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Aeroplanes/natural_stability_and_the_parachute_principle_in_aeroplanes_1911.md

@@ -0,0 +1,1376 @@
+THE S & C SERIES
+No. 39
+
+<watermark>UC-NRLF</watermark>
+$B 276 897
+
+NATURAL STABILITY IN AEROPLANES
+W. LEMAITRE
+
+<img>YB 1581</img>
+<stamp>8th NET</stamp>
+
+<img>
+  <description>A bookplate with a central emblem featuring a shield with a sun and a globe, flanked by two figures. Below the emblem, "EX LIBRIS" is inscribed.</description>
+</img>
+
+UNIVERSITATIS CALIFORNIAE
+
+MATTIETIS MDCCCLXIII
+
+EX LIBRIS
+
+<img>A blank page with a light beige background.</img>
+
+<img>A blank page with a light beige background.</img>
+
+NATURAL STABILITY
+
+<img>A blank page with a light beige background.</img>
+
+UNIV. OF
+CALIFORNIA
+
+<img>A black and white illustration of a futuristic ship with various antennas and wires extending from it.</img>
+<watermark>IN VIA OF CALIFORNIA</watermark>
+
+NATURAL STABILITY
+AND
+THE PARACHUTE PRINCIPLE
+IN AEROPLANES
+
+BY
+W. LEMAITRE
+Hon. Sec., Aeroplane Building and Flying Society
+
+WITH 24 ILLUSTRATIONS
+
+<img>A stylized logo with the letters "C" and "A" intertwined.</img>
+
+LONDON
+
+E. & F. N. SPON, LTD., 37 HAYMARKET
+New York
+
+SPON & CHAMBERLAIN, 102 LIBERTY STREET
+1911
+
+TL574
+S7L4
+
+<img>A blank page with some faint text at the top left corner.</img>
+
+<watermark>NO VIUO
+APROCHIAO</watermark>
+
+CONTENTS
+
+|  | PAGE |
+|---|---|
+| FRONTISPICE | iv |
+| PREFACE | ix |
+
+CHAPTER I. THE IMPORTANCE OF STABILITY | 11 |
+|---|---|
+| II. SPEED AS A MEANS OF STABILITY | 14 |
+| III. THE LOW CENTRE OF GRAVITY | 17 |
+| IV. SHORT SPAN AND AREA | 28 |
+| V. VARIABLE SPEED AND THE PARACHUTE PRINCIPLE | 36 |
+| VI. THE DESIGN WHICH FULFILS THE CONDITIONS | 39 |
+
+274247
+
+<img>A blank page with a light beige background.</img>
+
+PREFACE
+
+SINCE there is nothing new under the sun, it is useless to pretend that there is anything new in the design here advocated or the theories advanced. Both are rather the result of a commonsense consideration of the different points of all flying machines, natural and artificial, and an endeavour to select from the great number of good points those which seem most likely to blend together into a practical machine.
+
+The conclusions reached are the result of a quite independent investigation, carried on over three years by means of numberless experiments, and the writer has endeavoured to make no single statement which he cannot by some experiment amply prove.
+
+<img>A blank page with a light beige background.</img>
+
+<img>UNIV OF CALIFORNIA</img>
+
+NATURAL STABILITY IN AEROPLANES
+
+CHAPTER I.
+
+THE IMPORTANCE OF STABILITY.
+
+IN considering the whole question of aviation, it becomes evident that the one point to strive for at the present juncture is stability. If we are ever to have a practical flying machine, that is, a machine which we can use as we do a yacht, a motor car, or a bicycle, it must be one that we can trust to keep its balance by reason of the natural forces embodied in it, and without any effort of control on the part of the pilot. It may be objected that a bicycle does not do this, and that if it were so inclined as to fall, the upsetting of a bicycle is a very small matter, whereas the tilting of an aeroplane mostly means sudden death to its occupant, and it is probable that if the same consequences followed the tilting of a bicycle, bicycles would soon have been made with four wheels.
+
+At present aeroplanes are the most unstable of all things. The least gust, the least shifting of weight,
+
+<page_number>12</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+the slightest difference in the density of the strata of the supporting air, and the machine sways, and if not instantly corrected by the pilot the sway becomes a tilt, the tilt a dive, and the rest is silence. The first aeroplane which I saw was so unstable that twenty minutes in one of them was as much as the most iron-nerved man could stand, the continual strain being too exhausting to keep up for any length of time. By throwing out extensions and outriggers in all directions we have altered that to a certain extent, but only to an extent—we have not yet got rid of it. The monoplane is probably the most unstable, as might be expected from its smaller surface, but the biplane is still more so.
+
+And the difficulty seems to arise chiefly from the fact that the machines are built round the propeller. In the case of a yacht or a car, the machine is built first and the propelling means is fitted on as an auxiliary. The consequence is that an aeroplane which is safe enough while the propeller is exerting atractive force of some 250 lbs., becomes, the moment this power is for any reason stopped, merely a shallow con-
+struction with no means of resisting the pull of gravity. It is true that most machines may be made to glide if the pilot is clever enough and quick enough to steer them into the proper gliding angle, but the machine that will naturally and by reason of its design assume its proper gliding angle when the propelling force is withdrawn, has not yet been built.
+
+Such a machine would have "Natural Stability."
+
+THE IMPORTANCE OF STABILITY
+
+It will be recognized that this natural stability, which depends on the design of the machine, is some-
+thing entirely different from "automatic stability" of which there are many systems, all having this one defect : they are liable to go wrong. The move-
+able planes, gyroscopes, compensating balancers, pen-
+dulums, etc., they are all liable to go wrong and
+refuse to act the moment a sudden strain makes their
+perfect action most important.
+
+Considering that the propeller is the only means
+the aeroplane has of keeping in the air at all, the
+question arises : Is it possible to design a machine
+that will be stable to the extent of descending safely
+when it stops, and that will yet be a good
+and speedy flyer?
+
+That is the problem we have to solve.
+
+I4 NATURAL STABILITY IN AEROPLANES
+
+CHAPTER II.
+SPEED AS A MEANS OF STABILITY.
+
+It is recognized on all hands that speed is a great factor in the problem of stability. To begin with, a machine going at high speed would be practically untouched by gusts of wind, different densities of air strata, holes in the air, etc. Also its greater momentum would tend to keep it in a straight line, not only relative to its course but also relative to itself. That is so because the lift acting on a horizontal plane would tend to keep in the same plane and would not easily tilt or sway out of it. Both these effects of natural law show that a high speed machine must be more stable than a low speed machine. How then are we to design a high speed machine ?
+
+Leaving aside the question of higher power, the first point that suggests itself is to lessen the head resistance. All fast things, boats, birds, arrows, even motor cars have wings. The naturalist will object that a bird with its wings outspread is not long and narrow, but in the sense in which this illustration is meant, the bird's wings, being merely its propelling apparatus, do not count, and when the bird is at its fastest, as in the swoop of a hawk or an
+
+SPEED AS A MEANS OF STABILITY <page_number>15</page_number>
+
+eagle, the wings are shut tightly to the body so as to offer no resistance to its lightning passage through the air. If we are to follow previous experience in Nature in our machines, we must necessarily reduced speed. To drive through the air at a high speed with a machine of 40 foot span is a practical impossibility, both because of the tremendous power it would require and also by reason of the great strength the plane must have to withstand the resistance of the air.
+
+In reducing the span, however, we reduce the lifting surface of the machine. But on the other hand it must be remembered that the lifting efficiency is increased by increasing the speed. Lift is the product of supporting surface and speed. A small plane driven at a high speed will give as great a lift as a large plane driven at a low speed. Speed, again, is the difference between the propelling power and the head resistance, and we can increase the speed by decreasing the resistance. It follows, then, that we need not necessarily give up lifting power by reducing the span of the wings. A greater speed gives greater lift, but an increase of efficiency by reason of the greater speed would go to make up for the loss of span.
+
+It is, then, quite possible to design a short span machine which shall be as efficient for lift as a long span machine, and which will have the advantage of possessing, by reason of its speed, much greater stability.
+
+16 NATURAL STABILITY IN AEROPLANES
+
+But the span is not the only factor in the speed problem. In the low speed machines at present in use we have found it necessary to curve the planes to get greater efficiency. This efficiency is also gained at the expense of stability. It has been recognized that the higher the speed the less is the need of camber. This is the same problem over again. A high speed flat plane will give as much lift as a low speed cambered plane, and we gain in stability with every additional mile per hour.
