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1. The angle of incidence of the main surface or the tail surface may be wrong. The greater the angle of incidence, the greater the drift. The less the angle, the less the drift.
2. If the alignment of the fuselage, fin in front of the rudder, the struts or stream-line wires, or, in the case of the Maurice Farman, the front outriggers, are not absolutely correct—that is to say, if they are turned a little to the left or to the right instead of being in line with the direction of flight—then they will act as a rudder and cause the aeroplane to turn off its course.
3. If any part of the surface is distorted, it will cause the aeroplane to turn off its course. The surface is cambered, i.e., curved, to pass through the air with the least possible drift. If, owing perhaps to the leading edge, spars, or trailing edge becoming bent, the curvature is spoiled, that will result in changing the amount of drift on one side of the aeroplane, which will then have a tendency to turn off its course.
LATERAL INSTABILITY (FLYING ONE WING DOWN).—The only possible reason for such a condition is a difference in the lifts of right and left wings. That may be caused as follows:
1. The angle of incidence may be wrong. If it is too great, it will produce more lift than on the other side of the aeroplane; and if too small, it will produce less lift than on the other side—the result being that, in either case, the aeroplane will try to fly one wing down.
2. Distorted Surfaces.—If some part of the surface is distorted, then its camber is spoiled, and the lift will not be the same on both sides of the aeroplane, and that, of course, will cause it to fly one wing down.
Longitudinal Instability may be due to the following reasons:
1. The stagger may be wrong. The top surface may have drifted back a little owing to some of the wires, probably the incidence wires, having elongated their loops or having pulled the fittings into the wood. If the top surface is not staggered forward to the correct degree, then consequently the whole of its lift is too far back, and it will then have a tendency to lift up the tail of the machine too much. The aeroplane would then be said to be "nose-heavy."
A 1/4-inch area in the stagger will make a very considerable difference to the longitudinal stability.
2. If the angle of incidence of the main surface is not right, it will have a bad effect, especially in the case of an aeroplane with a lifting tail-plane.
If the angle is too great, it will produce an excess of lift, and that may lift up the nose of the aeroplane and result in a tendency to fly "tail-down." If the angle is too small, it will produce a decreased lift, and the aeroplane may have a tendency to fly "nose-down."
3. The fuselage may have become warped upward or downward, thus giving the tail-plane an incorrect angle of incidence. If it has too much angle, it will lift too much, and the aeroplane will be "nose-heavy." If it has too little angle, then it will not lift enough, and the aeroplane will be "tail-heavy."
4. (The least likely reason.) The tail-plane may be mounted upon the fuselage at a wrong angle of incidence, in which case it must be corrected. If nose-heavy, it should be given a smaller angle of incidence. If tail-heavy, it should be given a larger angle; but care should be taken not to give it too great an angle, because the longitudinal stability entirely depends upon the tail-plane being set at a much smaller angle of incidence than is the main surface, and if that difference is decreased too much, the aeroplane will become uncontrollable longitudinally. Sometimes the tail-plane is mounted on the aeroplane at the same angle as the main surface, but it actually engages the air at a lesser angle, owing to the air being deflected downwards by the main surface. There is then, in effect, a longitudinal dihedral as explained and illustrated in Chapter I.
CLIMBS BADLY.—Such a condition is, apart from engine or propeller trouble, probably due to (1) distorted surfaces, or (2) too small an angle of incidence.
FLIGHT SPEED POOR.—Such a condition is, apart from engine or propeller trouble, probably due to (1) distorted surfaces, (2) too great an angle of incidence, or (3) dirt or mud, and consequently excessive skin-friction.
INEFFICIENT CONTROL is probably due to (1) wrong setting of control surfaces, (2) distortion of control surfaces, or (3) control cables being badly tensioned.
WILL NOT "TAXI" STRAIGHT.—If the aeroplane is uncontrollable on the ground, it is probably due to (1) alignment of undercarriage being wrong, or (2) unequal tension of shock absorbers.
CHAPTER IV
THE PROPELLER, OR "AIR-SCREW"
The sole object of the propeller is to translate the power of the engine into thrust.
The propeller screws through the air, and its blades, being set at an angle inclined to the direction of motion, secure a reaction, as in the case of the aeroplane's lifting surface.
This reaction may be conveniently divided into two component parts or values, namely, Thrust and Drift (see illustration overleaf).
The Thrust is opposed to the Drift of the aeroplane, and must be equal and opposite to it at flying speed. If it falls off in power, then the flying speed must decrease to a velocity, at which the aeroplane drift equals the decreased thrust. The Drift of the propeller may be conveniently divided into the following component values:
Active Drift, produced by the useful thrusting part of the propeller.
Passive Drift, produced by all the rest of the propeller, i.e., by its detrimental surface.
Skin-Friction, produced by the friction of the air with roughness of surface.
Eddies attending the movement of the air caused by the action of the propeller.
Cavitation (very marked at excessive speed of revolution). A tendency of the propeller to produce a cavity or semi-vacuum in which it revolves, the thrust decreasing with increase of speed and cavitation.
THRUST-DRIFT RATIO.—The proportion of thrust to drift is of paramount importance, for it expresses the efficiency of the propeller. It is affected by the following factors:
Speed of Revolution.—The greater the speed, the greater the proportion of drift to thrust. This is due to the increase with speed of the passive drift, which carries with it no increase in thrust. For this reason propellers are often geared down to revolve at a lower speed than that of the engine.
Angle of Incidence.—The same reasons as in the case of the aeroplane surface.
Aspect Ratio.—Ditto.
Camber.—Ditto.
In addition to the above factors there are, when it comes to actually designing a propeller, mechanical difficulties to consider. For instance, the blades must be of a certain strength and consequent thickness. That, in itself, limits the aspect ratio, for it will necessitate a chord long enough in proportion to the thickness to make a good camber possible. Again, the diameter of the propeller must be limited, having regard to the fact that greater diameters than those used to-day would not only result in excessive weight of construction, but would also necessitate a very high undercarriage to keep the propeller off the ground, and such undercarriage would not only produce excessive drift, but would also tend to make the aeroplane stand on its nose when alighting. The latter difficulty cannot be overcome by mounting the propeller higher, as the centre of its thrust must be approximately coincident with the centre of aeroplane drift.
MAINTENANCE OF EFFICIENCY.
The following conditions must be observed:
1. PITCH ANGLE.—The angle, at any given point on the propeller, at which the blade is set is known as the pitch angle, and it must be correct to half a degree if reasonable efficiency is to be maintained.
This angle secures the "pitch," which is the distance the propeller advances during one revolution, supposing the air to be solid. The air, as a matter of fact, gives back to the thrust of the blades just as the pebbles slip back as one ascends a shingle beach. Such "give-back" is known as Slip. If a propeller has a pitch of, say, 10 feet, but actually advances, say, only 8 feet owing to slip, then it will be said to possess 20 per cent. slip.
Thus, the pitch must equal the flying speed of the aeroplane plus the slip of the propeller. For example, let us find the pitch of a propeller, given the following conditions:
Flying speed ... 70 miles per hour. Propeller revolutions ... 1,200 per minute. Slip ... 15 per cent.
First find the distance in feet the aeroplane will travel forward in one minute. That is—
369,600 feet (70 miles) ———————————- = 6,160 feet per minute. 60 " (minutes)
Now divide the feet per minute by the propeller revolutions per minute, add 15 per cent. for the slip, and the result will be the propeller pitch:
6,160 ——- + 15 per cent. = 5.903 feet. 1,200
In order to secure a constant pitch from root to tip of blade, the pitch angle decreases towards the tip. This is necessary, since the end of the blade travels faster than its root, and yet must advance forward at the same speed as the rest of the propeller. For example, two men ascending a hill. One prefers to walk fast and the other slowly, but they wish to arrive at the top of the hill simultaneously. Then the fast walker must travel a farther distance than the slow one, and his angle of path (pitch angle) must then be smaller than the angle of path taken by the slow walker. Their pitch angles are different, but their pitch (in this case altitude reached in a given time) is the same.
