Meet Japan’s “Cherry Blossom” Manned Missiles: Rocket-Powered Kamikaze Killers

September 1, 2019 Topic: Security Blog Brand: The Buzz Tags: JapanImperial JapanWorld War IIMilitaryTechnology

Meet Japan’s “Cherry Blossom” Manned Missiles: Rocket-Powered Kamikaze Killers

The ultimate terror weapon? 

On April 12, 1945 the U.S. destroyer Mannert L. Abele was on radar picket duty seventy miles west of Okinawa—scanning the eyes for incoming Japanese aircraft. A huge U.S. fleet was stationed nearby supporting Marine and Army soldiers locked in a bloody struggle to capture the Japanese island. In return, scores aircraft, flown by barely-trained pilots, were flying from Kyushu to bomb the U.S. ships—or even crash straight into them in Kamikaze attacks.

Abele’s mission as a radar picket was to detect incoming aircraft so they could be intercepted by U.S. fighters before they reached the valuable carriers and transport vessels crammed full of soldiers closer to the island. The destroyer’s 5” dual-purpose guns could also attempt to pick off the Japanese aircraft—or even attract their attention.

This is what happened at 1:45 PM that day, when between one and two dozen Japanese fighters and dive bombers swarmed around the hapless destroyer from all sides, orbiting just out of range.  An hour later, five aircraft peeled down in a dive-bombing attack.  While the destroyer’s gun crew managed to down a lone Zero fighter from two miles away, something struck the Abele hard and fast. 

Captain James Stewart of the neighboring rocket-armed landing ship LSM(R)-189 described the suddenness of the attack:

"It is difficult to say what it was that hit the DD 733. This officer personally saw what appeared to be two (2) planes orbiting in a northerly direction from the DD 733, and then suddenly, what appeared to be, one plane, accelerated at a terrific rate, too fast for us to fire at. This plane dove at an angle of approximately 30 degrees, starting at about four miles [7.5 km] away. Since we had no air search radar, the above statements are merely my own conclusions."

The mysterious craft knocked out the power for the bridge control systems and the guns, broke Abele’s keels, and destroyed her engineering room.

Less than a minute a later, a second aircraft slammed into the luckless destroyer, causing a huge explosion that literally split the 2,200-ton destroyer in two.  The two halves promptly sank, taking 84 of her 336 crew members with her. 

The nearby LSM(Rs) 189 and 190 charged forth to rescue the survivors and shot down two more fighters.  Decades later, survivor Roy Anderson published the book Three minutes off Okinawa recounting the terrifying incident.

Another destroyer, USS Jeffers, managed to blast down one of the same mysterious aircraft that had slammed into Abele—but was nonetheless badly damaged in the ensuing explosion.

This was one of the first strikes involving a terrifying a new weapon: a rocket-powered aircraft deployed in the air by a larger bomber mothership to launch a one-way attack on ships below. In other words, a cruise missile with an expendable human serving as the guidance system.

This Kamikaze missile had been designed at the Imperial Japanese Navy’s Yokosuka Naval Air Technical Arsenal, and was designated the MXY-7 Ohka (“Cherry Blossom.”)  The idea behind the stubby-winged Okha Model 11 was that Japan’s Kamikaze pilots were expending valuable combat aircraft, and too many were being intercepted before they could reach their targets.  The Cherry Blossom promised to be cheaper but harder to hit.

The Ohka’s three Type 4 rocket boosters allowed the manned missile to jet at 400 miles per hour in level flight—not bad—and attain up to 600 miles per hour in dive, far faster than any fighter then in service.  Furthermore, the Ohka wouldn’t require all the expensive components like landing gear a traditional aircraft incorporated to get pilots safely back onto the ground.  Instead, the Ohka’s carried a 1.25-ton ammonium-nitrate warhead—enough for even one Ohkas to sink a destroyer with a direct hit.

The only problem was getting the Cherry Blossoms into position, as the Ohkas had only enough solid-fuel propellant to fly about 20 nautical miles.  That often meant Allied fighters got to the lumbering twin-engine G4M2 ‘Betty’ bombers before they were within range to release their Ohkas.  On multiple occasions, entire squadrons of Bettys were shot down before they could get in range.  Allied pilots even nicknamed suicide craft ‘baka’, or ‘fools in Japanese.

Still, some Ohkas did get through.  The destroyer Hugh W. Hadley was so crippled by an Ohka attack she had to be decommissioned.  Another Ohka carved into destroyer USS Shea, penetrating clear through the ship’s bridge structure and passing out the other side into the water, killing 35 men and knocking out most of the ships guns and communication systems.

Altogether, Ohka attacks sank or heavily damaged seven ships—at t the cost of hundreds of Japanese pilots piloting the Ohkas and their bomber motherships.

Japan built 852 Ohkas all told, and even had plans to launch Ohka’s off the side of coastal cliffs, in the event of a U.S. invasion of Honshu and Hokkaido.  There were more sophisticated models in the works, including two-seat trainers and a thermo-jet powered Model 22 that could fly further on its own power, and could be carried by faster P1Y1 Ginga bombers, improving chances of evading interception prior to launch.  Though 50 Model 22s were built, none entered service.

There was also a turbojet-powered Ohka Model 33 designed for launch from a four-engine G8N1 Renzan strategic bomber, a Model 43 with folding wings designed for catapulting off of submarines, and a second turbojet-powered Ohka Model 53 designed to be towed behind an aircraft, instead of carried underwing.  None ever saw action.

Records also suggest a non-suicidal bomber interceptor variant of the Okha called the Suzuka-24 was also built, ditching the warhead for two 20-millimeter cannons.  These were twice launched at U.S. B-29 bombers over Japan, without successfully hitting them.  At least, reports indicate their pilots survived.

By then, Germany and the United States were already employing the first remotely-guided anti-ship cruise missiles and suicide drone aircraft—basically, Ohkas that did not require human sacrifice. But in the final stages of World War II, Japan was in no position to develop, mass-produce and operationally deploy such weapons, and was compelled to sacrifice the lives of its young men instead.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.