+
+The third point to be considered in the problem of speed is the resistance caused by the multitude of struts and wires, the body of the pilot, the tanks, engine, etc., all of which resist the air in all directions from the body of the aeroplane. It has occurred to our builders that if the whole of these things could be collected together and enclosed in a light covered-in car of a proper shape, the skin friction of such a car would be much less than the total head resistance offered by the different obstructions so covered. And there is another advantage to be gained here, for if, at 40 miles per hour, the force of the wind is very strong and uncomfortable for the pilot, the position at such speeds as 70 or 100 miles per hour would be quite impossible.
+
+<page_number>17</page_number>
+
+CHAPTER III.
+THE LOW CENTRE OF GRAVITY.
+
+The first thing that occurs to the investigator on the subject of stability is that nature offers us a sure means of keeping our machines upright by adopting the simple method of placing all the heavier parts at the bottom. In all other constructions we have adopted this plan with perfect success. In boats, yachts, cars, locomotives, everything man uses in fact, the simplest, best and most obvious method of keeping a thing upright is to utilize the force of gravity, place the lighter or supporting parts above and the weight below, and the thing is done.
+
+This simple method of obtaining stability did not escape the aeroplane designers, and we have had several machines which embodied this principle, more or less. Unfortunately, however, they all proved failures. A machine would not design and, with the weight high, it was so well trimmed that it was unstable. Put the weight low and you got rid of the instability, and at the same time the machine became unmanageable. It looked as if flying and instability were interchangeable terms. So, as it was a machine that would fly the designers were after, the weight was
+
+B
+
+18 NATURAL STABILITY IN AEROPLANES
+
+kept up and the stability was left to the pilot. The machines were made "sensitive" as it is called, that is to say, sensitive to a touch of the rudder or the balancers. They are also, it is true, equally sensitive to a gust of wind or a slight shifting of weight or pressure, and this has caused the smashing of a good many machines and some pilots ; but after all this is the fortune of war, and no one is compelled to go up in an aeroplane.
+
+The one thing about it is that it does not seem to have occurred to our designers that if their pet design would not fly with the weight low, perhaps it might be possible to alter the design instead of altering the position of the centre of gravity, and so obtain what we are all looking for, a naturally stable machine that is yet sensitive to control.
+
+There are two chief difficulties in the way of the low centre of gravity machine. One is that the heaviest portion of the machine being somewhat below its support, it is apt to give rise to a pendulum or swaying motion. The other is that of tilting, or banking up, in turning a corner. These are really two developments of the same difficulty, i.e. pendulum motion.
+
+If we take a strip of stiff paper to represent a plane and put a small weight in the centre of the plane, the model on being tilted to either side does not tend to sway (Fig. 3). If we put our weight on any piece of wire an inch or so below the plane (Fig. 3) and set the model free, it will probably acquire a
+
+THE LOW CENTRE OF GRAVITY
+
+19
+
+swinging motion as it descends. That is the whole trouble. The trouble is real enough, but the fallacy is in supposing it to be all the fault of the low centre of gravity.
+All ships that were ever designed have a low centre of gravity, and some do not, and others do not, which, in itself, should be proof sufficient that it is the design of the machine and not the position of the ballast that is at fault.
+
+Let us now try some experiments. It will be noticed that in the machines which have employed
+
+<img>Fig. 1.</img>
+<img>Fig. 2.</img>
+<img>Fig. 3.</img>
+
+the low centre of gravity the span of the wings has usually been 30 feet or more, and the centre of gravity about 6 feet below the centre. Here is a paper model of a machine with a high centre of gravity (Fig. 1). Now bend the paper upwards as in Fig. 2 and you get rid of the swaying. Also, of course, you get rid of the supporting surface. But there is probably some point of greatest efficiency where you may compromise. If you take model 2 and bend it slightly (Fig. 4) it will sway, but not much, not so much as Fig. 2. Now B2
+
+20 NATURAL STABILITY IN AEROPLANES
+
+with a pair of scissors clip the wings a bit at a time, and you will find that as the span gets shorter the swaying decreases, and that when you have the three points formed by the ends of the two wings and the weight equidistant from the centre where they meet,
+
+<img>Fig. 4.</img>
+
+the plane is stable (Fig. 5). The reason is that it is not the pendulum with the weight at the bottom that swings so much, but the long wings that see-saw. By shortening the wings you have reduced the length of the see-saw, which is the same as reducing the length of the pendulum, and consequently, by pendulum law,
+
+<img>Fig. 5.</img>
+
+the oscillations must be much quicker and shorter and will at once damp out. It is curious that this point seems to have escaped the designers. It is well known that all pendulum motion tends to damp out, and the shorter the pendulum the quicker it comes to rest. Hitherto the idea has been to shorten it vertically,
+
+THE LOW CENTRE OF GRAVITY
+
+but the same effect exactly is obtained by shortening it horizontally, and the low centre of gravity remains to give stability. It was stated by some sagient objector to the low centre of gravity, that the pendulum motion would be too slow to be useful in machine work. A pendulum which increased its swing at every stroke would be something new in the scientific world.
+
+Another development of the pendulum difficulty is the probable fore and aft sway, but this may be overcome by increasing the supporting surface of the tail. Many machines do not lift with the tail at all, and those that do employ lifting tails, have them with very small surface. Consequently, the centre of gravity is nearly always out of the main plane, and the whole machine, turning on its centre of gravity in all directions as on a pivot, is liable to swing fore and aft. If the supporting surface of the tail be increased and the centre of gravity carried further aft, this pendulum motion is also rendered impossible, and the machine is stable both ways.
+
+A few illustrations may serve to make the advan-
+tages of the low centre of gravity more clear, and to avoid any confusion between what is meant to be still and in still air. Let Fig. 6 represent an ordinary flat plane having its centre of gravity coincident with its centre of pressure, the centre of pressure of each half or wing being at A. The plane is in equi-
+brium. Now allow it to tilt (Fig. 7), and it will be seen that it is still in equilibrium, since the weight is in the centre and the wing tips equidistant from it.
+
+<img>A diagram showing a flat plane with its center of gravity coincident with its center of pressure.</img>
+<img>A diagram showing a flat plane tilted slightly to one side.</img>
+
+<page_number>22</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+Let it tilt still more till it is vertical (Fig. 8), and the balance is still the same. It is evident, therefore, that such a plane would travel equally well in any of the positions shown, and that it can only be kept in position (Fig. 6) by the skilful manipulation of the pilot.
+
+<img>Fig. 6.</img>
+
+<img>Fig. 7.</img>
+
+<img>Fig. 8.</img>
+
+In the same way, the machine having no lifting tail is longitudinally unstable, for, being balanced on its centre of pressure which would be coincident with its centre of gravity and probably lie 2 feet from the trailing edge of the plane—it may assume any position (Figs. 9, 10, 11 and 12), and still be in equilibrium, when it is evident that the proper position
+
+THE LOW CENTRE OF GRAVITY <page_number>23</page_number>
+
+(Fig. 9) is only maintained by the constant control of the tail elevator.
+
+Now take the case of a machine having a low centre of gravity. Its natural position is shown at Fig. 13, and it is at once evident that any other position such as Figs. 14 and 15 could not be maintained
+
+<img>A diagram showing a machine with its tail elevator raised to maintain a low centre of gravity.</img>
+Fig. 9.
+
+<img>A diagram showing a machine with its tail elevator lowered to maintain a low centre of gravity.</img>
+Fig. 11.
+
+<img>A diagram showing a machine with its tail elevator in an intermediate position between Figs. 9 and 11.</img>
+Fig. 10.
+
+<img>A diagram showing a machine with its tail elevator in an intermediate position between Figs. 9 and 11.</img>
+Fig. 12.
+
+<img>A diagram showing a machine with its tail elevator in an intermediate position between Figs. 9 and 11.</img>
+Fig. 13.
+
+for a moment, since the weight being at an angle, must inevitably drag the machine back to its natural position (Fig. 13). In the same way with regard to longitudinal balance, a machine with two lifting surfaces such as Fig. 13, is in its natural position with the centre of gravity perpendicularly under the centre of pressure, any other position, such as Fig. 17, A, is im-
+
+24 NATURAL STABILITY IN AEROPLANES
+
+possible, as the gravity pull must drag the machine along the dotted line till it resumes its proper and natural position (B).
+
+The next difficulty is in the banking or tilting caused by the turning of the machine in going round a curve. In a very interesting discussion carried on
+
+<img>Figs. 14, 15, 16.</img>
+
+in the "Aero," it was stated that a low centre of gravity machine could not bank up, as the pull of gravity acting on the low weight would prevent it.
+
+It was also stated by another writer that the machine would bank up too much and sink down too easily because the greatest weight having the greatest momentum would swing out too much. There is
+
+THE LOW CENTRE OF GRAVITY <page_number>25</page_number>
+
+evidently some confusion here. Let us consider the question.