In order to test the pitch angle, the propeller must be mounted upon a shaft at right angles to a beam the face of which must be perfectly level, thus:
First select a point on the blade at some distance (say about 2 feet) from the centre of the propeller. At that point find, by means of a protractor, the angle a projection of the chord makes with the face of the beam. That angle is the pitch angle of the blade at that point.
Now lay out the angle on paper, thus:
The line above and parallel to the circumference line must be placed in a position making the distance between the two lines equal to the specified pitch, which is, or should be, marked upon the boss of the propeller.
Now find the circumference of the propeller where the pitch angle is being tested. For example, if that place is 2 feet radius from the centre, then the circumference will be 2 feet x 2 = 4 feet diameter, which, if multiplied by 3.1416 = 15.56 feet circumference.
Now mark off the circumference distance, which is represented above by A—B, and reduce it in scale for convenience.
The distance a vertical line makes between B and the chord line is the pitch at the point where the angle is being tested, and it should coincide with the specified pitch.
You will note, from the above illustration, that the actual pitch line should meet the junction of the chord line and top line.
The propeller should be tested at several points, about a foot apart, on each blade; and the diagram, provided the propeller is not faulty, will then look like this:
At each point tested the actual pitch coincides with the specified pitch: a satisfactory condition.
A faulty propeller will produce a diagram something like this:
At every point tested the pitch angle is wrong, for nowhere does the actual pitch coincide with the specified pitch. Angles A, C, and D, are too large, and B is too small. The angle should be correct to half a degree if reasonable efficiency is to be maintained.
A fault in the pitch angle may be due to (1) faulty manufacture, (2) distortion, or (3) the shaft hole through the boss being out of position.
2. STRAIGHTNESS.—To test for straightness the propeller must be mounted upon a shaft. Now bring the tip of one blade round to graze some fixed object. Mark the point it grazes. Now bring the other tip round, and it should come within 1/8 inch of the mark. If it does not do so, it is due to (1) faulty manufacture, (2) distortion, or (3) to the hole through the boss being out of position.
3. LENGTH.—The blades should be of equal length to 1/16 inch.
4. BALANCE.—The usual method of testing a propeller for balance is as follows: Mount it upon a shaft, which must be on ball-bearings. Place the propeller in a horizontal position, and it should remain in that position. If a weight of a trifle over an ounce placed in a bolt-hole on one side of the boss fails to disturb the balance, then the propeller is usually regarded as unfit for use.
The above method is rather futile, as it does not test for the balance of centrifugal force, which comes into play as soon as the propeller revolves. It can be tested as follows:
The propeller must be in a horizontal position, and then weighed at fixed points, such as A, B, C, D, E, and F, and the weights noted. The points A, B, and C must, of course, be at the same fixed distances from the centre of the propeller as the points D, E, and F. Now reverse the propeller and weigh at each point again. Note the results. The first series of weights should correspond to the second series, thus:
Weight A should equal weight F.
Weight B should equal weight E.
Weight C should equal weight D.
There is no standard practice as to the degree of error permissible, but if there are any appreciable differences the propeller is unfit for use.
5. SURFACE AREA.—The surface area of the blades should be equal. Test with calipers thus:
The distance A—B should equal K—L.
The distance C—D should equal I—J.
The distance E—F should equal G—H.
The points between which the distances are taken must, of course, be at the same distance from the centre in the case of each blade.
There is no standard practice as to the degree of error permissible. If, however, there is an error of over 1/8 inch, the propeller is really unfit for use.
6. CAMBER.—The camber (curvature) of the blades should be (1) equal, (2) decrease evenly towards the tips of the blades, and (3) the greatest depth of the curve should, at any point of the blade, be approximately at the same percentage of the chord from the leading edge as at other points.
It is difficult to test the top camber without a set of templates,[18] but a fairly accurate idea of the concave camber can be secured by slowly passing a straight-edge along the blade, thus:
The camber can now be easily seen, and as the straight-edge is passed along the blade, the observer should look for any irregularities of the curvature, which should gradually and evenly decrease towards the tip of the blade.
7. THE JOINTS.—The usual method for testing the glued joints is by revolving the propeller at greater speed than it will be called upon to make during flight, and then carefully examining the joints to see if they have opened. It is not likely, however, that the reader will have the opportunity of making this test. He should, however, examine all the joints very carefully, trying by hand to see if they are quite sound. Suspect a propeller of which the joints appear to hold any thickness of glue. Sometimes the joints in the boss open a little, but this is not dangerous unless they extend to the blades, as the bolts will hold the laminations together.
8. CONDITION OF SURFACE.—The surface should be very smooth, especially towards the tips of the blades. Some propeller tips have a speed of over 30,000 feet a minute, and any roughness will produce a bad drift or resistance and lower the efficiency.
9. MOUNTING.—Great care should be taken to see that the propeller is mounted quite straight on its shaft. Test in the same way as for straightness. If it is not straight, it is possibly due to some of the propeller bolts being too slack or to others having been pulled up too tightly.
FLUTTER.—Propeller "flutter," or vibration, may be due to faulty pitch angle, balance, camber, surface area, or to bad mounting. It causes a condition sometimes mistaken for engine trouble, and one which may easily lead to the collapse of the propeller.
CARE OF PROPELLERS.—The care of propellers is of the greatest importance, as they become distorted very easily.
1. Do not store them in a very damp or a very dry place.
2. Do not store them where the sun will shine upon them.
3. Never leave them long in a horizontal position or leaning up against a wall.
4. They should be hung on horizontal pegs, and the position of the propellers should be vertical.
If the points I have impressed upon you in these notes are not attended to, you may be sure of the following results:
1. Lack of efficiency, resulting in less aeroplane speed and climb than would otherwise be the case.
2. Propeller "flutter" and possible collapse.
3. A bad stress upon the propeller shaft and its bearings.
TRACTOR.—A propeller mounted in front of the main surface.
PUSHER.—A propeller mounted behind the main surface.
FOUR-BLADED PROPELLERS.—Four-bladed propellers are suitable only when the pitch is comparatively large. For a given pitch, and having regard to "interference," they are not so efficient as two-bladed propellers.
The smaller the pitch, the less the "gap," i.e., the distance, measured in the direction of the thrust, between the spiral courses of the blades (see illustration on preceding page).
If the gap is too small, then the following blade will engage air which the preceding blade has put into motion, with the result that the following blade will not secure as good a reaction as would otherwise be the case. It is very much the same as in the case of the aeroplane gap.
For a given pitch, the gap of a four-bladed propeller is only half that of a two-bladed one. Therefore the four-bladed propeller is only suitable for large pitch, as such pitch produces spirals with a large gap, thus offsetting the decrease in gap caused by the numerous blades.
The greater the speed of rotation, the less the pitch for a given aeroplane speed. Then, in order to secure a large pitch and consequently a good gap, the four-bladed propeller is usually geared to rotate at a lower speed than would be the case if directly attached to the engine crank-shaft.
[Footnote 18: I have heard of temporary ones being made quickly by bending strips of lead over the convex side of the blade, but I should think it very difficult to secure a sufficient degree of accuracy in that way.]
CHAPTER V
MAINTENANCE
CLEANLINESS.—The fabric must be kept clean and free from oil, as that will rot it. To take out dirt or oily patches, try acetone. If that will not remedy matters, then try petrol, but use it sparingly, as otherwise it will take off an unnecessary amount of dope. If that will not remove the dirt, then hot water and soap will do so, but, in that case, be sure to use soap having no alkali in it, as otherwise it may injure the fabric. Use the water sparingly, or it may get inside the planes and rust the internal bracing wires, or cause some of the wooden framework to swell.
The wheels of the undercarriage have a way of throwing up mud on to the lower surface. This should, if possible, be taken off while wet. It should never be scraped off when dry, as that may injure the fabric. If dry, then it should be moistened before being removed.
Measures should be taken to prevent dirt from collecting upon any part of the aeroplane, as, otherwise, excessive skin-friction will be produced with resultant loss of flight speed. The wires, being greasy, collect dirt very easily.
CONTROL CABLES.—After every flight the rigger should pass his hand over the control cables and carefully examine them near pulleys. Removal of grease may be necessary to make a close inspection possible. If only one strand is broken the wire should be replaced. Do not forget the aileron balance wire on the top surface.
