The Martin Model 187 Baltimore — designated A-30 by the USAAF — was a twin-engine light attack bomber that served as one of the most capable tactical aircraft of the Mediterranean and Middle East theatres in World War II. Developed as a direct evolution of the Martin Maryland, the Baltimore featured a deeper, narrower fuselage, heavier armament, and a more powerful powerplant, making it a formidable low-level attack platform. Online Aviation Library has assembled the surviving primary-source technical documentation spanning the full Baltimore family, from the earliest Mk I Pilot's Notes through the joint USAAF/RAF flight operating instructions covering all marks.

What This Collection Covers

Pilot's Flight Operating Instructions (USAAF / Joint)

• A.P. No. 2017A TO E — Pilot's Flight Operating Instructions for Army Models RA-30-MA, A-30A-MA and British Models Baltimore I to V. Published under joint authority. Dated 30 August 1943. Formerly classified Restricted. Printed by Motschall Co., Detroit (2500 copies, 11-29-43). Notice: this document contains information affecting the National Defense of the United States within the meaning of the Espionage Act, 50 U.S.C., 31 and 32, as amended.

RAF Pilot's Notes — Air Publication 2017A

• Air Publication 2017A — Pilot's Notes — The Baltimore I Aeroplane, including II and III. Two Double-Row Cyclone GR,2600 A.5.B-5 Engines. Reference: B.A.C./5.41/G.L.M.C. Black cloth-bound RAF Pilot's Notes format — the standard British aircrew pocket reference for the Baltimore I/II/III.
• Air Publication 2017A, Volume I — The Baltimore I, II & III Aeroplane. Two Double-Row Cyclone GR-2600 A5B-5 Engines. Dated October 1941. The earliest surviving primary-source volume of the AP 2017A series — issued within months of the Baltimore's entry into RAF service.
• Air Publication 2017A — Pilot's Notes (Fixed Copy) — The Baltimore I, II & III Aeroplane. Two Double-Row Cyclone GR-2600 A5B-5 Engines. Dated October 1941. A second surviving copy of the AP 2017A Pilot's Notes, preserved with minor condition variations — useful for cross-referencing page states and revision markings.

Aerodynamic Reports

• Deep fuselage cross-section design: narrowed and deepened relative to the Martin Maryland to facilitate intra-crew movement, at the cost of increased frontal area
• Mid-wing cantilever monoplane construction optimizing high-speed structural rigidity
• High wing loading: designed for structural efficiency, resulting in higher touchdown speeds than contemporary light bombers
• Compressibility testing: post-war, the US Navy utilized the Baltimore's clean aerodynamics for control surface testing, pushing the airframe to a maximum dive speed of Mach 0.74

Engine Technical Notes

The Baltimore was powered by two Wright GR-2600-A5B Double Cyclone 14-cylinder, air-cooled radial engines producing 1,700 hp (1,268 kW) each. Documentation covers:

• Geared reduction drives with constant-speed, fully feathering propellers optimizing thrust across altitude bands
• Close-fitting NACA cowlings with adjustable trailing-edge gills balancing engine cooling against parasitic drag
• Torque management procedures for the high power-to-weight ratio configuration

Handling & Stability Studies

• Directional instability: the high torque of the Wright R-2600 engines relative to gross weight created severe directional stability problems during takeoff
• Ground-looping tendency: prone to sudden swing on takeoff if throttle application was asymmetric or too rapid
• Single-engine safety speeds: high minimum control speeds demanding immediate pilot correction during powerplant failure
• Glenn L. Martin Company Report 408: static structural tests applied to the vertical fin to guarantee rudder control authority during extreme aerodynamic loads

Engineering Bulletins

• Crew safety restrictions: bulletins noting the narrow fuselage cross-section made it extremely difficult for an injured crew member to escape or shift positions mid-flight
• Fuel range modifications: engineering provisions for auxiliary fuel tank installation in the bomb bay, converting the tactical bomber into a long-range reconnaissance or ferrying platform
• Armament upgrades: production block progression (Mk I to Mk V) standardizing defensive layout revisions from open flexible steps to specialized twin-gun powered dorsal turrets

Performance Data Reference

Document Manifest

⚠️ Regulatory Notice: Under FAA 14 CFR § 43.13 and EASA Part-M, any mechanic performing maintenance on an active aircraft must use current, manufacturer-approved revision-controlled data. This archival document does not satisfy that requirement.

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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