+
+In turning there are three forces to take into consideration:
+(1) The centrifugal force, which tends to make the machine fly off at a tangent to the curve at which it is turning.
+(2) The action of gravitation.
+
+<img>A diagram showing a curved path with points labeled A, B, and C.</img>
+Fig. 17.
+
+(3) The extra lift given by the wing on the outside of the curve, owing to the fact that it travels faster through the air.
+
+The centrifugal force acts strictly in proportion to the mass it acts on, but, at the same time it must be remembered that the greater force acting on the greater mass has the greater mass to move. That is to say, that if the top part of the machine was very
+
+26 NATURAL STABILITY IN AEROPLANES
+
+light and the bottom part very heavy, the force acting on the light part would be sufficient to send that part swinging out when rounding a curve, and the greater force acting on the greater mass at the bottom would be sufficient to pull that out exactly by some degree. Consequently, if the whole configuration is considered, the whole machine would swing out with- out tilting at all, retaining its upright position.
+But here we must take another factor into considera- tion, the resistance of the air. This resistance would be greater on the greater surface of the light top part than on the heavy bottom part, and consequently the bottom part would, automatically, swing out most, giving a steady sinking. This effect is accentuated by the extra lift given to the upper wing by reason of its greater speed. As we then take the force of gravita- tion into the problem we shall see that we have two factors—unequal speed and unequal air resistance—tending to bank up the machine, and one force—gravity—tending to pull it straight again. At a certain angle due to the amount of force exerted by each of these, the two opposing factors would balance, and the machine would remain level.
+
+It would appear that most of the difficulties con- nected with the low centre of gravity machine are the result of hazy thinking and slip-shod reasoning, and that they do not exist in fact. And let it be remem- bered that the low centre of gravity machine with short span has not yet been tried except by the writer, who has succeeded in making a paper model on this
+
+THE LOW CENTRE OF GRAVITY <page_number>27</page_number>
+
+plan turn in its own length without in any way losing
+its stability, swaying, banking too much, turning over,
+sliding sideways, or doing any of the frightful things
+which some people declare it must do. What it does
+do is to keep on going forward and start from the
+most impossible positions and always land on its feet.
+
+<page_number>28</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+CHAPTER IV.
+SHORT SPAN AND AREA.
+
+Both on account of speed, and also on account of stability, with a low centre of gravity, we are forced in the direction of the short span machine. How are we to construct a machine with a span short enough to damp out swaying and yet with sufficient lifting surface to raise the machine and its load?
+
+The position is somewhat simplified, as already pointed out, by the fact that though the lift is decreased by the increase in speed, it is to a great extent compensated by the increase in speed. Also another compensation is effected by the fact that fore and aft stability requires a lifting tail.
+
+Lift is largely in proportion to the length of the entering edge of the plane, but it does not always follow that this entering edge must be at right angles to the direction of flight. The Dunne machine obtains its lift with an entering edge that is entirely at an angle of some 45 degrees, and its shape is an exact replica of the form of prehistoric man and the paper darts of our schooldays, a design, by the way, that was patented in 1860.
+
+At first sight it would seem that the lift on a plane
+
+SHORT SPAN AND AREA <page_number>29</page_number>
+
+shaped thus (Fig. 18), would only be equal to the lift given by a plane with an edge as long as the distance between A and C, thus (Fig. 19); but this is not so.
+Although the lift is not so great as it would be if the edge was straight in one line (Fig. 20), it is very much
+
+<img>Fig. 18.</img>
+greater than it would be on Fig. 19. The probability is that it is about half-way between (19) and (20), but probably nearer to (20) than (19). There are no exact data to go on, but the efficiency of the Dunne machine would seem to show this.
+
+<img>Fig. 19.</img>
+
+Again, in seeking for planes that offer the least resistance to the air, one of the best that suggests itself is the T-shape (Fig. 21), and this may be improved by cutting off useless corners (Fig. 22). A plane of
+
+<img>Fig. 20.</img>
+
+30 NATURAL STABILITY IN AEROPLANES
+
+this shape lends itself to great strength of construction owing to its small extending parts. It is compact, it gives an entering edge half as long again as its span, and gives a lift in proportion to that edge, and it is in
+
+<img>Fig. 21.</img>
+<img>Fig. 22.</img>
+
+itself stable. Having thus evolved a suitable plane for the front of the machine, the best thing to do is to base the back plane on the same design, and join the two planes together to form the supporting surface of the machine, allowing sufficient space between them
+
+<img>Fig. 23.</img>
+
+to avoid any interference or overlapping. The design then stands thus (Fig. 23), when the back plane is a slightly smaller copy of the front one. The position of the centre of gravity in this design would be coin-
+
+SHORT SPAN AND AREA <page_number>31</page_number>
+
+cident with the centre of pressure longitudinally and laterally, and would be situated about at A. A paper model on these lines with a low centre of gravity may be easily constructed and will prove useful in illustrating the different points here stated. The paper
+
+<img>Figs. 24.</img>
+<img>Figs. 25.</img>
+
+should be cut out sufficiently wide to allow of a central longitudinal fold (Figs. 24 and 25), and a roll of paper should be made for ballast and pushed through the fold as shown in Fig. 26 at the point marked A.
+
+<img>Fig. 26.</img>
+
+The writer, when exhibiting at Olympia this year, distributed 500 of these paper models, and the almost uncanny way in which they righted themselves when started from all sorts of impossible positions greatly
+
+32 NATURAL STABILITY IN AEROPLANES
+
+interested the visitors. In fact, numbers of persons spent considerable time and ingenuity in trying to force the little glider to turn over or dive, but quite without success.
+
+In order to test the turning capacity of this design, a rudder should be fixed to the tail, and the model launched at a moderate speed, when it will be found that it turns quickly and without any pendulum motion, and without any perceptible tilt. And although the writer's experiments with the paper model and with many larger ones on the same plan have run into thousands, none of the models have ever been induced to turn down in any considerable but on their feet. The largest model which measured 6 by 6 in. in length, was launched both upside down and with its head pointing vertically to earth from a height of 30 ft., and in each case righted before it reached the ground and landed on its skids.
+
+As a further lifting surface, a very simple expedient offers itself in the shape of a duct built on the box-kite principle. The diamond-shaped box has been proved over and over again to be a very efficient lifting surface. It is used as a tail unit on an aeroplane (Fig. 27). It is also a great stabilizer, since the air entering into the diamond-shaped opening is collected and compressed into the top angle there, and the whole box is thus practically suspended from its apex line in absolute stability. The lifting efficiency of such a box—or rather the top portion of the box, for the bottom part is not needed on our machine—is
+
+SHORT SPAN AND AREA
+
+<page_number>33</page_number>
+
+<img>
+A diagram showing the different parts of an aircraft wing. The top diagram shows the span of the wing, with the leading edge at the top and the trailing edge at the bottom. The middle diagram shows the area of the wing, with the upper surface shaded in grey and the lower surface shaded in white. The bottom diagram shows the lift force on the wing, with a line drawn from the leading edge to the trailing edge.
+</img>
+
+FIG. 27.
+
+Main Plane.
+
+Open Space.
+
+Car.
+
+FIG. 28.
+
+Landing surface of Car.
+
+C
+
+34 NATURAL STABILITY IN AEROPLANES
+
+considerably greater than the value of the entering edge, and if run the whole length of the machine it forms a triangular girder of great strength, giving rigidity to the whole structure. The lifting efficiency is doubled by allowing the centre third of the girder to be open, as the dead air from the front part escapes, and the back part forms a new entering edge.
+
+There is also another lifting factor to be considered, and this is the car. If the car is formed with a flat bottom, this at once becomes an efficient lifting plane, and if the car is suspended with an open space between it and the under surface of the plane, the loss caused by the near-bottomed raft is compensated for by the lift given by the deflected air to the under surface of the main plane (see Fig. 28).
+
+It will be recognized that in the design here being gradually evolved, the great lifting surfaces of the ordinary machine have not been largely reduced, they have simply been broken up into several smaller surfaces, each of which retains its efficiency. Something of the same nature happened in prehistoric days, when on account of their narrowness, some people had to abandon the flat-bottomed raft with its huge supporting surface, for the new-fangled and dangerously narrow boat.
+
+When all the different surfaces here mentioned are taken into consideration, it will be found that the lifting surface in a monoplane machine of this design, with a span of 20 feet, is equal to the lifting surface
+
+SHORT SPAN AND AREA <page_number>35</page_number>
+
+of an ordinary bi-plane with a span of 40 feet. And as the head resistance is less than half that of the bi-plane the speed should be very much greater. At the same time the increased speed renders the planes more efficient, area for area, than the planes of the slower machine.
