The Curtiss Model F was an early single engine flying boat that saw extensive service as a US training aircraft during the First World War.
The Model F evolved from the Curtiss Flying-Boat No.2, the first successful flying boat. Glenn Curtiss had already produced a number of seaplanes, but these were all floatplanes. Flying-Boat No.1, his first attempt to produce a flying boat, where the base of the fuselage was also the float, wasn’t a success. This was followed by Flying-Boat No.2. This aircraft was originally built with a low set bow elevator, single-surface wings (one level of material stretched over a framework, compared to the standard two level wing with top and bottom surfaces). It was powered by a single pusher engine mounted between the wings. It was originally built with a long smooth hull, but this version was unable to take off. Curtiss then added a ‘step’ just behind the centre of gravity, which reduced the length of hull that remained in contact with the water at take-off speed. With this modification the aircraft successfully took off in July 1912.
Flying-Boat No.2 set the basic pattern for a whole series of experimental single engine flying boats, ending with the Type F. This included the Type C, of which five were purchased by the US Navy in 1913. Each of these was slightly different, although the C-2 was very similar to the early Type F apart from having a longer wingspan on the upper wing. The C-2 was most notable for flying under the control of a Sperry gyroscopic autopilot in August 1913. The C-3 (navy designation AB-3) saw limited front line service, flying a series of patrols over Veracruz harbour early in the American intervention in Mexico in 1914, which began with the occupation of Veracruz in 1914. This made it the first US Navy aircraft to be used in combat.
The Model F itself was produced in several variants. The 1913 version was a two-bay biplane, with a wooden fuselage, including a plywood covered single-step hull, and fabric covered wings and tail surfaces. The ailerons were carried between the wings and controlled by a shoulder yoke. The crew of two sat side by side in a cockpit in front of the wings. It was powered by a 75hp Curtiss O engine, driving a pusher propeller. This version was used by both the US Army and the US Navy.
The 1914 Model F had rounded wing-tips, equal span wings, a stronger hull, and strong struts to support the engine. The ailerons were carried between the wings and extended well past the ends of the main wings. This version was also ordered by the US Navy, and after the US entry into the First World War became the standard US Navy primary training flying boat, with 144 ordered after the entry into the war.
The 1917 Model F replaced the shoulder-yoke controls with the Deperdussin system. Some examples had the ailerons moved to a long span upper wing. The 100hp Curtiss OXX-3 engine was used from 1917. The increase in power more than compensated for an increase in weight, and the 1917 model could reach 68mph, an increase of 13mph over the original 1913 version.
A number of Model Fs were converted into ambulance aircraft, capable of carrying a stretch on top of the hull behind the cockpit.
As well as serving in the US, the Model F was sold to Russia for service in the Baltic and Black Seas and eight were licence built in Italy
The Model F played a part in introducing the British aviation pioneer John Porte to Glenn Curtiss. In 1913 Porte joined a syndicate formed by Ernest C Bass, which invited Curtiss to bring one of his Model F boats to England. Curtiss and the aircraft arrived at Brighton in October 1913. It didn’t live up to expectations, with one of its British test pilots declaring that it was ‘absolutely unstable in every direction’, but even so there was enough interest for a flying boat training school to be set up with Porte as its instructor. However he wasn’t there for long, as he had impressed Curtiss enough to be invited to the States to act as one of the pilots of the new Curtiss H-1 America, which was being built to attempt to fly across the Atlantic. Porte would later return to Britain, where he would help to develop the Felixstowe F-boats, improved variants of the Curtiss H boat.
Model MF (Model 18)
The Model MF (Modernized F) was an improved version of the Model F, with an improved structure and sponsons on either side of the forward hull to improve stability on the water. Production aircraft used the 100hp OXX-3 introduced in later Model Fs, but the type was also used to test a variety of 150hp engines. The US Navy acquired 102 Model MFs, 22 built by Curtiss and 80 by the Naval Aircraft Factory.
Model F (1913)
Engine: Curtiss O
Span: 41ft 8in
Length: 27ft 4in
Gross weight: 1,760lb
Max speed: 54.8mph
Climb rate: 1,200ft in 7.6 mins
Endurance: 4 hours
Model F (1917)
Engine: Curtiss OXX-3 inline piston engine
Crew: 2 (side by side)
Span: 45ft 1 1/4in
Length: 27 ft 9 3/4 in
Height: 11ft 2 3/4in
Empty weight: 1,860lb
Gross weight: 2,460lb
Max speed: 68 mph
Climb Rate: 2,300ft in 10 minutes
Service ceiling: 4,500ft
Endurance: 5 hours 30 minutes