The Mitsubishi Ki-15 (codenamed "Babs" by the Allies) was a light-class aircraft of the Japanese Empire, utilized in both bombing and reconnaissance roles throughout the latter half of the 1930s and into the early part of the 1940s. For its time, it was an all-modern aircraft with good performance and seen with aerodynamic refinements throughout including a faired over undercarriage and enclosed cockpit. While still in service when World War 2 began in September of 1939, it was quickly superseded by more modern types coming online into the 1940s. Production was limited to about 490 aircraft serving with Japanese Army and Navy forces. A few fell to the Chinese in the post-war years.
In 1935, the IJA requested a new, modern, fast-plane for the reconnaissance role and Mitsubishi delivered with its Ki-15 prototype. The aircraft featured a slim, rounded fuselage containing the engine in a front compartment, the cockpit over midships, and a conventional tail unit at rear. The engine was a large radial installation driving a two-bladed propeller unit. The cockpit was a two-man, tandem-seat design with a long-running greenhouse-style canopy. The tail unit incorporated sole vertical tail fin and low-mounted horizontal tailplanes. The main wing appendages were low mounted ahead of midships. The undercarriage was fixed and of the tail-dragger configurations while the main legs were spatted over in large, tear-drop style fairings for aerodynamic cleanliness. Construction included use of stressed skin metal. The overall design of the Ki-15 was indeed consistent with high-speed performers of the period emerging from Britain, Germany, France, and the United States.
Power was initially from a Nakajima Ha.8 series radial piston engine developing up to 750 horsepower. Performance included a maximum speed of 298 miles per hour with a cruising speed of 200 miles per hour. Range was out to 1,500 miles and its service ceiling peaked at 37,400 feet.
As with other early Japanese combat aircraft, the Ki-15 was minimally armed, standardized with a sole 7.7mm machine gun. It could carry a conventional bomb load of up to 550lbs.
A prototype Ki-15 made a first flight during May 1936 and subsequent flight testing proved the design sound. It was a stable mount, good at the controls, and quite fast for the time - reaching speeds near 300 miles per hour. Convinced of its potential, the Japanese Army ordered the prototype into serial production during May of 1937 under the designation of "Army Type 97 Command Reconnaissance Plane Model 1". Deliveries totaled 437 examples.
The Second-Sino War pitted Japan against China and officially spanned from 1937 to 1945 - though minor fighting had been occurring since 1931. As such, all manner of military weaponry was pressed into service during the conflict including the new Ki-15. The Ki-15 was able to out fly all existing Chinese Air Force aircraft and was utilized in the bombing and reconnaissance roles where her speed could be of good value.
By September of 1939, with the war still progressing, the Ki-15 line was improved through the Ki-15-II variant which incorporated the Mitsubishi Ha-26-1 series radial of 900 horsepower. The extra horsepower output improved performance even more while its more contained dimensions improved pilot views over the long nose during flight and ground running. The IJN ordered the modified type through 20 examples as the "Navy Type 98 Reconnaissance Plane Model 1". In time, another re-engined form emerged with a Nakajima Sakae12 series radial engine and 30 of these were taken on by the IJN as dedicated fast reconnaissance mounts.
The Ki-15 line soldered on into the fighting of 1943 before it was given up as a primary frontline participant. Its direct replacement emerged as the Mitsubishi Ki-30 back in 1938 while the Ki-15 was forced to take on more secondary roles such as that of training and local defense support - its days as a premier mount now over. Remaining stocks were also pressed into desperate service as kamikaze strike aircraft into the closing months of the war. Mitsubishi engineers still attempted to further the line with another re-engined version (Mitsubishi 102 radial of 1,050 horsepower) through the "Ki-15-III" but testing of this prototype did not secure further orders for the Japanese military.
Some Ki-15s were captured and reused by Chinese forces as primary trainers following the war. These final forms were not given up until 1951.