Blog on World of Civil Airplanes : Martin Mariner Flying Boat,

MARTIN PBM AIRCRAFT

Jagriti Srivastava

The Martin PBM Mariner was a patrol bomber flying boat of World War II and the early Cold War period. It was designed to complement the Consolidated PBY Catalina in service. A total of 1,366 were built, with the first example flying on 18 February 1939 and the type entering service in September 1940.

In 1936 Martin offered the US Navy the design of a patrol-bomber flying boat, known as the Martin 162. The model 162 was an all-metal aircraft, with flush riveting. It had a deep fuselage, a gull wing to keep the two propellers well above the spray, and twin tailfins. The 162 had a two-step bottom. The wingtip floats retracted inwards. The 162 was much bigger and more advanced than the Consolidated PBY that was then entering service, so Martin first built a flying quarter-scale model, the Martin 162A, powered by a Pobjoy engine. Apparently it had a single engine, driving two propellers by gearing and extension shafts. The 162A flew in 1937.

The full-scale prototype, the XPBM-1, was ordered on 30 June 1937 and made its first flight on 18 February 1939. The Navy had already ordered 20 production aircraft, designated PBM-1. These entered service in 1940, and distinguished themselves from the prototype by a dihedralled tailplane. The tailplane now had the same dihedral as the wing centre section; the tailfins remained orthogonal to the tailplane, and this gave the tail a toed-in appearance which was an easy recognition feature. The PBM-1s were powered by 1600hp Wright R-2600-6 engines, and had a crew of seven. The defensive armament included nose and dorsal turrets, a gun position in the extreme tail, and beam guns. The aircraft could carry 907kg of bombs, which were stored in the aft part of the engine nacelles.

The PBM-2 was an experimental long-range version, which was strengthened to be launched by catapult. This version did not enter production.

The next production version was the PBM-3. They had 1700hp R-2600-12 engines, more armament, more fuel, and a crew of nine. The vulnerable retractable stabilizing floats were replaced by fixed ones. The first 50 ones were completed as PBM-3R transports, without military equipment. The PBM-3C combat model had search radar in a dorsal bulge, just aft of the flight deck. Crutches under the wing roots could carry 21-inch torpedoes. Power-operated turrets in the nose, tail and dorsal position now each had two .50 guns. This version appeared in September 1942. The PBM-3D had 1900hp R-2600-22 engines and even more armament. The engines nacelles had been extended, so that bomb load could be increased to 1814kg. The PBM-3S on the other hand, had decreased armament: Only four machineguns, all hand-held. This weight saving compensated for a larger fuel load, because the PBM-3S was a long-range antisubmarine aircraft.

VARIANTS

The XPBM-1 showing the original retractable floats.

XPBM-1 (Model 162)

Prototype. Powered by two 1,600 hp (1,194 kW) R-2600-6 engines.

PBM-1 (Model 162)

Initial production version. 5× .50 inch (12.7 mm) machine guns. Two R-2600-6 engines; 21 built.

XPBM-2 (Model 162)

Conversion of one PBM-1 as experimental catapult-launched long range strategic bomber.

PBM-3 (Model 162B)

Improved version. 1,700 hp (1,270 kW) R-2600-12 engines; 32 built.

PBM-3R (Model 162B)

Unarmed transport version of PBM-3. 18 new build plus 31 converted from PBM-3.

PBM-3C (Model 162C)

Improved patrol version with twin .50 in machine guns in nose and dorsal turrets, and single guns in tail turret and waist positions. AN/APS-15 radar in radome behind cockpit; 274 built.

PBM-3B (Model 162C)

Designation for ex-RAF Mariner GR.1A after return to U.S. Navy.

PBM-3S (Model 162C)

Dedicated anti-submarine aircraft with reduced armament (2× fixed 0.50 in machine guns in nose, single machine gun in port waist position and single gun in tail turret) and increased range; 94 built as new plus 62 conversions.