+
+<img>A page from a book, likely a technical or scientific text, discussing aircraft design. The text is centered on a white background with black text. The page number "35" is at the top right corner. There is a small number "2" at the bottom center of the page.</img>
+<page_number>2</page_number>
+
+36 NATURAL STABILITY IN AEROPLANES
+
+CHAPTER V.
+
+VARIABLE SPEED AND THE PARACHUTE PRINCIPLE.
+
+HITHERTO, on the score of efficiency and also of stability, our investigations have led us to seek for speed as the grand panacea. But there are usually two sides to a question, and though, while in the air, speed may be most desirable, on the ground course, it introduces difficulty at both starting and landing. A machine built to fly at 80 miles per hour would have to get up something like 60 miles per hour before it could rise. And this difficulty is nothing like the problem that presents itself when we consider how it is to land in safety from a flight at such a speed. It becomes evident that some provision must be made for starting and landing at some more practicable rates; we must have a variable speed.
+
+To construct a high speed machine into a low speed machine means either variable surface area, variable camber, or variable angle of incidence. Any of these is possible, but the choice must be decided by simplicity of action. To spread extra wings when rising or landing is a cumbersome suggestion full of pitfalls and liable to accidents through the failure of mechani-
+
+<table>
+  <tr>
+    <td>CHAPTER V.</td>
+  </tr>
+  <tr>
+    <td>VARIABLE SPEED AND THE PARACHUTE PRINCIPLE.</td>
+  </tr>
+  <tr>
+    <td>HITHERTO, on the score of efficiency and also of stability, our investigations have led us to seek for speed as the grand panacea. But there are usually two sides to a question, and though, while in the air, speed may be most desirable, on the ground course, it introduces difficulty at both starting and landing. A machine built to fly at 80 miles per hour would have to get up something like 60 miles per hour before it could rise. And this difficulty is nothing like the problem that presents itself when we consider how it is to land in safety from a flight at such a speed. It becomes evident that some provision must be made for starting and landing at some more practicable rates; we must have a variable speed.</td>
+  </tr>
+  <tr>
+    <td>To construct a high speed machine into a low speed machine means either variable surface area, variable camber, or variable angle of incidence. Any of these is possible, but the choice must be decided by simplicity of action. To spread extra wings when rising or landing is a cumbersome suggestion full of pitfalls and liable to accidents through the failure of mechani-</td>
+  </tr>
+</table>
+
+VARIABLE SPEED AND PARACHUTE PRINCIPLE <page_number>37</page_number>
+
+cal devices, which, experience shows, always have a way of failing at inopportune moments. To vary the camber of the planes is easier, but having decided on using flat planes it would be loss of strength to make these flexible, and an increase of mechanical complications to have to flex them. It would be easy to alter the angle of incidence by having the leading edge capable of a rotary movement, and machines have been constructed employing this principle. But the easiest plan of all, since it does away with all machinery, is that of being to lift not the planes themselves, but the whole machine. Thus suppose the angle of incidence, in order to get an efficient lift, to be 1 in 5, the lifting plane, all in the same line, would be set on its chassis so that it pre- sented an angle of 1 in 5. The machine would then lift at a much slower speed. Naturally, the tail being the furthest from the centre of gravity would lift first, and as soon as the speed was sufficient the plot would also rise. Then, as the weight of the tail on the ground, thereby raising the leading edge of the lifting plane, and the machine would rise. As the speed increased the tail would continue to rise, till at the maximum speed, the plane would be at the minimum angle with the horizontal, i.e. at its lowest angle of incidence.
+
+This solves the problem of starting and to some extent of landing, but we have not yet come to the end of our resources. Most landings are effected by shutting off the engine and planting down. All flying machines will glide if put at the proper angle, and it
+
+38 NATURAL STABILITY IN AEROPLANES
+
+is the business of the pilot to attend to this when he stops the engine. But to glide with the same wing area as is used in flying, means to glide at the same ratio. In order to do this, it is necessary that we have no area, i.e. it is possible to increase the area used for descent without interfering with the area used for flight? In the design we are engaged in consider-
+ing, it is possible, and without any mechanical devices.
+There is a large space between the front plane and the back plane which is at present unused. It is of very little value in flight, being in apericoid aspect and having practically no entering edge. But if this space is covered, it will give us a very light weight, and descent becomes a very efficient parachute. Further than this, if openings be cut in this plane immediately under the centre of the two box-kite ducts, the air under the longitudinal plane, having offered its resist-
+ance to the vertical passage of that plane, will escape into the duct and again offer considerable resistance to the descent of this closed-in surface before it escapes finally out of the end of the duct.
+
+A most important point these lines will need putting at any angle. It will assume a proper angle when left to itself by reason of its design and the way the weight is balanced between the supporting planes, and it will descend by partly gliding and partly parachuting at a steep angle but quite slowly. While,
+if the pilot so choose, he can, by raising the tail, increase the speed to a glide, which he can turn into a parachute action at any moment.
+
+39
+
+CHAPTER VI
+THE DESIGN WHICH FULFILS THE CONDITIONS.
+
+In constructing any sort of machine it is usual to first obtain the most important device and then to build up the accompanying parts to that. We have now succeeded in evolving the thing we set out to look for, i.e., a plane which will fly and lift with the minimum of head resistance, and which is absolutely stable laterally and longitudinally by reason of its construction and without any interference from the pilot or the employment of balancing devices of any description. We have now to fit the propelling apparatus, car, and chassis on to this.
+
+Fortunately, the designer finds that lends itself easily to manipulation which is not always the case with models. The short span of the planes, for instance, with the dihedral angle, at once suggests girder construction (see Figs. 29, 30), which is, perhaps, the strongest of all devices, being an M strut girder, familiar to us in numerous bridges.
+
+The photograph which forms the frontispiece of this book, and which, by the way, makes the car look much too large owing to its position nearest the camera, represents a 6-foot model which was exhibited at the
+
+<page_number>40</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+Olympia Show, in order to show the construction of a full-sized machine made to the design of the paper model. This has since been considerably simplified, though the broad lines have been retained, by doing away with the back plane and the whole of the front plane.
+
+The whole of the back plane is now supported by two curved members, which start from the girder of the leading edge and curve down to the T-section longi-
+<img>Fig. 29.</img>
+
+Fig. 30.
+
+tudinals which form the rigid part of the chassis. These longitudinals and the skids end at the leading edge of the back plane and the laminated skids and wheels are placed there. The machine is built without a wire and without a casting. It was made entirely of wood, but is so designed that it can be made entirely out of steel tube by using the ordinary screw connexions. If built of timber, the joints are made with strips of steel bolted and screwed on to the wood. The girders forming the leading edge of each
+
+DESIGN WHICH FULFILS THE CONDITIONS <page_number>41</page_number>
+
+plane have sockets formed in the upright struts of the M into which the ribs fit (see Fig. 30), and these are solid pieces on edge tapering to the trailing edge, where they are clipped together. A slight overlap holds them together by their construction, while very strong, is yet sufficiently flexible to bend considerably before it reaches breaking point. Longitudinal rigidity is secured by means of the triangular duct which forms a complete girder from end to end. A sufficient number of uprights fill the space between the plane and the two T-section longitudinals which form the rigid bottom of the machine. On these latter the floor is fixed and the whole machine is assembled, all the obstructions and putting the pilot in a plot of safety, enclosed on all sides in the middle of the strongest part of the machine, with the strongest portion of that part between him and the ground.
+
+The centre of gravity is situated behind the pilot in the back of the car, near the floor, and here is space for the oil and petrol tanks. The engine is in front of the pilot, who thus is able to control it and watch it, and at the same time is free from the danger of being too far away from his work when steering. As the machine turns horizontally and vertically on its centre of gravity, the front part of the car forms a sort of baffle or blinker for the rudder and elevator to act against. Both these are at the tail of the machine, where they have the most leverage, and these two are controlled by the one lever, which is pushed forward or pulled backward to raise or lower the
+
+42 NATURAL STABILITY IN AEROPLANES
+
+elevator, and turned bicycle fashion to move the rudder. As the machine balances itself, there is no need for any balancing device either automatic or controlled.
+
+The propellers may be two or more, and those in front find a very firm fixing in the intersection of two strong struts, which join the wingtips to the bottom of the car, and the supports which run from the centre of the car to the floor. The joint is formed by the intersection of the longitudinal and lateral girder. At the back there may be two propellers fixed as in the front, or one large one at the rear of the car.
