tition for the longest glide under certain conditions which were laid down.

This competition took place at Itford and created widespread interest, and opened the eyes of people in this country to what had been going on abroad.

Fortunately the wind blew from a suitable direction and with suitable strength and some remarkably good flights took place. Within two days a flight of nearly two hours had been made on a British monoplane, and before the end of the week the German record had been beaten in a flight of 3 hours 20 minutes by a French machine.

The landing after this flight was made almost in the pitch dark, and when it is considered that the type of machine was a most unconventional one with a novel form of control, and that the only previous glide had been one of a few seconds, there can be no doubt that this performance was a very remarkable feat on the part of the designer and of the pilot and one most significant of the possibilities of the glider as a method of experiment.

As events turned out, the competition was one of controllability rather than of efficiency, and meritorious as were the British machines in some respects, it was evident that there was room for improvement in controllability.

As far as the writer is aware, none of the competitions have demonstrated what is the true gliding angle or overall efficiency attainable in a modern glider. All that can be said is that one machine looks better than another in this respect. It has been said that there are gliders whose angle of descent is only 1 in 15, or even 1 in 20, but the writer has seen no proof as yet that any glider has accomplished, in fact, an angle even as good as 1 in 12. It should not be difficult to work out a method of experiment determining this with reasonable accuracy.

Limitations and Usefulness of Gliders.

There would appear to be very little likelihood that engineless aeroplanes can ever be of practical service in journeying from place to place, or even that they will be much used for sport. The necessity of an up-current of some kind to support the machine renders the first almost impossible, and confines the second to special localities. The sport of motor cycling would be a tame affair if it was limited to hill climbing up special hills.

There are possibilities in the use of gliders for purposes of training pilots, and there are certainly possibilities in the development of small sporting machines of 15 to 20 h.p. capable of horizontal flight with, say, 5 h.p. and doing 100 miles or so to the gallon, but the real immediate value of gliders lies, as it always has done, in the opportunity they afford of technical experiment in a simple and inexpensive manner.

In experiments with engine-driven aeroplanes, the horse-power of the engine and the efficiency of the propeller are always difficult to estimate exactly. The detail design has to be carried out with care and attention in order to keep the percentage weight of the structure within fairly close limits, while the cost of the experimental work is almost prohibitive to private firms.

On the other hand, with gliders, the motive power, which is the force of gravity, is perfectly definite in amount and always reliable, and for many purposes the machine can be built in a simple, roughand-ready manner as long as the external form is correct.

Col. Ogilvie.

As already indicated, there are two main technical problems in the commercial aeroplane of the day, and it is suggested that solutions of either, or of both, are more likely to be found by means of experimental work with gliders than by other means.

The first is the increasing of aerodynamic efficiency, to enable considerably greater loads to be carried for the same power, or the same load for less power. The overall efficiency, the ratio of lift to drag, or, in other words, the inverse of the gliding angle of the commercial aeroplane of the day is about 8 to 1, in some cases even less. To put the result in another way, about 60 horse-power is required to carry each individual passenger for the usual 3-hour journey at a speed which is necessary to combat the normal wind conditions. This 60 h.p. per passenger is obviously a very high figure, and gives an indication of the reason for the high cost of aerial transport. It should be noted that in addition to the heavy fuel costs entailed by the poor efficiency, there are heavy capital and insurance costs, all of which would come down if the overall efficiency could be increased, as it is perfectly certain it could be provided that an adequate amount of experimental work can be done.

The second problem for solution is the improvement of controllability at low flying speeds, so that in the event of an engine stoppage, the aeroplane can be landed in awkward fields with greater safety than at present.

It is well known to aeronautical engineers that an aeroplane, the stalling speed of which has been tested to be, say, 50 miles per hour in good weather on a large aerodrome, is never, in the event of a forced landing, glided in at a speed of less than 60 miles per hour. This additional 20 per cent. over the stalling speed adds greatly to the difficulties of the landing and to the shock in the case of an accident, and would be entirely unnecessary if the pilot had an aeroplane over which, even in gusty weather, he had complete control right down to the stalling speed. This difficulty is such a commonplace among pilots that it does not occur to them to worry about it, but it is a problem to which a great deal of attention is being paid, and to an attack on which the Aeronautical Research Committee is devoting a considerable amount of the resources at its disposal. The recent gliding competition at Itford Hill showed how much room there was for improvement in the controllability of the aeroplanes entered, and instilled a belief that other competitions would cheaply and quickly effect much improvement.