Once a day try the tension of the control cables by smartly moving the control levers about as explained elsewhere.
WIRES.—All the wires should be kept well greased or oiled, and in the correct tension. When examining the wires, it is necessary to place the aeroplane on level ground, as otherwise it may be twisted, thus throwing some wires into undue tension and slackening others. The best way, if there is time, is to pack the machine up into its "flying position."
If you see a slack wire, do not jump to the conclusion that it must be tensioned. Perhaps its opposition wire is too tight, in which case slacken it, and possibly you will find that will tighten the slack wire.
Carefully examine all wires and their connections near the propeller, and be sure that they are snaked round with safety wire, so that the latter may keep them out of the way of the propeller if they come adrift.
The wires inside the fuselage should be cleaned and regreased about once a fortnight.
STRUTS AND SOCKETS.—These should be carefully examined to see if any splitting has occurred.
DISTORTION.—Carefully examine all surfaces, including the controlling surfaces, to see whether any distortion has occurred. If distortion can be corrected by the adjustment of wires, well and good; but if not, then some of the internal framework probably requires replacement.
ADJUSTMENTS.—Verify the angles of incidence, dihedral, and stagger, and the rigging position of the controlling surfaces, as often as possible.
UNDERCARRIAGE.—Constantly examine the alignment and fittings of the undercarriage, and the condition of tyres and shock absorbers. The latter, when made of rubber, wear quickest underneath. Inspect axles and skids to see if there are any signs of them becoming bent. The wheels should be taken off occasionally and greased.
LOCKING ARRANGEMENTS.—Constantly inspect the locking arrangements of turnbuckles, bolts, etc. Pay particular attention to the control cable connections, and to all moving parts in respect of the controls.
LUBRICATION.—Keep all moving parts, such as pulleys, control levers, and hinges of controlling surfaces, well greased.
SPECIAL INSPECTION.—Apart from constantly examining the aeroplane with reference to the above points I have made, I think that, in the case of an aeroplane in constant use, it is an excellent thing to make a special inspection of every part, say, once a week. This will take from two to three hours according to the type of aeroplane. In order to carry it out methodically, the rigger should have a list of every part down to the smallest split-pin. He can then check the parts as he examines them, and nothing will be passed over. This, I know from experience, greatly increases the confidence of the pilot, and tends to produce good work in the air.
WINDY WEATHER.—The aeroplane, when on the ground, should face the wind; and it is advisable to lash the control lever fast, so that the controlling surfaces may not be blown about and possibly damaged.
"VETTING" BY EYE.—This should be practised at every opportunity, and, if persevered in, it is possible to become quite expert in diagnosing by eye faults in flight efficiency, stability, and control.
The aeroplane should be standing upon level ground, or, better than that, packed up into its "flying position."
Now stand in front of it and line up the leading edge with the main spar, rear spar, and trailing edge. Their shadows can usually be seen through the fabric. Allowance must, of course, be made for wash-in and wash-out; otherwise, the parts I have specified should be parallel with each other.
Now line up the centre part of the main-plane with the tail-plane. The latter should be symmetrical with it. Next, sight each interplane front strut with its rear strut. They should be parallel.
Then, standing on one side of the aeroplane, sight all the front struts. The one nearest to you should cover all the others. This applies to the rear struts also.
Look for distortion of leading edges, main and rear spars, trailing edges, tail-plane, and controlling surfaces.
This sort of thing, if practised constantly, will not only develop an expert eye for diagnosis of faults, but will also greatly assist in impressing upon the memory the characteristics and possible troubles of the various types of aeroplanes.
MISHANDLING ON THE GROUND.—This is the cause of a lot of unnecessary damage. The golden rule to observe is, PRODUCE NO BENDING STRESSES.
Nearly all the wood in an aeroplane is designed to take merely the stress of direct compression, and it cannot be bent safely. Therefore, in packing an aeroplane up from the ground, or in pulling or pushing it about, be careful to stress it in such a way as to produce, as far as possible, only direct compression stresses. For instance, if it is necessary to support the lifting surface, then the packing should be arranged to come directly under the struts so that they may take the stress in the form of compression for which they are designed. Such supports should be covered with soft packing in order to prevent the fabric from becoming damaged.
When pulling an aeroplane along, if possible, pull from the top of the undercarriage struts. If necessary to pull from elsewhere, then do so by grasping the interplane struts as low down as possible. Never pull by means of wires.
Never lay fabric-covered parts upon a concrete floor. Any slight movement will cause the fabric to scrape over the floor with resultant damage.
Struts, spars, etc., should never be left about the floor, as in such position they are likely to become scored. I have already explained the importance of protecting the outside fibres of the wood. Remember also that wood becomes distorted easily. This particularly applies to interplane struts. If there are no proper racks to stand them in, then the best plan is to lean them up against the wall in as near a vertical position as possible.
TIME.—Learn to know the time necessary to complete any of the various rigging jobs. This is really important. Ignorance of this will lead to bitter disappointments in civil life; and, where Service flying is concerned, it will, to say the least of it, earn unpopularity with senior officers, and fail to develop respect and good work where men are concerned.
THE AEROPLANE SHED.—This should be kept as clean and orderly as possible. A clean, smart shed produces briskness, energy, and pride of work. A dirty, disorderly shed nearly always produces slackness and poor quality of work, lost tools, and mislaid material.
GLOSSARY
The numbers at the right-hand side of the page indicate the parts numbered in the preceding diagrams.
Aeronautics—The science of aerial navigation.
Aerofoil—A rigid structure, of large superficial area relative to its thickness, designed to obtain, when driven through the air at an angle inclined to the direction of motion, a reaction from the air approximately at right angles to its surface. Always cambered when intended to secure a reaction in one direction only. As the term "aerofoil" is hardly ever used in practical aeronautics, I have, throughout this book, used the term SURFACE, which, while academically incorrect, since it does not indicate thickness, is the term usually used to describe the cambered lifting surfaces, i.e., the "planes" or "wings," and the stabilizers and the controlling aerofoils.
Aerodrome—The name usually applied to a ground used for the practice of aviation. It really means "flying machine," but is never used in that sense nowadays.
Aeroplane—A power-driven aerofoil fitted with stabilizing and controlling surfaces.
Acceleration—The rate of change of velocity.
Angle of Incidence—The angle at which the "neutral lift line" of a surface attacks the air.
Angle of Incidence, Rigger's—The angle the chord of a surface makes with a line parallel to the axis of the propeller.
Angle of Incidence, Maximum—The greatest angle of incidence at which, for a given power, surface (including detrimental surface), and weight, horizontal flight can be maintained.
Angle of Incidence, Minimum—The smallest angle of incidence at which, for a given power, surface (including detrimental surface), and weight, horizontal flight can be maintained.
Angle of Incidence, Best Climbing—That angle of incidence at which an aeroplane ascends quickest. An angle approximately halfway between the maximum and optimum angles.
Angle of Incidence, Optimum—The angle of incidence at which the lift-drift ratio is the highest.
Angle, Gliding—The angle between the horizontal and the path along which an aeroplane, at normal flying speed, but not under engine power, descends in still air.
Angle, Dihedral—The angle between two planes.
Angle, Lateral Dihedral—The lifting surface of an aeroplane is said to be at a lateral dihedral angle when it is inclined upward towards its wing-tips.
Angle, Longitudinal Dihedral—The main surface and tail surface are said to be at a longitudinal dihedral angle when the projections of their neutral lift lines meet and produce an angle above them.
Angle, Rigger's Longitudinal Dihedral—Ditto, but substituting "chords" for "neutral lift lines."
Angle, Pitch—The angle at any given point of a propeller, at which the blade is inclined to the direction of motion when the propeller is revolving but the aeroplane stationary.
Altimeter—An instrument used for measuring height.
Air-Speed Indicator—An instrument used for measuring air pressures or velocities. It consequently indicates whether the surface is securing the requisite reaction for flight. Usually calibrated in miles per hour, in which case it indicates the correct number of miles per hour at only one altitude. This is owing to the density of the air decreasing with increase of altitude and necessitating a greater speed through space to secure the same air pressure as would be secured by less speed at a lower altitude. It would be more correct to calibrate it in units of air pressure. [1]
Air Pocket—A local movement or condition of the air causing an aeroplane to drop or lose its correct attitude.
