Yokosuka / Kugisho MXY7 Ohka (Baka)
Technical Information

Background
In the middle of 1944 as the Pacific War turned against Japan, a rocket powered kamikaze plane armed with a bomb was conceived by Imperial Japanese Navy (IJN) Ensign Mitsuo Ohta aided by students from the University of Tokyo Aeronautical Research Institute. In August 1944, the concept was submitted to the Imperial Japanese Navy (IJN) 1st Naval Air Technical Arsenal (Dai-Ichi Kaigun Koku Gijitsusho) abbreviated Kugisho.

The proposal was favorably received and assigned to a team of engineers led by Masao Yamana, Tadanao Mitsugi and Rokuro Hattori and assigned the designation MXY7 Ohka meaning Cherry Blossom. The rocket plane was designed to be air dropped by a medium bomber, glide towards the target then ignite three Type 4 Mark 1 Model 20 rockets to fly at high speed to the target and on impact the 1,200 kg (2,600 pounds) nose warhead of would explode.

By the end of September 1944, ten unpowered prototypes were completed and ready for testing. During October 1944 unpowered flight testing began at Sagami. On November 19, 1944 the rocket powered version made a first successful test flight at Kashima and was deemed as successful and authorized for production.

Wartime History
A single Ohka could be mounted below a Type 1 Attack Bomber / G4M2 Betty and air dropped near the target. Only the Model 11 was used in combat flown by pilots of the Jinrai Butai (Thunder Gods Corps).

On March 8, 1945 a B-29 photographic reconnaissance over Kanoya Airfield photographs the MXY7 Ohka parked on the ground. Initially the new type is given the Allied codename Viper. Later, renamed Baka, the Japanese word for stupid. Also known as the Baka Bomb.

On March 21, 1945 the fist Kikusui (Floating Chrysanthemum) kamikaze mission is ordered by Vice Admiral Matome Ugaki using the MXY7 Ohka (Baka) against U.S. Navy warships off Japan. Eighteen G4M2 Bettys with Ohka took off from Kanoya Airfield escorted by Zeros on a mission against U.S. Navy Task Force 58 (TF 58) aircraft carriers off Japan. Thirty miles away, all eighteen Bettys were shot down before they could launch their Ohka and the attack was a failure. In total, the operation costs 137 air crew and all 15 Ohka pilots.

On April 12, 1945 off Okinawa an Ohka sinks USS Mannert L. Abele (DD-733). This was the first ship hit and sunk by an Ohka. The same day, an Ohka damaged USS Stanly (DD-478) and USS Jeffers (DMS-27). On May 4, 1945 off Okinawa an Ohka damages USS Shea (DM-30) and USS Gayety (AM-239) was damaged by a near miss by kamikaze and Ohka.

On May 11, 1945 USS Hugh W. Hadley (DD-774) is damaged by Ohka.

In total, Ohkas were credited with damaging seven U.S. ships, sinking or severely damaging three and causing significant damage to three others

Model 11
About 755 Model 11s were built by Yokosuka with a 2,646 pound warhead. A total of 155 were built at Yokosuka and another 600 were built at Kasumigaura Naval Air Arsenal. This was the only variant that was used in combat. During 1945, several were captured by American forces at Yontan Airfield on Okinawa and sent back to the United States for evaluation and display.

Model 22
Built by Kugisho the MXY7 Model 22 Ohka was powered by three Ishikawajima Tsu-11 Tsu-11 "Campini" motor jet engines. A total of fifty were manufactured armed with a 1,323 pound warhead before production shifted to underground factories. Only three Tsu-11 engines were built. Most of the airframes remained incomplete and the end of the Pacific War before this variant could enter operational service.

Model 33
The Pacific War ended before Model 33 could be manufactured. The model 33 was to be powered by a single Ne-20 engine with an 800 kg warhead (1,800 pounds).

Model 43A Ko
The Pacific War ended before Model 44A Ko could be manufactured a version with folding wings that could be catapult launched from submarines.

Model 43B Otsu
The Pacific War ended before the Model 44B Otsu could be manufactured. This version had folding wings and could be catapult launched from caves to oppose an American landing against the Japanese home islands.

Model 53
The Pacific War ended before the Model 53 could be manufactured. This version was to be powered by a single Ne-20 engine that could be launched while being towed by a larger aircraft.

K-1
A total of 45 K-1 training versions were built with a landing skid and flaps and lacked a warhead. The nose was filled with water ballast that was expelled before landing.

Model 43 K-1 Kai Wakazakura
Two seat trainer version with flaps and landing skid with a Type 4 Mark 1 Model 20 rocket motor for limited powered flight for use as a trainer.

Suzuka-24
The Pacific War ended before the Suzuka-24 could be manufactured. This variant was an interceptor version with two 20mm cannons in the nose to attack B-29 Superfortress and was reportedly used twice.

Production
A total of 852 were built.

References
Japanese Aircraft of the Pacific War (1987) pages 476-482, 556, 566

Technical Details (Ohka 11)
Crew  One (pilot)
Engine   3 x solid propellant rockets with total thrust of 800 kg
Span  4.12m
Length  6.88m
Height  1.15m
Maximum Speed  403 mph
Range  70 miles
Armament  none
Bombload  1,600 kg / 2,600 lb Ammonal warhead