+
+They are all worked from the one engine and the thrust is slightly less than the force of gravity. Each propeller is placed just under the leading edge of a plane, Fig 31, the idea being that a certain amount of air is always thrown out by centrifugal force all round a revolving propeller, and this air, which, ordinarily, is lost, must, when thrown upwards, exert a lift on the under surface of the plane. Also, when thrown downwards, it must be resisted by impinging on the planting surface of the car, tend to impel it forward. Fig. 32. Where four propellers are used, the back pair should be of greater pitch than
+
+<img>Fig. 31.</img>
+
+Also see page 106.
+
+DESIGN WHICH FULFILS THE CONDITIONS <page_number>43</page_number>
+
+the front pair, as they must to a certain extent, work in the stream from the front pair. There are several ways of coupling the propellers to the engine, but in the model they are shown coupled up by belts, which seems to be the most efficient and lightest device.
+
+In order to cool the engine and keep the air in the car clear, a ventilating pipe is led from the front of the car to the engine, and the air, rushing through
+
+<img>A diagram showing a section of a car with arrows indicating airflow.</img>
+Fig. 32.
+
+this at the speed of the machine, plays over the engine and is conducted out through a large opening and discharged into the back.
+
+The whole of this part of the machine is rigid and braced together by means of struts, though whether made of steel tube or timber, there must always, from the nature of the construction, be a certain amount of elasticity which makes for strength, a great
+
+<page_number>44</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+advantage over a construction braced rigidly by non-
+elastic wires, which snap instead of giving to a sudden
+strain.
+
+Under the two rigid T-section longitudinals there are a number of elastic laminated wood springs set at
+an angle, and the lower ends of these are pivoted on to a long elastic skid. This skid is made in laminations,
+which interlock joints being cut from the planks
+where the two planes intersect in the middle of the machine, which is one of the strongest joints in the
+whole construction. From this point it bends out in
+a semicircle to protect the propeller and the front of
+the machine and car, this portion of it being very
+elastic by reason of the laminations having free play
+one upon the other. At the bottom of the semicircle
+the skid is joined to the slanting skids or springs
+depending from the bottom of the machine, and here
+the laminations are made together so that the skid
+is stiffer. The skid runs the whole length of the
+machine like the runner of a sledge. On this skid
+the wheels are sprung with a steel spring lever
+arrangement, Fig. 33. The shock of landing is, there-
+fore, taken first on the wheels, and should it be suffi-
+ciently heavy to cause the skids to touch the ground
+there is still the series of laminated wood springs to
+absorb any vibrations and prevent any possible shock
+to the car. The whole lower half of the machine is built up
+in reason of these precautions that the whole lower half
+of the front of it may be made of protected glass, to
+enable the pilot to get a clear view of his surroundings.
+
+DESIGN WHICH FULFILS THE CONDITIONS <page_number>45</page_number>
+
+<img>A diagram showing a curved structure with a spherical object attached to it.</img>
+<page_number>Fig. 33</page_number>
+
+<page_number>46</page_number>
+NATURAL STABILITY IN AEROPLANES
+
+The dimensions of the full-sized machine are estim-
+ated to be as follows :-
+<table>
+  <tr>
+    <td>Span</td>
+    <td>.</td>
+    <td>20 feet</td>
+  </tr>
+  <tr>
+    <td>Length</td>
+    <td>.</td>
+    <td>43 feet</td>
+  </tr>
+  <tr>
+    <td>Parachuting area</td>
+    <td>.</td>
+    <td>500 square feet</td>
+  </tr>
+  <tr>
+    <td>Efficient lifting area</td>
+    <td>.</td>
+    <td>360 square feet</td>
+  </tr>
+  <tr>
+    <td>Weight (all up)</td>
+    <td>.</td>
+    <td>800 lb.</td>
+  </tr>
+</table>
+
+It will be understood that though only 360 square
+feet is counted as efficient for lifting, the whole 500
+square feet is efficient as parachuting surface in
+descending. The weight of the machine compares
+very favourably with existing machines, and the load
+of 24 lbs. per square foot, gives plenty of margin for
+passenger carrying.
+
+The chief advantages claimed for this machine are :-
+(1) Speed.
+(2) Stability.
+(3) Strength of construction.
+(4) Shock absorbing capacity.
+
+It is a practical impossibility for the machine to
+turn over or be blown over, and it will recover its
+balance if started at any angle. If allowed to dive
+vertically, either tail first or head first, it will recover
+its position in six times its own length, purely by its
+own balance, without any effort of the pilot.
+
+LONDON PRINTED BY WILLIAM GOWEN AND SONS, LIMITED,
+GREAT WINDMILL STREET, W., AND DUKES STREET, STAMFORD STREET, L.S.
+
+<page_number>1</page_number>
+
+<img>A blank page with a faint vertical line on the left side.</img>
+
+S. & C. List January 1912
+
+A COMPLETE LIST
+
+Of the Books included in the
+
+S. & C. Series
+
+OF
+
+ELEMENTARY MANUALS
+
+FOR
+
+Mechanics and Students
+
+PUBLISHED BY
+
+E. & F. N. SPON, Ltd., LONDON
+
+<img>A page from a catalog listing books in the S. & C. Series.</img>
+
+THE S. & C. SERIES
+Uniform, in cloth. Price 1s. 6d. net each.
+
+1. Modern Primary Batteries. By N. H. Schneider.
+2. How to Install Electric Bells, Annunciators and alarms. By N. H. Schneider.
+3. Electrical Circuits and Diagrams, Part I. By N. H. Schneider.
+4. Electrical Circuits and Diagrams, Part II. By N. H. Schneider.
+5. Experimenting with Induction Coils. By N. H. Schneider (Z. S. Norris).
+6. The Study of Electricity for Beginners. By N. H. Schneider.
+7. Dry Batteries, how to make and use them. By A Dry Battery Expert.
+8. Electric Gas Lighting. By N. H. Schneider.
+9. Model Steam Engine Design. By R. M. de Vignier.
+10. Inventions, how to Protect, Sell and Buy Them. By F. B. Wright.
+11. Making Wireless Outfits. By N. Harrison.
+12. Wireless Telephone Construction. By N. Harrison.
+13. Practical Electrics; a Universal Handy Book on Everyday Electrical Matters.
+14. How to Build a 20-foot Bi-plane Gilder. By A. P. Morgan.
+15. The Model Vaudeville Theatre. By N. H. Schneider.
+16. The Fireman's Guide; a Handbook on the Care of Boilers. By K. P. Dahlstrom.
+17. A.C.T., of the Steam Engine, with a Description of the Automatic Governor; By P. Lax.
+18. Simple Soldering, both Hard and Soft; By E. Thatcher.
+
+E.& F.N.SPON, Ltd., LONDON
+
+THE S. & C. SERIES
+
+Uniform, in cloth, Price 1s. 6d. net each.
+
+10. Ignition Accumulators, their Care and Management. By H. H. U. CROSS.
+20. Key to Linear Perspective. By C. W. Dymond, F.S.A.
+21. Elements of Telegraphy. By ARTHUR CROUCH.
+22. Experimental Study of the Gyroscope. By V. E. JOHNSON, M.A.
+23. The Corliss Engine. By J. T. HENBURN.
+24. Wireless Telegraphy for Intending Operators. By C. K. P. EDEN.
+25. Wiring Houses for the Electric Light. By N. H. SCHNEIDER.
+26. Low Voltage Electric Lighting with the Storage Battery. By N. H. SCHNEIDER.
+27. Practical Silo Construction in Concrete. By A. A. HOUGHTON.
+28. Molding Concrete Chimneys, Slate and Roof Tiles. By A. A. HOUGHTON.
+29. Molding and Curing Ornamental Concrete. By A. A. HOUGHTON.
+30. Concrete Wall Forms. By A. A. HOUGHTON.
+31. Concrete Monuments, Mausoleums and Burial Vaults. By A. A. HOUGHTON.
+32. Concrete Floors and Sidewalks. By A. A. HOUGHTON.
+33. Molding Concrete Bath Tubs, Aquariums and Natatoriums. By A. A. HOUGHTON.
+34 to 38 inclusive: *Works on Concrete Structures*, by A. A. HoUGHTON, and now in the Press.
+39. Natural Stability and the Parachute Principle in Aeroplanes. By W. LAMBERT.
+40. Builders' Quantities. By H. M. LEWIS.
+
+E.& F.N.SPON., Ltd., LONDON.
+
+<page_number>A 8</page_number>
+
+No.'1.--The S. & C. Series, Price 1/6 net
+
+# MODERN PRIMARY BATTERIES.
+
+THEIR CONSTRUCTION,
+USE AND MAINTENANCE.
+
+Including Batteries for Telephones, Telegraphs, Motors, Electric Lights, Induction Coils, and for all Experimental Work.
+
+BY
+NORMAN H. SCHNEIDER.