Aspect-Ratio—The proportion of span to chord of a surface.
Air-Screw (Propeller)—A surface so shaped that its rotation about an axis produces a force (thrust) in the direction of its axis. [2]
Aileron—A controlling surface, usually situated at the wing-tip, the operation of which turns an aeroplane about its longitudinal axis; causes an aeroplane to tilt sideways. [3]
Aviation—The art of driving an aeroplane.
Aviator—The driver of an aeroplane.
Barograph—A recording barometer, the charts of which can be calibrated for showing air density or height.
Barometer—An instrument used for indicating the density of air.
Bank, to—To turn an aeroplane about its longitudinal axis (to tilt sideways) when turning to left or right.
Biplane—An aeroplane of which the main lifting surface consists of a surface or pair of wings mounted above another surface or pair of wings.
Bay—The space enclosed by two struts and whatever they are fixed to.
Boom—A term usually applied to the long spars joining the tail of a "pusher" aeroplane to its main lifting surface. [4]
Bracing—A system of struts and tie wires to transfer a force from one point to another.
Canard—Literally "duck." The name which was given to a type of aeroplane of which the longitudinal stabilizing surface (empennage) was mounted in front of the main lifting surface. Sometimes termed "tail-first" aeroplanes, but such term is erroneous, as in such a design the main lifting surface acts as, and is, the empennage.
Cabre—To fly or glide at an excessive angle of incidence; tail down.
Camber—Curvature.
Chord—Usually taken to be a straight line between the trailing and leading edges of a surface.
Cell—The whole of the lower surface, that part of the upper surface directly over it, together with the struts and wires holding them together.
Centre (Line) of Pressure—A line running from wing-tip to wing-tip, and through which all the air forces acting upon the surface may be said to act, or about which they may be said to balance.
Centre (Line) of Pressure, Resultant—A line transverse to the longitudinal axis, and the position of which is the resultant of the centres of pressure of two or more surfaces.
Centre of Gravity—The centre of weight.
Cabane—A combination of two pylons, situated over the fuselage, and from which the anti-lift wires are suspended. [5]
Cloche—Literally "bell." Is applied to the bell-shaped construction which forms the lower part of the pilot's control lever in a Bleriot monoplane, and to which the control cables are attached.
Centrifugal Force—Every body which moves in a curved path is urged outwards from the centre of the curve by a force termed "centrifugal."
Control Lever—A lever by means of which the controlling surfaces are operated. It usually operates the ailerons and elevator. The "joy-stick." [6]
Cavitation, Propeller—The tendency to produce a cavity in the air.
Distance Piece—A long, thin piece of wood (sometimes tape) passing through and attached to all the ribs in order to prevent them from rolling over sideways. [7]
Displacement—Change of position.
Drift (of an aeroplane as distinct from the propeller)—The horizontal component of the reaction produced by the action of driving through the air a surface inclined upwards and towards its direction of motion plus the horizontal component of the reaction produced by the "detrimental" surface plus resistance due to "skin-friction." Sometimes termed "head-resistance."
Drift, Active—Drift produced by the lifting surface.
Drift, Passive—Drift produced by the detrimental surface.
Drift (of a propeller)—Analogous to the drift of an aeroplane. It is convenient to include "eddies" and "cavitation" within this term.
Drift, to—To be carried by a current of air; to make leeway.
Dive, to—To descend so steeply as to produce a speed greater than the normal flying speed.
Dope, to—To paint a fabric with a special fluid for the purpose of tightening and protecting it.
Density—Mass of unit volume; for instance, pounds per cubic foot.
Efficiency—
Output ——— Input.
Efficiency (of an aeroplane as distinct from engine and propeller)—
Lift and Velocity —————————————- Thrust (= aeroplane drift).
Efficiency, Engine—
Brake horse-power ——————————— Indicated horse-power.
Efficiency, Propeller—
Thrust horse-power ———————————————— Horse-power received from engine (= propeller drift).
NOTE.—The above terms can, of course, be expressed in foot-pounds. It is then only necessary to divide the upper term by the lower one to find the measure of efficiency.
Elevator—A controlling surface, usually hinged to the rear of the tail-plane, the operation of which turns an aeroplane about an axis which is transverse to the direction of normal horizontal flight. [8]
Empennage—See "Tail-plane."
Energy—Stored work. For instance, a given weight of coal or petroleum stores a given quantity of energy which may be expressed in foot-pounds.
Extension—That part of the upper surface extending beyond the span of the lower surface. [9]
Edge, Leading—The front edge of a surface relative to its normal direction of motion. [10]
Edge, Trailing—The rear edge of a surface relative to its normal direction of motion. [11]
Factor of Safety—Usually taken to mean the result found by dividing the stress at which a body will collapse by the maximum stress it will be called upon to bear.
Fineness (of stream-line)—The proportion of length to maximum width.
Flying Position—A special position in which an aeroplane must be placed when rigging it or making adjustments. It varies with different types of aeroplanes. Would be more correctly described as "rigging position."
Fuselage—That part of an aeroplane containing the pilot, and to which is fixed the tail-plane. [12]
Fin—Additional keel-surface, usually mounted at the rear of an aeroplane. [13]
Flange (of a rib)—That horizontal part of a rib which prevents it from bending sideways. [14]
Flight—The sustenance of a body heavier than air by means of its action upon the air.
Foot-pound—A measure of work representing the weight of 1 lb. raised 1 foot.
Fairing—Usually made of thin sheet aluminium, wood, or a light construction of wood and fabric; and bent round detrimental surface in order to give it a "fair" or "stream-like" shape. [15]
Gravity—Is the force of the Earth's attraction upon a body. It decreases with increase of distance from the Earth. See "Weight."
Gravity, Specific—
Density of substance —————————— Density of water.
Thus, if the density of water is 10 lb. per unit volume, the same unit volume of petrol, if weighing 7 lb., would be said to have a specific gravity of 7/10, i.e., 0.7.
Gap (of an aeroplane)—The distance between the upper and lower surfaces of a biplane. In a triplane or multiplane, the distance between any two of its surfaces. [16]
Gap, Propeller—The distance, measured in the direction of the thrust, between the spiral courses of the blades.
Girder—A structure designed to resist bending, and to combine lightness and strength.
Gyroscope—A heavy circular wheel revolving at high speed, the effect of which is a tendency to maintain its plane of rotation against disturbing forces.
Hangar—An aeroplane shed.
Head-resistance—Drift. The resistance of the air to the passage of a body.
Helicopter—An air-screw revolving about a vertical axis, the direction of its thrust being opposed to gravity.
Horizontal Equivalent—The plan view of a body whatever its attitude may be.
Impulse—A force causing a body to gain or lose momentum.
Inclinometer—A curved form of spirit-level used for indicating the attitude of a body relative to the horizontal.
Instability—An inherent tendency of a body, which, if the body is disturbed, causes it to move into a position as far as possible away from its first position.
Instability, Neutral—An inherent tendency of a body to remain in the position given it by the force of a disturbance, with no tendency to move farther or to return to its first position.
Inertia—The inherent resistance to displacement of a body as distinct from resistance the result of an external force.
Joy-Stick—See "Control Lever."
Keel-Surface—Everything to be seen when viewing an aeroplane from the side of it.
King-Post—A bracing strut; in an aeroplane, usually passing through a surface and attached to the main spar, and from the end or ends of which wires are taken to spar, surface, or other part of the construction in order to prevent distortion. When used in connection with a controlling surface, it usually performs the additional function of a lever, control cables connecting its ends with the pilot's control lever. [17]
Lift—The vertical component of the reaction produced by the action of driving through the air a surface inclined upwards and towards its direction of motion.
Lift, Margin of—The height an aeroplane can gain in a given time and starting from a given altitude.
Lift-Drift Ratio—The proportion of lift to drift.
Loading—The weight carried by an aerofoil. Usually expressed in pounds per square foot of superficial area.
Longeron—The term usually applied to any long spar running length-ways of a fuselage. [18]
Mass—The mass of a body is a measure of the quantity of material in it.
