Model flying machines. Toy flyer. Farman's biplane. Model voisinaeroplane. Model Wright aeroplane.

In 1870, M. Penaud, of the French Aeronautical Society, invented a method by which it was possible to give reciprocating action to wings by means of twisted rubber bands.

He constructed a machine, consisting of two superposed screws, turning in different directions, kept apart by two strips of wood, between which were placed the rubber bands. When the rubber was sufficiently twisted and the machine thrown off by hand, it would fly to the height of 50 feet or more, or fly in a horizontal direction.

Stringfellow used a small steam engine to run a screw propeller, 16 inches diameter, with four blades, on a model, having two fixed wings or planes, 10 feet from tip to tip. Total weight was 6.1; lbs. He made the flyer travel for about 40 yards through the air.

M. Penaud experimented with other models, and was able to get better results from them, but his motive power in all cases was from twisted rubber bands. Others, again, used a small engine driven by compressed air, as their motive power.

Toy flying machine

To construct a working model flying machine of the monoplane type, which will fly for a short distance when thrown off from the hand into the air, is not a very difficult task for any young lad with a mechanical turn of mind, who is able to use tools, such as a small saw, a pocket knife, a plane, a rasp, a fine file, with sandpaper for finishing purposes.

On Sheet No. I will be found the working drawings of a very simple type of flying machine with the dimensions appended. Take two pieces of ash wood, each 14% inches by ginch, remove the corners with a knife, plane each strip circular and leave it inch thickfi" Smooth all over with sandpaper. The two form the longitudinal spars Sp, Sp’ of the body (Figs. I, 21'). At a distance of§ inch from both ends of each spar, a shoulder must be formed as at S (Fig. 3 1‘).

Both spars must be treated in the same way. The end cross ties are cut to sizes given from ash, one, CT, tapers in front and is thicker in the medium line on the under surface than at the sides (Figs. 1, 41'). The rear tie CT' is i inch deep ; fixed to its under surface, by screws, is a brass strip with two lugs, this forms the bearingi for the propeller spindle (Fig. 2 In CT, on the flat end, drill two holes, each % inch diameter, passing inwards for inch. Each hole is a inch from the centre line. Drill two corresponding holes in CT’. Glue the spars Sp, Sp' to CT so that the shoulders S of each (Fig. 31') are pressed firmly against the end of CT. Next glue CT’ on to the opposite ends of the spars in the same way. Put a cross ash stay 1% inch by inch by 53;, inch between the spars on the top surface to steady them (Fig. I This is shown in the drawing as being sprigged down; it might be better to glue and bind it on with thin brass wire, as this will not weaken the spars so much (having no nails put through them). The frames are now ready for the pllnes and propeller. On the frame, in front of CT’ (Figs. 1, 2 l), we fix a plane or pair of wings, both cut as a single piece out of, say, Bristol board, cartridge paper, or thin wood (the material must be very light) to the sizes given. The wings are rounded off at the tips, and may be fixed flat on the frames at right angles to them, or be set with a tilt so that they slope upwards from the base line to the tips (Fig. 4 *). A transverse line is drawn across through the centre CL, and on each side of this line bend the plane A, so that the wing tips slope slightly upwards (Fig. 4 *), and fix the wings at a slight angle with the central portion (which rests on the frame) by means of lint thread ties LT (Fig. 5 *). The ends of the threads are fastened thus.

Each is tied to a thread loop on the plane, or passed round a small paper rivet, put through the wing and riveted underneath. A flat surface about 2 inches wide is left at the centre of the plane in order to glue it to the spars Sp, Sp', the wings are fixed with glue and binding wire. Their cross-centre line coincides with that of the frame. The wings might be “ cambered” (see p. 105). In this case we glue the plane at its centre to a small piece of wood, which is curved on the top to fit the camber, and which is flattened on the under surface and glued to Sp, and Sp’ (Figs. 2, 6 *). To keep the wing curved, lint thread ties should be stitched to it, and passed, on the under surface, at intervals from the front to the rear edge.

A much lighter plane is made by taking a piece of {‘5 inch cane, 3 feet 8 inches long, bending this to form the framework of the plane to the outline (Fig. 1 *) ; the overlapping joint can be scarfed, then joined with glue and binding wire, or lint threads; two on each side, passing from the front to the rear, will retain the frame in shape. This must be covered with special AA fabric material, 1' and a piece I foot 8% inches by 3% inches will allow of the ends being turned under and glued to the cane. The plane must be laid on the frame of the machine, glued to it and fastened with binding wires; it must be kept flat and not cambered.

The elevator, or small plane, E (Figs. 1, 2 *), is made of the same material as the large plane to the sizes given. It is glued on to a bit of wood cut with a taper so as to give the plane a very slight elevation at its front edge. It is set so that its centre line coincides with the centre line of the frames. In Fig. 2 the plane is set at a little too high a slope upwards in front, a less slope might be better.

Glue E on to a piece of wood, prepared beforehand, with a slight taper (Figs. 2, 7 *). Before gluing on E make a small clip of light springy sheet brass, drill a hole through its centre, and one through the centre of the block TB. Take a strong pin, push it through the holes in SpC and TB, put a small tin or brass washer, T37, inch diameter, over the pin, cut the stem short, turn down the end of the pin and solder to the washer. This makes SpC be firmly fixed to TB, and yet free to swivel. Place the block TB (having E glued to it) in its place over Sp and Sp' close up to CT, or further back (TB slides along) as required, to get a balance, when the propeller and planes are attached. Turn the clip round so that its ends rest underneath against Sp and Sp', and E will be held firmly in position. The elevator can be made of cane and fabric in the same way as the main plane. We require a piece of § inch cane, say, 1 foot 7 inches long, and a piece of fabric 83 inches by 2 inches. These sizes are ample.

The propeller (Fig. I *) is a two-bladed one, the arms are each made of a piece of cane, 5 inches by g inch, glued into the boss, and to each arm (which is bent round at the free end) is glued a piece of fabric material 3% inches by 1% inch cut to shape shown. This forms the blade. The boss is made of ash, rounded off with knife or file, or turned on the lathe. Through the centre drill a small hole for the spindle, and on the circumference, at opposite ends of the diameter, drill two holes, each } inch in depth, radially inwards into which the propeller arms are glued. When the fabric is put on the arm, there is a free edge of that material left on one side which forms the entering edge when revolving.

