per hour (180.2 m/s) in level flight and 576 miles per hour (257.5 m/s) or even 650 miles per hour (290.6 m/s) in a dive). Later versions were designed to be launched from coastal air bases and caves, and even from submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s equipped with aircraft catapult
Aircraft catapult
An aircraft catapult is a device used to launch aircraft from ships—in particular aircraft carriers—as a form of assisted take off. It consists of a track built into the flight deck, below which is a large piston or shuttle that is attached through the track to the nose gear of the aircraft, or in...
s, 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. The USS Mannert L. Abele
USS Mannert L. Abele (DD-733)
USS Mannert L. Abele , an Allen M. Sumner-class destroyer, is the only ship of the United States Navy to be named for Mannert Lincoln Abele, a World War II submarine commander who posthumously received the Navy Cross for his heroism in the Pacific Theater. The destroyer was the first US warship...
was the first Allied ship to be sunk by Ohka aircraft, near Okinawa on 12 April 1945.
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 Kenchō-ji
Kencho-ji
Kenchō-ji is a Rinzai Zen temple in Kamakura, Kanagawa Prefecture, Japan, which ranks first among Kamakura's so-called Five Great Zen Temples and is the oldest Zen training monastery in Japan. These temples were at the top of the Five Mountain System, a network of Zen temples started by the Hōjō...
Kamakura, and the Yasukuni Shrine
Yasukuni Shrine
is a Shinto shrine located in Chiyoda, Tokyo, Japan. It is dedicated to the soldiers and others who died fighting on behalf of the Emperor of Japan. Currently, its Symbolic Registry of Divinities lists the names of over 2,466,000 enshrined men and women whose lives were dedicated to the service of...
in Tokyo.
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
s. There was one experimental variant of the Model 11, the Model 21, which had thin steel wings manufactured by Nakajima
Nakajima Aircraft Company
The Nakajima Aircraft Company was a prominent Japanese aircraft manufacturer throughout World War II.-History:...
. It had the engine of the Model 11 and the airframe of the Model 22.
The Ohka K-1 was a unpowered trainer version with water ballast instead of warhead and engines, to provide pilots with handling experience. 45 were built by Dai-Ichi Kaigun Koku Gijitsusho.
The Model 22 was designed to overcome the short standoff distance problem by using a Campini
Secondo Campini
Secondo Campini was an Italian engineer and one of the pioneers of the jet engine.Campini was born at Bologna, Emilia-Romagna. In 1931 he wrote a proposal for the Italian Air Ministry on the value of jet propulsion and in 1932 demonstrated a jet-powered boat in Venice...
-type thermojet engine, the Tsu-11
Tsu-11
The Tsu-11 was a primitive, motorjet-style jet engine produced in small numbers in Japan in the closing stages of World War II. It was principally designed to propel the Japanese Ohka flying bomb, a kamikaze weapon....
. This engine was successfully tested, and 50 Model 22 Ohkas were built at Yokosuka to accept this engine. The Model 22 was to be launched by the more agile Yokosuka P1Y3
Yokosuka P1Y
|-See also:-References:NotesBibliography* Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam 7 Company Ltd., 1970. ISBN 0-370-00033-1 ....
Ginga "Frances" bomber, necessitating a shorter wing span and much smaller 600 kg (1,320 lb) warhead. None appear to have been used operationally, and only three of the experimental Tsu-11s engines are known to have been produced.
The Model 33 was a larger version of the Model 22 powered by an Ishikawajima Ne-20
Ishikawajima Ne-20
|-See also:- References :* -National Air and Space Museum...
turbojet with a 800 kg (1,760 lb) warhead. The mothership was to be the Nakajima G8N
Nakajima G8N
|-See also:-References:NotesBibliography* Collier, Basil. Japanese Aircraft of World War II. New York: Mayflower Books, 1979. ISBN 0-8317-5137-1....
Renzan. Model 33 was cancelled due to the likelihood that the Renzan would not be available.
