Martin Model 187

XA-23, A-30 British "Baltimore" Light Bomber
Variants/Specifications

Although it was produced in greater numbers than any other Martin plane except for the B-26, the Model 187 Baltimore remains little known. Ordered as a joint project in May 1940 by the Anglo-French Purchasing Commission (Martin's old customers the Dutch also showed interest), production was intended to follow that of the Model 167 in the French-financed C Building at Middle River. The French were happy with the 167 design, but the British worried that it would be obsolescent by delivery in 1941. Under their impetus a new Model 187 emerged, with the same wings, cabin layout, and armament as the 167, but a third larger, with bigger Wright R-2600 engines, a deeper fuselage, and a new tail. Martin negotiated another lucrative contract for 400 planes, but it depended upon obtaining permission from U.S. authorities for delays in B-26 deliveries. This was granted in exchange for self-sealing tanks and armor to be added without charge to Air Corps B-26's.

In June 1940 the whole order was taken over by the British. Besides dubbing it "Baltimore," the Air Ministry in London took an active role in the new plane's design. Additions included fittings for larger bombs, engine air filters for desert operations, and a powered gun turret. What the British really wanted was a plane like the B-26, which they asked to buy as soon as RAF representatives got a look at one in November 1940. American officials were also eager to standardize on a single design, but Martin successfully pleaded that work on the Model 187 had gone too far. Cancellation would waste tooling and parts already in hand. Presumably the 187's contract price of $120,000, versus $78,000 for each B-26, also played a role.

As it turned out, Matin's engineering deparment became seriously overburdened in 1940-41 with seven different designs - the PBM, Mars, B-26, XB-27 and 33, Maryland II, and Baltimore - under way simultaneously. Delays mounted. Scheduled for delivery at the beginning of 1941, the first Baltimore did not fly until June. With the same engines as the PBM but less than half the weight, it was a hot plane. Early diving tests encountered trans-sonic compressability problems at Mach .74. One dive was clocked at a true speed of 560 mph, though indicated air speed was closer to 400. The sound barrier was still an aerodynamic mystery in 1941; Martin undertook makeshift alterations on the Baltimore's tailplane that required still further delays. Other teething problems affected the landing gear, hydraulics, windshield, engines, and brakes. As a stopgap, 52 early B-26 Marauder I's were sent to the RAF instead.

Installation of the turrets and desert air filters were postponed until the 151st Baltimore. The first 50 planes, Baltimore Mark I's, mounted single Browning .30-caliber machine guns in open rear cockpits; another hundred Mark II's had twin mounts. Exposed to cold air at altitude, the Brownings froze on their first combat mission; RAF field modifications substituted British .303 Brownings. The last 250 planes of the original order, manufactured in early 1942 and designated Baltimore III's, finally mounted four-gun Boulton-Paul hydraulic turrets. Only then was it noticed that the turret blocked the upper escape hatch for the two crewmen in the rear compartment. More modifications and delays followed.

Forty per cent of the British-purchase Baltimores had been earmarked for Singapore, which fell to the Japanese before any could be delivered. All 400 then went to British forces in Egypt, the first ones arriving just in time for Rommel's final offensive in the spring of 1942. Two squadrons, including the operational training unit, were thrown into the desperate defensive stand at El Alamein in June. Sent in at low altitude and without fighter escort, they suffered the same heavy losses as Marylands had the year before (and Marauders were to suffer a year later). Matters improved when Baltimore units adopted medium-altitude formation bombing with fighter escort. German and British soldiers in the desert were to describe the squadron formations sailing serenely above them as "the eighteen imperturbables." Along with RAF Bostons (Douglas A-20's), Baltimores supported the advance of the Eighth Army from Alamein through Libya to Tunisia, then across to Sicily and Italy. The Desert Air Force, as it continued to be called even in Italy, pioneered methods of ground support later used by the rest of the RAF and by U.S. Army Air Forces.

Two Lend-Lease orders of 575 and 600 Baltimores also went to the RAF. Lend-lease items theoretically belonged to the United States and had to use standardized American equipment. Most noticeably this meant low-profile Martin electric gun turrets with two .50 caliber machine guns. These were popular with Baltimore crewmen, but meant further production delays in mid 1943 as electrical systems and fuselage structures required redesign. Baltimore Marks IIIA (U.S. designation A-30), IV, and V, (A-30A's) differed mostly in internal modifications of radio and instrumentation. The last few production blocks of Baltimore V's also replaced the .30-caliber wing, scatter, and rear-hatch guns with .50's.

Gradually superseded by Marauder III's in bombing squadrons, Baltimores flew a wide variety of missions in the Mediterranean Theater. These included reconnaissance, target-towing, maritime patrol, and night intruder missions. Baltimores even served as highly uncomfortable fast transports. Long patrol missions over the eastern Mediterranean and Aegean were particularly dangerous; lone Baltimores had to rely on their speed and firepower to escape German fighters. That speed came at a price, as Baltimores were difficult planes to keep straight and level on take-off and landing; accidents were not uncommon. Like the Marauder, though, the Baltimore acquired a reputation for sturdiness. Ten British squadrons used Baltimores in combat, along with three South African, two Australian, one Greek, one Free-French, and two Italian Co-Belligerant Air Force squadrons. In hopes that it might join the Allies, neutral Turkey also received 71 planes.

Various schemes for improving the design cropped up. The U.S. XA-23 version ordered in 1940 would have been ludicrously over-powered with Wright R-3350 engines; it was wisely cancelled. In 1942 and 1943 Martin suggested lengthening the 187's fuselage to accommodate extra fuel tanks and a torpedo, a heavily gunned solid-nose ground-attack version, and even a long-range fighter design. Late in 1943 two prototype A-30C/Baltimore VI G.R.'s were built for maritime reconnaissance. The whole program was cancelled abruptly in April 1944.

Most Baltimores were scrapped soon after the war, though a single RAF squadron in Kenya used them in aerial mapping and locust control until 1948. Remembering, perhaps, the early test dives, the Navy commissioned a set of flying tests of trans-sonic airfoils in 1946, using a single Baltimore reclaimed from the British. It was calculated that the airflow over a diving Baltimore's fuselage reached Mach .82, and the test airfoils were mounted just behind the cockpit. After the tests, the plane was donated to the Baltimore Public Schools. Neither it nor any of the other 1,575 Baltimores survives today.

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