Momentum—The product of the mass and velocity of a body is known as "momentum."
Monoplane—An aeroplane of which the main lifting surface consists of one surface or one pair of wings.
Multiplane—An aeroplane of which the main lifting surface consists of numerous surfaces or pairs of wings mounted one above the other.
Montant—Fuselage strut.
Nacelle—That part of an aeroplane containing the engine and/or pilot and passenger, and to which the tail-plane is not fixed. [19]
Neutral Lift Line—A line taken through a surface in a forward direction relative to its direction of motion, and starting from its trailing edge. If the attitude of the surface is such as to make the said line coincident with the direction of motion, it results in no lift, the reaction then consisting solely of drift. The position of the neutral lift line, i.e., the angle it makes with the chord, varies with differences of camber, and it is found by means of wind-tunnel research.
Newton's Laws of Motion—1. If a body be at rest, it will remain at rest; or, if in motion, it will move uniformly in a straight line until acted upon by some force.
2. The rate of change of the quantity of motion (momentum) is proportional to the force which causes it, and takes place in the direction of the straight line in which the force acts. If a body be acted upon by several forces, it will obey each as though the others did not exist, and this whether the body be at rest or in motion.
3. To every action there is opposed an equal and opposite reaction.
Ornithopter (or Orthopter)—A flapping wing design of aircraft intended to imitate the flight of a bird.
Outrigger—This term is usually applied to the framework connecting the main surface with an elevator placed in advance of it. Sometimes applied to the "tail-boom" framework connecting the tail-plane with the main lifting surface. [20]
Pancake, to—To "stall."
Plane—This term is often applied to a lifting surface. Such application is not quite correct, since "plane" indicates a flat surface, and the lifting surfaces are always cambered.
Propeller—See "Air-Screw."
Propeller, Tractor—An air-screw mounted in front of the main lifting surface.
Propeller, Pusher—An air-screw mounted behind the main lifting surface.
Pusher—An aeroplane of which the propeller is mounted behind the main lifting surface.
Pylon—Any V-shaped construction from the point of which wires are taken.
Power—Rate of working. [21]
Power, Horse—One horse-power represents a force sufficient to raise 33,000 lb. 1 foot in a minute.
Power, Indicated Horse—The I.H.P. of an engine is a measure of the rate at which work is done by the pressure upon the piston or pistons, as distinct from the rate at which the engine does work. The latter is usually termed "brake horse-power," since it may be measured by an absorption brake.
Power, Margin of—The available quantity of power above that necessary to maintain horizontal flight at the optimum angle.
Pitot Tube—A form of air-speed indicator consisting of a tube with open end facing the wind, which, combined with a static pressure or suction tube, is used in conjunction with a gauge for measuring air pressures or velocities. (No. 1 in diagram.)
Pitch, Propeller—The distance a propeller advances during one revolution supposing the air to be solid.
Pitch, to—To plunge nose-down.
Reaction—A force, equal and opposite to the force of the action producing it.
Rudder—A controlling surface, usually hinged to the tail, the operation of which turns an aeroplane about an axis which is vertical in normal horizontal flight; causes an aeroplane to turn to left or right of the pilot. [22]
Roll, to—To turn about the longitudinal axis.
Rib, Ordinary—A light curved wooden part mounted in a fore and aft direction within a surface. The ordinary ribs give the surface its camber, carry the fabric, and transfer the lift from the fabric to the spars. [23]
Rib, Compression—Acts as an ordinary rib, besides bearing the stress of compression produced by the tension of the internal bracing wires. [24]
Rib, False—A subsidiary rib, usually used to improve the camber of the front part of the surface. [25]
Right and Left Hand—Always used relative to the position of the pilot. When observing an aeroplane from the front of it, the right hand side of it is then on the left hand of the observer.
Remou—A local movement or condition of the air which may cause displacement of an aeroplane.
Rudder-Bar—A control lever moved by the pilot's feet, and operating the rudder. [26]
Surface—See "Aerofoil."
Surface, Detrimental—All exterior parts of an aeroplane including the propeller, but excluding the (aeroplane) lifting and (propeller) thrusting surfaces.
Surface, Controlling—A surface the operation of which turns an aeroplane about one of its axes.
Skin-Friction—The friction of the air with roughness of surface. A form of drift.
Span—The distance from wing-tip to wing-tip.
Stagger—The distance the upper surface is forward of the lower surface when the axis of the propeller is horizontal.
Stability—The inherent tendency of a body, when disturbed, to return to its normal position.
Stability, Directional—The stability about an axis which is vertical during normal horizontal flight, and without which an aeroplane has no natural tendency to remain upon its course.
Stability, Longitudinal—The stability of an aeroplane about an axis transverse to the direction of normal horizontal flight, and without which it has no tendency to oppose pitching and tossing.
Stability, Lateral—The stability of an aeroplane about its longitudinal axis, and without which it has no tendency to oppose sideways rolling.
Stabilizer—A surface, such as fin or tail-plane, designed to give an aeroplane inherent stability.
Stall, to—To give or allow an aeroplane an angle of incidence greater than the "maximum" angle, the result being a fall in the lift-drift ratio, the lift consequently becoming less than the weight of the aeroplane, which must then fall, i.e., "stall" or "pancake."
Stress—Burden or load.
Strain—Deformation produced by stress.
Side-Slip, to—To fall as a result of an excessive "bank" or "roll."
Skid, to—To be carried sideways by centrifugal force when turning to left or right.
Skid, Undercarriage—A spar, mounted in a fore and aft direction, and to which the wheels of the undercarriage are sometimes attached. Should a wheel give way the skid is then supposed to act like the runner of a sleigh and to support the aeroplane. [28]
Skid, Tail—A piece of wood or other material, orientable, and fitted with shock absorbers, situated under the tail of an aeroplane in order to support it upon the ground and to absorb the shock of alighting. [28a]
Section—Any separate part of the top surface, that part of the bottom surface immediately underneath it, with their struts and wires.
Spar—Any long piece of wood or other material.
Spar, Main—A spar within a surface and to which all the ribs are attached, such spar being the one situated nearest to the centre of pressure. It transfers more than half the lift from the ribs to the bracing. [29]
Spar, Rear—A spar within a surface, and to which all the ribs are attached, such spar being situated at the rear of the centre of pressure and at a greater distance from it than is the main spar. It transfers less than half of the lift from the ribs to the bracing. [30]
Strut—Any wooden member intended to take merely the stress of direct compression.
Strut, Interplane—A strut holding the top and bottom surfaces apart. [31]
Strut, Fuselage—A strut holding the fuselage longerons apart. It should be stated whether top, bottom, or side. If side, then it should be stated whether right or left hand. Montant. [32]
Strut, Extension—A strut supporting an "extension" when not in flight. It may also prevent the extension from collapsing upwards during flight. [33]
Strut, undercarriage— [33a]
Strut, Dope—A strut within a surface, so placed as to prevent the tension of the doped fabric from distorting the framework. [34]
Serving—To bind round with wire, cord, or similar material. Usually used in connection with wood joints and wire cable splices.
Slip, Propeller—The pitch less the distance the propeller advances during one revolution.
Stream-Line—A form or shape of detrimental surface designed to produce minimum drift.
Toss, to—To plunge tail-down.
Torque, Propeller—The tendency of a propeller to turn an aeroplane about its longitudinal axis in a direction opposite to that in which the propeller revolves.
Tail-Slide—A fall whereby the tail of an aeroplane leads.
Tractor—An aeroplane of which the propeller is mounted in front of the main lifting surface.
Triplane—An aeroplane of which the main lifting surface consists of three surfaces or pairs of wings mounted one above the other.
Tail-Plane—A horizontal stabilizing surface mounted at some distance behind the main lifting surface. Empennage. [36]
Turnbuckle—A form of wire-tightener, consisting of a barrel into each end of which is screwed an eyebolt. Wires are attached to the eyebolts and the required degree of tension is secured by means of rotating the barrel.
Thrust, Propeller—See "Air-Screw."
Undercarriage—That part of an aeroplane beneath the fuselage or nacelle, and intended to support the aeroplane when at rest, and to absorb the shock of alighting.
Velocity—Rate of displacement; speed.
