The Martin P5M Marlin (P-5 Marlin after 1962), built by the

Glenn L. Martin Company The Glenn L. Martin Company, also known as The Martin Company from 1917 to 1961, was an American aircraft and aerospace industry, aerospace manufacturing company founded by aviation pioneer Glenn L. Martin. The Martin Company produced many impo ...

of Middle River, Maryland, is a twin piston-engined

flying boat A flying boat is a type of seaplane with a hull, allowing it to land on water. It differs from a floatplane in having a fuselage that is purpose-designed for flotation, while floatplanes rely on fuselage-mounted floats for buoyancy. Though ...

that entered service in 1951, and served into the late 1960s with the

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

performing naval patrols. It also served with the

United States Coast Guard The United States Coast Guard (USCG) is the maritime security, search and rescue, and Admiralty law, law enforcement military branch, service branch of the armed forces of the United States. It is one of the country's eight Uniformed services ...

and the

French Navy The French Navy (, , ), informally (, ), is the Navy, maritime arm of the French Armed Forces and one of the four military service branches of History of France, France. It is among the largest and most powerful List of navies, naval forces i ...

, with 285 being produced.

Development

Built as a successor to the PBM Mariner, it had better engines, an improved hull, and a single vertical fin tail. The XP5M Marlin prototypes were based on the last PBM-5 Mariners, the company designation being Model 237. The type was heavily improved, again leading to the P5M-2 (Model 237B), which was redesignated SP-5B. A number of P5M-1 models were also used for training, designated TP-5A (after 1962).

Design

The Marlin was designed as a gull-winged aircraft to place the engines and propellers high above the spray. Power was provided by two

Wright R-3350 The Wright R-3350 Duplex-Cyclone is an American twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly . Power ranged from , depending on model. Developed before World War II, the R-3350's design requi ...

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

s. The rear hull did not lift sharply from the water at the tail, instead rising up steadily, a Martin innovation; this gave the aircraft a longer base of flotation and reduced "porpoising" over waves. The prototype XP5M-1 had nose and tail turrets with twin cannon in each, as well as a dorsal turret with two 0.5 in (12.7 mm)

M2 Browning machine gun The M2 machine gun or Browning .50-caliber machine gun (informally, "Ma Deuce") is a heavy machine gun that was designed near the end of World War I by John Browning. While similar to Browning's M1919 Browning machine gun, which was chamber ...

s. The cockpit area was the same as the Mariner's. It first flew on 30 May 1948.Swanborough and Bowers 1976, p.323. The first of 167 production P5M-1 aircraft was produced in 1951, flying on 22 June 1951. Changes from the prototype included a raised flight deck for improved visibility, the replacement of the nose turret with a large

radome A radome (a portmanteau of "radar" and "dome") is a structural, weatherproof enclosure that protects a radar antenna (radio), antenna. The radome is constructed of material transparent to radio waves. Radomes protect the antenna from weathe ...

for the AN/APS-44 search radar, the deletion of the dorsal turret, and new, streamlined wing floats. The engine nacelles were lengthened to provide room for weapons bays in the rear. The P5M-1 was followed by 116 P5M-2 planes. These had a

T-tail A T-tail is an empennage wikt:configuration, configuration in which the tailplane of an aircraft is mounted to the top of the vertical stabilizer, fin. The arrangement looks like the capital letter T, hence the name. The T-tail differs fr ...

to put the tail surfaces out of the spray, an AN/ASQ-8 MAD boom at the rear of the tail-tip, no tail guns (the gun position replaced by the antenna for the AN/APN-122 Doppler Navigation Set), better crew accommodation, and an improved bow to reduce spray during takeoff and landing.

Operational history

U.S. Navy

The last flying boat operations of the United States Navy were

Operation Market Time Operation Market Time was the United States Navy, Republic of Vietnam Navy and Royal Australian Navy operation begun in 1965 to stop the flow of troops, war material, and supplies by sea, coast, and rivers, from North Vietnam into parts of Sout ...

patrols by Patrol Squadron 40 (VP-40) during the

Vietnam War The Vietnam War (1 November 1955 – 30 April 1975) was an armed conflict in Vietnam, Laos, and Cambodia fought between North Vietnam (Democratic Republic of Vietnam) and South Vietnam (Republic of Vietnam) and their allies. North Vietnam w ...

