The Martin Baltimore (Model 187) was a light-/medium-class bomber whose design developed from the Martin Maryland series aircraft. Despite it being an American design, the twin-engine, four-crew platform was never fielded by the United States war machine n World War 2. Its primary operator became the United Kingdom largely by way of Lend-Lease which allowed America to supply war goods to her Allies without formally entering the war. The Baltimore would see operational service fin the conflict from 1942 into the middle of 1945, covering various battlescapes such as North Africa, the Middle East and the European Theater. By the end of the war, nearly 1,600 examples would be in circulation under no fewer than six major production marks.
The Baltimore was developed under the A-23 designation following its origination from the preceding A-22, which served as the Martin Maryland (detailed elsewhere on this site). The A-23 was given a revised, deeper fuselage design for more internal volume as well as uprated engines to help improve performance and first flew on June 14th, 1941. While the initial customer for the A-23 was the French (the USAAC passed on the design), the Fall of France in May of 1940 precluded its deliveries and a resources-strapped Britain accepted the order. As such, the name of Baltimore was bestowed on the line and the name stuck with the design for the entirety of its service career. A-23s arrived in the latter portion of 1941 and were baptized in combat over the skies of the Middle East.
This mark was then followed by the Mk II which added two more 7.7mm machine guns, one to the trainable dorsal and ventral positions. 100 of the variant were produced.
The Mark III arrived by mid-1942 and featured a power-assisted Boulton-Paul dorsal turret which could be arranged with either quad (4) or dual (2) 7.7mm machine guns. The Mk III was also fitted with 2 x Wright GR-2600-19 "Cyclone" radial piston engines capable of 1,660 horsepower each providing the Baltimore with a maximum speed of over 300 miles per hour. Fuselage design made the Baltimore Mk appear very tall and narrow which restricted internal operating spaces for the four crewmembers (pilot, navigator/bombardier, radio operator and dedicated gunner). The nose assembly was consistent with other America-designed bombers of the time and featured a heavily glazed cone leading up to the stepped cockpit. Wings were mid-mounted on the fuselage with a dorsal turret seated along the fuselage spine, facing rear, and ahead of the single vertical tail fin. Bomb bay doors made up nearly the entire length of the fuselage underside. The Mk III was produced across 250 examples in all.
Though not a groundbreaking design by any means, the Baltimore was reportedly a very capable light bomber in its intended role. The performance capabilities and 2,000lb internal bombload provided desperate operators with much-needed offensive punch for a crucial phase of the war.
The Mk III was then followed by the Mk IIIA which were covered by the USAAF (United States Army Air Forces) and passed onto the RAF. Due to their largely American origins, these were fitted with Martin-branded powered turrets armed with 2 x 12.7mm heavy machine guns. 281 of the type were manufactured and recognized as Martin Model A-30.
The Mk IV was another USAAF order passed on under Lend-Lease to the RAF. These were armed with 4 x 12.7mm heavy machine guns at the wings for a much improved offensive punch over the original 7.7mm fittings. 294 examples were produced and known as Martin Model A-30-MA.
The Mk V were given 2 x Wright R2600-29 radial piston engines and wings armed with 12.7mm machine guns. Power was served through 2 x Wright GR-2600-A5B geared radial engines of 1,700 horsepower for a maximum speed of 305 miles per hour, cruise speed of 225 miles per hour and range of 980 miles. 600 of this mark were produced and ordered through the USAAF appearing as late as May of 1944.
Two Baltimores were converted as maritime reconnaissance prototype platforms in a short-lived program. The fuselage was extended for increased fuel stores and provisions for carrying torpedoes. The nose was to be solid in its design and house a search radar for anti-ship duties over water. The formal designation was to be Baltimore GR.Mk VI and some 900 were on order before the entire project was shelved.
The Baltimore also served Commonwealth forces in Australia, Canada and South Africa. Other operators went on to include Free France, Greece, the Co-Belligerent Italian Air Force and Turkey. However, no one power was served by Baltimores as well as the British who fielded it across twelve total squadrons including one training and one Fleet Air Arm group.
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Glenn L. Martin Company - USA Manufacturer(s)
France (Free French); Kingdom of Italy (Co-Belligerent Forces); Turkey; United Kingdom; United States Operators
4 x 7.7mm Browning Machine Guns in wings
2 OR 4 x 7.7mm Browning Machine Guns in dorsal turret.
2 x 7.7mm Browning Machine Guns in ventral gun position.
Maximum ordnance loadout of up to 2,000lbs.
Model 187 - Modified Light Bomber platform based on the Martin Maryland design.
Mk I - RAF use; initial production mark; sans power-operated dorsal turret; single 7.7mm machine gun in dorsal mount.
Mk II - RAF use; early production examples sans power-operated Boulton-Paul dorsal turret.
Mk III - RAF use; fitted with power-operated dorsal turret with 2 or 4 x 7.7mm machine guns.
Mk IIIA - RAF use based on the USAAF order of the A-30 Baltimore Light/Medium Bomber; fitted with Martin 250CE-brand turret fielding 2 x 12.7mm machine guns.
Mk IV - Based on the Mk IIIA model.
Mk V - Fitted with uprated Wright-brand GR-2600 powerplants; 12.7mm machine guns in wing mounts as opposed to 7.7mm caliber; appearing in 1944.
A-30 - USAAF Brand
A-30A - USAAF Brand
A-30A-10-MA - USAAF Brand
RA-30 - Reconnaissance Variant
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