Kawasaki Ki-32 "Mary" — Army Type 98 Light Bomber

The Kawasaki Ki-32 (Allied codename "Mary", 九八式軽爆撃機, Kyūhachi-shiki Kei Bakugekiki) holds a singular place in Imperial Japanese Army Air Force history as the last IJAAF light bomber to use a liquid-cooled inline engine. Designed at Kawasaki's Kagamigahara bureau and entering service in 1938, the Ki-32 served extensively in the Second Sino-Japanese War before being superseded by more modern types.

Due to the deliberate destruction of IJAAF technical archives in August 1945, surviving primary documentation for the Ki-32 is exceptionally rare. This Living Collection consolidates the most significant surviving artifacts: the original 1939 manufacturer operating handbook — indexed post-war by the U.S. Strategic Bombing Survey (USSBS) as Report No. 15n(11) and preserved by the National Diet Library of Japan (PID: 8815752) — together with the Ha-9 engine manual and photographic archive.

Collection Contents

No Variant — Common Documents

• Ki-32 Operating & Maintenance — Kawasaki Ki-32 Type 98 Light Bomber Instruction Manual · 川崎キ32 九八式軽爆撃機説明書 · Japanese Language · Imperial Japanese Army Air Headquarters (Rikugun Koku Honbu) · September 1939 · USSBS Index Section 2, Report No. 15n(11)
• Ki-32 Engine — Kawasaki Ha-9 Type 95 Aircraft Engine Instruction Manual · 九五式ハ〇〇馬力發動機説明書 · Japanese Language
• Ki-32 Slides, Photos & Brochures — Ki-32 Photographic Collection · English Language

Engine Technical Notes — Kawasaki Ha-9-IIb

The Ki-32 was powered by the Army Type 98 (Kawasaki Ha-9-IIb) — a V-12 liquid-cooled piston engine and the last of its type to power an IJAAF light bomber.

• Take-off Power: 850 hp (634 kW)
• Sea Level: 775 hp (578 kW)
• Maximum Rating: 950 hp (709 kW) at 12,470 ft (3,800 m)
• Engineering History: March 1937 flight tests revealed chronic crankshaft failures. Emergency Kawasaki bulletins mandated crankshaft reinforcement, delaying deployment relative to the competing radial-engined Mitsubishi Ki-30.
• Combat Vulnerability: Coolant lines and radiators were highly exposed to ground fire; cooling system punctures caused rapid engine seizure and were a primary source of combat losses.

Performance Data

Handling, Stability & Aerodynamic Notes

• Dive-Bombing Capability: Mid-wing monoplane with internal bomb bay. 1937 IJAAF competitive trials confirmed superior structural rigidity over the Ki-30, permitting safe dive-bombing runs at angles up to 60 degrees.
• Fixed Undercarriage: Wide-track fixed cantilever gear with open-sided wheel fairings — continuous drag penalty on top speed, but highly stable and forgiving on unpaved forward airfields in China.
• Archival Note: Formal aerodynamic stability studies (elevator/rudder moment coefficients) from the Kagamigahara design bureau are considered lost. Surviving data derives from 1939 Army performance evaluation sheets and post-war USSBS compilation.

Primary Archival Sources

• National Diet Library (NDL), Japan — Digitized USSBS microfilms; search Japanese designation 九八式軽爆撃機 (PID: 8815752)
• National Institute for Defense Studies (NIDS), Tokyo — Surviving Imperial Army administrative and technical combat logs
• Smithsonian NASM — Captured Japanese technical manuals cataloged by U.S. military intelligence post-WWII

This is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.

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