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Design and trial of MXY7(Baka)
Design specification
Wing area6.0m2
Total weight2,140kg
Own weight440kg
Tail rokcets360kg
Wing rockets140kg
Naito wrote an action report of USS Belleau Wood, CVL-24 on Mar 21st 1945 simply in his book.
1347 Radar sighted unknown aircraft
1448 Finished Fighers landing
1457 Radar screen cleared

I felt their sucide attackers'munen. The crews of 160 were lost on the day inculding carried Betties and escorted fighters.

Who approved a sucide bomb plan that a Betty hung it under the belly? Totsuka Michitaro was a Koku honbucho of IJN from Dec 1942 to the end of Apr 1945. The desing was done in air arsenal of IJN in Kanagawa and University of Tokyo. The propulsion was a liquid rocket engine in the original proposal. The photo shows a rocket engine for another trial rocket plane.

A head of IJNGS was very interested in an idea of airborne sucide weapon from Genda's explanation. The report was held in a meeting on 5th Aug. Oikawa, a new chief of IJNGS approved the weapon development. IJNGS requested Kouku HQ to make the weapon. The Koku HQ ordered Koku gijyutu-shou to make 100 trials till the end of Oct and called them code name Marudai buhin.

Rocket engine
The marudai buhin was called MXY7 in the Koku gijyutu-sho. Miki Tadanao was a chief designer. Hattori Rokurou was a structure designer. Washizu Kyuichirou was an computational analyst. They finished basic design in a week. The Koku Gijyutu-sho changed an engine for poweder fuel. The design of propulsion time of MXY7 was less than 10 seconds. It was to load with 3 rockets of thrust 800kgf in the tail and 2 another rockets of thrust 400kgf under both of the wing at first. The bomb has an armored plate behind pilot and floor. The table shows the specification of design. Science section did a wind tunnel experiment on 25th Aug. Washizu computed basic characteristics from the experiment. The maximum gliding speed was 350kt. The crusing gliding speed was 250kt. The range was 10 folds of released altitude. The attack angle was 5.7deg only. IJNGS judged that the range was 5 folds of the released altitude. The Koku gijyutsu-syou suggested to escort fighters enough to defend Betty. I do not know why IJNGS and Kouku HQ judged the weapon reasonable. Tada Takeo was Gunmu kyokucho of IJN from Aug 1944 to May 1945. Deputy minister of IJN was Inoue Shigemi from Aug 1944 to May 1945. And Minister of IJN was Yonai Mitumasa from Jul 1944 to Nov 1945. The koku HQ ordered Koku gijyutu-sho 100 MXY7 by the end of Nov. IJN Kure Arsenal designed and productioned warheads of MXY7.

721st Kokutai
The 721st Kokutai was established mainly for air suicide attack. It was equipped with Betty, Zero and Ouka (MXY7). The troop used a gliding manned bomb called marudai buhin or Ouka. However, Mother aircarft carrying the winged bomb was too slow to access near targets. The first operation failed on 21st Mar 1945. So the 721st Kokutai transferred pilots of escort fighters to sucide pilots. They rode Zeros loaded a 500kg bomb. IJN began a bomber pilot to ride a figher carrying a bomb because shortage of fighter pilots in the Mariana battle. IJN called a bomb fighter Bakusen. The 721st Kokutai started Bakusen sucide on 2nd Apr in the Okinawa Battle. In the results, one hit Hancock on 7th Apr, 2 hit Kidd and Missouri on 11th Apr, 4 hit Hazelwood, Haggard and Harry F. Bauer on 29th Apr, 2 hit Bunker Hill on 11th May, one hit Enterprise.
721 Kokutai

721st Kokutai Bakusen sucide attack in the Okinawa Battle
Gunzo, p189 No77
USS Hancock(CV-19) : 62 men were killed
USS Kidd(DD-661) : 38 men were killed
USS Missouri(BB-63) : superfical damage
USS Hazelwood(DD-531) : 77 men were killed
USS Haggard(DD-555)
USS Harry F. Bauer(DM-26)
USS Bunker Hill(CV-17) : 389 men were lost
USS Enterprise(CV-6) : 14 men were killed

721st Kokutai
IJN ordered Okamura a chief for preparing Marudai buhin troop on 15th Sep at Yokosuka. IJN ordered Okamura a commander of 721st Kokutai at Hyakuri-ga-hara on 1st Oct. The 721st Kokutai moved to Kami-no-ike on 7th Nov. Crews of MXY7 began gliding from a Betty at 3,000m height on 13th Nov. I think 721st Kokutai judged operational release altitude was not 6,000m but 3,000m. A Betty had to come near an enemy warship 30km at least to attack.

    turn on the left 90deg twice
    half flap, turn on the left 90deg, speed at 130kt
    full flap, speed at 110kt, turn on the left
    pull control stic at 1m height, slide on ground
Nagano Osami inspectd the 721st Kokutai on 20th Nov. Chief of IJNGS, Oikawa Koshirou inspected on 23rd. Commander of GF, Toyoda Soemu and his staffs inspected on 1st Dec. Minister of IJN Yonai Mitsumasa inspected on 3rd. The 3 important leader of IJN admitted airborne sucide attack and hope taiatari. How did they think the result of the Mariana Battle? If they thought reasonable, how betty could come near 30km enemy aircraft carriers?

