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Martin PBM-3 / PBM-5 Mariner Maritime Reconnaissance Flying Boat (1941)

Authored By Staff Writer | Last Updated: 11/3/2011

While a serviceable and very capable aircraft in its own right, the Mariner floatplane would never reach stardom as the older Consolidated PBY Catalina achieved.

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Picture of Martin PBM-3 / PBM-5 Mariner
Pic of the Martin PBM-3 / PBM-5 Mariner
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The Martin PBM-3 / PBM-5 Mariner was a World War 2-era flying boat used in the maritime reconnaissance role. Martin designed and marketed the type in direct competition with Consolidated, which had already made a "splash" with their PBY Catalina flying boat series in operation with the United States Navy. Despite being of a more modern design and an equally capable performer, the Mariner would never quite take the top spot away from the Catalina series.

The Mariner first appeared in 1937 as the Martin Model 162 project, giving birth to the prototype XPBM-1 as a twin engine flying boat with a high-mounted monoplane gull wing (cranked at the engine nacelles), twin tail rudders, retractable stabilizing floats and a deep hull-like fuselage. This early version featured 2 x Wright Cyclone R-2600-6 radial engines with a total output of 1,600 horsepower each and first flew in 1939. The PBM-1 followed in 1941, with some 20 models entering active US Navy service with Patrol Squadron VP-74. The first large order came for the PBM-3 and was the first in the series to feature fixed floats, a feature that would become standard in future models as well. A lengthened engine nacelle also greeted this model series and allowed for a greater external ordnance load to be carried (the bomb bays were held inside the engine nacelles).

A crew of 7 to 9 men operated the type. Armament generally consisted of a twin 12.7mm gun mounting at the bow, tail and dorsal positions with an additional 2 x 12.7mm machine guns at the beam (waist) positions firing through hatches. The bombload was a respectable 8,000 pounds (PBM-3D).

The PBM-3 would become the first widely-produced and modified model in the series with unarmed transport and passenger transport derivatives joining the base production model. Five PBM-3B's were sent to Britain via Lend-Lease for evaluation as the Marine GR.Mk I (the Royal Air Force eventually received some 32 total Mariners). The PBM-3C model was designed with standardized British and American equipment as needed along with ASV search radar (identified as fixture above the cockpit). The R-2600-22-powered PBM-3D model featured improved armor and defensive armament (also with ASV search radar). A specialized anti-submarine model appeared as the PBM-3S and featured improved range. The designation to PBM-5 appeared as the final version of the Mariner. This model sported improved defensive armament (no fewer than 8 heavy caliber machine guns) Pratt & Whitney radials and AN/APS-15 series search radar.

The Mariner primarily served in the Pacific Theater, where it was sent on reconnaissance, hunting and shadowing missions against the dwindling numbers of Japanese Navy elements. As the theater gradually collapsed on the Empire, more land-based aircraft with greater range could be counted to complete the role of the Mariner and as such the aircraft gradually fell by the wayside. Some 1,700 of the type were produced covering various models for use by American and British forces.

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Specifications for the
Martin PBM-3 / PBM-5 Mariner
Maritime Reconnaissance Flying Boat


Focus Model: Martin PBM-3D Mariner
Country of Origin: United States
Manufacturer: Martin Company - USA
Initial Year of Service: 1941
Production: 1,717


Crew: 7 to 9


Length: 79.82ft (24.33m)
Width: 118.01ft (35.97m)
Height: 27.49ft (8.38m)
Weight (Empty): 33,175lbs (15,048kg)
Weight (MTOW): 58,001lbs (26,309kg)


Powerplant: 2 x Wright Cyclone R-2600-22 14-cylinder air-cooled radial engines developing 1,900hp each.


Maximum Speed: 211mph (340kmh; 184kts)
Maximum Range: 2,240miles (3,605km)
Service Ceiling: 19,800ft (6,035m; 3.7miles)
Rate-of-Climb: 452 feet per minute (138m/min)


Hardpoints: 2
Armament Suite:
2 x 12.7mm machine guns in bow turret
2 x 12.7mm machine guns in dorsal turret
2 x 12.7mm machine guns in tail turret
1 x 12.7mm machine gun in left beam position
1 x 12.7mm machine gun in right beam position

Up to 8,000lbs (3,629kg) of bombs.


Variants:
Martin Model 162 - Original Martin Company Designation


XPBM-1 - Prototype Designation; fitted with 2 x Wright Cyclone R-2600-6 radial engines of 1,600 horsepower.

PBM-1 - Initial Production Models; retractable underwing floats; 20 produced.

PBM-3 - Fixed underwing floats; 379 produced; elongated engine nacelles; increased bombload.

PBM-3R - Unarmed Dedicated Transport; accommodations for up to 20 passengers; 50 produced.

PBM-3C - Equipment standardized between American and British likes; 274 produced; ASV search radar.

PBM-3D - Fitted with R-2600-22 type engines; improved armor and defensive armament; 201 produced; ASV search radar.

PBM-3S - Long-Range Anti-Submarine Variant; 156 produced.

PBM-5A - Increased defensive armament; fitted with AN/APS-15 search radar; 2 x Pratt & Whitney R-2800-34 engines; 631 produced from 1944 onwards.

Marine GR.Mk I - British Lend-Lease Designation; limited to 5 examples.


Operators:
Argentina, Australia, Netherlands, the United Kingdom and the United States of America.