Martin P4M Mercator

The Martin P4M Mercator was a long range reconnaissance aircraft, powered by a mix of piston and jet engines, and that saw service as an ECM aircraft in the 1950s.

The P4M was designed in response to a US Navy requirement for a long range maritime reconnaissance aircraft that was issued in July 1944. Martin came up with a dual power aircraft, using two Pratt & Whitney R-4360 piston engines and two Allison J33 turbo-jets. The engines were carried in an unusual configuration, with one piston and one jet engine in each nacelle. The radial piston engines were at the front, with the air intake for the jet underneath the nacelle, level with the leading edge of the wing and the jet pipe at the back of the nacelle. The nacelles were carried on straight, mid mounted wings. It has a tricycle undercarriage, with the main wings just outside the nacelle, folding outwards. The idea of this configuration was to use the more efficient piston engines on safe parts of each trip and add the jet engines when over the target

Martin P4M-1 Mercator from below, 1961
Martin P4M-1 Mercator
from below, 1961

The P4M could carry a 6,000lb bomb load in its reconnaissance version. It was armed with four 20mm cannon, two in the nose turret and two in the tail turret and four 0.5in machine guns, two in a dorsal turret and one on each side of the fuselage.

Two XP4M-1 prototypes were ordered on 6 July 1944 and the first made its maiden flight on 20 September 1945. The Navy then placed an order for 19 production aircraft, as the P4M-1. The first of these was delivered to Patrol Squadron VP-21 on 28 June 1950. It used them as minelayers for the next three years, before converting to the P2V-6 Neptune in February 1953.

In the mid 1950s some aircraft were equipped with Electronic Countermeasures Equipment, becoming the Navy’s first ECM aircraft as the P4M-1Q. These aircraft were used to equip squadron VQ-1, formed in June 1955. This squadron was based in Japan, and operated off the coast of Korea during the Korean War. One aircraft was lost on 22 August 1956, when it was shot down 32 miles off the coast of China wit the loss of the entire crew. A second aircraft was badly damaged by MiG-15s off Korea in June 1959, but managed to make it back to Japan where the pilot successfully landed. VQ-1 retired its last P4M in May 1960.

The aircraft was also used by VQ-2, from its base at Port Lyautey in French Morocco.

Engine: Two Pratt & Whitney R-4360-4 (or -20A) Wasp Major and two Allison J33-A-17 (or -10A)
Power: 3,250hp per piston engine and 4,600lb thrust per jet
Crew: 10 to 13
Span: 114ft 0in
Length: 84ft 0in
Height: 23ft 1in
Max Take-off Weight: 88,378lb
Maximum Speed: 410mph at 20,100ft, 379mph at sea level
Cruising Speed:
Ceiling: 34,600ft
Range: 2,840 miles
Guns: Four 20mm cannon, two in nose turret, two in tail turret, four 0.5in machine guns, two in dorsal turret, one on each side of fuselage
Bomb load: 6,000lb

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How to cite this article: Rickard, J (6 December 2018), Martin P4M Mercator ,

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