The blades ~must have the same permanent twist, and both of them must be set at the same angle, looking in opposite directions. ' Through the sheet-brass lugs, attached to the underside of CT' (Fig. 2 *) drill two horizontal holes, an easy fit for the propeller shaft to revolve in. The lugs must be light and narrow; they cause less friction than if the shaft passed through a tunnel in CT'. Use a piece of steel wire for the propeller axle, such as a thin knitting needle or a cycle spoke; it must be an easy fit in the lugs LL'. Cut off the wire to the proper length, then bend a hook (Fig. 9 *) at one end. To do this the wire must have the temper removed, by being heated to a bright red heat in a gas Bunsen burner, and then allowed to cool very gradually. When cool, the hook is easily made on the end, being bent with pliers. Pass the free end of the wire underneath the main body, and push it through the brass bearing under C'l" (Figs. 2, 8 *), thread on one or two glass beads to act as washers, to prevent the propeller boss PB from rubbing against .CT', next pass it through PB; with pliers bend over the end parallel to the spindle, and with a light hammer drive it through a hole in the boss, parallel with the central hole, and then turn over the end again with pliers (Fig. 8 *) ; this rigidly fixes the propeller on its spindle, so that the former cannot turn without the latter. This spindle has not been hardened, but this is unnecessary, since the strain of the elastic is not very great, when flying.

Having fixed up the propeller we must procure, say, 9 feet 3 inches of g" X 5‘5” elastic. This is passed over the hooks and the two ends are tied with a firm knot, the excess being cut off. A skein " of eight strands should pass between the hooks. The front book, which passes through CT (Fig. 2 r), is similar to the stern book, but of a little thicker material, and of hard drawn brass to allow of a screw thread being made on its stern; two small brass nuts (as light as possible) must be screwed to fit the stern, one is screwed up to the base of the hook and soldered here to form a collar to bear against CT. The other nut, when tightly screwed up outside of (IT, and soldered over, will hold the hook and prevent it from revolving with the rubber. Should it tend to move at all then the outside or front nut must be tightened up. The rubber strands, when put over both books, should not be drawn too tight, but they should be slightly stretched and have sufficient tension to prevent undue slackness. A wooden propeller may be used. Take a piece of beechwood 71;” X 12-" X {3", round off the edges and remove the corners. After steaming, twist the ends, in opposite directions to an angle of 45° with each other, to form the blades. Bend the end of the wire spindle into a flat loop, pass this round the propeller at the centre, then twist the end of the wire firmly round the spindle to lighten the loop and retain the latter in place. Cut off the excess wire.

To balance the flyer it must be suspended, by a thread or twine, from some fixed point, over its centre of gravity, note if it tends to hang with the propeller end projecting downwards, or wire aersd. If it does not hang horizontally, then E must be moved along forwards or backwards over Sp, Sp’, till balance is got; should this not be sufficient then small bits of tin, sheet brass, or even wood, should be put on with seccotine or glue underneath E, or under the wings, where required, till it hangs horizontally and does not tend to droop. When this is attained the balance is right. There will be some trouble, perhaps, in getting correct adjustment, but the good results, which may be looked for, will justify any amount of labour and patience bestowed on the machine.

To test its capacity for flight, the amateur must hold the flyer with his left hand, so that it projects horizontally and remains on an even keel. With his right hand he must twist the elastic, or wind up the propeller in a clockwise direction (as viewed from the rear), till the rubber skeins are thoroughly twisted, and to do this may require about 200 turns of the propeller. Catch hold of the flyer with the right hand, holding it by the fore and middle finger (one below and the other above Sp and Sp'just behind, and above and below the main planes} and with the thumb prevent the propeller from revolving; then throw the machine off the hand with a steady, straight forward throw, so as not to jerk it sideways to upset the balance. With a little practice, if the machine has been properly balanced, it will fly some distance before the energy of the elastic motor is expended. This experiment should be done either inside a large hall or out of doors, on a very calm day, to get the best results.

Weight of the flying machine — In round numbers, approximately 1 square foot of plane surface is used for every 1 lb. of weight lifted in a flying machine. As this one has— length X breadth = area = 2'75” X 19-5” = 53'6 sq. in. = 0'372 sq. ft.

then I sq. ft. : 0-372 sq. ft. :: 16 oz. : x = 6 ozs. nearly. Thus, 6 025. is the utmost limit of weight which this plane will lift, so the machine must be kept well under this weight in order to give good results, say, under 2 025.

Model Farman flying machine

As some readers might wish to construct something better than the toy model just described, and yet do not see their way to construct, at least at the first attempt, one of the more complex models to be described later on in this book, we now describe the construction of a model “Farman” flying machine, which has some resemblance to the real flyer, and which, we trust, will be a source of instruction in making, and of amusement when completed. The working drawings are given on Sheet No. 2. The length of each deck or plane is 3 feet 6 inches, width 7 inches, and they are set at 7 inches apart. Make the deck frames of birch, ash, or spruce. Cut out four pieces, each 3 feet 6 inches by 1 inch by Tag inch to form the main spars TS, TS' (Figs. 1, 2, 3 *). Sixteen vertical struts (eight in front and eight behind the decks) are required, of the same kind of wood, each 651 inches by 7} inch square, VS (Figs. I, 2 *). Four end cross ties, CT, are required, each 6%- inches by inch by inch.

