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Curtiss F5L

The twin-engine F5L was one of the Felixstowe F series of flying boats developed by John Cyril Porte at the Seaplane Experimental Station, Felixstowe, England, during the First World War for production in America.

A civilian version of the aircraft was known as the Aeromarine 75.

Porte had taken the Curtiss H-12, an original design by the American Glenn Curtiss, and developed it into a practical series of flying boats at the Felixstowe station.

They then took their F.5 model and further redesigned it with better streamlining, a stronger hull using veneer instead of doped linen and U.S.-built 330 hp (later 400 hp) Liberty 12A engines.

The prototype was built and tested in England and the design then taken over by the Naval Aircraft Factory, Philadelphia, where further modifications were made to suit their production methods under wartime conditions.

The American-built version was also known as the Curtiss F5L and (in civilian operation) as the Aeromarine 75.

The F5L was built by the Naval Aircraft Factory (137), Curtiss (60) and Canadian Aeroplanes Limited (30).

Some were converted for civilian use by the Aeromarine Plane and Motor Company in 1919.

The F5L entered U.S. service at the end of the war and was the U.S. Navy’s standard patrol aircraft until 1928, when it was replaced by the PN-12.

In civil service, named the Aeromarine 75, the Felixstowe F5L could accommodate 10 passengers and was operated by Aeromarine Airways on flights from Key West to Havana, carrying the first U.S. Post Office international air mail on flights from New York City to Atlantic City, and from Cleveland to Detroit.





5,224 lb (2,370 kg) useful load


49 ft 4 in (15.04 m)

Upper wingspan

103 ft 9.25 in (31.63 m)

Lower wingspan

74 ft 4 in (22.66 m)


18 ft 9.25 in (5.72 m)

Wing area

1,394 sq ft (129.5 m2)

Empty weight

8,720 lb (3,955 kg)

Gross weight

14,334 lb (6,502 kg)


2 × Liberty L-12A V-12 water-cooled piston engines,

400 hp (300 kW) each


2-bladed fixed-pitch propellers


Maximum speed

90 mph (140 km/h, 78 kn)

Cruise speed

74 mph (119 km/h, 64 kn)

Stall speed

57 mph (92 km/h, 50 kn)


830 mi (1,340 km, 720 nmi)

Rate of climb

260 ft/min (1.3 m/s)

Time to altitude

2,600 ft (792 m) in 10 minutes

Wing loading

9.5 lb/sq ft (46 kg/m2)



2 x machine guns


Provision for bombs.

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