Other unbuilt planned variants were the Model 43A with folding wing
Folding wing
A folding wing is a design feature of aircraft to save space in the airfield, and time, and is typical of naval aircraft that operate from the limited deck space of aircraft carriers. The folding allows the aircraft to occupy less space in a confined hangar because the folded wing normally rises...
s, to be launched from submarines, and the Model 43B, a catapult/rocket assisted version, also with folding wings so that it could be hidden in caves. A trainer
Trainer (aircraft)
A trainer is a class of aircraft designed specifically to facilitate in-flight training of pilots and aircrews. The use of a dedicated trainer aircraft with additional safety features—such as tandem flight controls, forgiving flight characteristics and a simplified cockpit arrangement—allows...
version was also under development for this version, the two-seat Model 43 K-1 Kai Wakazakura (Young Cherry), fitted with a single rocket motor. In place of the warhead, a second seat was installed for the student pilot. Two of this version were built.
Finally, the Model 53 would also use the Ne-20 turbojet
Ishikawajima Ne-20
|-See also:- References :* -National Air and Space Museum...
, but was to be towed like a glider and released near its target.
Operational history
The Yokosuka MXY7 Ohka was used mostly against American ships invading Okinawa, and if launched from its mothership, could be extremely effective due to to its high speed in the dive. In the first two attempts to ship the Ohkas to Leyte Gulf through aircraft carriers, the carriers and were sunk by the US submarines USS Archer-Fish and USS RedfishUSS Redfish (SS-395)
USS Redfish , a Balao-class submarine, was the first ship of the United States Navy to be named for the redfish, a variety of salmon also called blueback, sawqui, red salmon, and nerka. Her keel was laid down on 9 September 1943 by the Portsmouth Navy Yard of Kittery, Maine...
, in which in both cases the explosions of their Ohkas contributed to their sinkings, preventing their presence at the Battle of Leyte Gulf
Battle of Leyte Gulf
The Battle of Leyte Gulf, also called the "Battles for Leyte Gulf", and formerly known as the "Second Battle of the Philippine Sea", is generally considered to be the largest naval battle of World War II and, by some criteria, possibly the largest naval battle in history.It was fought in waters...
.
On 21 March 1945, 16 Ohka-carrying "Betty
Mitsubishi G4M
The Mitsubishi G4M 一式陸上攻撃機, 一式陸攻 Isshiki rikujō kōgeki ki, Isshikirikkō was the main twin-engine, land-based bomber used by the Imperial Japanese Navy Air Service in World War II. The Allies gave the G4M the reporting name Betty...
" bombers were to be escorted by 55 Zeros
A6M Zero
The Mitsubishi A6M Zero was a long-range fighter aircraft operated by the Imperial Japanese Navy Air Service from 1940 to 1945. The A6M was designated as the , and also designated as the Mitsubishi A6M Rei-sen and Mitsubishi Navy 12-shi Carrier Fighter. The A6M was usually referred to by the...
to attack Task Group 58.1 . Another two "Bettys" were to escort and provide navigation and observation. Due to technical problems, 25 Zeros had to turn back or could not take off. The Ohka attack force was intercepted by 16 US Navy Grumman F6F Hellcat fighters and the Ohkas were immediately jettisoned by the "Bettys," some 113 km (70 mi) from the target. None of the "Bettys" returned, no ships were attacked and 16 of the Jinrai Butai were killed, with only 15 damaged Zeros making it back to their base.
Attacks intensified in April 1945. On 1 April 1945, six "Bettys" attacked the U.S. Fleet off Okinawa. At least one made a successful attack, with its Ohka thought to hit one of the 406 mm (16 in) turrets on the battleship , causing moderate damage. Postwar analysis indicated that no hits were recorded and that a near-miss took place. The transports , , and were also hit by kamikaze aircraft, but it is unclear whether any of these were Ohkas from the other "Bettys". None of the "Bettys" returned.
The American military quickly realized the danger and concentrated on extending their "defensive rings" outward to intercept the "Betty"/Ohka combination aircraft before the suicide mission could be launched. On 12 April 1945, nine "Bettys" attacked the U.S. Fleet off Okinawa. The destroyer was hit, broke in two, and sank, witnessed by LSMR-189
LSMR-189
USS LSM-189 was a LSM-188 class Landing Ship Medium of the United States Navy during World War II. She was commanded by Lieutenant James Malcom Stewart, USNR during the Battle of Okinawa.-Service history:...
