The Curtiss HS was a single-engined patrol
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 ...
built for 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 ...
during
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
. 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.
Development and design
In late 1916, the
Curtiss Aeroplane Company produced a new twin-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 ...
, which was smaller than both the current
Curtiss H-12 being built for Britain's
Royal Naval Air Service
The Royal Naval Air Service (RNAS) was the air arm of the Royal Navy, under the direction of the Admiralty (United Kingdom), Admiralty's Air Department, and existed formally from 1 July 1914 to 1 April 1918, when it was merged with the British ...
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
The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...
before the prototype flew, but the prototype was disappointing and the US Army cancelled its order for H-14s.
[Bowers 1979, pp. 93–94.]

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.
[Swanborough and Bowers 1976, p.109.]
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 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.
[Bowers 1979, pp. 102–103.] 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, 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
The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support s ...
(25) and
Loughead (2). A further 25 were assembled by the US Navy from spare parts postwar.
[Bowers 1979, p.103.]
Operational history
The HS-1L began to enter service early in 1918, flying anti-submarine patrols from a number of
Naval Air Station
A Naval Air Station (NAS) is a military air base, and consists of a permanent land-based operations locations for the military aviation division of the relevant branch of a navy (Naval aviation). These bases are typically populated by squadron ...
s on the Eastern Seaboard of the United States, and from the
Panama Canal Zone
The Panama Canal Zone (), also known as just the Canal Zone, was a International zone#Concessions, concession of the United States located in the Isthmus of Panama that existed from 1903 to 1979. It consisted of the Panama Canal and an area gene ...
. Two HS-1Ls operating from
Chatham, Massachusetts
Chatham () is a New England town, town in Barnstable County, Massachusetts, Barnstable County, Massachusetts, United States. Chatham is located at the southeastern tip of Cape Cod and has historically been a fishing community. First settled by th ...
, made the only confirmed aircraft attack on a German in American waters on July 21, 1918, but this was unsuccessful, with bombs failing to explode and the submarine escaping.
[Owers 1999, p.68.] From August 1918, in order to compensate for Canada's lack of patrol aircraft, US Navy HSs operated from two bases in
Nova Scotia
Nova Scotia is a Provinces and territories of Canada, province of Canada, located on its east coast. It is one of the three Maritime Canada, Maritime provinces and Population of Canada by province and territory, most populous province in Atlan ...
. Twelve HS-2Ls were donated to Canada at the end of the war.

Large numbers of HS boats were also used by US Navy forces in France, with deliveries starting on May 24, 1918, flying their first patrols on June 13. About 160 HS-1Ls and -2Ls were deployed to France.
[Owers 1999, p.70.][Bowers 1979, p.102.] Following the
Armistice
An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from t ...
, the HS boats based in Europe were scrapped apart from four aircraft based in the Azores, which were acquired by Portugal, while the US Naval Air Service shrank considerably, with many Naval Air Stations closing, resulting in considerable numbers of HS boats becoming surplus to requirements and available for sale at $200 to $500 without engines.
[Owers 1999, p.71.] HS-2Ls continued in use by the US Navy as a patrol aircraft and a trainer until 1928.
Following the Armistice, eleven HSs passed into US Coast Guard service, remaining in service until 1926.
[Owers 1999, p.75.] As many as 83 HS boats were used by the
United States Army Air Service
The United States Army Air Service (USAAS)Craven and Cate Vol. 1, p. 9 (also known as the ''"Air Service"'', ''"U.S. Air Service"'' and before its legislative establishment in 1920, the ''"Air Service, United States Army"'') was the aerial warf ...
for communications and survey purposes from overseas bases, although they were not given US Army serial numbers.
Surplus HSs were also widely exported. Amongst Military users was Brazil, who received six aircraft in 1918.
Two HS-2Ls were used in an attempt to bomb the rebel held Forte de
Copacabana during the 1922
''Tenente'' revolt.
Many were used in Canada as the first bush plane. One survives in the
Canada Aviation Museum in
Ottawa
Ottawa is the capital city of Canada. It is located in the southern Ontario, southern portion of the province of Ontario, at the confluence of the Ottawa River and the Rideau River. Ottawa borders Gatineau, Gatineau, Quebec, and forms the cor ...
after being rescued from Foss Lake, Ontario.
Variants

