Imagine that this is 1945, but a different world, a counterfactual 1945. World War II was in full swing; the U.S. strategic bombing campaign continued to increase in intensity as its efforts to deny its enemy the means to wage total war encountered increasingly determined resistance. Now, all of a sudden, American forces are coming up against radically new and dangerous foreign aircraft. Generations of exotic, high-performance propeller-driven aircraft are challenging the best the U.S. can produce. More ominously still, revolutionary jet-powered and rocket-powered fighters are cutting a swath through American bombers and fighters while sophisticated guided missiles pound home against the Allies. These last-minute “wonder weapons” are changing the momentum of the war and threaten to prolong this deadly conflict or even overturn what was widely seen as a decided Allied victory. Is this the technologically advanced Germany of countless “what-if” historians? No, it’s Japan as it would have looked if more of its intended new weapons had succeeded in rising high enough in the sky in enough numbers to tilt the exile.
Thankfully for the Allies, the above scenario didn’t happen. In reality, Japan was running out of raw materials, skilled manpower, and time. Nevertheless, the final months of the war found it developing a host of new advanced aircraft, in one last burst of creative effort with the hope of stopping the relentlessly encroaching Allies. Faced with the challenges offered by superb American fighters and bombers, Japanese aircraft manufacturers first designed modifications to existing designs, then new aircraft, which incorporated high-powered, turbo- and supercharged engines at least comparable or superior to America’s best efforts. Already in service with the Imperial Japanese Army Air Force was the Nakajima Ki-84, known to the Allies as Frank, a fighter of the first rank that, at its best, could hold its own against the North American P-51D over China and the Philippines. However, if Japan was to successfully counter the increasing Allied threat, particularly from the B-29s that pounded the heart of the country, better aircraft were needed now.
Into this mix, the Nakajima Aircraft Company entered the fray with the Ki-87, an equally single-seat, turbosupercharged, heavily armed, high-altitude fighter powered by 2,400 horsepower, that could reach 440 miles per hour. It might be mentioned that the engine was a drawback, and it produced only one prototype that was made into production before the war ended. Running concurrently, Tachikawa came up with an improved version of the fighter, the Ki-94-II, looking very similar and capable of an estimated top speed of 450 miles per hour. This was good enough for an order to be placed for 18 service test aircraft, but by this time the first flight had been scheduled for August 18, 1945 – three days after Japan’s surrender.
There were many other advanced propeller-driven fighters under construction or on the drawing board from Kawasaki and Mitsubishi during this time. But of course probably the most interesting of them all was the Kyushu J7W1 Shinden, a canard design driving a six-bladed pusher propeller built for the Imperial Japanese Navy. Besides its engine’s being in the rear and keeping its elevators in the nose, the J7W1 was the lone canard ascent to production in the order of all combatants through the war. It was Navy Captain Masaoki Tsuruno who had conceived the idea: he hoped that, when developed, the jet engine would replace the 2,130 horsepower Mitsubishi 18-cylinder radial. In the meantime, construction was authorized in June 1944 for this sorely needed high-altitude fighter. The prototype was ready 10 months later. Unfortunately for Japan, engine and propeller vibration problems delayed flight tests until early August 1945, so only two were built. With a projected top speed of 466 mph, the Shinden would be expected to represent quite a force to be reckoned with, and the jet-powered one even more so.
It seems that there was no part of aircraft development in which Japanese engineers were not open to tweaking and changing, and jet technology was certainly no exception to that rule. In September 1944, design work began on the Nakajima Kikka, the only Japanese wartime jet to take to the skies. Loosely based on the outline of the Me 262, the Kikka was smaller and built with folding wings to hide in caves. When the Ne-12 turbojet engines proved incapable of developing sufficient thrust, imaginative engineers designed and built the Ne-20, based simply upon photographs of the German BMW 003. One hundred and forty-seven pounds of thrust apiece were provided in the Kikka with two engines, giving the aircraft the requisite top speed of 435 miles per hour. The first flight for the Kikka came on August 7, 1945, another example of “too little, too late.”. A second prototype was also built but never flown with 18 others under construction. A faster version was envisioned with two Ne-130 engines, which were to produce twice the thrust, but the war ended before tests were made.
