When I was asked some six months ago to contribute a paper to this Society dealing with the lessons to be learnt from the study of the causes of accidents when flying, I agreed to do so because it seemed to me that a discussion upon this subject could not fail to be of interest and advantage to pilots, constructors and others by bringing before them in collective form the accidents, preventable and otherwise, which have happened, and in particular those which have been investigated by the Accidents Investigation Committee of the Royal Aero Club, on which your Chairman of Council, General Ruck, and several other Fellows and Members of the Aeronautical Society are very useful workers.

A very large amount of valuable work has been done in measuring the forces on models of aeroplane surfaces placed in a wind channel, and the results obtained are of the greatest value to the designer. Doubt has however been thrown on the applicability of the results obtained to calculations referring to the full–size aeroplane in flight, and it is of great importance to obtain definite information regarding the corrections, if any, which should be applied to the wind channel results. The experiments described below were made with the object of comparing the pressure-distribution on an aeroplane wing in flight with the distribution measured on a model of the same wing in a wind channel. The measurements were carried out on an aeroplane constructed by the writer, which for the purpose: of the experiments was flown over the sands at Llanddona, on the east coast of Anglesey. The beach at this place is an ideal one for experiments of this nature, there being a stretch of hard level sand obtainable fully three miles long and over a mile broad.

In this lecture, which the Council of the Aeronautical Society, through Mr. Griffith Brewer, have done me the great honour to ask me to deliver before you, I propose to consider the rôle of speed or fast flying in aeroplanes.

As soon as aeroplanes were able to fly, the next preoccupation of designers was to make them fly as fast as possible. In order to stimulate constructors, Mr. James Gordon-Bennett created his International Aviation Cup, destined to consecrate every year the fastest flying machine. This contest, held yearly since 1909, will give us a valuable basis to examine the lessons which aviation has been able to draw from pure speed.

The following formulae have been devised for ascertaining the resistance and power of skimming boats, but they are equally applicable to the floats of hydroaeroplanes, although all the examples given are of skimming boats varying from 15 to 40ft. in length, the speeds varying from just under 28 knots up to 51 knots.

It will, of course, be readily understood that the power required to overcome the resistance caused by the floats on hydro-aeroplanes is the Effective Horse-Power (E.H.P.), which is the same as the H.P. required to tow a float at any given speed; while the formula for resistance only, does not take speed into account except in the ratio of

In the examples given it will be seen that the variation between R, as ascertained from actual trials by the ordinary ship formula of and r, ascertained by the formula of is very small; while, in the case of E.H.P. from trials, and e.h.p. by the formula the maximum error—if we except example No. 5 (which is a known bad boat)— is only 0.39%, and the average for the other nine examples is 0.2% for the A type, .04% for B, and 0% for C type.

The primary object of the paper which I had the honour to be asked to read' to you this evening, is not to be a mere recital of my experiences during the three years I have been actively piloting an aeroplane, although it has the title “Three Years’ Flying Experience” but I hope to be able to give to you a few points which should be of general interest, and perhaps beneficial to fellow–pilots and to others who have so kindly come here to–night to hear this paper.

I will first give you a few instances of my earliest failures, their causes and remedies. In fact, the solution of most of my troubles, when I look back, may be placed under the simple headings of inexperience and want of confidence, which, I suppose, are very nearly one and the same thing. The machines of three years ago, jt is true, were not so efficient, nor so safe, but that fact has really, in my opinion, no more than quite a small bearing on the results of those days.

I t is perhaps unfortunate, from the point of view of aviators, that the extinct flying reptiles known as “pterodactyls” or “pterosauria” no longer exist. There can be no doubt, that in the case of the more highly evolved members of the group the organisation was more specialised for flight than that of any other animal of which we have knowledge. Other flying animals can walk, run, or swim, besides fly. But in the case of the higher pterodactyls their structure is such that it is difficult to understand how they can have had any other means of progression than flying. With a body little larger than that of a cat they had a span of wing asserted in some cases to have reached 21 feet or more.

Members of this Society may be forgiven if, in view of the glorious progress of aviation, they regard the balloon as an extinct species of aeronautical apparatus. The object of this paper is to show that, in spite of the strides aviation has made, the balloon still has its part to play in the navigation and study of the air, and that those who go to the trouble of making balloon ascents not only reap considerable pleasure by employing that means of transit, but they also learn facts about the atmosphere which may be of service to them in becoming more than mere chauffeurs of aeroplanes.

The best sailors who navigate our steamships have served their apprenticeship on sailing vessels, where they learn the true force and effects of winds and gain a knowledge of the sea not so readily acquired under steam power. In the same way, I venture to suggest that the much–despised balloon is a means for acquiring a knowledge of the atmosphere which cannot be gained when tearing through the air at fifty miles an hour.

