Kawasaki Ki-48 "Lily" — Army Type 99 Twin-Engine Light Bomber

The Kawasaki Ki-48 (Allied codename "Lily", 九九式双軽爆撃機, Kyūkyū-shiki Sōkei Bakugekiki) was the Imperial Japanese Army's standard twin-engine light bomber from 1940 through the final stages of the Pacific War. Designed by Takeo Doi, the Ki-48 underwent continuous aerodynamic and structural refinement across its production variants, driven by hard lessons from combat deployment in China and the Pacific theater.

This Living Collection consolidates the surviving primary-source documentation: original Japanese technical logs, post-war Allied intelligence evaluation reports compiled by the U.S. Strategic Bombing Survey (USSBS) and the Technical Air Intelligence Center (TAIC), and engineering bulletins covering mid-war survivability retrofits.

Collection Contents

Variant Model 1-2 — Ki-48 (Models 1 & 2)

• Ki-48 Operating & Maintenance — Kawasaki Ki-48 Model 1 and Model 2 Type 99 Supplementary Diagrams and Attachments Instruction Manual, 飛行機教程案 · 九九式双軽爆撃機（一型二型）附図 · Japanese Language

No Variant — Common Documents

• Ki-48 Slides, Photos & Brochures — Ki-48 Photographic Collection · English Language

Primary Technical Documents

Captured documents translated and cataloged post-war by the USSBS and TAIC:

• Tokorozawa Army Air Maintenance School Operating Manual (October 1944) — USSBS Index Section 2, Report No. 15n(13). Covers flight preparation, weight distribution, and system operation for Models 1 and 2.
• Japanese Aircraft Manual — USSBS Report No. 1o-10, Section 2, Frame Numbers 157–160. Schematic lookups and maintenance instructions for field mechanics.
• TAIC Manual on Japanese Aircraft — Report No. 9-a-43, USSBS Index Section 6, Frame Numbers 123–126. Allied flight-testing intelligence summary for the Ki-48 airframe.

Aerodynamic & Stability Studies

• Prototypes (1939): Initial trials revealed severe tail flutter deficiencies. Five pre-production models were built to trial varying tailplane geometry adjustments before serial manufacture.
• Model II Fin Extensions (1942): Dorsal fin extension and slight fuselage lengthening to improve directional stability and counter yaw under increased payload.
• Model IIb Dive-Brakes: Structural wing reinforcements to support retractable ventral dive-brakes outboard of the engine nacelles.

Engine Technical Notes

Performance Data

• Maximum Speed: 480 km/h (298 mph) at 3,000 m (Model I) · 505 km/h (314 mph) at 5,600 m (Model II)
• Climb Performance: 5,000 m (16,405 ft) in 10 minutes
• Service Ceiling: 10,100 m (33,136 ft)
• Maximum Range: 2,400 km (1,491 miles)
• Bomb Load: Standard 400 kg (882 lb) internal · Structural maximum 800 kg (1,764 lb) on Ki-48-II

Engineering Bulletins — Survivability Retrofits

• Crew Armor: 12.5 mm plate behind bombardier · 6.5 mm plate under pilot's seat · 16.5 mm plates protecting ammunition reserves.
• Fuel System Safety: Replacement of unprotected wing fuel cells with leak-resistant laminated rubber self-sealing tanks.

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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