| Yokosuka MXY-7 Ohka | |
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| Ohka Type 11 replica at the Yasukuni Shrine Yūshūkan war museum. | |
| Role | Kamikaze Aircraft |
| National origin |  Japan |
| Manufacturer | Yokosuka, Kasumigaura Naval Air Arsenal |
| First flight | October 1944 (unpowered), November 1944 (powered). |
| Introduction | 1945 |
| Retired | 1945 |
| Primary user | Imperial Japanese Navy Air Service |
| Produced | 1944–1945 |
| Number built | 850 |
The Yokosuka MXY-7 Ohka, (櫻花 (Shinjitai: 桜花) "cherry blossom", Hebon-shiki transcription Ōka, ) 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")[2].
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 Kenchō-ji Kamakura, and the Yasukuni Shrine in Tokyo.
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Variants
The only operational Ohka was the Type 11. Essentially a 1,200 kg (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 37 km (20 nmi; 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 600 kg (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 800 kg (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.
Operational versions
- Kugisho/Yokosuka MXY-7 "Ohka" Type 11 Rocket Suicide Attacker. 852 built.
Non-operational versions
- Kugisho/Yokosuka "Ohka" Type 21 Rocket Suicide Attacker. Steel wings; one built.
- Kugisho/Yokosuka "Ohka" Type 22 Motorjet Suicide Attacker. 50 built.
- Kugisho/Yokosuka "Ohka" Type 33 Turbojet Suicide Attacker. Renzan drop launch.
- Kugisho/Yokosuka "Ohka" Type 43A Ko Turbojet Suicide Attacker. Submarine launched.
- Kugisho/Yokosuka "Ohka" Type 43B Otsu Turbojet Suicide Attacker. Cave launched.
- Kugisho/Yokosuka "Ohka" Type 53 Turbojet Suicide Attacker. Towed launch.
Trainer versions
- Kugisho/Yokosuka "Ohka" K-1 Suicide Attack Trainer
- Kugisho/Yokosuka "Ohka" K-1 Kai Suicide Attack Trainer
Surviving Examples
Some 850 were built, mostly Type 11. Surviving Ohkas include:
- Type 11: Royal Air Force Museum, Cosford. Ohka is Number, I-13 captured 1 April 1945 at Yontan, Okinawa.
- Type 11: Fleet Air Arm Museum, Yeovilton
- Type 11: Museum of Science and Industry in Manchester, Manchester
- Type 11: Defence Explosives Ordinance School, Kent
- Type 11: Indian Air Museum, New Delhi
- Type 11: Iruma Air Force Base, Iruma, Saitama
- Type 11: USMC Air Ground Museum, Quantico, Virginia
- Type 11: Yanks Air Museum Chino, California Ohka Number I-10
- Type 11: Planes of Fame Museum, Chino, California Ohka Number, I-18 captured at Yontan.
- Type 22: Smithsonian National Air and Space Museum, Washington, D.C. (restored 1993)
- Type 43 K-1 (rebuilt to represent a Type 11): National Museum of the United States Air Force, Dayton, Ohio
- Type 43 K-1: Navy Memorial Museum, Washington, D.C. Exhibit Photo
- Type 43 K-1 Kai: Smithsonian National Air and Space Museum, Washington, D.C.
Replicas:
- Type 11: Yasukuni Shrine, Tokyo.
- Type 11: Ohka Park in Kashima City.
- Type 11: Wings of Eagles Discovery Center, Elmira-Corning Regional Airport, Chemung County, New York.
 RAF Museum, Cosford. |
 Museum of Science and Industry, Manchester |
 Type 22, NASM, Steven F. Udvar-Hazy Center |
 Type 43 trainer, National Museum of the US Air Force |
Operational history
- 21 March 1945: 16 Ohka-carrying "Bettys" were to be escorted by 55 Zeros to attack Task Group 58.1 (Hornet, Bennington, Wasp, and Belleau Wood). Another two "Bettys" were to escort and provide navigation and observation. Due to technical problems, 25 Zeros have to turn back or cannot take off. The Ohka attack force is intercepted by 16 F6F Hellcats and the Ohkas are immediately jettisoned by the "Bettys" some 113 km (70 mi) from the target. None of the "Bettys" return, no ships are attacked, 16 of the Jinrai Butai are dead, and only 15 damaged Zeros make it back.
