The Curtiss HS-2L was an improved version of the HS-1 coastal patrol flying boat that could carry a heavier payload, making it more suitable for use against submarines.
The HS-1 had been developed as a single engined version of the famous Curtiss H family of twin engined pusher flying boats. It was developed from the prototype H-14 by replacing that aircraft’s two 100hp engines with a single 200hp Curtiss OXX-2. This version had been ordered into production for the US Navy, and soon entered service in home waters and from naval air stations around the coast of France. By this point the Curtiss engine had been replaced with a 350hp Liberty engine, to produce the HS-1L.
The original HS-1L could carry two 180lb depth charges, but after the aircraft entered service it soon became clear that this wasn’t powerful enough to damage a submerged U-boat. In order to increase the payload that could be carried the HS-2L was produced. This was done by fitting a new 12ft long centre section on the upper wing and 6ft long inner panels between the original lower wing and the fuselage. The wingspan rose to 74ft 1in. As a result of the changes maximum take-off weight rose by 522lb and the HS-2L could carry two 230lb bombs.
The change in design was introduced on the Curtiss production line, and the majority of HS-1Ls were completed as the HS-2L. However it isn’t clear how many of each type was produced. However all of the aircraft produced by other companies appear to have been HS-2Ls, so this includes 200 built by the Standard Aircraft Company, 150 by Lowe, Willard and Fowler, 60 by Gallaudet, 25 by Boeing and 2 by Loughhead.
A total of 182 HS-1Ls and HS-2Ls reached the US Naval Air Stations in France, but of these only 19 were definitely HS-2Ls. The first HS patrol was carried out on 13 June 1918, and the aircraft was used on anti-submarine patrols for the rest of the war. It was also used for the same role along the US coast.
After the war the HS-2L became the standard single-engine patrol and training flying boat for the US Navy, with some remaining in service until 1926. Although hundreds had been produced, another twenty-four were built after the war by using the spare parts scattered around various naval air stations.
Many HS-2Ls were sold onto the civil market after the war, working as passenger aircraft. The last few were still being used as survey aircraft in Canada in the early 1930s.
Engine: One Liberty 12
Crew: 2 or 3
Span: 74ft 1/2in
Height: 14ft 7 1/4in
Empty weight: 4,300lb
Gross weight: 6,432lb
Max speed: 82.5mph at sea level
Climb Rate: 10min to 2,300ft
Service ceiling: 5,200ft
Range: 517 miles
Armament: One flexibly mounted .30in Lewis gun
Bomb load: Two 230lb bombs