The several parts must be smoothed by file and sandpaper , and have the corners removed. They are fastened together with glue and sprigs to form one deck. Make the other deck in the same way, leave a clear space of 3% inches on each side of the centre line. When completed, join the two decks together by the struts with glue and sprigs (Fig. I *). A tailbox (Fig. 4 *) is required. Make it of the same kind of wood as the main decks; take four pieces of spruce or ash, each 3 feet 4 inches long, inch square, use the ends of these to form the four corners of the tailbox, make it 7 inches square over all, use eight pieces in all, four cross pieces, each 6% inches by i inch, and four uprights, or struts, each 6% inches by i inch, to make the frame. When put together, the tailbox has the four corners, which form the outrigger, projecting 33 inches in front (Figs. 4, 10, 13 *). At a distance of 1 inch from the ends of the lower pieces drill a hole through each to take a strong hard brass, steel, or iron wire, 1 foot 10 inches long (Fig. 5, 10 *). Construct two wooden elevating planes E, E', centre the plane at each end, drill inwards from the centres as far as the drill will go. Make a drill, from a thick knitting needle, with the stem 4% inches long, then drill again from each end; they are drilled lengthwise for the spindle. They should work stifily and remain in the position in which they are set. The spindle, inch in diameter, is screwed for a brass nut at each end. To ensure that it does not revolve in the bearings, take two bits of thin tin, each % inch byg inch, drill a hole at the centre in each for the spindle, and another hole (countersunk) for a wood screw. Screw one piece on the inside of each lower projecting support (Fig. 12 *). The hole for the spindle must correspond with that in the wood. Pass the spindle through them both, and solder it to each tin strip. On the outside of each bearing, solder a washer or collar (Figs. 5, 12 *), thread on the spindle the corresponding plane, then screw up the outside nut, which forces the plane against the washer and holds it in any position when tightened up. Do the same with the other plane and they are finished.

E, E' must be filed and smoothed all over and the corners rounded off. Leave them, say, 5 inch thick in the middle, tapering to £5 inch at the fore and 115 inch at the aft edge. The tailbox is strengthened by a few ribs put across the top and bottom decks. A piece of inch circular cane, split up lengthwise, will form two ribs. Cover the box over on the top, bottom, and sides with material such as oiled silk, linen, or tracing cloth, but light fabric material (purchased from the model makers) is best to use. The box is left open in front and behind. Cut the material a little larger than the part to be covered over. If linen is used it might have a hem. Stretch the material slightly,'then either sew or glue it to the frames. For each deck we require roughly 3 feet 8 inches by 9 inches of fabric; for each tailbox deck 9 inches square, and also 9 inches square for each side.

Fix the projecting ends of the tailbox to the main decks, the outriggers being put underneath the main spars, and fixed with screws and glue; the top projecting corners must be cut off flush with the front of the main deck (Fig. 10 *). The decks must have ribs placed between the spars (Fig. 3 *) similar to those of the tailbox. Cover both decks with the same kind of covering on one side only (it will be easiest to cover the upper one on the top surface and the lower one on the under surface). To save labour the ribs may be flat, whalebone would do, but if curved this would camber the surface and improve the efficiency. The struts supporting the decks can be strengthened with straining wires (Fig. 1 *); use fine brass wire, piano wire, or twine, put it on diagonally between the struts from one deck to the other, and thread it through holes in the transverse stays, or bind it round them, and fasten the ends by twisting them together with pliers, the wire being threaded from one corner to another and back again. The outrigger, carrying the tailbox, can be strengthened with struts and straining wires (Figs. 10, I3 *). It might be constructed of cane or split bamboo instead. In the lower deck, on each side of the middle line, at a distance of 3% inches is placed a strong cross spar 5; inch wide. To these the wheel supports are fixed by screws. These are made of brass, BA, cut out of a thin sheet. Each leg is bent at its free end into an angle and drilled for two wood screws (Figs. 6, 7 *).

There are two wheel frames, one at each side, they carry the bearings for the axles, which consist of simple holes drilled to receive them. The wheels should be of cast aluminium and can be purchased of a suitable size from some of the model makers. The wheels are soldered to a brass or iron axle, passing through their centres, and revolve together inside the frames (Figs. 6, 7, 13 *), being set at a distance of 6 inches apart. Two smaller wheels are placed in front of the tailbox (Fig. 8 *), one on each side (Fig. I 3 They revolve on axles, supported in forked arms of sheet brass,- each wheel frame is fixed to the outrigger by two screws, passing through a flange (bent on it) just in front of the tailbox.

The fork is made of a piece of wire or sheet brass, bent out near its lower extremity to form one leg of the fork, the other leg is riveted or soldered to it, both forks are drilled, near their extremities, for the axle which carries the wheel placed between them. The forks should be stiff, and the axle soldered to them on the outside (the wheel revolving loose on the axle). The flying machine must sit on the four wheels, all of which must bear on a level floor at the same time. The forks can be strengthened with tie rods, as in Sheet No. 5, Fig. 5.

The propeller is a three-bladed one with metal blades (Fig. 9*). There is not room for a two-bladed propeller, with sufficiently long blades, to revolve between the outriggers (Fig. 4*) without striking the spars, and this is why the propeller has three blades. A different form of blade is shown in Fig. 11,* rather larger and differently shaped from that in Fig. 9.

The boss (Fig. 9 *) is a bit of round brass rod, turned down to inch diameter on the lathe. Drill a hole through the centre, and make it a tight fit on the spindle. Drill a inch hole down to, and at right angles to the spindle hole ; tap this with a fine screw thread, and put in a set screw (fine screws can be purchased from the model makers). Around the circumference in the centre line, and at equal distances apart, drill three % inch holes diametrically inwards to a depth of % inch, and into each screw the arm of the blade and solder it over (the arm is flattened out at the extremity for riveting to the blade). A wooden boss may be used, with wooden blades, glued into sawcuts cut at 45° with the axis.1' All the blades must be set at the same twist. The motive power may either be a spring motor or an elastic motor. A spring motor may be purchased. We have seen them advertised to drive an 8-inch propeller and weigh no more than 3 02s. One this size can be had for a few shillings, and, we think, will be found suitable. The motor must run at a very high speed. Fix it in the centre of the chassis frame, resting on the lower deck, and screwed to cross spars specially put there for it to rest on. It should have lugs for the screws. The % inch steel spindle may project at least 4 inches from the rear of the motor (Fig. I 3 *) and carry the propeller at its extremity (behind the planes).

