The Felixstowe F.2 was an improved version of the Curtiss H-12 ‘Large America’, produced in Britain by fitting the Curtiss wings to a new hull that had been developed in an attempt to improve the earlier Curtiss H-4 ‘Small America’. The resulting aircraft was judged to be a great improvement on the Curtiss original on the water, and was followed by a series of further models, including the American-built F.5L.
The Felixstowe flying boats were developed by the remarkable John Porte. He had served in the Royal Navy before being invalided out in 1911. Early in 1914 he moved to American to help Glenn Curtiss with the design of the Curtiss H-1 America, a large flying boat designed to attempt a trans-Atlantic flight. Porte helped design the hull (or at least influenced the design), and would have been one of the pilots for the Atlantic crossing.
After the outbreak of war in 1914 Porte returned to Britain and rejoined the Navy. He was appointed as commander of the RNAS base at Felixstowe, and convinced the Admiralty to purchase the two H-1s, then to order a larger number of the generally similar Curtiss H-4s. These handled well on the sea and in the air, but were underpowered for service use, and the hull wasn’t robust enough for the North Sea. Porte began to experiment with modified hulls, before producing the Porte I, which combined a new hull with the wings of the H-4. This aircraft was then designated as the Felixstowe F.1, and was considered to be a significant improvement on the H-4.
There is some confusion about the actual designation of the aircraft that was developed into the prototype Felixstowe F.2. It was a Curtiss built aircraft, with the serial number 8650. In some sources this is recorded as having been a Curtiss H-12, but contemporary British documents referred to it as the Curtiss H-8, the first of fifty examples of that aircraft on order. Photographs of 8650 in its original configuration show an aircraft similar to the H-4, with a shallow V hull, but with a more shallow concave curve than the H-4. It had the standard H-boat tail and wings and the enclosed cockpit. In trials the H-8 proved to have a ‘hump’ speed of 18knots where it produced little lift but water resistance was at its greatest. At full loaded weight it was very difficult to get past the hump. With a lighter weight it could reach take-off speed. The H-8 designation appears to have been British, as this aircraft doesn’t resemble Curtiss’s photographs of their H-8. The rest of the original order for fifty H-8s was used to purchase forty-nine H-12s.
With the original Curtiss engines 8650 was unable to take off with a full military load. As a result the aircraft was given two 250hp Rolls-Royce engines, which allowed it to take off at the RNAS’s target weight, but the hydrodynamic performance got even worse.
Porte produced a new two-step hull similar to the three-step hull on the definitive F.1 and a modified tail, which were combined with the H-12 wings. The new hull was 42ft long, and had a ‘V’ shaped bottom with slopes of 20 degrees. The first step was below the rear spar, and the second step seven feet further back. The hydrodynamic lower part of the hull was much wider than the main hull. The original Curtiss hull was built as a single integrated structure, but Porte’s modified designs used a simple main fuselage, with the lower hydrodynamic part of the hull constructed separately and attached later. This made it much easier to experiment with different designs. This aircraft had a semi-enclosed cockpit.
The prototype of the F.2 was built by fitting the Porte II hull to the first H-8, no.8650. In its original configuration it kept the enclosed cockpit of the Curtiss design, and added a rounded top along the full length of the decking from the back of the cockpit to the tail. This was later cut down and ended at the back of the wings. As with the earlier F.1, the key change was the shape of the planing bottom. The H-8 had a shallow ‘V’ shape, with a concave surface between the keel and the tips of the low mounted sponsons. On the F.2 the tip of the nose was moved up, as were the sponsons, creating a much steeper ‘V’. The concave shape was replaced with a much straighter surface. This greatly improved landings, eliminating most of the shock suffered on the standard Curtiss boats. The impact of the ‘hump’ was greatly reduced, allowing the aircraft to take off at the correct full load. The new hull was also stronger than the Curtiss hull, but no heavier.
The prototype F.2 was built in the summer of 1916 and probably began tests in late July – the exact date of the conversion isn’t recorded, but the aircraft was being repaired in June, ‘being erected’ in the first half of July, and undertook duration, speed and altitude tests in the second half of July . The new hull was found to be stronger than that of the H-12, more buoyant, produced fairly shock-free landings, and was no heavier than the original design.
The sole F.2 entered service in late July 1916, and carried out a series of patrols over the North Sea before it was lost after putting down near the Sunk Light Vessel east of the River Naze on 30 September 1916.
Both the H-12s and the new Felixstowe F.2 was also given Rolls-Royce Eagle engines. After tests with the new design it was given more powerful 360hp Rolls-Royce Eagle VIII engines, becoming the Felixstowe F.2A, the main production version. Early aircraft were built with an enclosed cockpit for the pilots, later aircraft had an open cockpit, which was felt to give a better view. Production was quite widely spread, with six firms building the hulls and three building complete aircraft. Some of the hulls were used to modify existing H-12s to produce the H-12 Convert. The first F.2A was delivered in November 1917, going to the Felixstowe Seaplane School. By March 1918 orders had been placed for 161 aircraft, and by the end of the war the RAF was operating 53 F.2As. Around 173 F.2As were eventually built.
