The Felixstowe F.5 series originated in the United Kingdom as a militarized flying boat in the last year of World War 1 (1918). Her design was credited to Lieutenant Commander John C. Porte of the Royal Navy (out of the "Seaplane Experimental Station" at Felixstowe - hence her designation). Porte had already taken the Curtiss H.12 flying boat (Curtiss Model H) and modified it into a better product when he designed his Felixstowe F.2a series. The F.2a series would go on to become the standard Royal Navy Air Service flying boat of World War 1 while the follow-up F.5 led a healthy existence during the post-war period defined as the "inter-war" years (in both military and civilian guises).
Porte continued to evolve the F.2a design and eventually produced the Felixstowe F.3 series. However, the new design being larger and thusly heavier, it suffered from poor handling while still benefiting from having greater range and an increased bomb load capacity - two good qualities for a flying boat to have. As such, development continued and ultimately resulted in the completely redesigned "F.5", essentially a design intended to mate together the benefits of both preceding designs to make for a single excellent sea-borne patrol platform - first flight followed in May of 1918. Despite the improved qualities exhibited from the prototype, the powers that be deemed that the F.5 should incorporate as many production elements of the existing F.3 as possible to help keep costs down and numbers steady. This resulted in production versions of the F.5 lacking much of the performance displayed by the prototype, the end-product finding it hard to even match the performance the preceding F.2a and F.3 it was intended to best.
Regardless, the F.5 went on to become the standard flying boat of the British Royal Air Force from 1918 onwards though missing out on operational service in World War 1 altogether. Production of the base F.5 military boat was as follows: Short Brothers (23 examples); Phoenix Dynamo Manufacturing Company (17 examples); Gosport Aviation (10 examples); Dick, Kerr & Company (2 examples); Seaplane Experimental Station (1 example).
The Felixstowe F.5 maintained an elegant appearance consistent with flying boats of the time, made most identifiable by its hull-like fuselage. The fuselage was contoured where possible, bulbous at the lower portions to effectively displace water, with little detail to disrupt airflow. Wings were set amidships and were biplane in nature and slightly unequal in span, held in place by parallel bracing struts and cabling with pontoons located outboard. The engines were mounted between the upper and lower wing assemblies, well clear of salt spray from the sea. The fuselage tapered upwards towards the empennage which sported a single, large-area angular vertical tail fin and high-mounted, large-area horizontal tailplanes. Cabling extended from amidships rearwards towards the tail fin. The crew of four sat in open-air cockpits with accommodations for two pilots (seated side-by-side) and a pair of machine gunners - one manning the forward mount in the front circular cockpit and the other nestled between the two engine mounts amidships in another circular cockpit. Defensive armament centered around a collection of four Lewis aircraft machine guns, one set in a flexible mounting in the nose and the other two (or three) Lewis guns positioned along amidships. As a bomber, the F.5 could make use of four underwing bomb racks for the carrying of 4 x 230lb bombs. Power was derived from twin Rolls-Royce Eagle VIII series V12 inline piston engines delivering approximately 350 horsepower spinning two-bladed propellers. This provided for speeds of up to 88 miles per hour with a service ceiling of 6,800 feet and endurance for seven hours of flight time.
The base F.5 served with the British Royal Air Force and the Royal Naval Air Service branches. With the RAF, it made up the inventories of Squadrons No. 230, 231, 232, 238, 247, 249, 259, 261 and 267.
F.5 production was also undertaken by the Americans when the US Navy adopted the type into service in 1918. These were powered by a pair of Liberty engines and produced by Curtiss (60 examples), the US Naval Aircraft Factory (137 examples) in the US and by Canadian Aeroplanes (30 examples) out of Toronto, Canada. The Liberty-powered mounts came under the designation of "F.5L" and some 227 examples were built in all. F.5Ls were the US Navy's primary flying boat up until 1928 before being replaced by the PN-12 series. Curtiss F.5Ls also served in the civilian airliner role after some conversion. These were operated by the Aeromarine Plane and Motor Company beginning in 1919 under the company designation of "Aeromarine 75". Operators of this type included both the United States and Argentina.
Japan license-produced the F.5 for its Imperial Japanese Navy to the tune of 60 examples, these handled by the Hiro Naval Arsenal.
The F.5 served with the RAF up until August of 1925, replaced by the Supermarine Southhampton.