With a clockwork motor there is always the disadvantage that it might be damaged or broken by a fall, when the flying machine comes to earth after a flight. Of course an elastic motor is not affected in this way at all. An elastic motor can be used instead of a spring motor. To drive this propeller we require three columns of elastic geared together. Purchase three light gear wheels of the same sizes, and mount one on the propeller spindle, just in front of the propeller, between it and the hearing. The end of this spindle terminates in a hook, which must be in line with the central hook attached to the front cross spar. The two other spur wheels are fixed one on each side of the propeller spindle, so as to gear with the central gear wheel. Each of these is fixed on a short spindle terminating in a hook which is placed in line with one or other of the outer hooks on the front spar. If the distance between the hooks be 13.13 inches, and each column contains four strands of f; inch elastic, then we require in all about 16 feet 6 inches.

After the machine is completed, and before the motor and the propeller are put on, it must be very carefully balanced to see that it will fly well as a glider; when this has been attained put in the motor and the propeller and again carefully balance. An extra weight may require to be put in front to counteract the weight of the propeller, rubber, and gear wheels, in order to keep the machine on an even keel.

mtg/1: of the Flying Madame—By the rule given on p. 57, the total weight which the main planes will sustain is just 4lbs. Area ofboth decks = 4 sq. feet. 42” X 7” X 2 = 4 sq. feet. Area of tailbox 7” X 7” x 2 = 06 sq. foot. I sq. foot : 4'6 sq. feet :2 I lb. :x = 4'5 lbs. Much less than this will be lifted, for the lift, with 2 superposed planes, is not twice that of a single one, as both act on the same column of air. In constructing the model, the weight of the motor and propeller must be subtracted from the above, but the lighter the flyer is made the better will be the results obtained when flying.

Having completed the flying machine, it must be properly balanced and made, so that when suspended from the centre of the top plane by a piece of twine (attached to some fixed point) the machine will remain quite level, and not tend to droop either in front or at the rear. Small bits of lead as ballast may be fastened with sprigs or binding wires on the under surface, where required, to balance it. When balanced, wind up the spring motor, and on setting the propeller in motion, it should revolve at such a rate (it has no connection with the wheels) as to drive the flyer along upon its wheels on a smooth floor. If the floor slopes downwards better results may be expected as the speed will be greater. Then, if the machine has been correctly' proportioned and balanced, and made as light as possible, with the elevators set at the correct angle (this is found out by experiment), and if sufficient energy still remains in the motor, the flyer should ascend and fly, a short distance before the motor runs down. The best flight will be got when the machine is thrown off from the hand, as then the whole of the energy of the spring, and not a part of it only, will be used for driving the flyer through the air.

Should success not be attained at the first attempt, more adjustment will be required; either the propeller blades are not properly set, or the elevator is at a wrong angle—in fact, something is wrong somewhere. Do not be discouraged; persevere; make an alteration here and an alteration there, and we have no fear but success will finally reward the experimenter, who will find that patience and perseverance perform wonders, and that at last he has really constructed a good working model which will, let us hope, only be a stepping -stone to the making of a larger and more complicated flying machine, such as is described later on in this book. It must‘be clearly understood that in no flying machine are the wheels which it rests upon connected with the engine or motor; the thrust of the propeller on the air is sufficient to get up the required speed to cause the machine to ascend from the ground.

In Sheet No. 2, Figs. 10 and 12 are not drawn to scale, and in Fig. 13 the motor is not drawn to scale.

Model viosin aeroplane(biplane type)

Through the courtesy of the proprietors of Flz'g/zt, we have been permitted to take a few notes, and copy from the working drawings of a Voisin flying machine, so we are enabled to give working drawings, on Sheet No. 3 (containing , as well, a few original drawings of our own), for constructing this model. These drawings are not accurately to scale in every detail as this would render some of the parts far too weak for practical work, but the overall dimensions are about right, and the model will have a near semblance to the real machine. The minimum amount of wood consistent with strength and rigidity, should be used in the construction. The Voisin machine differs from that of Wright in having a tail and no wing warping device. The tail consists of an open-ended box carried at the rear for maintaining lateral stability, but it resembles Wright’s in being a double-decked machine. Each deck or plane (Figs. 1, 2, 3 *) has the main framework consisting of ribs lying across two main spars (Figs. 3, 4 The latter are made of ash, spruce, or beech wood, four in number ,' each is 5 feet by 11 inch by {’5 inch, two for each plane; 42 ribs are required, if spaced at 3 inches apart. They are shown at 2 inches apart in Fig. 4 *; each is 9 inches by i inch by 1%, inch. Wood or whalebone may be used. The under face is bevelled to lie on the front spar at an angle (Fig. 15 *) ; the ends are flush with this spar, which is under them, but the ribs overlap the rear spar, which is above them.* This overlapping allows, in the real fiyer, of the planes being flexible to some extent. Before being mounted, the ribs are permanently set to the required shape, and must be steamed. For this purpose we require a boiling kettle.

Hold each rib for some minutes close to the spout so as to receive the full force of the steam, gently twist it with the finger and thumb of both hands, and then clamp it down with its proper curvature (as found by templet) while it sets after steaming. All the ribs must have the same curvature. Another way, instead of steaming, is to cut the ribs to the correct curvature from a board with a band saw, but they will be weaker, and so it is best to make them a little thicker. In this way the deck is cambered, Le. has a curved transverse section (Figs. 1, 5 *). The decks must be covered over with fabric material, or silk proofing (as made for models) upon one side only ; hence, they are called single “ surfaced.” The material is put on so that it lies under the ribs, but the spars shou‘d be covered to avoid sharp angles (Fig. 5 The fabric material should be marked OB” and cut inch to 3 inch larger than the part to be covered over, the front edge is turned over the spar and the rear edge is turned over a thin piece of whalebone which is wired over the end of each rib, and which passes along the full length of the plane.