.An Illustrated Guide to The Air War Over Vietnam by Nalty, Bernard C., Watson, George M., and Neufeld, Jacob: Arco Publishing (1981) pp.106–107. Maritime surveillance patrols began in February 1965 to locate small craft transporting supplies from

North Vietnam North Vietnam, officially the Democratic Republic of Vietnam (DRV; ; VNDCCH), was a country in Southeast Asia from 1945 to 1976, with sovereignty fully recognized in 1954 Geneva Conference, 1954. A member of the communist Eastern Bloc, it o ...

Viet Cong The Viet Cong (VC) was an epithet and umbrella term to refer to the communist-driven armed movement and united front organization in South Vietnam. It was formally organized as and led by the National Liberation Front of South Vietnam, and ...

units in

South Vietnam South Vietnam, officially the Republic of Vietnam (RVN; , VNCH), was a country in Southeast Asia that existed from 1955 to 1975. It first garnered Diplomatic recognition, international recognition in 1949 as the State of Vietnam within the ...

.The Naval Air War in Vietnam by Mersky, Peter B, and Polmar, Norman: Nautical and Aviation Publishing Company of America (1981) p.30. VP-40 operated from seaplane tenders and patrolled off the

Mekong Delta The Mekong Delta ( or simply ), also known as the Western Region () or South-western region (), is the list of regions of Vietnam, region in southwestern Vietnam where the Mekong, Mekong River River delta, approaches and empties into the sea th ...

between Phú Quốc and Vung Tau.The Vietnam War by Bonds, Ray: Salamander Books (1979) p.132. VP-40 carried out the final U.S. Navy Marlin flight, which landed on

San Diego Bay San Diego Bay is a natural harbor and deepwater port in San Diego County, California, near the Mexico–United States border. The bay, which is long and wide, is the third largest of the three large, protected natural bays on California's of ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

on 6 November 1967. The last U.S. Navy P5M, redesignated an SP-5B in 1962, was flown to Naval Air Station Patuxent River,

Maryland Maryland ( ) is a U.S. state, state in the Mid-Atlantic (United States), Mid-Atlantic region of the United States. It borders the states of Virginia to its south, West Virginia to its west, Pennsylvania to its north, and Delaware to its east ...

, on 12 July 1968 for interim storage pending construction of a display area for it at the

Smithsonian Institution The Smithsonian Institution ( ), or simply the Smithsonian, is a group of museums, Education center, education and Research institute, research centers, created by the Federal government of the United States, U.S. government "for the increase a ...

Washington, D.C. Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and federal district of the United States. The city is on the Potomac River, across from Virginia, and shares land borders with ...

As a display area at the Smithsonian did not materialize, the aircraft later was moved to the National Naval Aviation Museum at Naval Air Station Pensacola,

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

,Flecknoe, Harold J. "Progress". ''United States Naval Institute Proceedings'', October 1968. where it is was on display as of 2010.

U.S. Coast Guard

Seven P5M-1Gs and four P5M-2Gs were built for the

for

air-sea rescue Air-sea rescue (ASR or A/SR, also known as sea-air rescue), and aeronautical and maritime search and rescue (AMSAR) by the ICAO and International Maritime Organization, IMO, is the coordinated search and rescue (SAR) of the survivors of emergenc ...

service, but the Coast Guard found the planes difficult to maintain and surplus to requirements. They were subsequently transferred to the U.S. Navy, which redesignated them TP-5As and used them as training aircraft because they had no provision for armament.

French Navy

The

took delivery of ten former U.S. Navy Marlins between 1957 and 1959 to replace

Short Sunderland The Short S.25 Sunderland is a British flying boat Maritime patrol aircraft, patrol bomber, developed and constructed by Short Brothers for the Royal Air Force (RAF). The aircraft took its service name from the town (latterly, city) and port of ...

s in maritime patrol service. They were based at

Dakar Dakar ( ; ; ) is the capital city, capital and List of cities in Senegal, largest city of Senegal. The Departments of Senegal, department of Dakar has a population of 1,278,469, and the population of the Dakar metropolitan area was at 4.0 mill ...

