In 1943, the Allied island-hopping campaign was underway and in 1944 the Japanese would see their island outposts, bases and strongholds destroyed and lost to them forever. In 1945, the Japanese lost their holdings in Burma, Borneo, Iwo Jima and Okinawa. Japanese military planners had no doubts that the Allies would continue their progress and land forces on the main islands of Japan. The Allies did indeed have such a plan known as Operation Downfall. The Japanese, to defend against the invasion they felt was coming, put into motion Ketsugo Sakusen or Operation Decision.
Operation Decision’s main component was the use of shimpu and shimbu missions targeting the Allied naval force, specifically landing craft, troop ships and support ships. To repel the invaders, all manner of craft were assembled for the Japanese defender of kokutai, the national polity of self sacrifice. Midget submarines such as the Kairyu, Koryu and the crude U-Kanamono, the Kaiten human torpedo, small explosive laden powerboats like the Maru-Ni (IJA) and Shinyo (UN), and even frogmen (the Fukuryu) were prepared for the final showdown. Even the best tanks, the Type 3 Chi-Nu and Type 4 Chi- To, were held in Japan to counter Allied armour. Aircraft would also play a significant role in the defence of Japan. It was estimated that 10,000 aircraft of every type would be available to throw at the Allied invasion fleet. It was thought that the mass wave tactics would result in a tremendous loss of aircraft which the Japanese industry in 1945 would be unable to keep pace with unless steps were taken to remedy such a situation. The Та-Go was one such remedy.
By 1945, Japanese industries were under regular bombardment from US airpower. In
addition to war factories being razed to the ground, Japan was being starved of materials needed to sustain weapon production. Aluminium was a key material in aircraft production and it was estimated that by December 1945, even with strict control, the supply of this metal would be exhausted. Consequently, wood was to become the main material for aircraft construction, regardless of the type of aircraft concerned. Examples included the Tachikawa Ki-106 (a wooden version of the Nakajima Ki-84 Hay – ate) and the Kugisho D3Y Myojo (which was the wood derivative of the Aichi D3A Val). With the loss of heavy industrial machinery, it fell more and more to smaller workshops to produce components and sub-assemblies for aircraft. Often the labour force was not as skilled as before and working with wood was easier as it did not require the sophisticated tools and jigs necessary for construction of more conventional aircraft using metal components.
Captain Yoshiyuka Mizuyama, an officer in the IJA’s aviation equipment section, was the man behind the Та-Go (Та being short for take-yari, or bamboo spear). It was his desire to design and build a plane that was simple in constmction, used the bare minimum of war critical materials and could be produced rapidly. By doing so, the Та-Go could quickly populate the aircraft pool available to units destined for shimbu missions and also replenish losses in short order. He hoped that the Та-Go could be used to defend the seaside cities of Osaka and Kobe. In an effort to help realise the Та-Go, Mizuyama approached the Tachikawa Hikoki K. K. with his concept. Despite Mizuyama being an IJA officer, Tachikawa refused to assist him as his plan had no official sanction and was not
approved by the Koku Hombu. As such, Tachikawa could not spare the capacity to develop the aircraft.
Undeterred, Mizuyama discovered a small shop in the city of Tachikawa within which he and his fellow men went about the task of designing and constructing the first prototype. Once the concept was completed, work began on building the Та-Go. Using wood lathes to construct the fuselage and other components, the aircraft was made from plywood while fabric was used for some of the skinning and coverings for the control surfaces. The pilot was given a simple acrylic glass canopy. Instrumentation was kept to the bare minimum. The landing gear was fixed. For a motor, a Hitachi Ha-13 Ко 9-cylinder, aircooled radial engine developing 450hp was selected, the cowling for it being made from plain sheet steel. The only armament was a single 500kg (1,1021b) bomb. In February 1945, the Та-Go prototype was nearly complete when Tachikawa was subjected to a bombing raid. In the ensuing attack, the shop was burnt to the ground and the Та-Go inside destroyed.
Despite the setback Mizuyama forged ahead, going to Nippon Kokusai Kogyo K. K. (Japan International Air Industries Co. Ltd.) to pitch his Та-Go. In the end the project was accepted and in part this may have been due to Kokusai’s experience with light aircraft such as the Ki-76 (known as Stella by the Allies) and the Ki-86 Ко (codenamed Cypress), the latter of which Kokusai had built as the prototype all-wood Ki-86 Otsu. Of course, Kokusai was not as heavily taxed by wartime demands from either the IJA or the UN and could thus allocate some assets to the development of the Та-Go. Despite Kokusai taking on the Та-Go project, it still remained an unofficial design and thus bore no Ki number.