The lower plane or deck is constructed in exactly the same way and to the same size. The ribs also must be curved so that this deck has the same camber as the other (Fig. I *). There is no covering put on between the decks, at the ends, in front, or at the rear. They are joined together by twenty vertical struts, VS (Fig. 3 *), each 8% inches by 3 inch by inch, these are fastened to the decks with glue and sprigs, but strut sockets and strut connections (sold by the model makers) can be used instead. The front and rear edges of the planes are stayed and braced together with diagonal tension wires,——piano wire does very well as it is very strong, but magnalium wire is lighter and still strong enough for our purpose. These wires ought to be tightened as required by using small brass strainers, which can be had from the model makers ; by using these all the parts can be kept quite rigid. The sharp corners had better be removed and the wood smoothed with sandpaper, as this diminishes atmospheric resistance during flight. The material required to cover the surface of each deck and allow, say, inch to overlap at front, back, and ends, is 5 feet 1.1; inch by 10,]; inches. No provision has been made for warping the wings or providing balancing planes. If it be desired to construct the latter, the easiest way will be as shown (Fig. 16 *). (Some planes are constructed in this way.) At the outer extremities of each wing or plane a few of the ribsj' are cut away flush with the rear spar, and into this space is fitted a small tip or flap, F,jlj similar to the main wing, provided with spars and ribs, and covered with fabric, then it is hinged to the wing at the rear with fabric or other cloth and glue, and it can be set at any angle by means ofa piece of twine, fastened to a lever, and to which the other balancing plane is attached as well.

In a real flying machine, the centre of pressure, or that point at which the pressure of the air supporting the machine acts, and the centre of gravity are rarely in the same point, the former is continually changing, hence devices, such as supplementary planes or methods of warping the extremities ‘of the wings, are required in order that the aviator shall maintain his lateral balance. The large tailbox, TB (Figs. 1, 2, 3, 6 ‘5), at the rear, is constructed of an elongated shape transversely, and is of similar construction to the main decks and of biplane form. Four ash or beech spars form the framework, each is 15 inches by inch by ‘3 inch. Cut out twelve ribs (six for the top and six for the bottom plane), space them at 3 inches apart, each is 8% inches by i inch by 73,-, inch; they are steamed and bent to give the deck a cambered section.

The deck surfaces are covered over in the same way as the main decks, except that the sides are covered in addition (see shaded lines, Fig. 1 *). The fabric is drawn tightly over the parts and stitched or glued all round the cross spars, struts, and ribs. We put no divisions or curtains in the tailbox, except that the rudder, R, makes a division in the fore and aft centre line. The tailbox is joined to the rear of the main decks by four long spars which form the outrigger, 0 (Fig. 1 *). Cane or bamboo might be used for these, they pass from the main front transverse spars of both decks of the tailbox to the rear spars of the main decks. The outrigger is joined to the decks by glue and binding wires, or by means of sockets, four vertical struts (two on each side) are placed between the spars to strengthen them, and steel or magnalium wire is placed diagonally between the struts and also between the tailbox decks at front, rear, and sides (Fig. 1 *). The rudder, R (Figs. 1, 2, 3, 6 *), can be made of wood 6 inches by 4% inches by {'5 inch thick at the front edge (where it is hinged) tapering to T15 inch at the rear edge. The taper must be the same upon both sides, and it must be filed and smoothed all over as well as rounded at front and rear edges. It is mounted between the tail decks (being put in place before the decks are joined together) and pivots on two wires (one at top and one at bottom) which enter holes in the rear transverse spars, and which are driven into the rudder for a short distance at the front edge. A small portion of the rudder projects behind the tailbox (Figs. 1, 2 *). It can have a small lever attached to it and be moved by lint threads or twine, which pass round a drum on the steering handle set on the main frame, as in the real machine, or it can be made a fixture. The amount of material required to cover the top, bottom, and sides of the tailbox, and also allow ofg inch at the ends for turning over, will be about, for each deck, 16}; inches by 10 inches, and for each side 9% inches by 9]; inches.

The elevator, E (Figs. 1, 2, 3, 7 *), is of the monoplane type and is double surfaced, it is divided into two equal portions on either side of the girder frame, which juts out in front of the main decks. Each half is formed of two transverse spars, each of these is 11% inches by g inch by inch. Six ribs join the spars together. In the real machine the ribs are left a little thicker at their centres to allow the spindle, on which the elevator pivots, to pass through them, but owing to the smallness of the ribs we cannot adopt this method here. The four inner ribs are each 6 inches by iinch by {‘5 inch, steamed and then bent to give the top a cambered surface, and afterwards cut at an angle in front to lie on the spars (Fig. 12 *). The two end ribs are each 6 inches by % inch by i inch, their upper surface must be flush with that of the other ribs when put together. To the under surface of these end ribs we fix, by two screws, a half (brass) bearing, which encircles the spindle for half its diameter only (this can be made of sheet brass or tin plate) (Fig. 8 *). We solder the elevator to the spindle, at both ends, where it passes through the half bearings. The elevator is now ready for covering with fabric material, it should be covered both on the top and bottom (Fig. 7 *). The material required, roughly, will be about 12% inches by 11 inches. This covers both surfaces. The other elevator is fitted up in the same way.

In the real machine the elevator is moved by means of a connecting rod attached to a steering wheel spindle, this slides along in its bearings, and so the pilot can set the elevator by pulling or pushing the steering wheel bodily to and fro, but this method we cannot adopt in the model, as the elevators must be set previous to flight taking place.

Having fixed one elevator to the spindle, pass the latter through the bearings BE, BE' (Fig. 12 *), having previously slipped over it a small spur wheel (one out of a clock might be suitable), solder on the other elevator at the opposite end, use washers, if required, outside the bearings, to keep the spindle from sliding along to one or other side. It will be seen that both of the elevators move together and rock with the spindle in the bearings BE, BE’, on the girder frame. Solder the spur wheel to the spindle on one side, close to one of the bearings, and let this gear into a brass worm (two small bevel spur wheels would do instead, but they would require to be very light) attached to one end of a spindle which passes through a brass bearing (thick enough to take a small set screw) on the girder frame, and ends in a hand wheel for the use of the aviator (Fig. I *).

To ensure the worm always engaging with the spur wheel, the neck of the spindle, just before entering the worm (which is soldered or screwed to it), should pass through a small sheet_brass bearing B’ (Fig. 2 *), set at right angles to the main bearing BE' (Fig. 12 *). This small (spindle) bearing keeps the spur wheels, or the worm and spur wheel, always in mesh, and does not allow the spindle to yield or spring when being turned by the hand wheel. The reason why we have set the spindle and spur wheel to one side is to get a fixture for the bracket. On turning the hand wheel or crank the elevators can be set in any desired position, and will remain as set, during flight, provided a very light set screw (g inch diameter) be put through the bearing B (Fig. 1 *) and tightened up.

