The Martin P4M Mercator was a maritime patrol and radar-reconnaissance aircraft in service with the US Navy during the Cold War. It was designed from the outset for speed and range, like the Consolidated PB4Y which it replaced. It had a long, thin wing to provide fuel capacity and a long range. Thus, it also resembled the Lockheed P-2 Neptune from the outside, but it was very different on the inside. Production totaled only 21 Mercators, with two prototypes and nineteen maritime and reconnaissance aircraft. During its 10-year career, it flew electronic surveillance missions along the coast of North Korea, China, and Vietnam, flying over the South China Sea. It also carried out information-gathering missions cruising over the Soviet Far East coastal territory in the 1950's. On August 22, 1956, one Mercator was shot down by Chinese fighters during a night radar intelligence mission 32 miles off the Chinese coast.
The Martin P4M prototype, the XP4M-1, performed its maiden flight on September 20, 1946. The flight test phase lasted four years as it was introduced into service in July 1950 as the P4M-1 Mercator. The power plant provision in this aircraft was unique. It had two engines on each side of wing; one piston and one jet engine. These two different types of engines were mounted in tandem, with the piston engine in front and the jet machine behind it, both sharing the same nacelle. This is the reason why, on the outside, it looked like a twin-engine plane, when, actually, the aircraft was powered by four engines. It was the only maritime patrol plane in which a crew member could stand fully erect inside the fuselage. All P4M-1 aircraft would be converted into the P4M-1Q 'Ferret' version, which would be used in the electronic surveillance role.
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| Above, ventral view of P4M-1Q variant as it flies over. |
Technical Description
The Martin P4M Mercator was a four-engine monoplane of all-metal construction. It was fitted with cantilever, high wing, with a straight leading edge and a trailing edge that tapered toward the distal portion of wing, whose outer panel had a slight dihedral angle. Its long fuselage was strong and heavy. The fore fuselage section consisted of the nose gun turret, the bomber navigator's station, the cockpit, and, behind it, the radar operator station. The aft fuselage portion, on the other hand, comprised the food galley, the power-operated deck turret, camera station, and the power-operated tail turret.
The Mercator was powered by two Pratt & Whitney R-4360-20 reciprocating piston engine, and two Allison J33-A-10A jet engines. Each of the piston engine was rated at 3,250 horsepower, while the jet engines generated 4,600 pounds of thrust each. The P4M was equipped with strong retractable landing gear, with the main wheel folding up outwardly into the outer wing panel and the front wheel retracting into the nose fuselage.
Specifications
Type: maritime patrol/reconnaissance aircraft
Length: 25.60 m (198 feet)
Wing Span: 34.75 m(114 feet)
Wing Area: 121.79 m2 (1,310 square feet)
Height: 7.95 m (26 feet)
Power Plant: two Pratt & Whitney R-4360-20A Wasp Major piston engines; two Allison J33-A-10A jet engines.
Maximum Speed: 660 km/h (409 mph)
Range: 4,570 km (2,833 miles)
Service Ceiling: 7,666 m (25,145 feet)
Armament: four 20-mm guns, set up in the nose twin turret and in the tail twin turret; four 12.7-mm (.50-cal) machine guns.
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| The third production P4M-1 in flight |
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| A Mercator banks as it turns to port. |
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| Above, the P4M-1Q variant for surveillance/reconnaissance missions. |
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| The cockpit and instrument panel of the Mercator. |