Volplane—A gliding descent.
Weight—Is a measure of the force of the Earth's attraction (gravity) upon a body. The standard unit of weight in this country is 1 lb., and is the force of the Earth's attraction on a piece of platinum called the standard pound, deposited with the Board of Trade in London. At the centre of the Earth a body will be attracted with equal force in every direction. It will therefore have no weight, though its mass is unchanged. Gravity, of which weight is a measure, decreases with increase of altitude.
Web (of a rib)—That vertical part of a rib which prevents it from bending upwards. [37a]
Warp, to—To distort a surface in order to vary its angle of incidence. To vary the angle of incidence of a controlling surface.
Wash—The disturbance of air produced by the flight of an aeroplane.
Wash-in—An increasing angle of incidence of a surface towards its wing-tip. [38]
Wash-out—A decreasing angle of incidence of a surface towards its wing-tip. [39]
Wing-tip—The right or left-hand extremity of a surface. [40]
Wire—A wire is, in Aeronautics, always known by the name of its function.
Wire, Lift or Flying—A wire opposed to the direction of lift, and used to prevent a surface from collapsing upward during flight. [41]
Wire, Anti-lift or Landing—A wire opposed to the direction of gravity, and used to sustain a surface when it is at rest. [42]
Wire, Drift—A wire opposed to the direction of drift, and used to prevent a surface from collapsing backwards during flight.
Wire, Anti-drift—A wire opposed to the tension of a drift wire, and used to prevent such tension from distorting the framework. [44]
Wire, Incidence—A wire running from the top of an interplane strut to the bottom of the interplane strut in front of or behind it. It maintains the "stagger" and assists in maintaining the angle of incidence. Sometimes termed "stagger wire." [45]
Wire, Bracing—Any wire holding together the framework of any part of an aeroplane. It is not, however, usually applied to the wires described above unless the function performed includes a function additional to those described above. Thus, a lift wire, while strictly speaking a bracing wire, is not usually described as one unless it performs the additional function of bracing some well-defined part such as the undercarriage. It will then be said to be an "undercarriage bracing lift wire." It might, perhaps, be acting as a drift wire also, in which case it will then be described as an "undercarriage bracing lift-drift wire." It should always be stated whether a bracing wire is (1) top, (2) bottom, (3) cross, or (4) side. If a "side bracing wire," then it should be stated whether right- or left-hand.
Wire, Internal Bracing—A bracing wire (usually drift or anti-drift) within a surface.
Wire, Top Bracing—A bracing wire, approximately horizontal and situated between the top longerons of fuselage, between top tail booms, or at the top of similar construction. [46]
Wire, Bottom Bracing—Ditto, substituting "bottom" for "top." [47]
Wire, Side Bracing—A bracing wire crossing diagonally a side bay of fuselage, tail boom bay, undercarriage side bay or centre-section side bay. This term is not usually used with reference to incidence wires, although they cross diagonally the side bays of the cell. It should be stated whether right- or left-hand. [48]
Wire, Cross Bracing—A bracing wire, the position of which is diagonal from right to left when viewing it from the front of an aeroplane. [49]
Wire, Control Bracing—A wire preventing distortion of a controlling surface. [50]
Wire, Control—A wire connecting a controlling surface with the pilot's control lever, wheel, or rudder-bar. [51]
Wire, Aileron Gap—A wire connecting top and bottom ailerons. [52]
Wire, Aileron Balance—A wire connecting the right- and left-hand top ailerons. Sometimes termed the "aileron compensating wire." [53]
Wire, Snaking—A wire, usually of soft metal, wound spirally or tied round another wire, and attached at each end to the framework. Used to prevent the wire round which it is "snaked" from becoming, in the event of its displacement, entangled with the propeller.
Wire, Locking—A wire used to prevent a turnbuckle barrel or other fitting from losing its adjustment.
Wing—Strictly speaking, a wing is one of the surfaces of an ornithopter. The term is, however, often applied to the lifting surface of an aeroplane when such surface is divided into two parts, one being the left-hand "wing," and the other the right-hand "wing."
Wind-Tunnel—A large tube used for experimenting with surfaces and models, and through which a current of air is made to flow by artificial means.
Work—Force x displacement.
Wind-Screen—A small transparent screen mounted in front of the pilot to protect his face from the air pressure.
Types of Aeroplanes.
The first machine to fly—of which there is anything like authentic record—was the Ader "Avion," after which the more notable advances were made as shown above.
The Henri Farman was the first widely used aeroplane. Above are shown the chief steps in its development.
THE AVRO.—The aeroplane designed and built by Mr. A. V. Roe was the first successful heavier-than-air flying machine built by a British subject. Mr. Roe's progress may be followed in the picture, from his early "canard" biplane, through various triplanes, with 35 J.A.P. and 35 h.p. Green engines, to his successful tractor biplane with the same 35 h.p. Green, thence through the "totally enclosed" biplane 1912, with 60 h.p. Green, to the biplane 1913-14, with 80 h.p. Gnome.
THE SOPWITH LAND-GOING BIPLANES.—The earliest was a pair of Wright planes with a fuselage added. Next was the famous tractor with 80 h.p. Gnome. Then the "tabloid" of 1913, which set a completely new fashion in aeroplane design. From this developed the Gordon-Bennett racer shown over date 1914. The gun-carrier was produced about the same time, and the later tractor biplane in a development of the famous 80 h.p. but with 100 h.p. monosoupape Gnome.
THE MAURICE FARMAN.—First, 1909, the 50-60 h.p. Renault and coil-spring chassis. 1910, the same chassis with beginning of the characteristic bent-up skids. 1911 appeared the huge French Military Trials 3-seater; also the round-ended planes and tails and "Henry" type wheels. This developed, 1912, into the square-ended planes and upper tail, and long double-acting ailerons of the British Military Trials. The 1913 type had two rectangular tail-planes and better seating arrangements, known affectionately as the "mechanical cow"; the same year came the first "shorthorn," with two tail-planes and a low nacelle. This finally developed into the carefully streamlined "shorthorn" with the raised nacelle and a single tail-plane.
THE SHORT "PUSHERS."—In 1909 came the semi-Wright biplane, with 35 h.p. Green, on which Mr. Moore-Brabazon won the "Daily Mail's" L1000 prize for the first mile flight on a circuit on a British aeroplane. Then the first box-kite flown by Mr. Grace at Wolverhampton. Later the famous "extension" type on which the first Naval officers learned to fly. Then the "38" type with elevator on the nacelle, on which dozens of R.N.A.S. pilots were taught.
SHORT TRACTORS, 1911-1912.—They were all co-existent, but the first was the "tractor-pusher" (bottom of picture). Then came the "twin-tractor plus propeller" (at top). A development was the "triple-tractor" (on the right), with two 50 h.p. Gnomes, one immediately behind the other under the cowl, one driving the two chains, the other coupled direct. Later came the single-engined 80 h.p. tractor (on the left), the original of the famous Short seaplanes.
THE VICKERS MACHINES: First the Vickers-R.E.P. of 1911, which developed into the full-bodied No. V. with R.E.P. engine, then the Military Trials "sociable" with Viale engine, and so to the big No. VII with a 100 h.p. Gnome. Contemporary with the No. V and No. VI were a number of school box-kites of ordinary Farman type, which developed into the curious "pumpkin" sociable, and the early "gun 'bus" of 1913. Thence arrived the gun-carrier with 100 h.p. monosoupape Gnome.
THE BRISTOL AEROPLANES.—First, 1910, Farman type box-kites familiar to all early pupils. Then the miniature Maurice-Farman type biplane of the "Circuit of Britain." Contemporaneous was the "floating tail" monoplane designed by Pierre Prier, and after it a similar machine with fixed tail. Then came the handsome but unfortunate monoplane designed by M. Coanda for the Military Trials, 1912.
THE BRISTOL TRACTORS.—Late 1912 came the round fuselaged tractor, with Gnome engine, designed by Mr. Gordon England for Turkey. 1912-13 came the biplane built onto the Military Trials monoplane type fuselage, also with a Gnome, designed by M. Coanda for Roumania. Then the Renault-engined Coanda tractor 1913, followed by 80 h.p. Gnome-engined scout, designed by Messrs. Barnwell and Busteed, which with Gnomes, le Rhones and Clergets, has been one of the great successes. Almost contemporary was the two-seater Bristol.
