Almost 3,000 early U.S. Navy, Marine Corps, and Army pilots are estimated to have learned to fly on the Curtiss N-9 floatplane. That iconic aircraft was initiated as a private venture by the Curtiss firm as a seaplane variant of the famed JN-4B “Jenny” landplane trainer then in production.1
The N-9 was an enlarged Jenny biplane with a lengthened center section, increased wingspans, and a revised control system dictated by the large, central float and wingtip floats that were added in the seaplane configuration. The N-9 had the Curtiss OXX-6 engine of 100 horsepower, which soon was found to be barely adequate for the aircraft. The biplane had tandem seating for the student and instructor.
The prototype N-9 flew on 16 November 1915, a year and a half before the United States’ entry into World War I. Flight tests indicated directional instability, and the production aircraft were provided with an enlarged vertical fin. By 1917, the Navy had ordered 500 N-9s as primary trainers, and the Army asked for 14 of the aircraft. But the Curtiss production facilities were overtaxed and were able to produce only 100 aircraft; thus, 460 of the N-9s were built for the Navy by the Burgess Company of Marblehead, Massachusetts. That firm already had experience in manufacturing floatplanes.
It generally was accepted at the time that floatplanes could not be “looped.” But Marine pilot First Lieutenant Francis T. Evans Sr. at the naval air station at Pensacola believed it was possible. On 13 February 1917, he flew an N-9 over the Gulf of Mexico and, on his fourth try, became the first person ever to loop a seaplane. Lacking witnesses, he flew over Pensacola airfield and repeated the feat.2 (In 1936, two decades later, he received the Distinguished Flying Cross for the achievement.)
During these flights Evans also developed spin and stall recovery techniques that still are in use by aviators around the world. Other naval aviators employed the N-9 in the development of shipboard aircraft catapults. The “cat” development involved the armored cruiser North Carolina (ACR-12), at the time operating out of Pensacola.
Meanwhile, the OXX-6 engine was found unsatisfactory for the N-9, as the aircraft required increased performance for gunnery and bombing training. Thus, the 150-horsepower Wright Hispano-Suiza Model A engine was provided, with those aircraft being designated N-9H (the “H” indicating Hispano). Those planes generally were referred to as the “Hisso” aircraft.
With the advent of the N-9H designation, those aircraft with OXX-6 engines became known as N-9C (for Curtiss).
The water-cooled Hispano-Suiza V8 engine was designed by Swiss automobile engine designer Marc Birkigt. Its use of aluminum components reduced weight by about 40 percent compared to previous engines of that type. The N-9H aircraft could easily be identified by the vertical radiator forward of the upper wing and small vertical fins on the upper wings above the stabilizing floats. (The use of a large spinner over the propeller hub precluded the use of a conventional nose radiator.)
The N-9s served as training aircraft throughout World War I. After the war, an additional 50 N-9H aircraft were assembled by the Navy at Pensacola through the practice of assembling available spare parts and engines into entirely new aircraft.
The U.S. Navy retired the last N-9s in 1928. Also, some of the aircraft went to Brazil’s naval air arm.
1. See Peter M. Bowers, Curtiss Aircraft 1907–1947 (Annapolis, MD: Naval Institute Press, 1979), 112–15.
2. Peter B. Mersky, U.S. Marine Corps Aviation Since 1912, 4th ed. (Annapolis, MD: Naval Institute Press, 2009), 5–6.