+55 Illustrations and 34 pages of Text.
+
+<img>
+A cylindrical battery with a spout on top.
+A cylindrical battery with a metal plate on top.
+A rectangular battery with a handle on top.
+</img>
+
+No. 2.—The S. & C. Series. Price 1/6 net.
+
+HOW TO INSTALL
+
+**ELECTRIC BELLS, ANNUNCIATORS, AND ALARMS.**
+
+INCLUDING
+
+Batteries, Wires and Wiring, Circuits, Fuses, Bells, Burglar Alarms, High and Low Water Alarms, Fire Alarms, Thermostats, Indicators, and the Location and Remedying of Troubles.
+
+By NORMAN H. SCHNEIDER.
+50 Illustrations and 63 pages of Text.
+
+<img>
+A diagram showing a circuit with various components such as batteries, wires, a bell, and a switch. The text "How to Install Electric Bells, Announciators, and Alarms" is written above the diagram.
+</img>
+
+No. 3. - The S. & C. Series. Price 1/6 net.
+
+# ELECTRICAL CIRCUITS AND DIAGRAMS
+
+ILLUSTRATED AND EXPLAINED.
+
+PART I.
+
+New and Original Drawings, comprising Alarms, Annunciators,
+Automobiles, Bells, Dynamos, Gas Lighting, Motors,
+Storage Batteries, Street Railways, Telephone,
+Telegraph, Wireless Telegraphy,
+Wiring and Teating.
+
+BY NORMAN H. SCHNEIDER.
+
+<img>A diagram showing an electrical circuit with various components such as a motor, transformer, and meters.</img>
+
+No. 4.—The S. & C. Series. Price 1/6 net.
+
+# Electrical Circuits and Diagrams
+
+## PART II.
+
+Alternating Current Generators and Motors, Single Phase and Polyphase Transformers, Alternating Current and Direct Current Motor Starters and Reversers, Arc Generators and Circuits, Switches, Wiring, Storage Battery Meter Connections.
+
+BY NORMAN H. SCHNEIDER.
+
+<img>A diagram showing a generator with various components labeled: RHEOSTAT, MAINS, EXCITER SWITCH, INDUCTOR GENERATOR, MAINS BRANCHES.</img>
+
+EXCITER
+
+No. 5.—The S. & C. Series. Price 1/6 net.
+
+EXPERIMENTING WITH
+INDUCTION COILS.
+Containing practical directions for operating Induction Coils and Tesla Coils; also showing how to make the apparatus needed for the numerous experiments described.
+
+BY
+H. S. NORRIE,
+Author of " Induction Coils and Coil Making."
+
+26 Illustrations and 73 pages of Text.
+
+<img>A diagram showing an induction coil with a spark gap and a Tesla coil. The Tesla coil has a large spool of wire and a small bulb-like device at the top.</img>
+
+No. 6.—The S. & C. Series. Price 1/6 net.
+
+THE
+
+STUDY OF ELECTRIGITY
+
+FOR BEGINNERS.
+
+Comprising the Elements of Electricity and Magnetism as Applied to Dynamos, Motors, Wiring, and to all Branches of Electrical Work.
+
+BY
+
+NORMAN H. SCHNEIDER.
+
+With Fifty-four Original Illustrations and Six Tables.
+
+<img>
+A diagram showing a simple electrical circuit with a battery, switch, lamp, and a series of symbols representing different components.
+</img>
+
+I = E R
+
+No. 7. -The S. & C. Series. Price 1/6 net.
+
+**DRY BATTERIES,**  
+ESPECIALLY ADAPTED FOR  
+Automobile, Launch and Gas Engine Work; Medical Coils, Bells,  
+Annunticators, Burglar Alarms, Telephones, Electrical  
+Experiments and all purposes requiring  
+a Good Battery.
+
+WITH THIRTY ORIGINAL ILLUSTRATIONS.
+
+<img>A cylindrical battery labeled "GAS ENGINE DRY CELL" with a metal cap on top.</img>
+<img>A cylindrical battery labeled "MEDICAL DRY CELL" with a metal cap on top.</img>
+<img>A rectangular battery labeled "GAS ENGINE DRY CELL" with a metal cap on top.</img>
+<img>A cylindrical battery labeled "FLASH LAMP DRY CELL" with a metal cap on top.</img>
+<img>A rectangular battery labeled "MOTOR CYCLE BATTERY" with a metal cap on top.</img>
+
+No. 8.—The S. & C. Series. Price 1/6 net.
+
+# Electric Gas Igniting APPARATUS
+
+How to Install Electric Gas Igniting Apparatus, including the Jump Spark and Multiple Systems for all purposes, with Suitable Batteries and Wiring,
+
+BY
+
+H. S. NORRIE.
+
+Author of "Inductive Coils and Coil Making."
+
+<img>A diagram showing the components of an electric gas igniting apparatus.</img>
+
+C
+
+No. 9.--The S. & C. Series. Price 1/6 net.
+
+# MODEL STEAM ENGINE DESIGN
+
+A HANDBOOK FOR THE DESIGNER OF SMALL STEAM ENGINES.
+
+By R. M. DE VIGNIER.
+
+<img>A steam engine with various gauges and dials.</img>
+
+Including original tables and calculations for speed, power, proportions of pumps, compound engines and valve diagrams.
+
+34 Illustrations and 94 pages of Text
+
+No. 10.—The S. & C. Series. Price 1/6 net.
+
+# INVENTIONS
+
+How to Protect, Sell, and Buy Them
+
+BY
+
+F. B. WRIGHT
+
+118 pages of Text
+
+No. 11. - The S. & C. Series. Price 1/6 net.
+
+# Making Wireless Outfits
+
+A CONCISE AND SIMPLE EXPLANATION ON THE CONSTRUCTION AND USE OF INEXPENSIVE WIRELESS EQUIPMENTS UP TO 100 MILES
+
+By NEWTON HARRISON, E.E.
+
+With 27 Illustrations and 61 pages of Text
+
+<img>A diagram showing a wireless communication system with various components labeled.</img>
+
+No. 12. -The S. & C. Series. Price 1/6 net.
+
+# Wireless Telephone Construction
+
+A Comprehensive Explanation of the Making of a Wireless Telephone Equipment for Receiving and Sending Stations with Details of Construction
+
+BY
+NEWTON HARRISON, E.E.
+
+With 43 Illustrations and 74 pages of Text
+
+<img>A diagram showing the components of a wireless telephone system. It includes a transmitter station on the left, a receiving station on the right, and various electrical components in between.</img>
+
+TRANSMITTING STATION
+RECEIVING STATION
+
+No. 13.—The S. & C. Series.
+Price 1/6 net.
+
+# Practical Electrics
+
+A Universal Handy Book
+
+ON
+
+ELECTRIC BELLS, BATTERIES, ACCUMULATORS,
+DYNAMOS, MOTORS, INDUCTION AND INTENSITY COILS,
+TELEPHONES, MICROPHONES, PHONOGRAPHS,
+PHOTOPHONES, ETC.
+
+With 124 Illustrations and 135 pages of Text
+
+<img>A diagram showing various electrical components and their connections.</img>
+
+No. 14.—The S. & C. Series. Price 1/6 net.
+
+# How To Build
+## A BI-PLANE GLIDER
+
+A PRACTICAL HANDBOOK ON IT'S CONSTRUCTION AND USE
+BY
+ALFRED POWELL MORGAN
+
+31 Illustrations and 60 pages of Text
+
+<img>A black-and-white illustration of a biplane glider with a man standing next to it on a grassy field.</img>
+
+<page_number>B</page_number>
+
+No. 15. - The S. & C. Series.
+Price 1/6 net.
+
+MODEL
+VAUDEVILLE THEATRES
+BY
+NORMAN H. SCHNEIDER
+
+With 34 Illustrations and 90 pages of Text
+
+<img>A decorative illustration of a stage with a curtain, a figure in the center, and silhouettes of people below.</img>
+
+No. 16.—The S. & C. Series. Price 1/6 net.
+
+THE FIREMAN'S GUIDE
+
+AND HANDBOOK ON THE
+
+CARE OF BOILERS
+
+BY
+KARL P. DAHLSTROM, M. E.
+
+<img>A black-and-white illustration of a large steam boiler.</img>
+<page_number>B3</page_number>
+
+No. 17.—The S. & C. Series. Price 1/6 net.
+
+**A B C**
+OF THE
+
+**STEAM ENGINE**
+
+AND
+
+**AUTOMATIC GOVERNOR**
+
+Six scale drawings of a High Speed Steam Engine and Automatic Governor. Each part is given in detail with its name and number for easy reference, with description. With a chapter on Lubrication and other practical information.