THE MARTINSYDES.—1909, first experimental monoplane built with small 4-cylinder engine. J.A.P.-engined machine, 1910, followed by the Gnome-engined machine, 1911. 1912, first big monoplane with Antoinette engine was built, followed by powerful Austro-Daimler monoplane, 1913. Then came the little Gnome-engined scout biplanes, 1914, some with, some without, skids.
THE CURTISS BIPLANES.—In 1909 came the "June-bug," the united product of Glen Curtiss, Dr. Graham Bell, and J. A. D. McCurdy. Then the box-kite type, 1909, on which Mr. Curtiss won the Gordon-Bennett Race at Reims. Next the "rear-elevator" pusher, 1912, followed by first tractor, 1913, with an outside flywheel. All purely Curtiss machines to that date had independent ailerons intended to get away from Wright patents. Following these came tractors with engines varying from 70 to 160 h.p., fitted with varying types of chassis. All these have ordinary ailerons.
THE BLERIOT (1).—The first engine-driven machine was a "canard" monoplane. Then came the curious tractor monoplanes 1908-1909, in order shown. Famous "Type XI" was prototype of all Bleriot successes. "Type XII" was never a great success, though the ancestor of the popular "parasol" type. The big passenger carrier was a descendant of this type.
THE BLERIOT (2):—1910, "Type XI," on which Mr. Grahame-White won Gordon-Bennett Race, with a 14-cylinder 100 h.p. Gnome. 1911 came the improved "Type XI," with large and effective elevator flaps. On this type, with a 50 h.p. Gnome, Lieut. de Conneau (M. Beaumont) won Paris-Rome Race and "Circuit of Britain." Same year saw experimental "Limousine" flown by M. Legagneux, and fast but dangerous "clipped-wing" Gordon-Bennett racer with the fish-tail, flown by Mr. Hamel. About the same time came the fish-tailed side-by-side two-seater, flown by Mr. Hamel at Hendon and by M. Perreyon in 1912 Military Trials. 1911, M. Bleriot produced the 100 h.p. three-seater which killed M. Desparmets in French Military Trials. 1912-13, M. Bleriot produced a quite promising experimental biplane, and a "monocoque" monoplane in which the passenger faced rearward.
THE BLERIOT (3)—1912 tandem two-seater proved one of the best machines of its day. 1913 "canard" lived up to its name. A "pusher" monoplane was built in which the propeller revolved on the top tail boom. This machine came to an untimely end, with the famous pilot, M. Perreyon. 1912 "tandem" was developed in 1914 into the type shown in centre; almost simultaneously "parasol" tandem appeared. 1914, M. Bleriot built a monoplane embodying a most valuable idea never fully developed. The engine tanks and pilot were all inside an armoured casing. Behind them the fuselage was a "monocoque" of three-ply wood bolted onto the armour. And behind this all the tail surfaces were bolted on as a separate unit.
THE CAUDRON.—1910, came the machine with ailerons and a 28 h.p. Anzani. 1911 this was altered to warp control and a "star" Anzani was fitted. From this came the 35 h.p. type of 1912, one of the most successful of school machines. Small fast monoplane, 1912, was never further developed. 1913 appeared the familiar biplanes with 80 h.p. Gnomes, and 5-seater with 100 h.p. Anzani for French "Circuit of Anjou." 1914 produced the "scout" biplane which won at Vienna. 1915 appeared the twin-engined type, the first successful "battle-plane."
THE DEPERDUSSIN.—In 1911 the little monoplane with a Gyp. engine. Then the Gnome-engined machine of the "Circuit of Europe." In 1912 came the Navy's machine with 70 h.p. Gnome, and Prevost's Gordon-Bennett "Bullet," 135 miles in the hour. The last was the British-built "Thunder-Bug," familiar at Hendon.
THE BREGUET.—First to fly was the complicated but business-like machine of 1909. Then came the record passenger carrier, 1910 (which lifted 8 passengers). 1911 the French Military Trials machine with geared-down 100 h.p. Gnome appeared. 1912 produced the machine with 130 h.p. Salmson engine on which the late Mr. Moorhouse flew the Channel with Mrs. Moorhouse and Mr. Ledeboer as passengers; also the machine with 130 h.p. horizontal Salmson, known as the "Whitebait." The last before the war was the rigid wing machine with 200 h.p. Salmson.
THE CODY.—First the Military Experiment of 1908, with an Antoinette engine, then improved type 1909 with a Green engine. Next the "Cathedral," 1910, with a Green engine, which won Michelin Prize. In 1911 "Daily Mail" Circuit machine, also with a Green, won the Michelin. This was modified into 1912 type which won Military Competition and L5,000 in prizes, with an Austro-Daimler engine, and later the Michelin Circuit Prize, again with a Green. 1912 the only Cody Monoplane was built. 1913 a modified biplane on which the great pioneer was killed.
THE NIEUPORT.—The first Nieuport of 1909 was curiously like a monoplane version of a Caudron. In 1910 came the little two-cylinder machine with fixed tail-plane and universally jointed tail. In 1911 the French Trials machine was built with 100 h.p. 14 cylinder Gnome, and is typical of this make. Also the little two-cylinder record breaker. A modification of 1913 was the height record machine of the late M. Legagneux.
THE R.E.P. MONOPLANES.—First came the curious and highly interesting experiments of 1907, 1908, 1909, and 1910. 1910-1911, the World's Distance Record breaker was produced; after it, the "European Circuit," all with R.E.P. engines. In 1913-14 came the French military type with Gnome engine and finally the "parasol," 1915.
THE MORANE: First the European Circuit and Paris-Madrid type. Then the 1912 types, with taper wing and modern type wing. The 1913 types, the "clipped wing," flown by the late Mr. Hamel, one of the standard tandem types now in use. About the same time came the "parasol." 1914-15 came a little biplane like a Nieuport, and the "destroyer" type with a round section body, flown by Vedrines.
THE VOISIN.—1908, the first properly controlled flight on a European aeroplane was made on a Voisin of the type shown with fixed engine. Then followed the record breaker of 1909 with a Gnome engine. In 1909 also the only Voisin tractor was produced. 1910 the Paris-Bordeaux type was built; 1911 the amphibious "canard" and the "military" type with extensions, and the type without an elevator. 1913 came the type with only two tail-booms and a geared-down engine, which developed into the big "gun" machine with a Salmson engine.
THE HANRIOT AND PONNIER MONOPLANES.—In 1909 came the first Hanriot with 50 h.p. 6-cylinder Buchet engine, and in 1910 the famous "Henrietta" type with E.N.Vs. and stationary Clergets. 1911 came the Clerget two-seater entered in French Military Trials, and 1912 the 100 h.p. Hanriot-Pagny monoplane which took part in British Military Trials. Sister machines of the same year were the single seater with 50 h.p. Gnome and the 100 h.p. Gnome racer with stripped chassis. In 1913 the Ponnier-Pagny racing monoplane with 160 h.p. Le Rhone competed in the Gordon-Bennett race, doing about 130 miles in the hour. The 60 h.p. Ponnier biplane was the first successful French scout tractor biplane.
THE WRIGHT BIPLANE.—The first power flights were made, 1903, on a converted glider fitted with 16 h.p. motor. The prone position of the pilot will be noted. By 1907 the machine had become reasonably practical with 40 h.p. motor. On this the first real flying in the world was done. In 1910 the miniature racing Wright was produced; also the type with a rear elevator in addition to one in front. Soon afterwards the front elevator disappeared, and the machine became the standard American exhibition and school machine for four years. In 1915 a machine with enclosed fuselage was produced.
THE BLACKBURN MONOPLANES.—In 1909 was built the curious four-wheeled parasol-type machine with 35 h.p. Green engine and chain transmission, on which flying was done at Saltburn. In 1911 the Isaacson-engined machine was built, together with a 50 h.p. Gnome single-seater on which Mr. Hucks started in the Circuit of Britain race. In 1912 another 50 h.p. single-seater was built on which a good deal of school work was done. A more advanced machine appeared in 1913 and a two-seater with 80 h.p. Gnome did a great deal of cross-country work in 1913-14.
