The Martin P6M SeaMaster was an advanced jet powered flying boat that was ordered into production, but only appeared in small numbers before the project was cancelled.
In 1952 the US Navy held a design contest for a jet powered mine laying flying boat. Convair and Martin both submitted designs, and the Martin Model 275 won the contest. Martin was given a contract to produce two XP6M-1 prototypes, the first of which made its maiden flight on 14 July 1955 and the second on 18 May 1956.
The Model 275 had a very distinctive appearance. The fuselage resembled a jet airliner more than a standard flying boat, being unusually narrow for its length compared to its predecessors with a length to beam ratio of over 13:1 (compared to 8.5:1 on the P5M Marlin, the last flying boat to enter US Navy service). It had high mounted wings with the four engines carried in nacelles above the wings to keep them away from spray during take-off and landing. The wings were sharply swept back. It had a high mounted ‘T’ tail, similar to that used on the P5M-2. The aircraft had an internal weapons bay, using Martin’s rotary bomb door to keep the water out. This bay could carry mines, bombs, cameras or other equipment. The XP6M-1 carried a crew of four and was armed with two 20mm cannon in a remotely controlled tail turret.
The Navy placed an order for six YP6M-1s and twenty-four P6M-2s. The YP6M-1s were all completing bringing the total number of development aircraft up to eight. Only three of the production aircraft were ever completed. Both prototypes crashed during flight tests, due to problems with the tail and tailplane actuating mechanisim.
The YP6M-1s were similar to the prototypes but with redesigned air intakes and fin fairing. The first made its maiden flight on 20 January 1958.
The P6M-2 was powered by four 17,500lb thrust Pratt & Whitney J75-P-2 turbojets, and the first made its maiden flight on 17 February 1959. However on 21 August 1959 the entire programme was cancelled. The existing aircraft were used for a short time at Harvey Point Naval Air Station, North Carolina, before later being scrapped.
The P6M was the last aircraft to be produced by Martin before the company merged with American-Marietta to become Martin Marietta. The merged company’s main military focus was missiles and rockets.
Engines: Four Allison J71 turbojets
Power: 13,000lb thrust with afterburn each
Engines: Four Allison J75-P-2 turbojets
Power: 17,500lb thrust non-afterburning
Take-off Weight: 160,000lb
Maximum Speed: Over 600mph
Combat radius: 1,500 miles