Mitsubishi Ki-30, part three

The Mitshubishi Ki-30 was designed and developed in response to an Imperial Japanese Army specification issued in May 1936 for a replacement of the Kawasaki Ki-3 light bomber. The scope of the issue was to replace it with a complete indigenous bomber both in design and manufacture.
Both Mitsubishi and Kawasaki were requested to build two prototypes each by December 1936. The specification requested a top speed of 400km/h (250mph) at 3000m (9840ft) high, a normal operating altitude from 2000m (6560ft) to 4000m (13130ft) high, the ability to climb to 3000m in 8 minutes and an engine which had to be either the 850hp Mitsubishi Ha-6, the 825hp Nakajima Ha-5 or the 850 Kawasaki Ha-9IIb, all of them radial and liquid cooled. The requisition also requested a normal bomb load of 300kg (660lb), with a maximum of 450kg (990lb), one forward-firing machine gun and another rearward-firing one in a defensive position with the ability to perform 60º dives for dive bombing and a loaded weight less than 3300kg (7280lb).
The first Mitsubishi prototype flew on 28th February 1937 and was powered by the Mitsubishi Ha-6 radial engine which drove a three-bladed propeller. It was originally designed with a retractable landing gear but the wind tunnel tests showed that the gain in speed was marginal due to the landing gear's extra weight. Therefore a fixed and spatted main wheels system arrangement was chosen instead. The wing was mounted at a point above the line of the aircraft's belly to fully enclose the bomb bay within the fuselage. The pilot sat just above the leading edge of the wing and the rear gunner/radio-operator just behind the wing trailing edge, in a long canopy which gave an excellent all-around vision.
A second prototype was completed the next month, this time fitted with the slightly more powerful Nakajima Ha-5 engine. Both were completed two months behind schedule and were overweight, however, both of them met or exceded the requirement's minimum specifications. As the second prototype could achieve a top speed of 423km/h (263mph) at 4000m high, the Imperial Japanese Army Air Force placed an evaluation order of 16 exemplars. Those were delivered in January 1938 and, after passing trials, the Army ordered the Ki-30 into production in March under the designation of Army Type 97 Light Bomber.
A total of 704 Ki-30s were built. Most of them, 636, were built by Mitsubishi Heavy Industries at the city of Nagoya from February 1937 until April 1940 and the 1st Army Air Arsenal --AKA Army Air Supply Workshop-- located at the city of Tachikawa manufactured 68 exemplars from 1939 until September 1941 when production of the type ceased.
The Ki-30 was used in combat for the first time in the Second Sino-Japanse War in spring 1938. It showed enough reliability to operate in rough airfields and it was highly effective when operated escorted by fighters. This success continued in the early stages of the Pacific War and the type saw extensive use in the Invasion of the Philippines. However, once unescorted, their losses quickly mounted up and the type was withdrawn to second line duties. During 1942 they served in the China-Burma-India Theatre of War, operating from Thailand. Anyway, by the end of 1942 the type was deemed as obsolete and was relegated to training roles only. Many of them were used as kamikaze aircraft towards the end of the war.

Sources:
1. https://en.wikipedia.org/wiki/Mitsubishi_Ki-30
2. https://www.valka.cz/Micubisi-Ki-30-Ann-t1289
3. The Hamlyn Concise Guide To Axis Aircraft Of World War II