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This study aims to develop a methodology to compare the feasibility of helicopter and seaplane regular transport of passengers towards destinations across a remote regional tourist context, where a lack of road and rail infrastructure make these alternative forms of air transport competitive.

The authors use a modal split model identifying the quota of passengers that potentially could utilize these two types of services, determined on the basis of previous studies on air transport demand. A technical analysis regarding transport supply is performed to identify the predominant features that should characterize helicopter/seaplane performances. An optimization model is applied to identify the routes that could overcome the breakeven point considering each of the two means of transport. The paper also takes into account the importance of each type of service and its influence on flight infrastructure costs.

Helicopter and seaplane services could improve the access for tourists with high values of time. The helicopter transport could capture a market share ranging from 5 to 20 per cent of tourist travel demand (the amphibian seaplane from 1 to 14 per cent). The shuttle services could be profitable especially for those regional origin–destination pairs involving the two major airports and the most UNESCO visited locations such as Agrigento and the Aeolian Archipelago (into the analyzed context of Sicily). The comparison between the two modes of transport shows that the helicopter has best performances and the seaplane has to land/take-off from sea.

The lack of data on the performances of the whole world production of seaplanes and helicopters (such as Russian, Chinese or US old machines) could give a distortion of the result. On the other hand, all mostly used machines in the world at the moment are considered. A survey on the fear of flight and on the choice between the two different forms of air transport could give a more precise result.

From an economic point of view, an operator could choose with more confidence the means of transport to use under different conditions. The activation of passenger services with seaplanes and helicopters can give an impulse to the growth of little operators and to the tourism. So, this study could be a starting point for authorities to plan a regional network of little general aviation airfields and seadromes (located in the great lakes or near the ports) near the major tourist locations. It could make possible to develop a synergic regional commuting traffic involving the seaplane and the helicopter.

Seaplanes and helicopters represent the most important means of transport when poor accessibility conditions and need of ready and fast connections coexist, for example, the commuting between airports and remote regions or downtowns with high tourist or business impact. The activation of passenger services with seaplanes and helicopters can give an impulse to the growth of little operators and to the tourism, consequently to the regional accessibility and economy.

There is a lack of studies involving the comparison between seaplanes and helicopters. This study could represent an important means to analyze the parameters that influence the possibility of activation for this kind of services and to find the factors that influence the feasibility of business with the two different machines. The encouraging performances of the flying boat suggest a future development of an innovative model of medium- and/or high-capacity amphibian seaplane dedicated to passenger transport. It should have take-off/landing performances less dependent on the sea state.

This paper aims to investigate the different analytical methods used to predict the performance of seaplanes to define the weaknesses in each method and be able to extend the analytical approach to include the nonlinear terms (unsteadiness).

First, the elemental hydrodynamic characteristics of seaplanes are discussed. Second, five different analytical methods are reviewed. The advantages and disadvantages of each method are stated. After that, the heave and pitch equations of seaplane motion are illustrated. The procedure of obtaining the solution of the heave and pitch equations of seaplane motion is explained. Finally, the results obtained from the most common methods are compared.

The results show that the methods are based on different assumptions and considerations. As a result, no method is optimal for all types of seaplanes. Moreover, some of the analytical methods do not study the stability of the seaplane, which is a major issue in the design of seaplanes. In addition, all methods consider the motion as steady and linear. The objective is to extend the work to include the nonlinear effects.

This paper presents some of the analytical methods used in describing the performance of seaplanes and explains how can they be applied. Moreover, it summarises the advantages and disadvantages of each method.

It is usual when carrying out tank tests on seaplane models to include measurements of the change in attitude when pitching moments of different amounts are applied. The measurements are generally made over a range of speeds in the neighbourhood of three‐quarters of the take‐off speed, in the neighbourhood of one‐third of the take‐off speed, and also with the hull or floats at rest. Curves of attitude against speed, with different applied moments, are shown in Fig. 11, for a twin‐float seaplane, and may be regarded as typical.

IN the last issue of this journal it was shown that the take‐off performance of seaplanes can be influenced greatly by design without adversely affecting the air performance. The various factors to be considered in an estimation of the take‐off performance were enumerated and typical curves of effective thrust, T', reaction drag, DR, and air drag, Da were given for a weight well below the limiting take‐off weight. It is shown in this part of the paper that there are two critical speeds and that failure to take off occurs at the lower of these speeds in some seaplanes and at the higher in others.

A SURVEY of the information available regarding the application of the results of tests of models in towing basins to the design of floats for seaplanes was made by the National Advisory Committee lor Aeronautics in 1929. It was found that the development of flying boats and seaplanes had been assisted very much in the United States, and possibly more in other countries, by tests of models in towing basins or tanks (References 1 and 2). Some tanks already existed which were designed especially for testing models of seaplane floats and the construction of other tanks for this special purpose was projected (References 3 and 4). There was no such tank in the United States; in fact, there were only two tanks, both constructed before the appearance of the seaplane and designed originally to test models of ships. The construction in the United States of a special towing basin that could be devoted to tests of models of seaplane floats and hulls might reasonably be expected to be of great assistance in the further development of this type of aircraft, the importance of which appeared to be increasing.

THE intention of this article is to show as clearly as possible, without undue technical matter, what has to be done to convert an ordinary landplane into a seaplane.

PROGRESS in most branches of engineering has been dependent upon model tests, and in no branch has the testing of models been of greater importance than in that of aeronautics. The earliest flights were made on models; and after the first successful flight of the full‐sized aeroplane, the development of aircraft to their present state of efficiency has been bound up, at every step, with the information obtained from model tests.

THE Hamburger Ha‐139 is an all‐metal, four‐engined, twin‐float seaplane recently built in Hamburg to meet the requirements of the Deutsche Lufthansa for transatlantic mail service. It was designed and built by the Hamburger Flugzeubau G.m.b.H., who are a new aviation department of Blohm and Voss, the well‐known shipbuilders of Hamburg. The company was formed in 1933 with Dr. Richard Vogt as Director and has in the past built several training machines ; the new Ha‐139 being the largest and most important machine built up to the present time. The seaplane has a gross weight of 16 tons and a range of 5,000 kilometres (3,100 miles) at its cruising speed of 250 k.p.h. (155 m.p.h.). The four engines give a total of 2,400 h.p.

BECAUSE of its ability to take off at the maximum weight that it can sustain in the air at sea level, the landplane has always had a greater range than the seaplane. With the advent of the retractable undercarriage, the landplane has now the added advantage of a much higher cruising speed and hence a further increase of range over the seaplane. The retraction of wing‐tip floats on the boat type of seaplane would compensate to some extent for the retractable undercarriage, but it is certain that we must increase the ratio of maximum take‐off weight to maximum flying weight before we can materially increase the range of all types of seaplanes.

THE desired qualities for high performance in take‐off were enumerated and discussed in Part I of this article, while certain suggestions were made in Part II, whereby the limiting take‐off weight of modern seaplanes could be increased without adversely affecting the air performance. So far no reference has been made to either atmospheric or sea conditions. In this country there is, on the average, only one dead calm day every three weeks, so that in practice a take‐off is seldom made in flat calm water and in no wind. Before leaving this subject therefore it is desirable to examine the performance of a seaplane in take‐off when there is a wind and to determine the probable effect of wind on the liimting take‐off weight.