There can be little doubt that these are only two instances out of many where we have good reason to expect substantial progress by means of experimental work with gliders.

Summing up, the principal value of gliders at the present time would appear to be as a method of experiment between the model in the wind-channel and the completed power-driven aeroplane, whereby new lines of thought in wing sections, in body shapes and in methods of control can be tried out in the air in a simple and inexpensive

manner.

The writer would conclude by an appeal to business men who are interested in civil aeronautics, from whatever point of view, to put up prizes not necessarily large ones-and so to stimulate competition among a large number of brains towards a solution of the problems which must be solved before commercial aviation, ultimately to be a necessary bulwark of the country, can become the practical

economic proposition, which is, no doubt, the hope of all present in this historic hall.

The CHAIRMAN: I am sure, my Lords and gentlemen, that we shall all join with Colonel Ogilvie in hoping that the funds which he referred to, in the last paragraph of his paper, as being desirable, will be speedily forthcoming.

I will now ask Mr. Fairey to read his paper on Seaplanes.

SEAPLANES.

Mr. C. R. FAIREY, M.B.E., F.R.Ae.S., Chairman of the Society of British Aircraft Constructors: Mr. Chairman, my Lords and Gentlemen, I think the subject of the Seaplane was included in the programme of the Air Conference chiefly to give the small brotherI was going to say, the poor relation of the aeroplane a chance to make its voice heard; but I find that, as a title for a paper, it is far too comprehensive. In view of that obvious fact I need, I think, make no apology for having only been able to touch upon one or two outstanding features of the questions of the design and operation of Seaplanes. I have made an attempt, firstly, to classify Seaplanes, not because the various types are not fully known to everybody who. will join in the discussion, but because nearly every point of design and operation is controversial. In touching every aspect of the question I have been forced to refer to it twice over in relation to each type. And, then, I have dealt with a few questions in the practical and theoretical aspect of design and operation.

It is a well-known fact that, although at quite an early stage, the design of aeroplanes settled down into practically one universal type, i.e., the tractor, owing to its preponderating advantages in general arrangement and performance; the seaplane is still in an unsettled state even as regards an accepted general arrangement of components, and there are quite sharply divided opinions as to the relative merits of different types due partly to the fact that proper comparative tests under varying conditions have never been made and much that is matter of opinion to-day could, by proper full-scale experiment be established as matter of fact.

Therefore, the design of seaplanes is a subject on which it is as difficult to dogmatise as it is easy to start a discussion, and it is only possible in a general paper on seaplanes to indicate some of the problems that most effect design and operations rather than state with any confidence what are their best solutions.

The various controversies that have taken place on the subject have ranged from questions of construction to discussions as to whether the type itself has any proper function, and whether seaplanes are really of any use at all. The author has, in fact, heard it argued that since mankind does not live on the sea the sea should be flown over and not landed on, the purpose of the flying machine being to communicate from one piece of land to another, or alternatively, to a ship where it can be landed on or launched from the deck.

Of the many fallacies in this argument the principal one lies in the fact that whatever stage of perfection aircraft engines may reach and whatever effect such improved reliability of engines may have on the design and use of flying machines, the propelling power can never be of such an order of reliability as to render the machine absolutely immune from forced landings. Even in the present stage of development of a ship engines a recent paragraph in the Press showed Col. Ogilvie.

that no less than 20 ships were adrift on the oceans of the world with broken-down engines within 24 hours, and since the breakdown of the power unit of a flying machine must result in a forced landing within the space of a few minutes it is obvious that the proper type of machine for flying over seas must be capable of alighting on and rising from the surface.

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Apart from that important fact, an equally great advantage of the seaplane is that coastal harbours, big rivers, and inland lakes provide natural aerodromes" from which it can be operated, and in certain districts, for example, Canada and the North of Russia, they can be used over country where aeroplanes could positively not fly in safety. Practically from one end of Canada to the other the countryside offers infinitely more safe alighting places for seaplanes than for land machines. The great rivers of the world provide readymade routes for seaplane services from which the danger of forced landings that would beset aeroplanes are nearly eliminated, and their equivalent for aeroplanes would be a continuous chain of aerodromes of quite prohibitive cost. The great archipelagoes of the Far East and the African swamps are examples of country where the seaplane is the only practical means of flying.