A simpler method of changing the angle of the elevators is by means of elastic bands. Two or three small hooks (of wire) are fixed to the top and bottom main spars of the girder frame (Fig. 12 *) at short distances apart. The upper books, 3 in number (more can be used), are fixed on one side, and the under hooks on the opposite side. Two small elastic bands are used, one is fixed by a screw, or sheetbrass clip (Fig. 17 *), which is screwed to the upper surface of the front cross spar of one elevator, and the other band is fastened in the same way to the under surface of the front cross spar of the other elevator. The bands must be of such a length that when equally tight they engage with the central hooks, and the elevators are horizontal, but when the upper band is slipped over the furthest away hook (from the front of the girder) and the other one is over the nearest hook, the elevators become tilted upwards; while movement of the elastic bands to opposite hooks tilts the elevators in the opposite direction. More hooks will give different degrees of elevation.

In front of the main decks there juts out the “ fusilage ” or main body (Figs. 1, 2, 12 *), I foot 3 inches long, 3% inches deep at rear, and 4 inches wide. The longitudinal spars are of ash, or beech, say, each is 1 foot 5 inches by % inch square, they are steamed and bent to shape shown, the sharp edges are removed and then they are sandpapered all over. The spars are braced together with struts and cross ties ; they are joined with glue and sprigs or connecting lugs. The frame is stiffened by means of diagonal straining wires to render it perfectly rigid (piano or magnalium wire can be used) (Fig. 12 *). The front part of this frame has an upward slope, and to the tips, fixed by screws on each side, are sheet-brass extensions BE, BE' (through which the elevator spindle passes), which are rounded in front. The longitudinal spars on both sides are joined at an angle in front and are fastened with connecting lugs.

The top, bottom, and sides of the frame are covered over with fabric material (from the hand wheel to the extremities). It should be put on each surface asa separate piece and glued to the spars and struts; this will make the neatest finish, the edges of the material being cut away flush with the edges of the spars and struts. For each side we require, roughly, a piece I foot 3% inches by 4% inches and for the bottom. 1 foot 5% inches by 4% inches; this size will do for the top also. When putting on the material, it should be cut to fit the several surfaces on which it lies. Thus it will be seen that the main decks of the Voisin flyer form a kind of lattice girder-framework, in which vertical struts (Fig. 12 *) alternate with diagonal staying wires. The rear spars of the main decks are carried across through the girder frame, and are attached to it by brass I angles and screws, while the front spar is divided at the part where it rests against the girder, the ends being fastened to vertical struts by means of brackets (Fig. I I *) (they may be made of aluminium) provided with flanges for screwing on, and into these brackets the extremities of the spars pass and are held in by screws. The decks must be fixed to the girder frame in such a way that the front edges are elevated above the rear edges ( Fig. I *).

The flying machine is suspended on the chassis by a pair of long spiral springs (Figs. 1, 3, 9 *). Each spring is mounted about an iron rod or spindle, which extends upwards from the chassis and passes through a bracket attached to the girder frame. This bracket forms an abutment to the upper end of the spring; besides this point the chassis is also attached to the frame by a radius rod, which is hinged to it in front of this point. In the real machine, when the springs are compressed, the radius rods cause the uprights with the springs to cant.

To make the chassis, take a piece of inch brass tube (over all), say, 3% inches long, bend a piece of strong sheet brass into a U shape; this forms the wheel forks WF. Solder the tube to WF near one extremity, putting it inside the U, bent at right angles. Take a strong piece of brass wire BW, flattening it out at the ends, bend it into a U shape, solder each limb to the outside of WF, and the bend of the U to the upper and back part of T slanting downwards to W F. These form two tie rods to strengthen the wheel forks.

Take a piece of strong brass wire to form the radius rod RR, which joins the lower end of the wheel frame with the body in front, flatten it out at both ends by hammering (do not make it too thin) then bend the rod near each end to shape shown in Fig. 9 *. At one end drill one, or it may be two holes for wood screws, countersink the heads, and at the other end drill a hole % inch diameter for the rod IR to pass which joins it to the wheel frame. File the brass and reduce the diameter of the rod, between the flattened ends; to save weight also finish off the ends neatly. Procure a piece of i inch steel or iron rod IR, say 11}3 inches long (the excess can be cut off). By heating the rod and hammering it at one end a head can be formed on it, either by a blacksmith or by the amateur hiinself. This head must be filed small and neatly rounded at the neck. Tap a screw thread on the other end of IR, say, about% inch long, and provide this end with a washer and a brass nut N, a washer may be put underneath. T must be a good sliding fit over IR, which it will be, being inch bore.

Pass IR through the hole in RR at one extremity, till it rests against the head, solder the two together, then pass IR through T and through the spiral spring Sp (which surrounds it) before putting it through the bracket AB (Figs. 9, 12 *), which is screwed to the side of the upper main spar of the girder frame and against which Sp also bears, a nut and a washer above and below are put on, and by means of this nut N the tension of the spring can be regulated. Accordingly as this spring is compressed or extended, the wheels will rise or fall to a certain extent and so yield to take the shock when striking the ground. In the real flyer there is a rubber pad which takes the shock in descending, but this is not required in the model. Near the free ends of the forks WF, a hole is drilled in each to form the wheel bearings, and a miniature cycle wheel, with rubber tyres, is fixed on a short axle (of brass wire) which is put through the wheel boss and soldered to the wheel forks. The other wheel frame is constructed in precisely the same way, and is fixed on the opposite side of the girder frame, say 4.]; inches apart.

Two tie rods, TR (Fig. 10 *), of brass wire, pass under the girder frame and join the wheel frames together, making the frame into one piece. To get a good joint between TR and T both ends of the rods should be bent into a circle which surrounds T and be soldered to it; one is placed at the lower end of T, and the other at the top end.

