P4M Mercator

Infobox Aircraft
name= P4M Mercator


caption= United States Navy P4M-1
type= Patrol bomber
national origin = United States
manufacturer= Martin
designer=
first flight= 20 October 1946
introduced= 1950
retired= 1960
status= Retired
primary user= United States Navy
more users=
produced=
number built= 21
variants with their own articles=

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.

Design and development

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.

Operational history

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 Philippines (and, later, Japan) by Fleet Air Reconnaissance Squadron One (VQ-1) along the Chinese borders and along the eastern Russian coasts, and were of a highly secret nature; the aircraft masqueraded as regular P2V Neptunes in radio communications. One Mercator was shot down by Chinese fighters in 1956, while another was attacked by two fighters in 1959 but escaped with injury to one crewman. The aircraft were also operated out of Morocco by VQ-2, where one aircraft was intercepted near Ukrainian airspace by Soviet MiG's. It escaped by flying under jet power but ran out of fuel and crashed into Mediterranean Sea 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.

Variants

;XP4M-1:Two prototype aircraft with two R-4360-4 engines.;P4M-1:Production aircraft with two R-4360-20A engines, 19 built.;P4M-1Q:M4M-1s redesignated when modified for radar countermeasures.

Operators

;USA
* United States Navy

pecifications (P4M Mercator)

aircraft specification

plane or copter?=plane
jet or prop?=both
crew=9
length main=85 ft 2 in
length alt=26.0 m
span main=114 ft 0 in
span alt=34.7 m
height main=26 ft 1 in
height alt=8.0 m
area main=1,311 ft²
area alt=122 m²
empty weight main=48,536 lb
empty weight alt=22,016 kg
loaded weight main=88,378 lb
loaded weight alt=40,088 kg
max takeoff weight main=lb
max takeoff weight alt=kg

more general=
engine (prop)=Pratt & Whitney R-4360 Wasp Major
type of prop=radial engines
number of props=2
power main=3,250 hp
power alt=2,420 kW
engine (jet)=Allison J33-A-23
type of jet=turbojets
number of jets=2
thrust main=4,600 lbf
thrust alt=20 kN
max speed main=410 mph
max speed alt=660 km/h
range main=2,840 miles
range alt=4,570 km
ceiling main=34,600 ft
ceiling alt=10,500 m
climb rate main=ft/min
climb rate alt=m/s
loading main=lb/ft²
loading alt=kg/m²
avionics=
*AN/APS-33 search radar
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

ee also

aircontent
similar aircraft=
* Avro Shackleton
* PB4Y Privateer
* P-2 Neptune
* P-3 Orion

lists=
* List of military aircraft of the United States (naval)