In 1908 the first Antoinette monoplane was produced by MM. Gastambide and Mengin. Then followed a machine with central skids, a single wheel, and wing skids. In 1909 came the machine with four-wheeled chassis and ailerons and later an improved edition which reverted to the central skid idea. On this M. Latham made his first cross-channel attempt. The next machine shed the wing skids and widened its wheelbase. During 1910-11 the ailerons vanished, warp control was adopted and the king-post system of wing-bracing was used. In 1911 the curious machine with streamlined "pantalette" chassis, totally enclosed body and internal wing-bracing, was produced for French Military Trials. In 1912 the three-wheeled machine was used to a certain extent in the French Army. Then the type disappeared.
In 1908 and 1909 detached experimental machines in various countries attained a certain success. The late Capt. Ferber made a primitive tractor biplane 1908. The Odier-Vendome biplane was a curious bat-winged pusher biplane built 1909. The tailless Etrich monoplane, built in Austria, 1908, was an adaptation of the Zanonia leaf. M. Santos-Dumont made primitive parasol type monoplanes known as "Demoiselles," in which bamboo was largely used. 1909 type is seen above. A curious steel monoplane was built by the late John Moisant, 1909. The twin-pusher biplane, built by the Barnwell Bros. in Scotland, made one or two straight flights in 1909. The Clement-Bayard Co. in France constructed in 1909 a biplane which did fairly well. Hans Grade, the first German to fly, made his early efforts on a "Demoiselle" type machine, 1908.
In 1910 a number of novel machines were produced. The Avis with Anzani engine was flown by the Hon. Alan Boyle. Note the cruciform universally jointed tail. The Goupy with 50 h.p. Gnome was an early French tractor, notable for its hinging wing-tips. The Farman was a curious "knock-up" job, chiefly composed of standard box-kite fittings. The Sommer with 50 h.p. Gnome was a development of the box-kite with a shock-breaking chassis. The Savary, also French, was one of the first twin tractors to fly. The model illustrated had an E.N.V. engine. Note position of the rudders on the wing tips. The Austrian Etrich was the first successful machine of the Taube class ever built.
INTERESTING MACHINES, 1910.—The Werner monoplane with E.N.V. engine, combined shaft and chain drive, was a variant of the de Pischoff. The Macfie biplane was a conventional biplane with 50 h.p. Gnome and useful originalities. The Valkyrie monoplane, another British machine, was a "canard" monoplane with propeller behind the pilot and in front of main plane. The Weiss monoplane was a good British effort at inherent stability. The Tellier monoplane was a modified Bleriot with Antoinette proportions. The Howard Wright biplane was a pusher with large lifting monoplane tail. The Dunne biplane was another British attempt at inherent stability. The Jezzi biplane was an amateur built twin-propeller.
SOME INTERESTING MACHINES, 1911.—The Compton-Paterson biplane was very similar to the early Curtiss pusher; it had a 50 h.p. Gnome. The Sloan bicurve was a French attempt at inherent stability with 50 h.p. Gnome and tractor screw. The Paulhan biplane was an attempt at a machine for military purposes to fold up readily for transport. The Sanders was a British biplane intended for rough service. The Barnwell monoplane was the first Scottish machine to fly; it had a horizontally opposed Scottish engine. The Harlan monoplane was an early German effort; note position of petrol tank.
The Clement-Bayard monoplane, 1911, was convertible into a tractor biplane. The standard engine was a 50 h.p. Gnome. The machine was interesting, but never did much. The Zodiac was one of the earliest to employ staggered wings. With 50 h.p. Gnome engine it was badly underpowered, so never did itself justice. The Jezzi tractor biplane, 1911, was a development of an earlier model built entirely by Mr. Jezzi, an amateur constructor. With a low-powered J.A.P. engine it developed an amazing turn of speed, and it may be regarded as a forerunner of the scout type and the properly streamlined aeroplane. The Paulhan-Tatin monoplane, 1911, was a brilliant attempt at high speed for low power; it presented certain advantages as a scout. A 50 h.p. Gnome, fitted behind the pilot's seat in the streamlined fuselage, was cooled through louvres. The propeller at the end of the tail was connected with the engine by a flexible coupling. This machine was, in its day, the fastest for its power in the world, doing 80 miles per hour. Viking 1 was a twin tractor biplane driven by a 50 h.p. Gnome engine through chains. It was built by the author at Hendon in 1912.
Much ingenuity was exerted by the French designers in 1911 to produce machines for the Military Trials. Among them was the 100 h.p. Gnome-Borel monoplane with a four-wheeled chassis, and the Astra triplane with a 75 h.p. Renault engine. This last had a surface of about 500 square feet and presented considerable possibilities. Its principal feature was its enormous wheels with large size tyres as an attempt to solve difficulties of the severe landing tests. The Clement-Bayard biplane was a further development of the Clement-Bayard monoplane; the type represented could be converted into a monoplane at will. The Lohner Arrow biplane with the Daimler engine was an early German tractor biplane built with a view to inherent stability, and proved very successful. The Pivot monoplane was of somewhat unconventional French construction, chiefly notable for the special spring chassis and pivoted ailerons at the main planes; this pivoting had nothing to do with the name of the machine, which was designed by M. Pivot.
The Flanders monoplane, 1912, with 70 h.p. Renault engine, was one of the last fitted with king-post system of wing bracing. The Flanders biplane entered for British Military Trials. Notable features: the highly staggered planes, extremely low chassis and deep fuselage. Also, the upper plane was bigger in every dimension than the lower; about the first instance of this practice. The Bristol biplane, with 100 h.p. Gnome engine, was also entered for the Trials, but ultimately withdrawn. The Mars monoplane, later known as the "D.F.W.," was a successful machine of Taube type with 120 h.p. Austro-Daimler engine. The building of the engine into a cowl, complete with radiator in front, followed car practice very closely. The tail of the monoplane had a flexible trailing edge; its angle of incidence could be varied from the pilot's seat, so that perfect longitudinal balance was attained at all loadings and speeds. The Handley-Page monoplane, with 70 h.p. Gnome engine, was an early successful British attempt at inherent stability.
The Sommer monoplane, with 50 h.p. Gnome, was a 1911-12 machine; it did a good deal of cross-country flying. The Vendome monoplane of 1912, also with 50 h.p. Gnome engine, was notable chiefly for its large wheels and jointed fuselage, which enabled the machine to be taken down for transport. The Savary biplane took part in the French Military Trials, 1911. It had a four-cylinder Labor aviation motor. Notable features are twin chain-driven propellers, rudders between the main planes, the broad wheel-base and the position of the pilot. The Paulhan triplane, which also figured in the French Military Trials, was a development of the Paulhan folding biplane. It had a 70 h.p. Renault engine. For practical purposes it was a failure. The R.E.P. biplane, with 60 h.p. R.E.P. engine, was a development of the famous R.E.P. monoplanes. Its spring chassis, with sliding joints, marked an advance. Like the monoplanes, it was built largely of steel.
In 1912 came the first really successful Handley-Page monoplane, with 50 h.p. Gnome engine. The Short monoplane, was built generally on Bleriot lines. Its chassis was an original feature. The Coventry Ordnance biplane was a two-seater tractor built for the British Military Trials. It had a 100 h.p. 14-cylinder Gnome engine, with propeller geared down through a chain drive. The machine was an interesting experiment, but not an unqualified success. The Moreau "Aerostable," fitted with a 50 h.p. Gnome, was a French attempt to obtain automatic stability, but it only operated longitudinally. The pilot's nacelle was pivoted under the main planes, wires were attached to the control members so that the movements of the nacelle in its efforts to keep a level keel brought them into operation. The Mersey monoplane, an entrant for the British Military Trials, was designed to present a clear field of view and fire. The 45 h.p. Isaacson engine was connected by a shaft to a propeller mounted behind the nacelle on the top tail boom. It was a promising experiment, but came to grief. The Radley-Moorhouse monoplane was a sporting type machine on Bleriot lines, with 50 h.p. Gnome engine. It was notable for its streamlined body and disc wheels.
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