If we make the wheel frame without any pivoting motion, then both wheels can be fixed on one (wire) axle; but if we wish the wheels to pivot like castors, then either we must fix each on a separate axle, or the axle, upon which both are fixed, must have a pivot joint, P] (Fig. 13 *), made on it near to the inner side of each wheel. The axle must be sufficiently long to begin with, and be cut near each end, thus there are three pieces, one long and two short. The long piece is flattened out near each end, the same is done with each shorter piece at one end only. The ends must all be trimmed off neatly and drilled with a hole through the centre of the flats; the long piece is riveted at each end to the shorter piece, with copper rivets riveted very loosely, to form pivot joints (the rivet is 53.5 inch diameter and the head is {5,- inch diameter; this is filed out of copper wire).

The tie rods, TR (Fig. 10 *), have also pivot joints P], they are bent round the wheel fork tubes at their ends and soldered, being made in the same way as the axle. Elastic bands can be used to return the wheels to their normal position. In Fig. I * wire tie rods are shown strengthening the wheel frame ; in the model these are not required, but, for appearance’ sake, light magnalium wires can be used to support the parts if desired. The wheel frame in the real “ machine is not quite so simple in construction as the above, but that given is easier for an amateur to construct and will have a swivelling movement.

Two smaller forked wheel frames (Sheet No. 2, Fig. 8, at end of book), (each containing a very small aluminium cycle wheel between the forks) are fixed, one on each side to the lower spar of the outrigger, just in front of the tailbox . The frame (consisting of stem and wheel forks) can be made of brass wire (see page 61), say, éinches long, the stems pass through brackets of strong sheet brass, or aluminium castings, one of which is screwed to the lower spar of the outrigger on each side, just in front of the tailbox. It will be seen that the frame rises and falls with the wheel, and has a little lateral movement as well, provided the nut N is not too tight and the spring greatly compressed. Elastic bands can be used to bring back the wheels to their normal position, should they get turned round (like castors) to one or other side ; they can be attached as shown on page 96 to front wheel forks. It would be possible to purchase all the wheels and wheel frames ready made, from the model makers, and save much labour in constructing them. Some “ Voisin ” flying machines are now constructed with five wheels, the fifth wheel being placed at the front extremity of the girder frame near the elevators, and this wheel is off the ground when the other wheels rest on it. Other flying machines are provided with runners or skates in addition to the wheels.

We now define the term “ Aspect ratio " (used by Mr. Lanchester in “ Aerodynamics ”) which means the ratio of the spread of the plane to the fore and aft depth,- the greater this is the less the area of surface required to sustain a given weight.

The 12 inch propeller (Fig.1 * and Sheet No. 5, Fig. 8, at end of book) can be purchased ready made, or is constructed of wood, sheet brass, aluminium, or magnalium. It may be two-bladed, or three-bladed. The boss and blades may be of metal or wood (see page 61) ; it is fixed just behind the main decks, in the centre line of the girder frame, and is mounted on the centre of a short hard brass spindle, which passes through a bearing and which has a hook at both ends. For motive power we require two elastic columns, one being placed in front of and the other behind the propeller; the front column passes between the propeller hook and a brass U-shaped bolt fixed to the centre of a strong spar across the front of the girder frame. By means of nuts on the outer ends of the bolt the elastic can be tightened up as required. The hind column passes, in a similar way, between the hind propeller hook and a U-shaped bolt, fixed to a cross spar in front of the tailbox.

Make both elastic columns of the same length. Thick skeins of elastic must be put over the U-shaped bolt and also over the propeller hook. Suppose the length of each column is, say, 1 foot 3 inches, and we use a skein of square inch elastic, consisting of 6 strands, then, roughly (to allow for tying the ends), we shall require 8 feet. Better results may be obtained by placing the propeller in the centre of the gap. This propeller, having an elastic column both in front and behind, will be more difficult to wind. Two smaller sized propellers, driven by geared elastic motors, might give a better balance to the machine than one propeller only would give ; this is the reason why both Cody and Wright adopt two propellers in their aeroplanes instead of one. A spring motor (see page 117) might be used, and this would be attached, through a flange, by screws to the floor of the girder frame, or an electric motor might be used (see page 117). In Fig. 2 * it will be seen that the upper plane is cut away at the rear, near the centre line, to allow of the propeller revolving without striking it. The machine must be carefully balanced, as already mentioned (see pages 56, 63). Lead is best to use for this purpose.

weight must not exceed 9 lbs. (see page 57), but the lighter it is constructed, consistent with strength, the better will be the results obtained in flight. The total weight we think should not be over 2 5 025., including ballast. It must be understood that it is not necessary to construct this machine, or any of them (given in the working drawings), exactly in conformity with every detail given. The weight may be somewhat reduced by using bamboo or cane, instead of wood, for the construction of the body, decks, and tailbox, also by putting in fewer struts and ribs and more straining wires. In Sheet No. 3, Figs, 5, 6, 7, 8, 9, 10,11,12,13, 14,15, 16, 17, are not drawn to scale.

Wright's flaing machine (biplane type)

The working drawings for making this model are given on Sheet No. 4.‘ Two'photos of the model (a non-flying one) are shown in Figs. 18, 19 (pp. 79, 81). In Fig. 18 the framework is shown without coverings, and Fig. 19 gives the finished model, with a dummy engine, radiator, and petrol tank, etc. Lint threads connect the engine pulleys with the propeller shafts. The working drawings are not strictly to scale, as we had no scale drawings of the real machine to work upon. The overall dimensions will, we think, be found fairly correct, and, when completed, the model will resemble the real flyer in appearance.

