The Second Boys' Book of Model Aeroplanes

by Francis A. Collins

In the case of the Antoinette aeroplane, of a monoplane type, a somewhat different device is depended upon for stability. The ailerons in this case are attached to the outer edges of the rear wing and are hinged so that they may be raised or lowered at will. One of these may be turned up while the other is turned down. Although these resemble the Farman ailerons, they are believed to be twice as effective since they may work in opposite directions, while those of the Farman aeroplane may only be inclined downward.

It will be noticed in the photographs of many successful model aeroplanes that the tips of the wings are flexed upward at an angle often as much as 45 degrees. These planes, it is believed, tend to lower the center of gravity, and in the case of a turn tend to bring the aeroplane to an even keel. Their head resistance in a straight flight is, of course, rather great. It is claimed that the Antoinette aeroplane is the easiest of all aeroplanes for a beginner, largely because of this adjustment of ailerons.

One of the most novel devices for gaining stability which has appeared during the year, is that of the Pfitzner monoplane, which gains lateral stability by means of an ingenious sliding wing tip which may be pushed out or drawn back at will. When the aeroplane begins to fall from its level, one of these wing tips is shot out, while the other is pulled in. This increased surface tends to throw one plane upward while the shorter plane, which for the time exerts less lifting power, falls correspondingly. The Pfitzner monoplane makes many sharp turns with very little tipping.

A New York aviator has succeeded, it is reported, in building a practicable aeroplane, which combines the best features of both the lighter and heavier than air machines. In the earlier stages of the development of aeronautics many believed that the solution of the problem was to be found in some such combination. The attempts usually consisted in adding large planes to dirigible balloons. Gradually, however, the combination was given up as impossible. The great dirigibles of to-day carry considerable plane surface, but this is intended to lend stability for guiding and not support.

The New York aviator, however, reverses matters and retaining the aeroplane form attempts to gain additional support from gas pockets. He does this by building his plane after the general Bleriot model but with a considerable space between the upper and lower surfaces, which he fills with gas. The machine has not yet been exhibited, but it is understood that this space is upwards of one foot in thickness and as wide and long as the planes. The front entering edge is kept sharp so that the wings, for all their size, meet as little resistance as possible. Whether the support gained from so small a body of gas is worth while, and counteracts the increased resistance of the enlarged wing, is of course an open question. The dirigible aeroplane has been flown successfully several times, however, with a passenger and is reported to have behaved well.

The new Paulhan biplane introduces an entirely new form of plane which is being watched with great interest. The wings have the appearance of being fluted or corrugated. The frames of the planes consist of a great number of ribs, running from front to rear, placed but a few inches apart. These ribs are made very flexible. The canvass covering of the planes is sewn with a series of pockets, exactly corresponding to the ribs. The wings are covered by merely pulling the canvass on the ribs and fastening it rigidly in place. This gives the canvass a tendency to arch between the ribs so that the planes consist of a series of corrugations. It is believed by some aviators that the supporting power of the aeroplane is increased in this way. It has the advantage at least of being very easy to adjust. A model aeroplane built on these lines should fly well and have a distinctive appearance.

Another feature of the new Paulhan which should appeal to the builder of model aeroplanes is its ingenious trussed girder. It is known as the Fabre girder. It is interesting to note here that the built-up girder was used in the model aeroplanes even before it was adopted in the man-carrying machines. The Fabre girder consists of two long strips of light wood connected by crosspieces of steel running diagonally. This form of construction gives unusual strength and is very light. It has its parallel in the beautifully built-up trusses to be found for instance in the models built by Mr. Mungokee. In this case the girders are made entirely of wood.

The question is often asked whether the rear edge of the front plane should be straight or brought back and tipped at either end. A study of the various models of the standard manufacturers shows that there is considerable difference of opinion among the experts. The builders of model aeroplanes in America still retain the straight line, while in England the tips are brought well back in a great many of the designs. The theory of this form is, obviously, that this tip tends to damp out any lateral motion, and makes for stability. In the most successful American models the rear line of the plane is kept straight without apparent loss of stability.

Turning now to the large machines, we find a similar contrast. In none of the Bleriot models is the rear line broken. The Wright, Curtis and Antoinette machines, even in their latest form, still retain the straight line. The Etrich monoplane has had good results with rear wing tips. The model has been accepted by the Austrian Minister of War who has ordered a fleet of twenty of these craft for the army.

The rear tip was first suggested by Lilienthal. The friends of this form claim that it more nearly approaches the form of a bird's wing than any of the other planes now in use. The depth of the main plane is nine and three-quarter feet and at the tips twelve feet. The entire tip is so adjusted that it may be flexed at will from the pilot's seat. It will be seen that this arrangement makes it possible to imitate the flight of a bird very closely. In adopting this idea in model aeroplanes it will be well to attach the extension by a hinge so that it may be turned up or down at will. Since it is placed well out from the main axis of the machine its leverage is naturally great.