How It Flies; or, The Conquest of the Air / The Story of Man's Endeavors to Fly and of the Inventions by Which He Has Succeeded

by Richard Ferris

When all the wooden parts are in place the entire outline of the upper plane and the upright walls is to be formed of silk thread carried from point to point, and tied upon very small pins (such as are used in rolls of ribbon at the stores) inserted in the wood. The glazed paper is put on double, glossy side out. Cut the pieces twice as large (and a trifle more) than is needed, and fold so that the smooth crease comes to the front and the cut edges come together at the rear. The two inner walls should be put in place first, so as to enclose the thread front and back, and the post, between the two leaves of the folded paper. Cutting the paper half an inch too long will give one fourth of an inch to turn flat top and bottom to fasten to the upper and lower decks respectively. The two outer walls and the upper deck may be cut all in one piece, the under leaf being slit to pass on either side of the inner walls. A bit of glue here and there will steady the parts to their places. The cut edges at the rear of the deck and walls should be caught together with a thin film of glue, so as to enclose the rear threads.

A, B, plan, and C, section, of steering plane; H, section of lower main plane; L, wood skeleton of upper plane; T, T, silk thread; O, O, posts; J, J, braces; E, rubber strands; D, forward hook; G, shaft; F, thrust-block; K, upper plane of paper; M, elevation of main planes, from the rear.

When the biplane is completed it is to be fastened securely to the spar in such a position that it is accurately balanced—from side to side. The spar may be laid on a table, and the biplane placed across it in its approximate position. Then move the plane to one side until it tips down, and mark the spot on the rear edge of the plane. Repeat this operation toward the other side, and the centre between the two marks should be accurately fastened over the centre line of the spar. Even with the greatest care there may still be failure to balance exactly, but a little work with a file on the heavy side, or a bit of chewing gum stuck on the lighter side, will remedy the matter.

The body of the aeroplane being now built, it is in order to fit it with propelling mechanism. The motive power to whirl the propeller we have already prepared is to be the torsion, or twisting strain—in this case the force of untwisting—of india rubber. When several strands of pure rubber cord are twisted up tight, their elasticity tends to untwist them with considerable force. The attachment for the rubber strands at the front end of the spar is a sort of bracket made of the brass wire. The ends of the wire are turned up just a little, and they are set into little holes in the under side of the spar. Where the wire turns downward to form the hook it is bound tightly to the spar with silk thread. The hook-shaped tip is formed of the loop of the wire doubled upon itself. The rear attachment of the rubber strands is a loop upon the propeller shaft itself. As shown in the drawings, this shaft is but a piece of the brass wire. On one end (the rear) an open loop is formed, and into this is slipped the centre of the propeller. The short end of the loop is then twisted around the longer shank—very carefully, lest the wire cut into and destroy the propeller. Two turns of the wire is enough, and then the tip of the twisted end should be worked down flat with the file, to serve as a bearing for the propeller against the thrust-block. This latter is made of a piece of sheet brass (a bit of printers’ brass “rule” is just the thing) about 1/40 of an inch thick. It should be ¼ of an inch wide except at the forward end, where it is to be filed to a long point and bent up a trifle to enter the wood of the spar. The rear end is bent down (not too sharply, lest it break) to form the bearing for the propeller, a hole being drilled through it for the propeller shaft, just large enough for the shaft to turn freely in it. Another smaller hole is to be drilled for a little screw to enter the rear end of the spar. Next pass the straight end of the propeller shaft through the hole drilled for it, and with the pliers form a round hook for the rear attachment of the rubber strands. Screw the brass bearing into place, and for additional strength, wind a binding of silk thread around it and the spar.

Tie the ends of the rubber cord together, divide it into ten even strands, and pass the loops over the two hooks—and the machine is ready for flight.

To wind up the rubber it will be necessary to turn the propeller in the opposite direction to which it will move when the model is flying. About 100 turns will be required. After it is wound, hold the machine by the rear end of the spar, letting the propeller press against the hand so it cannot unwind. Raise it slightly above the head, holding the spar level, or inclined upward a little (as experience may dictate), and launch the model by a gentle throw forward. If the work has been well done it may fly from 150 to 200 feet.

Many experiments may be made with this machine. If it flies too high, weight the front end of the spar; if too low, gliding downward from the start, weight the rear end. A bit of chewing gum may be enough to cause it to ride level and make a longer and prettier flight.

A very graceful model is that of the monoplane type illustrated in the accompanying reproductions from photographs. The front view shows the little machine just ready to take flight from a table. The view from the rear is a snap-shot taken while it was actually flying. This successful model was made by Harold S. Lynn, of Stamford, Conn. Before discussing the details of construction, let us notice some peculiar features shown by the photographs. The forward plane is arched; that is, the tips of the plane bend slightly downward from the centre. On the contrary, the two wings of the rear plane bend slightly upward from the centre, making a dihedral angle, as it is called; that is, an angle between two surfaces, as distinguished from an angle between two lines. The toy wheels, Mr. Lynn says, are put on principally for “looks” but they are also useful in permitting a start to be made from a table or even from the floor, instead of the usual way of holding the model in the hands and giving it a slight throw to get it started. However, the wheels add to the weight, and the model will not fly quite so far with them as without.