It is constructed entirely of No. 17 (Stubb’s gauge) iron wire (for making birdcages), and sold at Id. per 4. feet lengths. If made of brass tube, inch diameter, with soldered joints, it would be stronger and better fitted to fly, if driven by an elastic or spring motor. The flying machine is of the double plane or deck type, with double elevator and rudder. To make one deck, take a piece of wire 5 feet 9 inches long; this forms the two transverse

spars and the end spars, bend to shape shovvn (Fig. I *). The front corners AB are nearly rectangular in shape, but the rear ones CD are rounded off as shown. With pliers, cut off the ends of the wires should they overlap, make a butt joint anywhere as shown at E ; solder the ends together. At a distance of % inch from the rear spar, solder a long wire FG to go along the full length of the plane (this could be omitted) (Fig. 1 Cut 42 pieces of wire, each 5% inches long, and curve them to the same curvature H (Fig. 2 *) ; these form the curved deck ribs. To get a good joint for soldering, one end of each should be bent at right angles and soldered to the top of the main spar AB (Figs. 1, 3 *). The other end of each is soldered to the rear spar CD, and also to the inner spar FG, where they cross (Fig. 1 *). A very firm and strong joint is got if all the cross stays are wired together with brass binding wire, twisted tightly at the ends with pliers, and then soldered over; but of course this adds greatly to the labour, and must be neatly done or it will not look well.

The two flat end cross spars AFLM, shown by dotted lines (Fig. 2 *), may be cut away with pliers or filed through near the angles, as the curved spars H are quite strong enough to hold the frames together. When finished, lay this plane aside till the lower plane KLML is constructed (Figs. 2, 3 *). It is made in the same way and to the same size, so the above descriptions serve for both. The deck ABCD is joined to the deck KLMN by twenty-two vertical struts or tie rods P, there being eleven on each side. Each strut is cut to 5% inches, as this length allows of the wire being turned over at right angles near each end in order to make a stronger soldered joint, and also to give bearing surface for the binding wire, which must be put on before soldering. It is not absolutely necessary to wire each spar to the top

and bottom planes, but every second one may be wired with advantage. The spread of each plane or deck is 2 feet 6 inches, and the width 5 inches, with an area of 150 square inches. In Fig. 8 * the area given is that for both planes. The elevator is double, and consists of two decks, similar to the main decks, but on a smaller scale (Figs. 4, 5 *). The upper one is joined by struts to the lower one. The transverse spars (front and rear) are made of one piece of wire, 2 feet T1 inch long, moulded to shape shown, and somewhat pointed at the ends, and the ends of the wire are soldered by a butt joint (the excess wire being cut off). Nine slightly arched ribs cross from one spar to the other, and are soldered and wired to them ; each rib is 2% inches long. The lower deck is made in the same way and to the same size. The two decks are united together by twenty-two struts T (ten on each side and one at each end). At a distance of 1% inch on each side of the transverse or short centre line, but placed in the longitudinal centre line, are two struts fastened at top and bottom to the ribs. They project downwards below the lower plane, and are soldered and wired to the upper extremities of the skates (Figs. 7, IO, 11 *), and so join the latter to the elevator. Attached to the central struts are two small D-shaped tin discs F (Fig. 5 *) set in the gap between the planes; they can be soldered in position. These planes serve as the prow, and render the machine sensitive to the rudder. In the real machine the upper deck of the elevator can be set at different angles by means of a lever, as the pilot desires,- but in the model we make the elevator a fixture, as otherwise it would be more complicated to construct, and there would be no advantage gained, as its position could not be altered when flying. The correct angle to set the elevator at must be found by experiment.

The rudder (Fig. 6 *) is a double one; it is formed of two rudders joined together. A side view of one of them is shown at G’. This is made of wire, 91; inches long, bent into a rectangular shape, and the ends are soldered with a butt joint. The frame is strengthened by one cross tie in the centre, bound by wire and soldered. The other frame H’ is made in the same way, and when completed is joined to G’ by six cross stays, each 1% inch long, bound to the frames with wire and soldered. The rudder might be omitted in this model, but if adopted it is soldered and wired to the tie rods CD (Fig. 7 *) which join with the cross spars AB (Fig. 6*). These rods, forming the outrigger, should be strong; they pass above each deck and are soldered and wired to a vertical strut in the middle line.

To make the rudder act it must be pivoted. Solder two thin narrow sheet-brass strips on the rudder at AB instead of wire spars (Fig. 6 *), through the centre of each pass from within outwards a small pin or cheese-headed screw ; each screw also passes through a small brass block BB soldered one to the end of A, and the other to the end of B (a stronger joint is got if the ends of A and B pass for a little way into the blocks and are then soldered). Rivet the ends of the pins, or solder them over, to get swivel joints, the pins swivelling in A and B respectively. The rudder is moved by threads, one on each side, which are attached to the ends of a lever (in the form of a cross) placed on the main deck in the centre line, which can be moved from side to side, or fixed by a catch, to hold the rudder at any angle desired. The sides of both rudders are covered over with thin fabric (special AA type, as sold by the model makers) on their outer surfaces; this is pulled well over, and then stitched or glued round the frames. Solder to the under surface of the lower deck a piece of thin tin plate, about 1% inch wide, reaching from the front to the rear spar, AB to PG ,- arch it to the same curvature as the deck surface.

Its centre must coincide with the centre of the propeller spindle when fixed in place. Another piece of tin plate, the same size, is fixed under the other propeller shaft. These form the floor or supports which carry the propeller frames. The propellers are two in number, fixed behind the main decks (Figs. 7, 8, 9 *) ; each is made of aluminium or thin sheet brass, 6% inches diameter, 1 inch at tip, tapering to inch at the boss. Both blades can be cut from the same piece of metal, then centred, and drilled to ai inch hole for the boss to pass through. This is turned out of a piece of brass rod, on the lathe, to 57.3 inch diameter; leaving a narrow collar at one end, inch diameter, centre the boss, and drill so that it will screw firmly on to the end of the propeller spindle. The brass blades can be soldered to the boss, but aluminium ones must have the boss put through, and then be riveted over on the opposite side. In this case the centre hole should not be drilled till the boss is riveted over. The boss should be about 3,,- inch long.

The other propeller is constructed in the same way. Each must have its blades set at the same twist, and also set at a uniform pitch,T and at an angle with the spindle (experiment will show the proper angle, try 45°). The propeller frame is constructed of sheet brass (Fig. 7 *) shaped as a diamond frame; a hole must be drilled through it for the spindle bearings. A horizontal tie rod will stiffen the frame, which is mounted between the decks and fixed in place with solder and binding wires to the rear cross-transverse spar of the top deck, and to the tin plate on the lower deck. The other frame is fitted up in the same way.