Imagine 1945 in which, to a great many throughout the world, the end of World War II was considered anything but a sure thing. Strategic bombing was becoming a bloody business for American fliers as raiding planes met an unexpectedly stern reception of radically new and dangerous aircraft. High-performance propeller-driven planes and revolutionary jet and rocket fighters were beginning to meet death and destruction on American bombers and fighters. These so-called “wonder weapons” based on last-minute technologies could have increased the longevity of the deadly conflict, not to say turn the then agreed-upon victory for the Allies into defeat. As it turned out, in short, the not-so-high-tech Germany of legend but Japan itself could have been if the country had been able to deploy its new weapons in sufficient amounts.
At the end of the day, this wasn’t the case. Japan was short of raw materials, skilled personnel, and time. But by the final months of the conflict, Japan was designing a flock of super-planes in the desperate expectation of stopping the inexorable advance of the Allies. Early in the war, Japanese airplane designers adapted earlier designs and produced new plane types with high-powered, turbo- and supercharged engines equal to or better than the best that America had. The Imperial Japanese Army Air Force had service votes on the Nakajima Ki-84 (Allied name Frank), a fighter roughly equal to the North American P-51D, both in China and the Philippines. Japanese aircraft would need one last push, however, to have any hope of countering the growing Allied threat to Japan, particularly the B-29s striking at the heart of the country.
Advanced Propeller-Driven Aircraft
The threat was to be countered by Nakajima Aircraft Company’s Ki-87, a heavily armed and armored high-altitude fighter with a 2,400 horsepower turbo-supercharged engine; the 440 mph top speed never really materialized due to engine problems, and the type was delayed in reaching the production stage, only one prototype built. The Ki-94-II manufactured by Tachikawa had an estimated top speed of 450 mph. An order for 18 service test aircraft was placed, but the first flight would have taken place on August 18, 1945, three days after hostilities had ended.
Among the more promising designs was the Kyushu J7W1 Shinden, a canard design driving a six-bladed pusher propeller built for the Imperial Japanese Navy. With its engine in the rear and elevators in the nose, the J7W1 was the only canard design ordered into production by any combatant during the war. Navy Captain Masaoki Tsuruno hoped that a jet engine could eventually replace the 2,130 horsepower Mitsubishi 18-cylinder radial. Construction was authorized in June 1944, and the prototype was ready 10 months later. But engine and propeller vibration problems delayed flight tests until early August 1945, so only a couple were ever built. With an estimated top speed of 466 mph, the Shinden would have been a serious match for most American planes, especially in its jet-powered version, following the designation of (J7W2).
Jet Engine Technology
Aircraft jet engine development was something that the Japanese engineers were also showing a positive interest in. The Nakajima Kikka design was started in September 1944. In the bigger picture, it was just a rough copy of the Messerschmitt Me 262, only a little smaller, plus the folding wings, so it could be hidden in caves. When the expected thrust of the Ne-12 turbojet engines did not materialize, the engineers designed the Ne-20 engines based on photographs that depicted the unknown German BMW 003. The two engines powering the Kikka resulted in a top speed of 435 mph, with each engine deriving 1,047 pounds of thrust. The first flight of the Kikka was on August 7, 1945, but it was another example of “too little, too late.” A second prototype was constructed but never flown, along with 18 more under construction. A faster model powered by two Ne-130 engines was envisaged, but the war drew to a close with rapidity before tests could take place.
Rocket-Powered Interceptors
In possibly a more threatening development to the Allies, the Nazis were working on a rocket-powered interceptor. The Japanese were so worried about the US bomber threat that, by late 1943, they had bought the manufacturing rights for the Messerschmitt Me 163 rocket-powered interceptor, and its Walter HWK 109-509 engine. The Me 163 had a top speed of 596 mph, with a climb rate of 10,000 feet per minute. Other than its short range and duration, 10 minutes, the Me 163 appeared well suited to countering the B-29 threat.
The plans for the Me-163 were sent on two U-boats; one made the journey, and another did not. This also meant the Japanese military was left with basic data only. Not deterred by this, in July 1944, the Japanese Navy ordered Mitsubishi to go ahead with a development of its own, from the beginning designated the J8M, with an Army variant known as the Ki-200. Under engineer Mihiro Takahashi’s leadership, the team generated a glider version by December. Glide tests were successful, and the first J8M was completed in June 1945. On its first flight, however, the aircraft ended up crashing and killing the pilot, and further modifications to the power plant were not ready before the end of the war.
Kamikaze
From October 1944, during the U.S. liberation of the Philippines, to the end of the conflict, the Allies faced a deadly new weapon: the kamikaze. Hundreds of Japanese pilots volunteered to commit self-sacrifice and lose their lives by directing bomb-laden airplanes onto the Allied naval forces. The kamikaze were, in effect, guided missiles controlled by a sophisticated computer, a human being. Most of the aircraft were conventional fighters and bombers, but the Japanese Navy also designed the Ohka Model 11, a rocket-powered, human-guided flying bomb meant to fly below a Mitsubishi G4M “Betty” bomber until it came within sight of the U.S. fleet. When released from the bomber, the pilot of the Ohka would glide down with the base, ignite the rocket engine, and dive into the target. Very few Ohkas ever made it near the U.S. fleet as patrolling U.S. fighters shot down most of the “Bettys” before they could launch their Ohkas.
For this reason, the Japanese Navy requested a follow-on version with greater range, powered by a jet engine, to be developed in a project named Ohka Model 22. This was to be towed under a Yokosuka P1Y1 bomber, which could still fly faster than the Betty and utilized the Tsu-11 rudimentary turbojet as the power plant. The hope had been, of course, that the speed of the P1Y1 and the extra range would indeed allow the attacks to be initiated outside of patrolling US naval fighters. In the end, fifty Ohka Model 22s were built but none were ever launched. An advanced model, the Model 33, was to carry the more powerful Ne-20 turbojet for increased speed and range. This was to be carried aboard a gargantuan four-engine heavy bomber then under design: the bomber that was to be the Nakajima G8N1 “Rita.” Neither the Model 33 nor the “Rita” ever got completed.
As Japan’s aviation industry rushed forward, with new, more technologically advanced aircraft and weapons manufacture, a serious shortage of materials and skilled workers soon pressed both the industry and the military into developing still more elementary ideas. In January 1945, the Japanese Army ordered Nakajima to create a simple, easy-to-build suicide aircraft that could be mass-produced in enough numbers to stop the coming Allied invasion of Japan. It was constructed of wood and steel, and was capable of using a variety of existing radial engines; the prototype was produced in only 3 months. The Ki-115 Tsurugi was able to carry a 1,700-pound bomb and jettison its landing gear for its one-way flight. In 3 months, it was able to solve the problems of poor ground handling and difficult flying characteristics. Although 104 were built, none flew in combat.
The potentials of these wonder weapons and their achieved success were just too awful; what would become of the world if those aircraft had gone into service? However, this bombardment raid and the naval blockade, which surpassed the wildest prediction in its successes, starved the last reserves of fuel and resources that Japan had to have, while also wiping out the remainder of Japanese factories and infrastructure, making the fate of Japan’s wonder weapons nugatory.
Many of these are now on display at the Smithsonian’s National Air and Space Museum, which is fortunate to hold in its inventory the last surviving Kyushu J7W1 Shinden, the sole surviving Nakajima Kikka, the only surviving Ohka Model 22, and 1 of 4 surviving Nakajima Tsurugi’s among several other Japanese artifacts.