Floatplane fighters: wishful thinking or tactical resource?

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If you have a large central float, on occasions where the two outer floats dont both settle in the water, how do you taxi the plane?
I think the outer floats act more like a bicycle stand when the aircraft is still and they contribute little to planing when it's moving. Also, being further outside on the wing, they might be more useful to counter propeller torque than two closely spaced floats. I don't have data on which solution is better from the point of view of drag.
 
Before WW 2, when racing sea planes were the fastest flying machines, it may very well been a good idea.
The Schneider Trophy race was established even before ww1. At that time, seaplanes were indeed seen as the future of aviation. If you go to Milan, besides the city airport of Linate, you can still see the old port for seaplanes built in the early 1920s. It's quite impressive (and larger than the strip used by today airliners!)



When the Supermarine S6 and the Macchi MC72 established the speed records in the '30s, the Schneider Trophy kept its formula more for tradition than for a real technological reason. This doesn't mean that they aren't impressive machines in their own right. If you've ever seen them (Both the S6 and the MC72 are preserved in museums), you can appreciate how small they are, even smaller than a typical two seats light aircraft. Swap those huge floats for a retractable carriage and I bet they could still give a run for their money even to those pimped Reno racers!
 
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At least everyone had the sense to stay away from floatplane Zerstörers.
 
While being able to take off without a runway is certainly an advantage for any aircraft (STOL/VTOL planes have found their niche), when you know well in advance that your 'fighter' will be hopelessly under performing, why insist?
because was supposed to operate from place you can not have land fighter, so the choice was that or nothing, and i suppose their target were supposed not to be land fighters
 
I remember reading, someplace, that twin floats tend to have a lower total drag than the single central + stabilizing floats. I suspect this is one of those truths which are entirely true, but the spread (standard deviation) is so wide as to make the comparison largely meaningless.
I don't know why some nations, e.g., the US and Japan settled on a single central float plus stabilizing floats while others, e.g., Germany and the UK chose twin floats, but I suspect that water and shipboard handling were more important than drag, per se.
 
Helped by there being a race specifically for sea planes.
 
And I expect they were optimized for low altitude, lightly built and fueled only for short runs.

This does present a question on weight though. If we can believe Wikipedia, the famous Supermarine S.6B had an empty weight of 4,590 lbs. and a gross weight of 6,086 lbs. Those extra 1,496 lbs would include about 180 lbs. for the fully kitted pilot, 396 lbs. for the fuel (7.2 lbs. per imp gallon x 55 gallons). That's only about 576 lbs. Where's the other 900 lbs? Oil for certain, and maybe collant, but not 900 lbs. worth.
 
Maximum fuel capacity in the 1931 S.6B was 157.5 Impgal (111.5 in the starboard float, 46 in the port float), pumped to a small header tank in front of the cockpit (required for high-G turns, usually no more than 4G, but could be upto 6G).

Maximum oil capacity was 16 Impgal in the tail fin forward section oil tank (so 16 plus whatever was in the engine and piping).

PS. I think the 55 Impgal value was for the S.5 with the Napier Lion.
 
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they weren't running on normal aviation fuel.

And the fuel needed to run 380mph for 220 miles at low level may have been a lot more than 55 gallons?
Plus those engines weren't built with fuel economy in mind. By using a very rich mixture not only the chance of knock with high compression or boost is lower, but the engine also runs cooler.

Typical fuel for racing engines of the period was a mixture of methanol and benzene with other substances added to promote volatility or to restore some of the lubricating properties (useful to avoid the engine 'swallowing' the valves) that straight gasoline has. In terms of energy content per liter, I suspect these fuels weren't as good as gasoline, but they allowed engines with much higher compression or boost.
 
A few Rufes should keep a PBY ( a flying boat) away.

Exactly. This reason is why the floatplane fighter had a purpose, despite being little match for carrier based fighters.

(Both the S6 and the MC72 are preserved in museums),

To make a point, the S.6 and the trophy-winning S.6B were two different aircraft, but we get the gist. There are sadly few original Schneider trophy aircraft preserved, two in the UK, the S.6 in Southampton...

S.6 N248

And the trophy-winning S.6B at the Science Museum in London. The trophy itself is in a case behind the aircraft and its engine is on a rack in the museum.

S.6B S1595

There are four surviving at the one museum in Italy, including the M.39 with which the Italians won the trophy in 1926...

M.39

And the impressive MC.72, which never got to a trophy race.

MC.72

And of course in the NASM there's the Curtiss racer (I do have a photo of this before digital photography was a thing, but it's hidden away somewhere).

Perhaps the biggest advance from the Schneider trophy races was not the high-performance floatplane concept, but the development of engines, specifically the Rolls-Royce R engine and its potent fuel mix. A 'R' engine of 2,530 hp.

RAFM 16

The Fiat AS.6 from the MC.72 producing 2,841 hp, two coupled V-12s for an extra 300 hp compared to the 'R' engine's output. The Italians didn't gain as much from their engine development as the British did.

Fiat AS.6

The airframe and engine combination of RR and Supermarine proved a winner in the Spitfire with close co-operation between the two firms throughout the type's lengthy development, even if the S.6 airframe offered little to the Supermarine fighter.
 
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The Fiat AS.6 from the MC.72 producing 2,841 hp, two coupled V-12s for an extra 300 hp compared to the 'R' engine's output. The Italians didn't gain as much from their engine development as the British did.
Italy never lacked good or creative engineers, it lacked resources and also had a government that, for a time, favored radial engine construction when no Italian firm had experience with them (in fact, Italian firms had to license some design from Bristol/Rhone/Pratt & Whitney as a starting point)

Italy did produce some impressive in-line engines: the Isotta Fraschini Delta was an air-cooled V12 with hemi heads and dueal overhead camshafts that produced the same amount of power of the contemporary Rolls Royce Kestrel and the Jumo 210.

Before producing on license the German DB engines (which required German fuel anyway, while all Italian engines had to work with the inferior 80/87 gasoline domestically produced), Fiat was well ahead in the development of the A.38, an inverted V16 engine of 1400hp (with standard Italian gasoline) or 2000Hp (with high octane fuel). Such engine would have been the first choice for all series -5 aircrafts.
 
Italy did produce some impressive in-line engines: the Isotta Fraschini Delta was an air-cooled V12 with hemi heads and dueal overhead camshafts that produced the same amount of power of the contemporary Rolls Royce Kestrel and the Jumo 210.

They did indeed, but Britain and Germany's supercharger technology gave their engines an edge, the 'R' engine being influential in the development of the Merlin and Griffon and the use of special fuels. Italy's radial engined fighters, while neat looking designs were built in too few numbers and were too late to be any real opposition to equivalent European fighters, the use of the DB engines in the MC.202/205 and Fiat G.55 certainly gave their fighters extra capability but because of the aforementioned resource shortage, the country never had the industrial base to move forward with a consistently improving aircraft manufacturing industry for what the government was getting itself into.

Good looking but too little too late: Macchi 205...

C.205

Fiat G.55.

G.55

Italian ideals were behind those of Britain and Germany, favouring the Fiat CR.42 philosophy of manoeuvrability over performance to the extent that by 1940 it was the most numerous fighter in RA service.

Fiat CR.42, an obsolescent hangover from the CR.32 era tactics.

CR.42

The more modern G.50 had a foot in the past like the Hurricane and it was available in 1940 in double-digit numbers only. The Italians did not have a match in performance to the Spitfire and Bf 109 in 1940, the closest being the MC.200, but it was in fact not liked by its pilots at first and none saw combat in 1940 despite being available, although in only very small numbers in service.

MC.200 side
 

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