Curtiss Model N The Curtiss N - 9 was a floatplane variant of the Curtiss JN - 4 " Jenny " military trainer used during World War I by the United States Navy . Design and development . As a seaplane , the N - 9 was equipped with a single central pontoon mounted under the fuselage . A small float was fitted under each wingtip . With the additional weight of the pontoon , a number of structural and aerodynamic changes were required , the design of which made use of wind tunnel data developed at the Massachusetts Institute of Technology , meaning the N - 9 was the first American naval aircraft to incorporate wind tunnel data directly into its design . The wingspan was stretched an additional 10 feet ( 3 meters ) , the fuselage was lengthened , the tail surfaces were enlarged , and stabilizing fins were added to the top of the top wing . The N - 9 was initially powered by a 100 hp ( 75 kW ) Curtiss OXX - 6 engine . Curtiss was awarded an initial contract for 30 aircraft in August 1916 , and an additional 14 were ordered by the United States Army , which maintained a small seaplane operation . It quickly became apparent that the aircraft was underpowered , so Curtiss replaced the engine with a 150 hp ( 112 kW ) Hispano - Suiza , manufactured in the United States under license by Wright - Martin ' s Simplex division ( later Wright Aeronautical ) . The aircraft was redesignated N - 9H . A total of 560 N - 9s were built during World War I , most of which were " H " models . Only 100 were actually built by Curtiss . Most were built under license by the Burgess Company of Marblehead , Massachusetts . Fifty others were assembled after the war , from spare components and engines by the U . S . Navy at Naval Air Station Pensacola in Florida . Operational history . Although the consensus in early 1917 among aviators and even the N - 9s manufacturer was that the N - 9 could not be looped , the pioneering early United States Marine Corps aviator Francis Thomas Evans , Sr . , believed it was possible . On 13 February 1917 , he flew an N - 9 over the Gulf of Mexico off Pensacola , Florida , and began attempts to loop it . He succeeded on his fourth try , becoming the first person ever to loop a seaplane . Lacking witnesses , he flew over Naval Air Station Pensacola and repeated the feat . In 1936 , he received the Distinguished Flying Cross for this achievement . More important , however , were the stall and spin recovery techniques he discovered while flying the N - 9 that day . During his first three loop attempts , the N - 9 stalled before he reached the apex of the loop and fell into a spin . He found that by releasing back - pressure on the stick and aggressively applying opposite rudder to the direction of the spin he could change the spin into a normal dive and recover , something previously thought impossible in an N - 9 . His stall and spin recovery techniques remain in use to this day by aviators around the world . Over 2 , 500 U . S . Navy pilots received their seaplane training in N - 9s . Besides this primary role , though , the aircraft was also used to help develop shipborne aircraft operations during World War I , especially the development of ship - mounted launch catapults . In 1917 , several N - 9s were provided to the Sperry Gyroscope Company for conversion to the Hewitt - Sperry Automatic Airplane configuration , flight testing the new autopilot components intended to be used in pilotless " aerial torpedo es " . The U . S . Navy retired the N - 9s in 1927 as more modern trainers became available . Survivors . Only one example of the type has survived , and is now a part of the National Air and Space Museum collection . Originally on display at the Museum of Science and Industry in Chicago , Illinois , it was later transferred back to the U . S . Navy pending transport to the National Air and Space Museum . The Naval Air Engineering Laboratory in Philadelphia , Pennsylvania , fully restored it in 1966 .