The F.2A was produced by Saunders, Airco and May, Harden and May in Britain, with six companies building the hulls. Saunders built 67 hulls in six batches. Aldous produced 10 hulls, Dixon Brothers & Hutchinson 5, Summers and Payne 13, Camper & Nicholson 6 and Norman Thompson/ H. Williams & Co 4. The first production aircraft, a Saunders built aircraft, was delivered to Felixstowe in November 1917. By the end of May 1918 nearly 40 F.2As had been delivered, along with the first fifteen H.16s, and at the end of the war the RNAS had 53 F.2As and 69 H.16s on strength.
Some details of the wings are unclear. Most sources give details of who built the hulls and assembled the aircraft, but none explicitly state where the wings were built. There is no mention of them being produced by Curtiss and shipped across to Britain. Sadly the wingspan of the sole H.8 isn’t reported in any of my sources. The F.2A had a wingspan of 95ft 7.5in, but the contemporary Curtiss H-12 a span of only 92ft 8 1/2in, so the two aircraft didn’t use the same wings. The H-16 had a very similar span to the F.2A, but then may well have been based on it. The most likely solution is that wings using the Curtiss design, but with a slightly longer span than the H-12, were produced in Britain by the same companies that are recorded as building the aircraft.
The H.16 was the designation given to aircraft produced by Curtiss, generally described in British sources as the Curtiss designation for the F.2A, and in American sources as an improved H-12, or the Curtiss version of the F.2A. Both of these statements can of course be true, and plans of the H-16 and F.2A suggest that they were identical.
Two examples of the modified F.2C were produced. This has a lighter hull and was powered by two 275hp Rolls-Royce Eagle II engines, then by two 322hp Eagle VIs. This version of the F.2C performed slightly better than the F.2A, but the improvements weren’t enough to justify putting it into production. However the prototype F.2Cs were used operationally in 1917.
The F.2 was followed into production by the Felixstowe F.3, which gained range and payload but lost speed and manoeuvrability, making it less successful against enemy aircraft, but a better anti-submarine patrol aircraft. However the F.3 was declared obsolete in September 1921 leaving the F.2A and F.5 as the RAF’s standard flying boats. After the war some F.2As did finally serve overseas, and the last in British use were serving with No.267 Squadron on Malta until they retried in May 1923.
The F.2A entered service in February 1918, with the first aircraft operating from Great Yarmouth. The F.2A remained in service to the end of the war. It was agile enough to be used against Zeppelins and even some German floatplane fighters. The F.2A was only used from British bases, serving from Great Yarmouth, Calshot, Dundee, Felixstowe, the Orkneys, Killingholme and Westgate/ St Mildred’s Bay.
Many of them were used to patrol over the ‘Spider Web’, an area 60 nautical miles across centred on the North Hinder Light Vessel, crossed by most U-boats on their way to or from their bases. It took about ten hours for a U-boat to cross this area, but only an hour for a flying boat to reach the North Hinder Light Vessel. Although only one U-boat was sunk by air attack alone during the war, the Felixstowe and Curtiss aircraft carried out eighteen attacks on possible U-boats between May 1918 and the end of the war, each of them potentially disrupting the U-boat’s patrol.
The F.2A could carry up to seven guns including one or two Lewis guns in the nose, one on a dorsal Scarff ring, two in waist positions and one on the port side of the cockpit canopy. It could also carry one 230lb on a rack under each wing.
The F.2A was capable of holding its own against German float plane fighters. The largest clash between the two types came on 4 June 1918 when four F.2As and a H.12 Convert were sent to hunt seaplanes. One F.2A was forced to put down after suffering a problem with the petrol feed, and the crew ended up being interned in Holland. The H-12 was detached to protect the downed aircraft. The remaining F.2As encountered fourteen Brandenburg float planes near the coastal islands of Terschelling and Ameland and took part in a battle in which three German aircraft were shot down for no loss.
The F.2A was also used against Zeppelins, and on 10 May 1918 one of the Killingholme aircraft shot down Zeppelin L56 over Heligoland. The Zeppelin had a much higher service ceiling than the F.2A, but the aircraft was able to shoot at it from below, and caused damage that saw the airship burst into flames some time after the attack had ended.
The F.2A was also sometimes operated by the US Naval Air Service from bases in Britain.
On 20 July 1918 RAF Killingholme became an US Naval Air Station. At least five F.2A were transferred from British to American control for service at the new base, along with four H.12Bs and two H.16s.
The range of the F.2A was sometimes improved by towing the aircraft towards the enemy coast on lighters towed by destroyers, another of Porte’s ideas. They would then take off from the sea, allowing them to reach further along the German coast. The first of these operations was carried out on 19 March 1918, resulting in the loss of one German seaplane.
Engine: Two Rolls-Royce Eagle VIII 12-cylinder V piston engines
Power: 360hp each
Span: 95ft 7 1/2in
Length: 46ft 3in
Height: 17ft 6in
Empty weight: 7,549lb
Maximum take-off weight: 10,978lb
Max speed: 95mph at 2,000ft
Service ceiling: 9,600ft
Endurance: 6 hours
Armament: Four to seven free mounted 0.303in Lewis machine guns
Bomb load: two 230lb bombs on under wing racks