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In Italy, for 1931 races, an engine group has been realized, formed by two mated engines powering two counter-rotating propellers, similar to the ons used on torpedoes.
I believe that the useful power could be considered equivalent in both cases, that is absurdely high both in absolute value and compared with weight. This is a real mechanical prodigy which seemed impossible until soon.
But as architect, insinctively considering the artistic and phylosophical aspect of the things besides the scientific and technological one, I'd better prefer the progress to follow two ways simultaneously: engine power increase, and passive resistances decrease. I believe nevertheless that my concept could have been difficultly realized, because engine power improvement is tied to laboratory experiences, achievable in inteligently tooled test-beds, while aerodynamic progress requires tests "in corpore vili" on different and new kinds of machines.
These tests are often an though human play, where the price is quite high as it is the life of a young, exceptional and courageous pilot.
Once more it is deonstrated that human progress follows the easiest way. But now, having been almost completely paved this way thanks to Italian and British engine designers, a new deal opens for scientist and designers towards the solution of the aerodynamic problem, in order to create aircraft with the lowest possible resistance to movement.
In that direction I worked since 10 years, designing 7 different types of racing seaplanes and building some. Luck, in different ways, did not assist me but I hope that myself or other, starting from the concepts I am to expose, could realize the perfect racing seaplane: prefect because its speed should be, at low level and with propeller propulsion, up to the limit of practical human possibilities.
Such a concept has been confirmed in real life, and never as today, when seaplanes reached and surpassed the considerable speed of 50% of that of sound, we are all convinced that seaplanes are more suited to high speed that ground-based aircraft. That both because calm sea offers a take-off disnatce virtually unlimited, and because the wing itself and the hull-fuselage are used to sustain statically the still airframe, while ground aircraft cannot fly without the undercarriage: this, in turn, if retractable could lead to enlarge or deform wings, fuselage or both, with negative effects on airframe sleekness, mostly in racing aircraft which are normally small.
A first realization on such ideas is represented in figure 1 and dates back to 1921.
That seaplane, designed indeed for races but even suitable in similar forms for current air navigation, seems to me the simplest aerodynamically among small- and medium-sized, manned-fuselage aircraft, and gradually from it one could switch to a manned-wing, no-fuselage seaplane which should be the simplest conceivable aircraft and, perhaps, the future's plane.
Mechanical and aerodynamical difficulties can be easily identified and do not appear too big, and constructive challenges are identified as minor, while some perplexity could arise facing the unknown (then more challenging than today) of aerodynamical momenta due to propeller axle movements.
The wing could even be "V"-shaped, locking under the engine and having on the upper side a special mount for the engine itself. This way, the wing part near the hull could remain inmersed during stillstand conditions, and could give the aircraft the necessary transversal statical stability and even the dynamical one in the first moments of take-off float. The wing could move with the engine, with an important advantage in take-off and landing maneuvers.
fig. 1 - Pc.1 (4.5Kb)
Today one could think, in case of the wing moving with engine, to connect it to tailplane so that wing and tailplane itself could have the desired reciprocal angular shift.
Few years later I saw an idea analogous to mine, even with other goals and different means, patented in France by Mr. Levasseur.
Today, I believe that Pc.1 could offer an interesting study and possibility field, mainly combining it with Pc.7 in order to keep absolutely low the main section of the hull.
I stress that, descending from the above, hull and wing in Pc.1 could mutually help in seaplane floating, because the wing should have been covered in spruce as in Fokker constructions and cooperate with its ends (or with its centerpart in low-wing solution) to hydrostatic push and to Hydrodynamic one, offering also transverse stability to the system in initial take-off phases.
Mr. Arrigoni began designing the float, whose construction started at Bastianelli Company in Rome, but eventually was dismissed because of economic reasons.
I hab noted that P2 with Botali-Clement coolers hadflight characteristics practically coinciding with those I envisaged for P.2 in windtunnel tests, and also I had noted that P.2, without coolers, had a good sleekness. Thus, I designed the P.4, which is Pc.2 in my racing seaplanes series.
Some of the seaplanes designed in Italy in those years for Schneider Cup are represented in figure 2, documenting a part of the noble and important Italian contribution to racing seaplane problem.
fig. 2 - Idrovolanti Italiani per la Coppa Schneider (7.6Kb)
During the final design of Pc.3 I reduced to minimum the fuselage main section and was obliged, after tub tests, to change shape and volume of the floats. Thus, I believe that Pc.3 could have been aerodynamically better of Pc.2 and also of nr. 4 seaplane.
fig. 3 - Pc.3 (9.3Kb)
Pc.3 had been almost comleted, and eventually abandoned because of economic reasons. I hope the reader may concede to recognize my priority in the racing seaplane formula which later, thanks to Macchi and Supermarine, triumphed in Schneider Cup. It's not worth the objection about using a semi-thick wing instead of a thin, rodded wing as used by Macchi and Supermarine: both solutin are practically identical, even in weights, while semi-thick wing is constructively simpler.
First idea I conceived is sketched in figure 4.
fig. 4 - Pc.4 (6.2Kb)
But this design did not actually satisfy me when I had to concretize the construction. Take-off appeared difficult with such a great longitudinal hull angle between forward and back parts of the redan, and mechanism of side-floats retraction was not simple.
One can point out that my celebrated Colleague Eng. Marchetti designed and built an analogous kind of seaplane, but with two lateral floats and tailbeams. Such a seaplane was taken to Calshot but dd not compete.
I abandoned therefore the solution to find something simpler and more effective.
Basing on this concept, I studied two types of racing seaplanes Pc.5 and Pc.6.
Transversal stability into water was based on two wing-profile fins embedded in float, so that when the float itself was offthe fuselage the aircraft seemed a sesquiplane. In flight, the float and its fins were mechanically raised until the fuselage was partially hidden in a bay in the float itself. Meanwhile, the fins mated the central part of the main wing, so that the assembly became a monoplane which, without any float-fuselage interference and with a higher wing loading in flight with respect to the one necessary for take-off and landing, should offer resistance coefficients much lower than usual.
fig. 5 - Pc.5 - Pc.6 (10Kb)
Most difficult problem was obviously the transiton during raising and lowering of the float, presenting two distinct difficulties: the heavy weight and the aerodynamical unknown. Even accepting the weight increase due to mechanical devices, I needed obviously thorough windtunnel tests I could not afford, as I'll explain later.
Experiences held in Gottingen on monoplane wings splitting in biplane, but positive data were missing about aerodynamical forces to be developed during the travel of lower wing towards float. This posed me in doubt, and, thinking about pilot to perform the maneuver at very high speed and possibly with wing flutter, I dismissed the solution even if the work was well advanced and switched back to Pc.1 or something similar.
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