- 1 April 1945: Six "Bettys" attack the U.S. Fleet off Okinawa. At least one makes a successful attack, with its Ohka hitting one of the 406 mm (16 in) turrets on West Virginia, causing moderate damage. Alpine, Achernar, and Tyrrell are also hit by kamikaze aircraft, but it is unclear whether any of these were Ohkas from the other "Bettys". None of the "Bettys" return.
- 12 April 1945: Nine "Bettys" attack the U.S. Fleet off Okinawa. Mannert L. Abele is hit, breaks in two, and sinks. Witnessed by LSMR-189 CO James M. Stewart. Jeffers destroys an Ohka with AA fire 45 m (50 yd) from the ship, but the resulting explosion is still powerful enough to cause extensive damage, forcing Jeffers to withdraw. Stanly is targeted by two Ohkas. One strikes just above the waterline, with the charge punching through the other side of the hull before detonating, causing little damage to the ship, and the other Ohka narrowly missed and crashed into the sea, knocking off the Stanly's ensign in the process. One Betty returns.
- 14 April 1945: Seven "Bettys" attack the U.S. Fleet off Okinawa. None return. None of the Ohkas appear to have been launched.
- 16 April 1945: Six "Bettys" attack the U.S. Fleet off Okinawa. Two return, but no Ohkas hit their targets.
- 28 April 1945: Four "Bettys" attack the U.S. Fleet off Okinawa at night. One returns. No hits.
- 4 May 1945: Seven "Bettys" attack the U.S. Fleet off Okinawa. One Ohka hits the bridge of Shea, causing extensive damage and casualties. Gayety is also damaged by a near-miss by an Ohka. One "Betty" returns.
- 11 May 1945: Four "Bettys" attack the U.S. Fleet off Okinawa. Hugh W. Hadley is hit, suffers extensive damage and flooding. Vessel judged beyond repair.
- 25 May 1945: 11 "Bettys" attack the U.S. Fleet off Okinawa. Bad weather forces most of the aircraft to turn back, and none of the others score hits.
- 22 June 1945: Six "Bettys" attack the U.S. Fleet off Okinawa. Two return, but no hits were scored.
Specifications (Type 11)
General characteristics
- Crew: One
- Length: 6.10 m (20 ft 0 in)
- Wingspan: 5.10 m (16 ft 8 in)
- Height: 1.20 m (3 ft 11 in)
- Wing area: 6 m² (65 ft²)
- Loaded weight: 2,140 kg (4,720 lb)
- Powerplant: 3× rocket motors , 2.60 kN (587 lbf) each
Performance
- Maximum speed: 804 km/h (500 mph)
- Range: 36 km (23 mi)
- Wing loading: 356 kg/m² (72 lb/ft²)
- Thrust/weight: 0.38
- Dive speed (3×Rocket motors Full-Boost): 1,040 km/h (650 mph)
Armament
- 1,200 kg (2,646 lb) Ammonal warhead
See also
- Japanese Special Attack Units
- Secret and special weapons in Showa Japan
- Flying bomb
- Fritz X
- The Cockpit, an anthology of short films containing one about an Ohka pilot, reflecting Japanese sentiments of them
- Comparable Aircraft
- Fieseler Fi 103 (V-1 flying bomb)
- Messerschmitt Me 328
Notes
- ^ http://www.aerospaceweb.org/aircraft/attack/ohka/
- ^ "Yokosuka Ohka. A piloted glide bomb, called "Baka" (idiot) by the Allies." http://www.ww2pacific.com/suicide.html
External links
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Wikimedia Commons has media related to: Yokosuka MXY 7 Ohka |
- Morinoske: Pilot testimonials - and more
- Thunder Gods 1989 book about Ohka squadron
- The Cherry Blossom Squadrons 1973 book about Ohka squadron
- The History of Kamikaze Ohka 桜花 (Japanese)
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