CO James M. Stewart. destroyed an Ohka with AA fire 45 m (50 yd) from the ship, but the resulting explosion was still powerful enough to cause extensive damage, forcing Jeffers to withdraw. The destroyer was attacked by two Ohkas. One struck just above the waterline just behind the ship's bow, with the charge punching completely through the other side of the hull before splashing into the sea and detonating like a depth charge, causing little damage to the ship, and the other Ohka narrowly missed (likely due to the pilot being killed by anti-aircraft fire) and crashed into the sea, knocking off the Stanlys ensign in the process. One Betty returned. On 14 April 1945, seven "Bettys" attacked the U.S. Fleet off Okinawa. None returned. None of the Ohkas appeared to have been launched. Two days later, six "Bettys" attacked the U.S. Fleet off Okinawa. Two returned, but no Ohkas hit their targets. Later, on 28 April 1945, four "Bettys" attacked the U.S. Fleet off Okinawa at night. One returned. No hits were recorded.
May 1945 saw another series of attacks. On 4 May 1945, seven "Bettys" attacked the U.S. Fleet off Okinawa. One Ohka hit the bridge of a minesweeper, , causing extensive damage and casualties. was also damaged by a near-miss by an Ohka. One "Betty" returned. On 11 May 1945, four "Bettys" attacked the U.S. Fleet off Okinawa. The destroyer was hit and suffered extensive damage and flooding. The vessel was judged beyond repair. On 25 May 1945, 11 "Bettys" attacked the US Fleet off Okinawa. Bad weather forced most of the aircraft to turn back, and none of the others scored hits.
On 22 June 1945, six "Bettys" attacked the U.S. Fleet off Okinawa. Two returned, but no hits were scored. Postwar analysis concluded that the Ohka's impact was negligible with no US Navy capital ships actually hit during their attacks due to an extremely effective set of defensive tactics that were employed.
Variants
Operational variants
- Kugisho/Yokosuka MXY-7 "Ohka" Model 11 Rocket Suicide Attacker. 755 built.
Non-operational variants
- Kugisho/Yokosuka "Ohka" Model 21 Rocket Suicide Attacker. Steel wings; one built.
- Kugisho/Yokosuka "Ohka" Model 22 MotorjetMotorjetA motorjet is a rudimentary type of jet engine which is sometimes referred to as thermojet, a term now commonly used to describe a particular and completely unrelated pulsejet design.- Design :...
Suicide Attacker. 50 built. - Kugisho/Yokosuka "Ohka" Model 33 Turbojet Suicide Attacker. Renzan drop launch.
- Kugisho/Yokosuka "Ohka" Model 43A Ko Turbojet Suicide Attacker. Submarine launched.
- Kugisho/Yokosuka "Ohka" Model 43B Otsu Turbojet Suicide Attacker. Cave launched.
- Kugisho/Yokosuka "Ohka" Model 53 Turbojet Suicide Attacker. Towed launch.
Trainer variants
- Kugisho/Yokosuka "Ohka" K-1 Suicide Attack Trainer
- Kugisho/Yokosuka "Ohka" Model 43 K-1 Kai Suicide Attack Trainer
Surviving examples
Some 852 were built, mostly Model 11. Surviving Ohkas include:- Model 11: Royal Air Force MuseumRAF MuseumThe Royal Air Force Museum London, commonly known as the RAF Museum, is a museum located on the former Hendon Aerodrome, dedicated to the history of aviation and the British Royal Air Force. The museum is a non-departmental public body sponsored by the Ministry of Defence and a registered charity...
, CosfordRAF CosfordRAF Cosford is a Royal Air Force station in Cosford, Shropshire, just to the northwest of Wolverhampton and next to Albrighton.-History:...
. Ohka is Number I-13 captured 1 April 1945 at Yontan, Okinawa. - Model 11: Fleet Air Arm MuseumFleet Air Arm MuseumThe Fleet Air Arm Museum is located north of Yeovil, and south of Bristol. It has an extensive collection of military and civilian aircraft, as well as models of Royal Navy ships, especially aircraft carriers. Some of the museum has interactive displays...
, YeoviltonRNAS YeoviltonRoyal Naval Air Station Yeovilton, or RNAS Yeovilton, is an airfield of the Royal Navy, sited in South West England a few miles north of Yeovil in Somerset...
. - Model 11: Museum of Science and Industry in ManchesterMuseum of Science and Industry in ManchesterThe Museum of Science and Industry in Manchester, England, is a large museum devoted to the development of science, technology, and industry with emphasis on the city's achievements in these fields...
, Manchester. - Model 11: Defence Explosives Ordinance School, KentKentKent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...