+
+BY
+
+J. P. LISK, M.E.
+
+<img>A black and white illustration of a steam engine with a governor attached to it.</img>
+
+No. 18.--The S. & C. Series. Price 1/6 net.
+
+<img>A diagram showing a soldering iron with a wire being soldered to a metal rod.</img>
+
+# SIMPLE SOLDERING
+
+## BOTH HARD AND SOFT
+
+Together with Descriptions of Inexpensive Home Made Apparatus Necessary for the Art.
+
+By EDWARD THATCHER
+Instructor of DECORATIVE METAL WORK
+COLUMBIA UNIVERSITY
+NEW YORK
+
+52 Illustrations and 76 pages of Text.
+
+No. 19.—The S. & C. Series. Price 1/6 net.
+
+THE CARE AND MANAGEMENT OF
+
+IGNITION ACCUMULATORS
+
+AND
+
+Electric Light for the Million
+
+CONTAINING
+
+Practical information on the Charging and Repairing of Motor Cycle,
+Motor Car, and other similar Ignition Accumulators. Also
+the adaptation of a slightly larger genus to a unique
+system of Electric Lighting
+
+BY
+
+HAROLD H. U. CROSS
+
+With 12 Illustrations and 66 pages of Text
+
+CONTENTS
+
+The Charging of Accumulators—The Repairing of Accumulators
+—the Accumulator in the Home
+
+<img>A vintage electric motor and generator set.</img>
+
+No. 20.—The S. & C. Series. Price 1/6 net.
+
+A Key
+TO THE
+Theory and Methods
+OF
+LINEAR PERSPECTIVE
+
+BY
+CHARLES W. DYMOND, F.S.A.
+
+With 16 Illustrations in 6 Plates, and 32 pages of Text.
+
+The aim of the author of this brief treatise has been to include, within the smallest possible compass, everything that is required to convey to a reader, whose time is limited, a competent knowledge of the theory and the rudiments of the practice of drawing in perspective.
+
+No. 21.—The S. & C. Series. Price 1/6 net.
+
+# ELEMENTS OF TELEPHONY
+
+BY ARTHUR CROUCH
+
+Silver Medallist and Honourman in Telegraphy, and Honourman in Telephony, City and Guilds of London Institute, sometime Lecturer in these subjects at the Municipal Technical Schools, Norwath
+
+With 51 Illustrations and 90 pages of Text
+
+<img>A diagram showing a telephone receiver with wires connected to it.</img>
+<img>A schematic diagram showing electrical circuits and components.</img>
+
+No. 22.--The S. & C. Series. Price 1/6 net.
+
+# THE GYROSCOPE
+
+## An Experimental Study
+
+FROM SPINNING TOP TO MONORAIL
+
+BY
+
+V. E. JOHNSON, M.A.
+Author of "The Theory and Practice of Model Aeroplanes."
+Formerly Exhibitioner of Magdalene College, Cambridge.
+
+With 34 Illustrations and 40 pages of text.
+
+<img>A diagram showing a spinning top with a monorail track.</img>
+
+No. 23.—The S. & C. Series. Price 1/6 net.
+
+THE
+
+CORLISS ENGINE
+
+BY
+JOHN T. HENTHORN
+
+AND
+
+ITS MANAGEMENT
+
+BY
+CHARLES D. THURBER
+
+With 22 Illustrations and 95 pages of Text.
+
+CONTENTS:
+
+Introductory and Historical—Steam Jacketing—Indicator Cards
+—the Governor—Valve Gear and Eccentric—Valve Setting—
+Table for Laps—Steam Valves—Laboratory—Discussion of the
+Air Pump—Its Management—Cylinder Main Driving Gear
+Best Lubrictor for Main Driving Gear—Heating of Mills by
+Exhaust Steam—Engine Foundations—Diagrams and Templets for
+Foundations —Materials for Foundations — Proportions of Corliss
+Engines—Horse-power and General Dimensions—Principal Dimen-
+sions of Corliss Engines.
+
+No. 24.—The S. & C. Series. Price 1/6 net.
+
+**Operator's Handbook of**
+
+**WIRELESS TELEGRAPHY**
+
+A Simple Treatise upon the Theory and Working of Commercial Wireless Telegraphy for the Assistance of Intending Wireless Operators
+
+BY
+
+C. K. P. EDEN, B.Sc., etc.
+Consulting Engineer for Wireless Telegraphy Installations also Electrotherapeutic and Radiography Specialist.
+
+In the Press.
+
+**CONTENTS.**
+Detectors—Transmitters—Tuning Apparatus—Wireless Station Equipment—Aerials and Earths—Small Power Experimental Apparatus.
+
+No. 25.
+The S. & C.
+Series.
+
+Price
+1/6 net.
+
+<img>A vintage illustration of a light fixture.</img>
+
+WIRING HOUSES
+
+FOR
+
+THE ELECTRIC LIGHT
+
+BY
+
+NORMAN H. SCHNEIDER
+
+With 44 Illustrations and 86 pages of Text
+
+No. 26.—The S. & C. Series.
+Price 1/6 net.
+
+LOW VOLTAGE
+ELECTRIC LIGHTING
+WITH THE
+STORAGE BATTERY
+
+SPECIALLY APPLICABLE TO COUNTRY HOUSES
+FARMS, SMALL SETTLEMENTS, YACHTS, ETC.
+
+BY
+NORMAN H. SCHNEIDER
+
+<img>A diagram showing a storage battery with a generator and a motor.</img>
+25 Illustrations and 88 pages of Text
+
+No. 27.--The S. & C. Series. Price 1/6 net.
+
+PRACTICAL SILO CONSTRUCTION
+
+A TREATISE
+
+Illustrating and Explaining the most Simple and Easiest Practical Methods of Constructing Concrete Silos of all types; with Unpainted Forms and with Painted Forms; also, the most practical and economical forms given in this book will enable the Concrete Builder to successfully construct any of the most practical types of Concrete Silos in use today.
+
+BY
+A. A. HOUGHTON
+Author of "Concrete from Sand Molds," "Commercial Concrete Without Molds," etc., etc.
+
+18 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+Boston
+E. & F. N. SPON, Ltrn.; 57 HAYMARKET
+<page_number>1911</page_number>
+
+No. 28.---The S. & C. Series. Price 1/6 net.
+
+MOLDING CONCRETE CHIMNEYS
+SLATE & ROOF TILES
+
+A PRACTICAL TREATISE
+Explanatory of the Construction of Block and Monolithic Types of Concrete Chimneys, with easily constructed Molds for same, also the Molding of Concrete Roofs, also the Molding of Concrete Slabs, Roof Tiles and Slabs, are fully treated.
+
+BY
+A. A. HOUGHTON
+Author of "Concrete from Sand-Molds," "Ornamental Concrete Without Molds," etc., etc.
+
+15 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+London
+E. & F. N. SPON, LTD., 57 HAYMARKET
+1911
+
+No. 29.—The S. & C. Series. Price 1/6 net.
+
+MOLDING & CURING
+ORNAMENTAL CONCRETE
+
+A PRACTICAL TREATISE
+Covering the Various Methods of Preparing the Molds and Filling with the Concrete Mixture; Remediying Defects in the Cast; Surface Treatment for various effects; the proper Preparation of the Concrete, and the best Methods of thoroughly Curing the Work.
+
+BY
+A. A. HOUGHTON.
+Author of "Concrete from Sand Molds," "Ornamental Concrete Without Molds," etc., etc.
+
+5 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+<signature>Kenton</signature>
+E. & F. N. SPON, Ltd., 37 HAYMARKET
+1911
+
+No. 30.--The S. & C. Series. Price 1/6 net.
+
+CONCRETE WALL FORMS
+
+A PRACTICAL TREATISE
+
+Explanatory of the Construction of all types of Wall Forms, Clamps, Separators and Spacers for Reinforcement. Full Details and Work-
+ing Drawings of an Automatic Wall Clamp are given, with the operation of the various parts, including the Clamps, Retaining Walls, Placing Floor Joists, Molding Water Tables and Window Lobes; as well as Molding Floor Joists and other special operations for
+Concrete Walls, are also fully treated.
+
+BY
+A. A. HOUGHTON
+
+Author of "Concrete from Sand Molds," "Ornamental Concrete Without Molds," etc., etc.
+
+16 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+London
+E. & F. N. SPON, Ltd., 57 HAYMARKET
+1911
+
+C
+
+No. 31.—The S. & C. Series. Price 1/6 net.