Naito, p39, p41-42, p91, p101, p103-104
Koku Gijyutu-sho
The Air Museum Planes of Fame

MXY7 crews' rank and loss
1st PO
2nd PO
21Mar1st151 3254
01Apr2nd3- --21
12Apr3rd8- 3-23
14Apr4th7- -412
28Apr6th1- --1-
Total-551 11131812
GF planned MXY7 sucide operation. Betty was diffcult to fly with MXY7 in a long range. So aircraft carriers were to ferry MXY7. Aircraft carrier Unryu and Ryuho departed Sasebo and Kure on 17th and 18th Nov. 721st Koukutai lost 50 MXY7 and 30, when aircraft carrier Shinano and Unryu sank on 28th Nov 1944 and on 19th Dec. Ryuho arrived at Takao and ferried 58 MXY7. So 721st Koukutai did not advance the Philippines. The Kokutai operated in Kyushu. However, GF planned deploy 40 at Singapore, 30 at Shinchiku, 50 at Okinawa, 27 at Kanoya and Miyazaki till the end of Jan. GF also planned increase at Kanoya and Miyazaki, new deploy at Miyakojima, Ishigakijima, Kami-no-ike, Atsugi, Hachijyojima, Shanghai and Hainan-tou till the end of Mar.

The table shows MXY7 crews' rank and loss in the 10 operations. 18 Betty flew in the first operation. 3 of 18 were leader aircraft and equipped with a radar each. But all the 18 Betty were lost. A betty of the 6th operation only returned base. 78% of all the crews were petty officers. A MXY7 sank USS Mannert L. Abele(DD-733) on 12th Apr. This was the first and the last warship that MXY7 sank.

IJN failed to destroy USN task forces in the Okinawa Battle. The typical example was operation of MXY7 from 21st Mar to 22nd Jun. GF tried trainers as sucide to attack destroyers and transports. GF appointed 2 trainning student of Tokushima Kokutai and Kouchi Kokutai to sucide attack. It meant that IJN would intercept convoys in Kyushu on Nov 1945. 2 trainers sank USS Drexler and killed 158 men on 28th May.

    24thMay 16
    25thMay 1
    26thMay 1
    27thMay 16
    28thMay 4
    21stJun 8
    25thJun 7
    Total 54

Tokushima Koukutai
Kouchi Kokutai
Kouchi Koukutai
USS Mannert L. Abele(DD-733)
USS Drexler(DD-741)

5th air fleet
The 5th air fleet HQ telegrammed Ugaki's message at 1924 on 15th Aug 1945.

    Kako hantoshi ni watari kika kakutai syoushi no funsen nimo kakawarazu kyouteki wo gekisai koukoku-goji no tainin wo hatasukoto atahazarishi ha honsyoku fubin no itasutokoro nari. Honsyoku ha koukoku no mukyu to ten-kokubutai tokkou seishin no kouyou wo kakusin buka-taiin no ouka to chirishi Okinawa ni sinkou koukokubujin no honryou wo hakki kyouteki beikan ni totsunyu gouchin su. Shikika kakubutai ha honsyoku no i wo teishi arayuru kunan wo kokufuku seikyou naru kougun no saiken ni shiryoku¡¡wo tukushi kokukoku wo banse mukyu tarashimeyo.
    Dai gensui-heika banzai
    Syouwa 20 nen 8 gatsu 15 nichi 1924 suisei kijyou yori

The telegram said, 'koukoku' 4 times. Koukoku means Mikado's land. Ugaki thought he should die for Mikado naturally. He said, 'Shi ni basyo wo ataetekure.' It means I want my stage of death.

While examination department of Imperial Japanese Army Air Force did not adopt sucide aircraft Turugi(Ki-115) because of a lot of defects actually, though IJA had ordered production of them which Nakajima designed and made a few hundred.

2 IJA officers did sucide attack with a woman each in Manchuria on 19th Aug. The aircraft were Ki-36 or Ki-79 trainer. Name of one pair were Tanifuji Testuo and his wife asako. The other were Okura Iwao and Sumiko. 9 aircraft of the last IJN sucide attack was called Shinshu Fumetsu Tokubetsu Kougeki-tai(Sucide Attack).
Imai, p289-290

Ministry of Education
Manga of 'koukoku'
Bunka chou(Agency for Cultural Affairs) recommended a manga titled 'koukoku' no syugo-sha in 2005. Syugo-sha means a guardian. Ministry of Education made a song titled 'koukoku' no mamori in 1912.
Koukoku no Syugo-sha
Bunka-chou suisen sakuhin
Koukoku no tamenari
Agency for Cultural Affairs

After all, no one was resonsible for the immoral weapon and the unhuman operation. People of Japan allowed them to live on peace after the war. And some people incldinig Koizumi Jyunichiro praise the operation. Certainly almost sons of rulers never died by sucide attacks. Most of people praise someone does a sucide for their family, organization, group, and our nation even now. This is our dark crude property for 1,000 years long. Boys and girls are enthusiastic that a hero or heroin of mangas or TV dramas does a sucide for their families or organiztion. Some princes of Mikados were also driven to sucides for their clans as a result of power imbalance among rulers before modern times.
Chikamatu monogatari

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