Mizuyama’s design for Kokusai differed from the one he proposed to Tachikawa because the new version was significantly scaled down and much smaller. In so doing, this reduced the amount of assemblies needed to produce the aircraft which, by extension, lowered the man-hours required to build it. Fewer assemblies meant less use of construction materials. With the resizing, the Ha-13 radial became too large for the proposed airframe and so the Hitachi [Ha-47] 11 inline engine, rated at 1 lOhp, was selected as a replacement. This same engine was used in the Tokyo Koku Ki-107 all-wood two-seat trainer which was to be the replacement for the Ki-86 had the former made it into service.
In addition to the size reduction, steps were taken to simplify the Та-Go even more. Gone was the canopy and the pilot sat in a open cockpit with only a small acrylic glass windscreen as protection from the elements. For instrumentation, only the absolute basics were used consisting of a speedometer, altimeter, compass and the essential engine related gauges such as fuel and oil. The fuselage was slab sided and box shaped. While this granted easier construction, it was not the most aerodynamic design. Much of the fuselage used wood sparring and structure while the skinning was of plywood. The wings were low mounted with squared wing tips and they were hinged just outside of the landing gear to enable them to fold upwards to allow the aircraft to be hidden in caves as well as facilitate their construction within the confines of caves or small manufacturing lines. Both the vertical stabiliser and the horizontal stabilisers were rectangular in shape.
The landing gear was fixed, being made of steel tubing and fitted with rubber wheels, each gear supported by a single strut. To provide a modicum of streamlining the tubing that made up the landing gear was faired over using aluminium. The only measure of shock absorption came from the tyres and the tail skid, the latter also being built from steel tubing with a portion rubberised.
The [Ha-47] 11 engine was fitted with an angular plywood cowling, the engine driving a fixed-pitch, two-bladed wooden propeller. A metal engine mount was used while the fuel tank was situated on top of the engine and used a gravity feed system. Behind the tank and in front of the windscreen was a simple oil cooler, mounted flush in the fuselage. Given the much smaller dimensions of the revised Та-Go, it was no longer able to carry the 500kg (1,1021b) bomb Mizuyama’s original version was designed for. Instead, it could only carry a 100kg (2201b) bomb. The bomb was fitted to the underside of the fuselage and once in place could not be released by the pilot.
Mizuyama, with the assistance of his own men and Kokusai, had completed the first prototype of the new Та-Go by the middle of June 1945 and it was made ready for flight. On 25 June, the Та-Go took to the air for the first time with a Kokusai test pilot at the controls. Not surprisingly, the pilot reported handling concerns. After a number of additional test flights, revisions were made to the design. Once complete, Kokusai created a complete set of working blueprints for the production version. However, with the cessation of hostilities in August 1945, the Kokusai Ta-Go never entered production. The close of the war also saw the end of two Kokusai developments of the Та-Go, known as the Gi-Go and Tsu-Go. Both remain shrouded in mystery because no information on them has surfaced to date.
Ironically, Tachikawa would return to the Та-Go when the Gunjusho (Ministry of Munitions) authorised development of Mizuyama’s initial design following the completion of the Kokusai Та-Go prototype. The end of the war would find the Tachikawa Та-Go prototype incomplete. As a note, with the acceptance of the Та-Go by the Koku Hombu, a project number (meaning a Ki number) was assigned to the Та-Go – Ki-128. It has not yet been confirmed whether this Ki number applied to the Kokusai Та-Go, the Tachikawa Та-Go or both.
Та-Go – data
Messerschmitt P. l 104 Sprengstofftrager (Germany) Specifications are for the Kokusai Ta-Go.
Type Special Attack Aircraft
One Hitachi [Ha-47] 11,4-cylinder, air-cooled inline engine developing 1 lOhp for take-off driving a wooden, two-bladed propeller 7.1ft in diameter
One 100kg (2201b) bomb
None. A total of three Ta-Go aircraft were constructed: Mizuyama’s own prototype aircraft that was destroyed by fire prior to flight, the one built and flown at Kokusai, and the Tachikawa Ta-Go which remained incomplete at the end of the war.