PBM-3D (Model 162D)

Patrol bomber with increased power (two 1,900 hp (1,417 kW) R-2600-22s) and increased armament (twin 0.50 in machine guns in nose, dorsal and tail turrets, plus two waist guns). 259 built.

PBM-4 (Model 162E)

Proposed version with two 2,700 hp (2,015 kW) Wright R-3350 engines; unbuilt.

PBM-5 (Model 162F)

Version with 2,100 hp (1,566 kW) Pratt & Whitney R-2800 engines;628 built.

PBM-5E

Variant of PBM-5 with improved radar.

PBM-5S

Lightened anti-submarine variant of PBM-5.

PBM-5S2

Improved anti-submarine aircraft with revised radar installation.

PBM-5A (Model 162G)

Amphibian version of PBM-5, with retractable nosewheel undercarriage; 36 built plus four conversions.

Mariner I

British designation for 32 PBM-3B supplied to the Royal Air Force.

SPECIFICATIONS (PBM-1)

Data from Jane’s Fighting Aircraft of World War II

General characteristics

Crew: Seven

Length: 79 ft 10 in (23.50 m)

Wingspan: 118 ft 0 in (36 m)

Height: 27 ft 6 in (5.33 m)

Wing area: 1,408 ft² (131 m²)

Empty weight: 33,175 lb (15,048 kg)

Loaded weight: 56,000 lb (25,425 kg)

Powerplant: 2 × Wright R-2600-12 14-cylinder radial engines, 1,700 hp (1,300 kW) each

Performance

Maximum speed: 178 kn (205 mph, 330 km/h)

Range: 2,600 nmi (3,000 mi, 4,800 km)

Service ceiling: 19,800 ft (6,040 m)

Rate of climb: 800 ft/min (4.1 m/s)

Armament

Guns: 8 × .50 in (12.7 mm) M2 Browning machine guns (two each in nose, dorsal and tail turrets, one each in blisters amidships)

Bombs: 4,000 lb (1,800 kg) of bombs or depth charges or 2 × Mark 13 torpedoes

SURVIVORS

United States Navy PBM-5A (Bureau Number (BuNo) 122071) is the only surviving Mariner. It is on loan from the National Air and Space Museum in Washington, D.C. and is currently on display at the Pima Air & Space Museum adjacent to Davis–Monthan Air Force Base in Tucson, Arizona.Operated by the USN between 1948 and 1956, it is painted in the markings of Transport Squadron 21 (VR-21) and coded RZ 051 of the early 1950s.

Although only one complete Mariner aircraft exists, another aircraft (PBM-5 BuNo 59172) lies upside down under Lake Washington. It crashed on 6 May 1949, and after a number of unsuccessful attempts to recover the wreck over the following decades it is now used as a training site for divers.

The Model 162A (registered NX19168), the piloted quarter scale test aircraft, is on display at the Baltimore Museum of Industry.

ACCIDENTS AND INCIDENTS

On 30 November 1944, a U.S. Navy PBM-5 crashed into Mount Tamalpais in northern California killing eight naval aviators and naval aircrewmen. The aircraft had taken off from Naval Air Station Alameda and was part of a larger flight headed for Hawaii when it developed engine trouble shortly after takeoff.

United States Navy PBM-5 (BuNo 59225) based at Naval Air Station Banana River, Florida is believed to have been destroyed in a mid-air explosion in December 1945 off the coast of Florida near The Bahamas while searching for the missing TBM Avengers of Flight 19 from Naval Air Station Fort Lauderdale, Florida.

A U.S. Navy PBM-5 crashed on Thurston Island, Antarctica on 30 December 1946 while supporting Operation Highjump.

On 9 November 1958, an Aero-Topográfica PBM-5 (registration CS-THB) disappeared on a scheduled passenger flight from Cabo Ruivo, Lisbon, Portugal to Funchal Airport, Funchal, Madeira. The last radio transmission from the aircraft (when it was about 13°W) was: "I am forced to land immediately." No trace has ever been found of the aircraft, its six crew or 30 passengers

Regards,