* HS-1 - prototype with Curtiss engine.
[Bowers 1979, p.101.]
** 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.
[Bowers 1979, p.104.]
* HS-3L - Canadian modified version of HS-2L with modified wings (
Clark Y
Clark Y is the name of a particular airfoil profile, widely used in general purpose aircraft designs, and much studied in aerodynamics over the years. The profile was designed in 1922 by Virginius E. Clark using thickness distribution of the Germa ...
section). At least three converted.
[Owers 1999, p.67.]
Operators
;
*
Argentine Naval Aviation
The Argentine Naval Aviation (', COAN) is the naval aviation branch of the Argentine Navy and one of its four operational commands. Argentina, along with Brazilian Navy, Brazil is one of two South American countries to have operated two aircraft c ...
Operated 12 aircraft from 1921 to 1931.
;
*
Brazilian Naval Aviation - acquired six HS-2Ls in July 1918.
Retired in 1923.
;
*
Canadian Air Board - acquired 12 HS-2L from the
US 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 ...
following closure of its
Naval Air Station Halifax. Likely transferred to Canadian Air Force in 1923.
*
Canadian Air Force
The Royal Canadian Air Force (RCAF; ) is the air and space force of Canada. Its role is to "provide the Canadian Forces with relevant, responsive and effective airpower". The RCAF is one of three environmental commands within the unified Cana ...
- obtained HS-2L beginning in 1920.
[Bowers 1979, pp. 103–104.] 12 likely transferred from Air Board when it disbanded and in total operated 30. All retired in 1928.
;
*
Mexican Air Force
The Mexican Air Force (FAM; ) is the air service branch of the Mexican Armed Forces. It is a component of the Mexican Army and as such overseen by the National Defense Secretariat (SEDENA). The objective of the FAM is to defend the integrity, in ...
;
*
Peruvian Navy
The Peruvian Navy (, abbreviated MGP) is the branch of the Peruvian Military of Peru, Armed Forces tasked with surveillance, patrol and defense on lakes, rivers and the Pacific Ocean up to from the Peruvian littoral. Additional missions include ...
- received at least three HS-2Ls in 1920, remaining in service until 1926.
[Hagedorn 1992, p. 63.]
;
*
Portuguese Naval Aviation
The Portuguese Naval Aviation () constituted the Naval aviation, air component of the Portuguese Navy, from 1917 to 1957. The Portuguese Air Force maritime patrol units and the Navy's Helicopter Squadron (EHM, ) are the present successors of the f ...
- took over four ex-US Navy HS boats based in the
Azores
The Azores ( , , ; , ), officially the Autonomous Region of the Azores (), is one of the two autonomous regions of Portugal (along with Madeira). It is an archipelago composed of nine volcanic islands in the Macaronesia region of the North Atl ...
after the end of World War I, using them for training.
[Owers 1999, p.74.] Retired 1931.
;
*
United States Army Air Service
The United States Army Air Service (USAAS)Craven and Cate Vol. 1, p. 9 (also known as the ''"Air Service"'', ''"U.S. Air Service"'' and before its legislative establishment in 1920, the ''"Air Service, United States Army"'') was the aerial warf ...
operated in total 83 HS-2L
*
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 ...
operated 11 until 1926
*
United States Marine Corps
The United States Marine Corps (USMC), also referred to as the United States Marines or simply the Marines, is the maritime land force service branch of the United States Department of Defense. It is responsible for conducting expeditionar ...
*
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 ...
Specifications (HS-2L)
See also
*
Canadian Vickers - three HS-3L built
Notes
Bibliography
*
*
*
*
*
*
*
External links
* Contemporary technical description of the HS-1L and HS-2L with photographs and drawings.
The HS-1L Flying Boat Handbook
{{Authority control
1910s United States patrol aircraft
Flying boats
HS
Single-engined pusher aircraft
Biplanes
Aircraft first flown in 1917