The Floatplane Spitfires

July 15, 2022

The Spitfire is widely regarded as one of the finest fighter aircraft in history. Serving throughout the Second World War and proving adaptable enough to evolve as the conflict raged, the Spitfire was a keystone aircraft in British and Allied air forces and was built in large numbers.


As a result of this widescale construction and usage, the type found itself also used in a host of other roles other than as a fighter as originally intended; Photo reconnaissance, meteorological, carrier fighter, attack bomber, if a single seat aircraft could do it, then the Spitfire probably did.

Heck, they were even used to transport beer to thirsty troops fighting in Europe at one point!


And there was one other role, less-well known of, that the aircraft was tried in; one which is somewhat ironic as the lineage of the Spitfire runs directly from the Supermarine racing floatplanes of the pre-war years.

The Floatplane Spitfire.

Interest in the concept of having a seaplane variant of the Spitfire started with the German invasion of Norway on the 9th of April 1940. Both the British and French rushed troops to the country to confront the Germans, and one of the major issues faced by the Allies was the lack of airfields for them to operate fighters from.

But what Norway did have was miles of open waterways and fjords from which seaplanes could operate.

The British had in fact planned to build a float plane variant of the Blackburn Roc before the war. But this turret fighter was barely a functioning combatant in its original configuration, and the addition of heavy floats made it even more of a sitting duck.

Anyway, with nothing else suitable, the British decided that the best stop gap option was to see if they could convert one of their existing front-line fighters into a viable combat floatplane. Both Supermarine and Hawker were asked to examine the possibility of this with their respective Spitfire and Hurricane fighters, building test aircraft into floatplane configuration as a matter of utmost priority. To this end the government released several sets of floats that had been built for Rocs for trial fitting, with the understanding that should it prove successful fifty more would be made available to build floatplane fighters.

Hawker was dubious about whether the conversion would work on the Hurricane effectively, especially as the Roc was a heavier aircraft than both the Spitfire and the Hurricane and thus the floats designed for it were heavier and larger than needed. As the Hurricane already had inferior performance to the Spitfire, no doubt they appreciated that, at a time when they were already working flat out, the exercise for them would prove a waste of effort.

Scale model tests conducted at the Royal Aircraft Establishment at Farnborough would go on to prove this, demonstrating that the Hurricane would be liable to suffer water damage as a floatplane.

The Spitfire however, was deemed safe for actual conversion and so Supermarine tasked the Folland aircraft company with doing the conversion for them, and a single Spitfire Mk.I – R6722 – was provided for this.

Folland rapidly got the job done, and by the first week of June R6722 was ready for flotation and taxi trials. These didn’t go so well and the aircraft, which acquired the derogatory nickname of “Narvik Nightmare” was found to be very unstable in the water. Of course, the rapid and “lash-up” nature of the project makes this hardly surprising, and perhaps with more time better results would have been accomplished.

But while the floatplane project was proceeding rapidly, the war was moving even quicker. On the 24th of May the withdrawal of Allied troops from Norway was approved and France itself was collapsing to the German attack that had started two weeks before. Within a month the British had been driven off the continent and France had surrendered.

Now instead of needing aircraft for offensive operations the RAF needed every fighter it could get for home defence, and R6722 was rapidly converted back to her original configuration and posted to a combat squadron.

But this didn’t mark the end of the saga of the floatplane Spitfire, far from it. In June 1941 the RAE was asked to once again look at the possibility and ran some model tests once again.

Now the proposed aircraft for use was the Spitfire Mk.III, which was expected to become the new main variant and the RAE spent a few months working on the original test data and designing new floats designs.

But this too fizzled out by October of that year and once again the idea was shelved.

And then Japan launched their campaign to take over the Pacific in December 1941 and the possible need for a capable floatplane fighter arose again. This time a Mk.VB was used, W3760.