. - Model 11: Indian Air Museum, New Delhi.
- Model 11: Iruma Air Force Base, Iruma, SaitamaIruma, Saitamais a city in Saitama Prefecture, Japan, near Tokyo.As of 2010, the city has an estimated population of 149,269 and a population density of 3,340 persons per km². The total area is 44.74 km². The city consists of 6 areas, Toyooka, Kaneko, Higashikaneko, Fujisawa, Miyadera-Nihongi, and...
. - Model 11: Marine Corps Air-Ground MuseumMarine Corps Air-Ground MuseumThe Marine Corps Air-Ground Museum was located at Brown Field, Marine Corps Base Quantico, Quantico, Virginia. It housed a wide variety of historic Marine Corps vehicles/tanks , equipment, artillery pieces and aircraft to trace the evolution and significance of the Marine Air-Ground Team...
, Quantico, VirginiaQuantico, Virginia- Demographics :As of the census of 2000, there are 561 people, 295 households, and 107 families living in the town. The population density is . There are 359 housing units at an average density of .-Racial composition:...
. - Model 11: Yanks Air MuseumYanks Air MuseumThe Yanks Air Museum is a non-profit 501 organization dedicated to exhibiting, preserving and restoring American aircraft and artifacts.-Chino facility and exhibits:...
Chino, CaliforniaChino, CaliforniaChino is a city in San Bernardino County, California, United States. It is located in the western end of the Riverside-San Bernardino Area and it is easily accessible via the Chino Valley and Pomona freeways....
. Ohka Number I-10. - Model 11: Planes of FamePlanes of FamePlanes of Fame Air Museum is an aviation museum located in Chino, California, and Valle, Arizona. The museum has many flying and static aircraft, along with multiple rare examples under restoration.-History:...
Museum, Chino, California. Ohka Number I-18 captured at Yontan. - Model 22: Smithsonian National Air and Space MuseumNational Air and Space MuseumThe National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
, Washington, D.C.Washington, D.C.Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
(restored 1993). - K-1 (rebuilt to represent a Model 11, but retaining the landing skid): National Museum of the United States Air ForceNational Museum of the United States Air ForceThe National Museum of the United States Air Force is the official museum of the United States Air Force located at Wright-Patterson Air Force Base northeast of Dayton, Ohio. The NMUSAF is the world's largest and oldest military aviation museum with more than 360 aircraft and missiles on display...
, Dayton, Ohio. - K-1: U.S. Navy MuseumU.S. Navy MuseumThe National Museum of the United States Navy, or U.S. Navy Museum for short, is the flagship museum of the United States Navy and is located in the former Breech Mechanism Shop of the old Naval Gun Factory on the grounds of the Washington Navy Yard in Washington, D.C., USA.The U.S...
, Washington, D.C.Washington, D.C.Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
Exhibit Photo. - Model 43 K-1 Kai: Smithsonian National Air and Space MuseumNational Air and Space MuseumThe National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
, Washington, DC.
Specifications (Model 11)
See also
- Japanese Special Attack UnitsJapanese Special Attack UnitsDuring World War II, Japanese Special Attack Units , also called shimbu-tai, were specialized units of the Imperial Japanese Navy and Imperial Japanese Army normally used for suicide missions...
- Secret and special weapons in Showa Japan
- Flying bombFlying bombA flying bomb is a manned or unmanned aerial vehicle or aircraft carrying a large explosive warhead, a precursor to contemporary cruise missiles...
- Fritz XFritz XFritz X was the most common name for a German guided anti-ship glide bomb used during World War II. Fritz X was a nickname used both by Allied and Luftwaffe personnel. Alternate names include Ruhrstahl SD 1400 X, Kramer X-1, PC 1400X or FX 1400...
- The Cockpit, an anthology of short films containing one about an Ohka pilot, reflecting Japanese sentiments of them
External links
- "Baka... Flying Warhead", C.I.C. (Combat Information Center), U.S. Office of the Chief of Naval Operations, June 1945.
- Morinoske: Pilot testimonials
- Thunder Gods 1989 book about Ohka squadron
- The Cherry Blossom Squadrons 1973 book about Ohka squadron
- USS LSM(R)-193
- Popular Science,August 1945, Japanese Gamble On Human Bombs
- The History of Kamikaze Ohka 桜花