Martin P5M Marlin
As a new US Navy patrol flying-boat, Martin developed the Model 237 design, combining the wing and upper hull of the Mariner with the new lower hull structure. A PBM-5 Mariner served as the prototype XP5M-1 which, when ordered into production, was given the name Marlin.
The modified hull of the XP5M-1 incorporated radar-directed nose and tail turrets, as well as a power-operated dorsal turret, and power was provided by two 2424kW Wright R-3350 radial engines.
This prototype flew for the first time on 30 May 1948, but it was not until two years later that the P5M-1 was ordered into production, the first of these series aircraft being flown on 22 June 1951.
Initial deliveries, to US Navy Squadron VP-44, began on 23 April 1952 and the type remained in service until the mid-1960s.
In addition to those operated by the US Navy, 12 of the later P5M-2 version were supplied to France under the American MAP for use by the Aeronavale in 1959. In the French Aeronavale, where they were used for maritime patrol out of Dakar, West Africa, until 1964, after which they were returned to the Navy. The P5M-2 Marlin could carry up to 8,000 lb (3,629 kg) of assorted weapons. The P5M-1 has a low mounted " dihedral " tailplane, different hull shape and lower-powered engines, compared to the P5M-2.
The first of 28 P5M-2 Marlins to undertake a modernisation program was delivered to the US Navy in 1959.
Martin aircraft production ceased December 20,1960 when the last P5M- 2 Marlin was handed over to U.S. Navy.
Claiming high operational costs, the Coast Guard turned over all of its P5Ms to the Navy in 1961. Lacking most military equipment, they were used as crew trainers as P5M-1T and P5M-2Ts.
In September 1962, when all American military forces adopted the tri-service designation scheme, the P5M-1 became the P-5A, the P5M-1S the SP-5A, the P5M-1T the TP-5A, the P5M-2 the P-5B, the P5M-2S and P5M-2T the PT-2B.
In 1964, in an attempt to boost take-off power, one SP-3B was tested with a tail mounted 3000 lb.st Pratt & Whitney turbojet engine. They were not adopted for service.
No Marlins went to the reserves. As they were retired, they were stored until sold as scrap. A Navy SP-5B of VP-40 made the last operationsl flight on 6 November 1967.
The XP5M-1 prototype was later used (as the model 270) to test the 15:1 hull configuration for the P4M SeaMaster.