Perhaps even more threatening to the Allies, the Japanese undertook to introduce rocket-powered interceptors. Towards the end of 1943, the Japanese high command raised concern over the imminent danger posed by Boeing B-29 Superfortresses. Aware that Japan did not have an interceptor capable of attacking B-29s at over 10,000 meters, Japanese Military Attaches in Berlin obtained production licenses for the revolutionary Messerschmitt Me 163 rocket-powered interceptor and its Walter HWK 109-509 engine. The Me 163 was capable of flying 596 miles per hour—almost 200 miles per hour faster than any Allied fighter—and had a climb at the most incredibly steep rate of 10,000 feet per minute. Being hampered by short-range, 10-minute duration, the Me 163 seemed to be the remedy for the B-29 problem.
The plans for the Me-163 had been shipped on two U-boats; one of them was sunk and the Japanese military had to make do with just rudimentary data. Not to be put off, in July 1944 the Japanese Navy ordered Mitsubishi to develop their version of the aircraft designated the J8M; and in a rare example of interservice cooperation, an Army variant known as the Ki-200. Engineer Mijiro Takahashi led the project to produce a glider version, by December. The glide tests proved successful and the first J8M was completed in June 1945. The first flight of the aircraft ended in a fatal crash and modifications to the propulsion system were not completed before the war ended.
From October 1944 onwards, during the U.S. liberation of the Philippines, and thereafter up to the conclusion of hostilities, the Allies faced a lethal and potent new weapon: the kamikaze. Hundreds of Japanese pilots volunteered to sacrifice their lives by sending bomb-loaded planes to American and British naval forces. The Kamikaze were duly guided missiles with a control system of a computer– a human being. Most were the standard fighters and bombers, but the Japanese Navy also fashioned the Ohka Model 11, a rocket-powered, human-guided, flying bomb that was meant to be released from a Mitsubishi G4M “Betty” bomber under which it would travel until close to the target in the U.S. fleet. Released from the bomber, the Ohka pilot would glide down, turn on his rocket engine, and dive into his target: it was a simple pill. Few Ohkas ever made it near the U.S. fleet as patrolling U.S. fighters shot most of the “Bettys” down before they could get in range to launch their Ohkas.
To address this shortcoming, the Japanese Navy finally commissioned a design of an extended-range jet-powered model to be named the Ohka Model 22. Powered by a Tsu-11 primitive turbojet, the Model 22 was intended for vibratory flights under a Yokosuka P1Y1 bomber into battle—a lot swifter than the Betty. Hoped to make up for this and the added range of the Model 22 to launch attacks before the U.S. sea fighters on patrol. Only fifty Ohka Model 22s were ever built, and none were launched in anger. A refinement, the Model 33, was to have the more powerful Ne-20 turbojet for extra speed and range; the Nakajima G8N1 “Rita,” a massive four-engine heavy bomber then under development, was to carry the Model 33. Upon the completion of neither the Model 33 nor the “Rita,” however, these visions eventually faded. Behind the scenes, while the Japanese aviation industry busily churned out new, more technologically advanced aircraft and weapons, a lack of materials and skilled workers forced the industry and the military to try more elementary ideas. With this in mind, in January 1945, the Japanese Army ordered Nakajima to create a simple and easy-to-build suicide aircraft that could be mass-produced in large enough quantities to forestall the coming Allied invasion of Japan. The prototype Ki 115 Tsurugi, built of wood and steel, was capable of using a variety of existing radial engines and had been completed in only three months. It could carry a 1,700-pound bomb and jettison its landing gear for its one-way flight. Poor ground handling and difficult flying characteristics took three months to solve, and although 104 were built, none flew in combat.
A part of this was a fear of the potential capabilities and success of these “wonder weapons”: the limitless potential of what might be possible should these aircraft have entered service. However, the aims of the relentless B-29 bombing/mining campaign by the Allies, combined with the extraordinarily successful naval blockade, cut off Japan’s vital fuel, and resources, and destroyed Japanese factories and infrastructure—thereby rendering the fate of Japan’s wonder weapons moot.
A number of these fascinating aircraft are fortunate to have been preserved by the Smithsonian’s National Air and Space Museum. A few of these include but are not limited to, the sole surviving example of a Kyushu J7W1 Shinden, the last Nakajima Kikka, the only Ohka Model 22, and one of four remaining Nakajima Tsurugis.