Martin P4M "Mercator"
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Martin P4M-1 "Meractor"

    Maritime Patrol

The Martin P4M-1"Mercator"


Specification For P4M-1
    Engine: 2x Pratt Whitney R-4360 piston engines @ 3,250 hp each / 2x Allison J33-A-23 axial flow turbojets making 4,600 lb thrust each
    Wing Span: 114'
    Length: 85' 2''
    Height: 26' 1''
    Weight: Empty 48,536 lb / Loaded 88,378 lb
    Maximum Speed: 410 mph
    Ceiling: 16,900'
    Range: 2,840 miles
    Crew: 9
    Armament: 4x 20mm cannon (2 in nose and 2 in tail turrets) / 2x 0.50" machine guns in upper turret / 12,000 lb of ordnance in the bomb bay (including various bombs, mines, and aerial torpedoes)
History:
Work started at Martin on the Model 219 P4M-1 "Mercator" patrol plane for the US Navy in 1944, with it's first flight on the 20/10/1946. Like other Martin aircraft it was powered by 2x Pratt and Whitney R-4360 radial piston engines, however the "Mercator" also had two jets engines, the Allison J-33 mounted beneath the radials engines in the same nacelles, the idea was that this would enable Martin to combine the size and armament of four-engine planes with the economy and range of two-engine one, this did lead to problems as the combination two different types of powerplant with both being adjusted to burn a Highly Volatile common fuel was troublesome. This "problem" came to a head in August 1947 when one of the prototype XP4M-1's main fuel line burst on a test flight, the fumes killed a Martin flight test engineer and injured two others but these problems would be resolved in time, how ever the damage was done and in 1947 the US Navy chose the cheaper and more reliable Lockheed P2 "Neptune" powered by two piston engines, as its regular patrol plane. ( In 1950 the "Neptune" it's self would be fitted with two Westinghouse J-34-WE-36 axial flow turbojet engines for the same reasons as the "Mercator" was in the first place!)  
A "Mercator" of VQ-1 from the mid 1950's

But that was not the end of the story for the "Mercator" with nineteen being ordered in 1947 by the US Navy. In the beginning of 1951, the P4M-1"Mercator" was specifically modified for electronic reconnaissance as the P4M-1Q "Mercator". Most were delivered to Patrol Squadron 21, stationed at Patuxent River Naval Air Station in Maryland and later Port Lyautey in Morocco.

The P4 would be in service until 1960 being employed on missions along Chinese borders and far eastern Russian coasts with Fleet Air Reconnaissance Squadron VQ-1 from 1951, with one being shot down near Shanghai in 1956. The "Mercator also operating over the Atlantic with VQ-2

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