Senegal Senegal, officially the Republic of Senegal, is the westernmost country in West Africa, situated on the Atlantic Ocean coastline. It borders Mauritania to Mauritania–Senegal border, the north, Mali to Mali–Senegal border, the east, Guinea t ...

, in

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

. They were returned to the U.S. Navy in 1964.

Variants

Company designations

;M-237: Company designation for P5M-1 ;M-237B: Company designation for P5M-2 ;M-270: XP5M-1 prototype converted with a revised hull. ;M-290: Company designation for P5M-3 which was completely revised into the unbuilt four-engine P7M SubMaster

Pre-1962 designations

;XP5M-1 :Prototype converted from a PBM Mariner with modified hull and tail.Andrade 1979 p207 ;P5M-1 :Production model for the

, 160 built, later redesignated P-5A. ;P5M-1G :Modified P5M-1 for the

, seven conversions, later returned to the Navy as P5M-1T. ;P5M-1S :Modified P5M-1 with upgraded electronic and anti-submarine equipment, eighty conversions, later redesignated SP-5A. ;P5M-1T :Seven former USCG P5M-1Gs returned to Navy as crew trainers and one former P5M-1, later redesignated TP-5A. ;P5M-2 :Updated model, 108 built for the U.S. Navy and 12 built for the French Navy. The P5M-2 featured a T-tail in lieu of the low mounted horizontal stabilizer used on the P5M-1s. United States aircraft were later redesignated P-5B. ;P5M-2S :Most P5M-2s were modified with upgraded electronic and anti-submarine equipment, later redesignated SP-5B. ;P5M-2G :Four P5M-2s built for the USCG, later transferred to U.S. Navy as P5M-2s. ;P5M-3 :Completely revised as four-engine M-313 P7M-1 SubMaster. Mockup built in 1956 but lost to Lockheed P-3 Orion.

Post-1962 designations

;P-5A :P5M-1 redesignated in 1962.Andrade 1979 p157 ;SP-5A :P5M-1S redesignated in 1962. ;TP-5A :P5M-1T redesignated in 1962. ;P-5B :P5M-2 redesignated in 1962. ;SP-5B :P5M-2S redesignated in 1962.

Operators

; France *

; United States *

Surviving aircraft

One SP-5B is located at the National Naval Aviation Museum at Naval Air Station Pensacola,

. This aircraft, BuNo ''135533'', is believed to be the last remaining example of the Marlin. It is now displayed inside the new hangar (as of the spring of 2010) and much of the exterior has been restored. The restoration is being financed by the museum and the Mariner/Marlin Association."P5M Marlin/135533."
''National Naval Aviation Museum.'' Retrieved: 21 February 2015.

Specifications (P5M-2)

References

;Notes ;Bibliography *Andrade, John, ''U.S.Military Aircraft Designations and Serials since 1909'', Midland Counties Publications, 1979, . *Barth, Bruce D., "The Martin P5M 'Marlin'". Pacific Aero Press, 1994. *Roberts, Michael D. ''Dictionary of American Naval Aviation Squadrons: Volume 2 The History of VP, VPB, VP(HL) and VP(AM) Squadrons''. Washington DC: Naval Historical Centre, 2000. *Swanborough, Gordon and Bowers, Peter M. ''United States Navy Aircraft since 1911''. London:Putnam, Second edition 1976. . *The ''

Illustrated Encyclopedia of Aircraft The ''Illustrated Encyclopedia of Aircraft'' was a weekly partwork magazine by Aerospace Publishing (an imprint of Orbis Publishing) which was published in the United Kingdom (and sold in other countries too) during the early 1980s. The magazi ...

'' (Part Work 1982–1985), 1985, Orbis Publishing, Page 2420

External links

Naval Aviation Museum – Aircraft – 'P5M-2S (SP-5B) Marlin'
{{DEFAULTSORT:Martin P5m Marlin P5M Martin PM5 Marlin Flying boats High-wing aircraft Gull-wing aircraft T-tail aircraft Aircraft first flown in 1948 Twin piston-engined tractor aircraft