Fig. 2. Details of Forward Skids of Aeroplane Model
Propellers. The propellers D are two in number and are carried by the two long strips A. Each propeller is 5 inches in diameter, and is whittled out of a single block of white pine. The propellers have a pitch of about 10 inches. After the whittling is done they are sandpapered and coated with varnish. The thickness of the wood at the hub E₂, Fig. 3, of the propeller should be about 5/8 inch. At the rear ends of the strips A, bearing blocks E₁ are secured. These bearing blocks are simply small pieces of wood projecting about 5/8 inch laterally from the strips A. They are drilled to receive a small metal tube T₂ (steel, brass, or copper), through which tube the propeller shaft T₁ passes.
Fig. 3. Details of Propeller and Rudder of Aeroplane Model
The propeller shaft itself consists of a piece of steel wire passing through the propeller hub and bent over the wood, so that it can not turn independently of the propeller. Any other expedient for causing the propeller to turn with the shaft may obviously be employed. Small metal washers T₃, at least three in number, are slipped over the propeller shaft so as to lie between the propeller and the bearing block.
That portion of the propeller shaft which projects forwardly through the bearing block E₁ is bent to form a hook T₄. To the hook T₁ rubber strips T₂ by which the propellers are driven, are secured. The rubber strips are nearly as long as the main strips A. At their forward ends they are secured to a fastening consisting of a double hook G H, the hook G lying in a horizontal plane, the hook H in a vertical plane. The hook holds the rubber strips, as shown in Figs. 1 and 4, while the hook H engages a hook T. This hook is easily made by passing a strip of steel wire through the meeting ends of the main strips A, the portions projecting from each side of the strips being bent into the hooks I.
Skids. Three skids are provided, on which the model slides, one at the forward end, and two near the rear end. All are made of bamboo. As shown in Fig. 2 the front skid may be of any length that seems desirable. A 6-inch piece of bamboo will probably answer most requirements. This piece N is bent in opposite directions at the ends to form arms Z and U, The arm Z is secured to the forward ends of the two strips A, constituting the main frame, by means of thread and glue. The strips and skid are not held together by the same thread, but the skid is attached to the two strips after they have been wound. Hence, there are two sets of windings of thread, one for the two strips A themselves, and another for the skid and the strips. Strong thread and glue should be used, as before. In order to stiffen the skid, two bamboo struts W will be found necessary. These are bent over at the ends to form arms V₁, Fig. 2. Each of the arms is secured to the under side of a strip A by strong thread and glue. The arms X are superimposed and tied to the bamboo skid V with strong thread and glue.
Fig. 4. Details of Rear Skids on Aeroplane Model