The Curtiss HS was a single-engined patrol flying boat built for the United States Navy during World War I.
Large numbers were built from 1917 to 1919, with the type being used to carry out anti-submarine patrols from bases in France from June 1918.
It remained in use with the US Navy until 1928 and was also widely used as a civil passenger and utility aircraft.
In late 1916, the Curtiss Aeroplane Company produced a new twin-engined flying boat, which was smaller than both the current Curtiss H-12 being built for Britain’s Royal Naval Air Service and the earlier Curtiss H-4, with the new design given the factory designation Model H-14, although its design was unrelated to earlier Model H variants.
The H-14 was a conventional unequal-span, unstaggered biplane, powered by two 100 hp (75 kW) pusher Curtiss OXX engines mounted between the wings.
An order for 16 was placed by the United States Army before the prototype flew, but the prototype was disappointing, and the US Army cancelled its order for H-14s.
The prototype was converted to a single-engined aircraft powered by a 200 hp (149 kW) Curtiss V-X-X engine, also in a pusher configuration, during 1917, being redesignated as the Curtiss HS-1 (for H model with single engine).
The prototype was re-engined for use as a testbed for the new Liberty 12 engine, becoming the HS-1L, flying in this form on 21 October 1917.
While Curtiss’s V-X-X engine proved to be inadequate, as it did in its larger Model H cousins, the Liberty proved more suitable, and large orders were placed by the US Navy for the HS-1L.
The HS-1 was armed with two 180 lb (80 kg) depth bombs, but it was found that these bombs were too small.
In order to carry more powerful 230 lb (100 kg) bombs, Curtiss produced an increased-span version, the HS-2 with span increased by 12 ft (3.66 m) and an additional set of interplane struts, giving four-bay wings rather than the three-bay wings of the HS-1L.
Again, Curtiss specified one of their own engines, and again, the Navy substituted this with the Liberty engine in the definitive HS-2L.
The HS-3 was a further improved version with a new, wider hull flat-sided hull, that eliminated the typical Curtiss sponsons.
The end of the war brought an end to plans to mass-produce this version, only six being built.
The HS-1L and -2L were built in vast quantities: 675 by Curtiss themselves, and nearly as many again by various contractors that included L-W-F (250), Standard (80), Gallaudet Aircraft Company (60), Boeing (25) and Loughead (2).
A further 25 were assembled by the US Navy from spare parts postwar.
Variants
HS-1
Prototype with Curtiss engine.
HS-1L
Early production version of HS-1 with Liberty engine and short span (62 ft 1 in (18.92 m)) wings.
HS-2
Longer-span version with Curtiss engine
HS-2L
Definitive production version with Liberty engine and long span (74 ft 1 in (22.58 m)) wings.
HS-3
Improved version of the HS-2L, with new, wider hull and larger fin. Only six aircraft were built.
HS-3L
Canadian modified version of HS-2L with modified wings (Clark Y section). At least three converted.
Specifications
Crew
2 or 3
Length
39 ft 0 in (11.89 m)
Wingspan
74 ft 1 in (22.58 m)
Height
14 ft 7 in (4.45 m)
Wing area
803 sq ft (74.6 m2)
Airfoil
RAF 6
Empty weight
4,300 lb (1,950 kg)
Gross weight
6,432 lb (2,918 kg)
Powerplant
1 × Liberty L-12 V-12 water-cooled piston engine,
360 hp (270 kW)
Propellers
4-bladed fixed-pitch pusher propeller
Performance
Maximum speed
82.5 mph (132.8 km/h, 71.7 kn)
Range
517 mi (832 km, 449 nmi)
Endurance
4 hours 30 minutes
Service ceiling
5,200 ft (1,600 m)
Time to altitude
2,300 ft (700 m) in 10 minutes
Armament
Guns
1 × 0.300 in (7.62 mm) Lewis gun in flexible mount
Bombs
2 × 230 lb (100 kg) of bombs or depth charges carried under the wings.