From the Naval point of view, whatever may be done with specialised aeroplanes operating from carrier ships, it is ovbious that conditions will set a strict limit to size of such machines, and for long range reconnaissance at sea and for carrying big loads for offensive operations, the development of the seaplane is the all-important factor which must not be neglected.

MODERN TYPES OF SEAPLANES.

As mentioned before there is as yet no settled type with seaplanes as with aeroplanes, but they may be classified into two main types -the flying boat and the float seaplane. Each class can be subdivided into further types and it is impossible within the scope of one paper to more than mention the particular features of the main divisions. Each type has its particular advantages and its particular difficulties in design and operation, but apart from certain controversial features, many of which could be settled by careful experiments, preference for one type or another is mostly dictated by local requirements. With development in size certain characteristics will become predominant and greater settlement of type may be expected.

The flying boat.

In the flying boat the superstructure is built on a single central hull taking the place of the fuselage of the aeroplane, and since the centre of gravity is nearly always above the metacentre, lateral stability on the water is provided by wing tip floats. This type has been built in sizes varying from small single-seaters, such as the Supermarine Racer that won the Schneider Cup Race last year, to the large four-engined N4 of 32,000 lbs. gross weight.

With flying boats the superstructure and arrangement of engines, according to size and power, fall generally into line with the equivalent land aeroplane, and the principal division of type, apart from the constructional methods in building the hulls, comes with the arrangement of the step and shape of the hull beneath the water-line. Although there are very few examples of what might be called the single-step hull, the second step in most hulls is so atrophied as to

represent little more than a skin wave breaker to keep the tail clean. In operation the difference lies in the fact that the single-step type at or over hydroplaning speed exerts only small trimming moments due to water pressure which can be overcome by the air controls, the arrangement being roughly analogous to the ordinary two-wheeled type of land chassis, and the fore and aft latitude of the machine when taken off and landing is under the control of the pilot, the machine not being stable as a boat unless that control is exerted after a certain speed has been passed. It has the advantage of a large angular range of movement is available to assist the machine in riding over rough water head on to sea and to prevent any tendency to burrow in a head sea, but it is very subject to "porpoising" if not skilfully controlled.

With the two-step type in which the second step is highly developed the intention is that the hull shall be stable from zero to taking-off speed and shall itself take up the best attitude when running on the water. It needs, accordingly, less skill in piloting, but has not the advantage of the single-step in the rough sea. Most modern machines have adopted a compromise between these two conditions in which the second-step is very small and the best features of both types are obtained.

Under the water-line both these types of hull vary in design from the flat bottom of the Savonia type to the sharp V of the Linton Hope hulls, as, for example, the P5. The flat type by its greater hydroplaning efficiency is easier to take off smooth water but meets with correspondingly greater impact on landing. The V-type makes much easier landings but its hump speed is higher and not so sharply defined.

A new type of German boat has recently appeared, the Dornier, in which an attempt is made to avoid the use of wing tip floats by lateral extensions on the hull in the form of buoyancy chambers which are shaped in the form of thick wing sections and are intended to give some lift in the air. For smooth water this type appears promising but could not possibly have the lateral stability of the three-float machines. Attempts have also been made in Germany, in the Oberst boats, to provide the boat with sufficient beam to avoid the use of wing tip floats at all.

In the list given an attempt has been made to classify the existing modern seaplanes into their various classes. It should be noted that both France and Italy favour the flat-bottomed hull, but that all English designs are now V-pattern.

The float Seaplane.

The float type of seaplane is in appearance a normal aeroplane in which the floats or pontoons take the place of the usual landing chassis Actually, owing to the different distribution of masses and head resistance it is very different structurally and presents a different problem in stability and control.

There are many more variations of float shape for this type than for the boats. The principal division is the twin-float and the singlefloat of which the twin-float is the most popular, at least, in this country. Both single- and twin-floats type can be further divided into the single-step and two-step classes as are the boats, with an additional intermediate type with a single-step, but with a buoyancy chamber or extended stern of the float aft of the step, which provides complete or partial fore and aft stability on the water but exerts little or no hydroplaning effect, and this pattern is intended to combine the Mr. Fairey.