This aircraft had as its standard armament fit two 20mm cannon and four .303 Browning machine guns, and instead of being lumbered with whatever floats happened to be on hand, these components were expressly designed for purpose by Arthur Shirvall of Supermarine. He had designed the floats for the original Schneider Trophy racers from which the Spitfire had evolved.

W3760 was also given several additional modifications that the previous work had shown would be necessary; a ventral stabilising fin, larger rudder, a strengthened wing spar and a four bladed propeller.


The conversion was completed by the latter half of 1942 and the aircraft was put through its paces in October. There was a brief spell of excitement during these tests when one of the pilots, straying from the designated safe passage flight corridors, was engaged by the anti-aircraft defences of the city of Southampton, but fortunately was able to evade and return to base safely.

The aircraft then went for service trials in Scotland, but the floats proved to have issues with cracking and taking on water, and new ones had to be made for proper service trials to take place.

These showed that even with the additional drag and weight of the floats, W3760 could make a top speed of 324mph (521 km/h). While this was 40mph slower than the stock Mk.V, this was still considered acceptable.

Surprisingly the test pilots reported that the float Spitfire seemed to retain the manoeuvrability of the original fighter, and encouraged by this orders were given to Folland to convert two new Mk.Vs (serial numbers EP754 and EP951) into floatplanes.


This was quickly achieved, and these two aircraft, with newer Merlin 46 engines, demonstrated top speeds of 331mph (533 km/h).

Now with three of the fighters on hand, the RAF decided that they might have a suitable operation for them to take part in. With the recent defeat of Axis forces in North Africa, which had occurred in May 1943, the British had launched an operation in September to seize the Greek Dodecanese islands which are scattered off the coast of Turkey.

The surrender of Italy, whose troops formed a large part of the garrison on the islands, gave the British the opportunity to launch an attack to try to take the whole chain. German garrisons on the islands were largely reliant on air transportation to stay supplied, and the RAF thought that it they could use Spitfire floatplanes to attack them and disrupt German logistics. The idea was that the aircraft could hide amongst the many small islands in the area and use a submarine as a base.

So in October the three Mk.V floatplanes were dispatched to Egypt to undergo training and prepare for the operation. Based at an RAF flying boat station on the Great Bitter Lakes, the aircraft began working up for their mission, but hit a snag when it was found that W3760 was suffering from severe corrosion to her rear fuselage.


Indeed, the salt water of the lakes was not exactly ideal for the aircraft, but by November the mission was scrubbed anyway because the Germans, acting with great decisiveness, defeated the British invasion.

Apparently some thought was then given to sending the Mk.Vs to the Pacific, where they may have found some use, but it was thought that something better could be done and the three Mk.Vs would ultimately be scrapped in 1944 due to the corrosion they were suffering from.

The “something better” was in fact a fresh conversion. Still thinking that such Spitfire floatplanes might be useful in the Pacific, in the spring of 1944 an order was placed to convert a fresh Spitfire, this time a Mk.IX (serial number MJ892).


By July the aircraft was ready for testing, which took place at the Saunders-Roe factory in Beaumaris, Wales.

The Mk.IX float also encountered many of the same problems that had been found with the early models, plus some new ones. The air inlet would often ingest water on take-off, causing the engine to cut out, plus the aircraft, with a more powerful engine, tended to perform what is described as a “waddle” when taxiing.

However, the conversion was successful, and MJ892 proved to be the fastest of the floatplane Spitfire’s, recording a top speed 377mph (607km/h).

But again, the war had moved on and the need for such an aircraft didn’t really justify any major production order. The Mark.IX was used for testing for a few months and then was either scrapped or converted back to standard land configuration at the end of the war.

And that is the story of the floatplane Spitfires; Another interesting concept that never quite got its timing right.

Source / Related:

Spitfire The History Of A Legend

Spitfire VIII; The One That Kind of Missed the Bus

The Hillson FH.40 Slip Wing Hurricane

Neither Fish nor Fowl; The Blackburn B20, B40 and B44 Retracting Hull Flying Boats

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