The official document reproduced below, although in the nature of things destined soon to be out–of–date, is placed on record here, not because in a year or two it may read like Chaucer (to adapt Colonel Sykes’ happy expression, when speaking of the instructions issued in 1910, at the meeting of the 4th February), but because it is the first published attempt at official standardising of aircraft requirements. It is not proposed to subject it here to any detailed criticism, but it may be pointed out that the “minimum factor of safety of 6,” which is required, is not a factor of safety at all of anything like 6 in the ordinary engineering sense, but merely denotes the margin between the minimum and maximum stresses which are anticipated.

In view of the very interesting information about pterodactyls contained in the foregoing paper by Dr. Hankin and Mr. Watson it will be worth while to endeavour to reconstruct the animal and to ascertain as far as possible the effect of the various adjustments upon the shape of the membrane which forms the wing.

This can best be accomplished by a study of the drawings accompanying this paper.

In the first place, it is important to remember that the wing membrane (plainly visible in some of the smaller fossils) doubtless resembled that of a bat in being extremely extensible and elastic. Possibly it had muscles attached to it which could tighten it in various directions and possibly increase and diminish camber. Air pressure upon this membrane would be certain to make the back margin of the wing a curved line with the convexity upward and the front margin of the wing (formed chiefly by the supporting bones) would have to follow this curved line more or less closely, otherwise the angle of incidence would vary excessively in different parts of the wing.

As far as the writer is aware, Mr. Horace Darwin was the first to call attention to the fact that there is an essential difference in action between a spring-controlled and a gravity-controlled air speed indicator on an aeroplane.

This fact was put forward in the Wilbur Wright lecture of last year and the conclusion then reached was definitely in favour of the use of the gravity type, as being more useful to a pilot on a steeply banked turn.

Since that date, however, the discovery has been made that this type fails to give warning of “ stalling ” in straight flight (the very purpose for which the instrument is installed) and equally fails under the conditions of a banked turn.

The writer believes that he has the priority in this discovery, and therefore takes the present opportunity of publishing the following formal proof of the scientific theorem involved.

It is a matter of extreme importance to be able to measure accurately the speed of the air in any situation and under any condition, because all our knowledge of the dynamical properties of the air is dependent upon a correct measurement of its velocity, and because the safety of a pilot depends upon knowing accurately the speed at which he is flying. He is then able to guard himself against the risk of stalling his machine or of attaining too great a speed. An air speed indicator is really as indispensable to a pilot as a foot rule is to a carpenter or a “hooter” to a motorist.

The velocity of the air may be determined by three main methods.

In the first method the velocity is measured directly by the time taken by a particle, body or substance floating in or dragged along by the air to travel from one point to another.

A short summary of our knowledge of this subject may be of interest to readers of the Aeronautical Journal.

Dust devils, that is to say, columns of dust in rapid rotation, are occasionally seen in Agra. They only occur in hot, dry weather. Those of the largest size, having a diameter of two or three metres and a height of several hundred metres, only occur when the air is nearly calm. They travel to leeward at a speed of about four to six miles per hour. The dust, having reached the upper end of the column, spreads out into a diffuse, irregular mass, which may persist for some time after the dust devil that produced it has vanished.

Fig. i is copied from a book treating of dust devils and dust storms observed at and near Lahore (India) by P. F. H. Baddeley.

He states that they are never shaped like an inverted funnel, as is the case with whirlwinds in America, as described by Redfield.

I am honoured by the request of your Council to deliver the second Wilbur Wright Memorial Lecture, and for my subject have selected some points connected with the development of the aeroplane, that machine whose capabilities Wilbur Wright was among the first to recognise and which he did so much to create.

I will commence with some well–known words:—

“I have brought to a close the portion of the work which seemed to be specially mine, the demonstration of the practicability of mechanical flight; and for the next stage, which is the commercial and practical development of the idea, it is probable that the world may look to others. The world indeed will be supine if it do not realise that a new possibility has come to it and that the great universal highway overhead is now soon to be opened.”

In the previous contribution and in the reply to the discussion justice was not done to several points.

It was made clear that a circulation of air was established round the airscrew at standstill, creating a certain velocity before the airscrew disc in such a way as to modify fundamentally the thrust on the blades. But it was not explicitly stated that at full speed (of the aeroplane) this component of velocity was ignored altogether and each blade was assumed to be attacking “ still ” air.

This does not mean that the air was still until the blade actually drew level with it, for, if the analogy with lifting surfaces holds, we know that at a distance of twice the chord width in front of the blade the air is appreciably disturbed, and this disturbance may be by no means negligible even at four or five times the chord's width in front of the instantaneous position of the blade.