Ohka

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The Yokosuka MXY-7 Ohka (櫻花 "cherry blossom") was a purpose-built kamikaze aircraft employed by Japan towards the end of World War II. The United States gave the aircraft the name Baka (Japanese for "fool").

It was a small flying bomb that was carried underneath a Mitsubishi G4M "Betty", Yokosuka P1Y Ginga "Frances" (guided Type 22) or planned Heavy Nakajima G8N Renzan "Rita" (transport type 43A/B) bomber 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 engine(s) and dive against the ship to destroy. The final approach was almost unstoppable (especially for 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 were actually used this way. It appears that the operational record of Ohkas used in action includes three ships sunk or damaged beyond repair and three other ships with significant damage.

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 Yokisuka 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 Model 11, and was powered by three Type 4 Mark 1 Model 20 rockets. 150 were built at Yokosuka, and another 600 were built at the Kasumigaura Naval Air Arsenal.

[edit] Differing attitudes

There are sharply differing perspectives about the Ohka and her pilots inside Japan compared to perspectives outside Japan. 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 Zen temple in Kamakura, and the Yasukuni Shrine in Tokyo. The general Japanese view is not that the Ohka pilots were brainwashed and coerced youths or fanatical zealots, but were heroic and selfless in the face of overwhelming odds. Others go further, such as Yoshinori Kobayashi, one of Japan's most famous manga (comic) artists, who presents in his manga books the ohka and other kamikazes as epitomizing the values that have been lost in modern Japan. The contrast is drawn with the cost benefit analysis of the self proclaimed Islamic radical fundamentalists who employ suicide bombing, for the target of the special attack groups were only military and the reason for their sacrifice was the defence of their country and loved ones. [1]

[edit] Variants

The only operational Ohka was the Model 11. Essentially a 2,646 pound (1200 kg) bomb with wooden wings powered by three Type 4 Model 1 Mark 20 solid-fuel rocket motors, the model 11 achieved great speed but only very limited range. This was problematic as it required the slow heavily laden mother aircraft to approach within 20 nautical miles of the target, making them very vulnerable to fighter defences. There was one experimental variant of the model 11, the model 21, which had thin steel wings manufactured by Nakajima.

The Ohka 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 Model 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 pound (600 kg) 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 model 22 powered by an Ishikawajima Ne-20 turbojet with a 1,764 pound (800 kg) warhead. The mothership was to be the G8N Renzan four-engined bomber. 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 person 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, Type 53 was also to use the Ne-20 turbojet but was to be towed like a glider and released near its target.

[edit] Operational versions

• Kugisho/Yokosuka MXY-7 "Ohka" Model 11 Rocket Suicide Attacker. About 800 built.

[edit] Non-operational versions

• Kugisho/Yokosuka "Ohka" Model 21 Rocket Suicide Attacker- steel wings. One built
• Kugisho/Yokosuka "Ohka" Model 22 Turbojet Suicide Attacker. Fifty built
• Kugisho/Yokosuka "Ohka" Model 33 Turbojet Suicide Attacker. Renzan drop.
• Kugisho/Yokosuka "Ohka" Model 43A Ko Turbojet Suicide Attacker. Sub launch
• Kugisho/Yokosuka "Ohka" Model 43B Otsu Turbojet Suicide Attacker. Cave launch
• Kugisho/Yokosuka "Ohka" Model 53 Turbojet Suicide Attacker. Towed launch

[edit] Trainer versions

• Kugisho/Yokosuka "Ohka" K-1 Suicide Attack Trainer
• Kugisho/Yokosuka"Ohka" K-1 Kai Suicide Attack Trainer

[edit] Surviving aircraft

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 — Planes of Fame Museum, Valle, Arizona Ohka Number I-18 captured at Yontan
• Type 22 — Smithsonian National Air and Space Museum, Washington DC (restored 1993) Photo here.
• Type 43 K-1 (rebuilt to represent a Type 11) — National Museum of the United States Air Force, Dayton, Ohio Exhibit photos.
• Type 43 K-1 — Navy Memorial Museum, Washington DC Exhibit Photo
• Type 43 K-1 Kai — Smithsonian National Air and Space Museum, Washington DC

Replicas:

• Type 11 — Yasukuni Shrine, Tokyo.
• Type 11 — Ohka Park in Kashima City.

[edit] Operational history

• March 21, 1945 — Sixteen Ohka-carrying Betty G4M2e mother ships were to be escorted by 55 Zeros to attack Task Group 58.1 (Hornet, Bennington, Wasp, Belleau Wood). Another two Bettys were to escort and provide navigation and observation. Due to technical problems, all but 30 zeros have to turn back or cannot take off. The Ohka attack force is intercepted by 50 F6F Hellcats and the Ohkas are immediately jettisoned by the Bettys some 70 miles (113 km) 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.
• April 1 1945 — Six Bettys attack the US Fleet off Okinawa. At least one makes a successful attack, with its Ohka hitting one of the 16" (406 mm) turrets on the 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.
• April 12 1945 — Nine Bettys attack the US Fleet off Okinawa. Mannert L. Abele is hit, breaks in two, and sinks. Jeffers destroys an Ohka with AA fire 50 yards (45 m) 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.
• April 14 1945 — Seven Bettys attack the US Fleet off Okinawa. None return. None of the Ohkas appear to have been launched.
• April 16 1945 — Six Bettys attack the US Fleet off Okinawa. Two return, but no Ohkas hit their targets.
• April 28 1945 — Four Bettys attack the US Fleet off Okinawa at night. One returns. No hits.
• May 4 1945 — Seven Bettys attack the US Fleet off Okinawa. One Ohka hits the bridge of Shea, causing extensive damage and casualties. Vessel judged beyond repair. Gayety is also damaged by a near-miss by an Ohka. One Betty returns.
• May 11 1945 — Four Bettys attack the US Fleet off Okinawa. Hugh W. Hadley is hit, suffers extensive damage and flooding. Vessel judged beyond repair.
• May 25 1945 — Eleven Bettys attack the US Fleet off Okinawa. Bad weather forces most of the aircraft to turn back, and none of the others score hits.
• June 22 1945 — Six Bettys attack the US Fleet off Okinawa. Two return, but no hits were scored.

[edit] 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)
• Max takeoff weight: kg (lb)
• Powerplant: 3× rocket motors , 2.60 kN (587 lbf) each

Performance

• Maximum speed: 630 km/h (390 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 (2,650lb) trinitroaminol warhead

[edit] Related content

Comparable aircraft

Fieseler Fi 103 (V-1 flying bomb)

Designation sequence

MXY-4 - MXY-5 - MXY-6 - MXY-7 - MXY-8 - MXY-9

[edit] External links

• Thunder Gods 1989 book about Ohka squadron
• The Cherry Blossom Squadrons 1973 book about Ohka squadron
• The History of Kamikaze Ohka 桜花 (Japanese)