+
+CONCRETE MONUMENTS
+MAUSOLEUMS
+AND BURIAL VAULTS
+
+A PRACTICAL TREATISE
+Explanatory of the Molding of various types of Concrete Monuments,
+with the Construction of Molds for same. Lettering and Orna-
+ments, with their execution, are fully treated. Plans and Designs for
+Mausoleums and Burial Vaults are given,
+with complete Details of Construction.
+
+BY
+A. A. HOUGHTON
+Author of "Concrete from Sand Molds," "Ornamental Concrete
+Without Molds," etc., etc.
+
+18 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+London
+E. & F. N. SPON, Ltd., 57 HAYMARKET
+<page_number>1911</page_number>
+
+No. 32.--The S. & C. Series. Price 1/6 net.
+
+CONCRETE FLOORS & SIDEWALKS
+
+A PRACTICAL TREATISE
+
+Explaining the Molding of Concrete Floor and Sidewalk Units with Plain and Ornamental Surfaces, also the Construction of Plaits and Strips, etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc., etc.
+
+Instructions are given for all classes of this work, such Illustrations of the easily constructed Metals for Diamond, Hexagonal, Octagonal Floor Tile
+
+BY
+A. A. HOUGHTON
+Author of "Concrete from Sand Molds," "Ornamental Concrete Without Molds," etc, etc.
+
+8 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+Boston
+E. & F. N. SPON, LTD.,
+57 HAYMARKET
+1911
+
+No. 33. The S. & C. Series. Price 1/6 net.
+
+MOLDING CONCRETE BATH TUBS, AQUARIUMS AND NATATORIUMS
+
+A PRACTICAL TREATISE
+
+Explaining the Molding in Concrete of Various Styles of Bath Tubs, Laundry Tubs, etc., with Several Connected Modes for the Purpose. The Molding of Aquariums and Natatoriums, as well as the Water-proofing Methods used for same, are fully treated.
+
+BY
+
+A. A. HOUGHTON
+
+16 FULL PAGE ILLUSTRATIONS
+
+New York
+THE NORMAN W. HENLEY PUBLISHING CO.
+London
+E. & F. N. SPON, LTD., 57 HAYMARKET
+1911
+
+No. 39.—The S. & C. Series. Price 1/6 net.
+
+NATURAL STABILITY AND THE PARACHUTE PRINCIPLE IN AEROPLANES
+
+BY W. LEMAITRE
+Hon. Sec., Aeroplane Building and Flying Society
+
+<img>A simple diagram of a parachute with a line extending downwards to a square symbol.</img>
+
+With 34 Illustrations and 48 pages of Text
+
+Preface—The Importance of Stability—Speed as a Means of Stability—The Law of Inertia—The Parachute Principle—Variable Speed and the Parachute Principle—The Design which fulfils the Conditions.
+
+No. 40.—The S. & C. Series.
+Price 1/6 net.
+
+# BUILDERS' QUANTITIES
+
+BY HORACE M. LEWIS
+Associate Institution of Municipal and County Engineers
+Member of Royal Sanitary Institute
+Lecturer on Builders' Quantities, Polytechnic School of Technology
+
+## CONTENTS
+
+General Introduction — How to Measure Areas, with worked Examples — Methods of Measurement:
+Excavator—Sewers and House Drains—Bricklayer—Reinforced Concrete—Mason—Slater—Slate Mason—Tiler—Stone, Tiling and Slatting—Plasterer—Carpenter—Joiner and Ironmonger—Smith and Founder—Hot Water System—Lighting—Bells—Plumber—Painter, Glazier and Paperhanger—Examples of Billing.
+
+With 6 Illustrations and 54 pages of Text
+
+This work is intended to give an elementary knowledge of the subject of Builders' Quantities, and to meet the want for a cheap yet reliable handbook, within the reach of every building student and all engaged in the Building Trade. With this work any one connected with the Trade can measure up efficiently according to the customary methods of measurement, in the " London Standard."
+
+THE S. & C. SERIES
+
+Uniform, in cloth, Price 1s. 6d. net each.
+
+---
+
+1. Modern Primary Batteries. By N. H. SCHNEIDER.
+2. How to Install Electric Bells, Annunciators and Alarms. By N. H. SCHNEIDER.
+3. Electrical Circuits and Diagrams, Part I. By N. H. SCHNEIDER.
+4. Electrical Circuits and Diagrams, Part II. By N. H. SCHNEIDER.
+5. Experimenting with Induction Coils. By N. H. SCHNEIDER (H. S. Norris).
+6. The Study of Electricity for Beginners. By N. H. SCHNEIDER.
+7. Dry Batteries, how to make and Use them. By A DRY BATTERY EXPERT.
+8. Electric Gas Lighting. By N. H. SCHNEIDER.
+9. Model Steam Engine Design. By R. M. de VIGNIERIE.
+10. Inventions, how to Protect, Sell and Buy Them. By F. B. WRIGHT.
+11. Making Wireless Outfits. By N. HARRISON.
+12. Wireless Telephone Construction. By N. HARKEIRON.
+13. Practical Electrics; a Universal Handy Book on Everyday Electrical Matters.
+14. How to Build a 20-foot Bi-plane Glider. By A. F. MORGAN.
+15. The Model Vaudreuil Theatre. By N. H. SCHNEIDER.
+16. The Fireman's Guide; a Handbook on the Care of Boilers by K.P.DALLSTROM.
+17. A.B.C.of the Steam Engine, with a Description of the Automatic Governor. By J.J.LISS.
+18. Simple Soldering, both Hard and Soft. By E.THATCHER.
+
+E.&F.N.SPON., Ltd., LONDON
+
+THE S. & C. SERIES
+
+Uniform, in cloth, Price 1s. 6d. net each.
+
+---
+19. Ignition Accumulators, their Care and Management. By H. H. U. CROSS.
+20. Key to Linear Perspective. By C. W. DYMOND, F.S.A.
+21. Elements of Telephony. By Arthur CROUCH.
+22. Experimental Study of the Gyroscope. By V. E. JOHNSON, M.A.
+23. The Corliss Engine. By J. T. HENTBORN.
+24. Wireless Telegraphy for Intending Operators. By C. K. P. EDEN.
+25. Wiring Houses for the Electric Light. By N. H. SCHNEIDER.
+26. Low Voltage Electric Lighting with the Storage Battery. By N. H. SCHNEIDER.
+27. Practical Silo Construction in Concrete. By A. A. HOUGHTON.
+28. Molding Concrete Chimneys, Slate and Roof Tiles. By A. A. HOUGHTON.
+29. Molding and Curing Ornamental Concrete. By A. A. HOUGHTON.
+30. Concrete Wall Forms. By A. A. HOUGHTON.
+31. Concrete Monuments, Mausoleums and Burial Vaults. By A. A. HOUGHTON.
+32. Concrete Floors and Sidewalks. By A. A. HOUGHTON.
+33. Molding Concrete Bath Tubs, Aquariums and Natatoriums by A.A.HOUGHTON.
+34 to 38 inclusive: Works on Concrete Structures, by A.A.Houghton, and now in the Press.
+39. Natural Stabilty and the Parachute Principle in Aeroplanes. By W.LAMMERT.
+40. Builders' Quantities By H.M.Lewis.
+
+E.& F.N.SPON, Ltd., LONDON
+
+<img>A blank sheet of paper.</img>
+
+UNIVERSITY OF CALIFORNIA LIBRARY,
+BERKELEY
+
+THIS BOOK IS DUE ON THE LAST DATE STAMPTED BELOW
+
+Books not returned on time are subject to a fine of 50c per day after the first day.
+
+$1.00 per volume after the sixth day. Books not in good condition will be charged if applicable.
+
+OCT 1 1928
+
+APR 31 1930
+
+<page_number>50m-7, 27</page_number>
+
+YB 15811
+
+274247
+Lemnitza
+TH574
+S7L4
+
+UNIVERSITY OF CALIFORNIA LIBRARY
+
+<img>A blank page with a light brown background.</img>

Aeroplanes/piper_cub_airframe.md

@@ -0,0 +1,65 @@
+<img>A detailed technical drawing of a Piper Cub aircraft.</img>
+**Piper Cub**
+**Special**
+(Model 1941)
+**Piper Aircraft Corporation**
+**Lake Erie, Pennsylvania & Co.**
+
+**SCALE**
+5 IN. = 1 FT.
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NG0000" on the fuselage.</img>
+
+<img>A stylized illustration of a Piper Cub with "NGOOGO" on the nose section. The nose section has three circular dials, possibly indicating speed, altitude, and other flight parameters. The word "CUB" is written below these dials. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at the bottom left corner of this image. The word "CUB" is also written at the top right corner of this image. The word "CUB" is also written at the bottom right corner of this image. The word "CUB" is also written at the top left corner of this image. The word "CUB" is also written at