SST class airship

{{short description|World War I airship class}}

{{Use dmy dates|date=June 2017}}

{{Use British English|date=June 2017}}

The SST (Sea Scout Twin) class of non-rigid airship or "blimp" was developed in Great Britain during World War I from the earlier SS class airship. The main role of these craft was to escort convoys and scout or search for German U-boats.[http://aht.ndirect.co.uk/airships/ss/index.html "Submarine Scout Class"] Airship Heritage Trust. Retrieved on 25 March 2009. A secondary purpose was to detect and destroy mines.[https://books.google.com/books?id=HXyTAgAAQBAJ&dq=mines+destroyed+submarine+scout+airships&pg=PA103 TAnti-Submarine Warfare in World War I: British Naval Aviation. Retrieved on 13 September 2018.]

Designs were submitted in 1917 for a twin-engined SS class airship, the idea being that should there be an engine failure, the craft would not be rendered helpless and therefore less likely to be lost.Whale (2008), p.61. The first submission was a failure, but the second showed promise and was put into production. Designated the SST class, the first of 13 examples entered service in June 1918, and the last in May 1919, three of which, S.S.T.9, 11 and 12 were purchased by the US Navy.[http://aht.ndirect.co.uk/airships/Technical%20Spec/SST%20Airships.htm "Ship Identification : SST AIRSHIPS".] AHT. Retrieved on 26 March 2009.

The SST used a larger {{convert|100000|ft3|m3|abbr=on}} envelope than any of the other SS class types, and was equipped with a streamlined and waterproofed car that could accommodate a crew of five. Two {{convert|100|hp|kW|abbr=on}} Sunbeam or {{convert|75|hp|kW|abbr=on}} Rolls-Royce Hawk engines were each mounted on a gantry either side of the car, and drove {{convert|9|ft|m|abbr=on}} diameter four-bladed propellers in pusher configuration.Whale (2008), p.62. At {{convert|57|mph|km/h|abbr=on}}, the SSTs had a greater top speed than all other SS class types, had the highest useful lift, and could stay airborne for up to two days.See comparative specifications for all SS class variants They were also cheaper to produce and easier to handle than the successful C Star class airship. Three SST were transferred to the Navy in June 1919. No Serial Numbers were assigned and there is no evidence they operated by the Navy.Shock, James R., U.S. Navy Airships 1915-1962, 2001, Atlantis Productions, Edgewater Florida, {{ISBN|0-9639743-8-6}}, page 43 The 3 SST's were transferred to the Army in 1919-1920. The Army operated the SST's until late 1923 or early 1924.Shock, James R., U.S. Army 1908-1942, Airships 1908-1942, 2002, Atlantis Productions, Edgewater Florida, {{ISBN|0-9639743-9-4}}, page 49

Experiments involving SSTs were carried out at the end of the war; one notable example being SSE.3 (SS Experimental) that had an envelope design known as shape "U.271", the shape from which the hulls of both R100 and R101 were derived.[http://www.flightglobal.com/pdfarchive/view/1930/untitled0%20-%200087.html "Twenty-one Years of Airship Progress"] p87 Flight, 3 January 1930 Retrieved on 27 March 2009.