Two turning - two burning |
Martin P4M-1 "Mercator" April1948
The Martin P4M Mercator was a twin-engined martime reconnaissance aircraft built by the Glenn L. Martin Company. The Mercator was an unsuccessful contender for a United States Navy requirement for a long-range maritime patrol bomber, with the Lockheed P2V Neptune chosen instead. It saw a limited life as a long-range electronic reconnaissance aircraft. Its most unusual feature was that it was powered by a combination of piston engines and turbojets, the latter being in the rear of the engine nacelles. Work began on the Model 219 in 1944, with the first flight being on 20 October 1946. A large and complicated aircraft, it was powered by two Pratt & Whitney R4360 Wasp Major 28-cylinder radial engines. To give a boost during takeoff and combat, two Allison J33 turbojets were fitted in the rear of the two enlarged engine nacelles, the intakes being beneath and behind the radial engines. The jets, like those on most other piston/jet hybrids, burned gasoline, not jet fuel. A tricycle undercarriage was fitted, with the nosewheel retracting forwards. The single-wheel main legs into coverless fairings in the wings, so that the sides of the wheels could be seen even when retracted. The wings themselves, unusually, had a different airfoil cross-section on the inner wings than the outer. Heavy defensive armament was fitted, with two 20 mm cannon in an Emerson nose turret and a Martin tail turret, and two 0.5 in (12.7 mm) machine-guns in a Martin dorsal turret. The bomb-bay was, like British practice, long and shallow rather than the short and deep bay popular in American bombers. This gave greater flexibility in payload, including long torpedoes, bombs, mines, depth charges or extended-range fuel tanks. The US Navy chose the smaller, simpler and cheaper P2V Neptune for the maritime patrol requirement, but nineteen aircraft were ordered in 1947 for high-speed minelaying purposes; these were modified for the electronic reconnaissance (or SIGINT, for signals intelligence) mission in 1951, to replace the PB4Y-2 Privateer. The crew was increased to 14 and later 16 to operate all the surveillance gear, and the aircraft was fitted with a large number of different antennas. Missions were flown from the with the loss of all crew. The Mercators were replaced by the EA-3 Skywarrior, which being carrier-based had a greater degree of flexibility. Final withdrawal from service was in 1960, and all of the remaining P4Ms were scrapped.
General characteristics Crew: 9 Length: 85 ft 2 in (26.0 m) Wingspan: 114 ft 0 in (34.7 m) Height: 26 ft 1 in (8.0 m) Wing area: 1,311 ft² (122 m²) Empty weight: 48,536 lb (22,016 kg) Loaded weight: 88,378 lb (40,088 kg) Max takeoff weight: lb (kg) Powerplant: 2× Allison J33-A-23 turbojets, 4,600 lbf (20 kN) each 2× Pratt & Whitney R-4360 Wasp Major radial engines, 3,250 hp (2,420 kW) each Performance Maximum speed: 410 mph (660 km/h) Range: 2,840 miles (4,570 km) Service ceiling 34,600 ft (10,500 m) Rate of climb: ft/min (m/s) Wing loading: lb/ft² (kg/m²) Armament 4x 20 mm cannon in nose and tail turrets 2x .50 cal (12.7 mm) machine guns in dorsal turret Up to 12,000 lb (5,400 kg) of bombs, mines, depth charges, or torpedoes Avionics AN/APS-33 search radar. USN 97 René Hieronymus Scale 1:72 Building time: approx. 63 hrs.
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