- [PLATE I. Launching a Model Aeroplane.]
- [FIG. 1. Diagram showing a kite held in the air by the action of a wind. The dotted lines and arrow heads represent the direction and force of the wind.]
- [FIG. 2. Diagram representing a typical monoplane. The only remaining requisition is that the aeroplane may be guided at will, caused to rise or fall or be steered to the right and left. The devices used to accomplish this are two rudders called respectively the "elevator" and the "steering rudder." The "elevator" takes the form of a small surface carried either in front or behind the main supporting surfaces and enables the machine to take an upward, a horizontal or downward course accordingly as it is adjusted. It acts as a rudder to steer the aeroplane up or down or to hold it to its course in exactly the same manner that a ship's rudder steers it to the right or left. When it is desired to direct the aeroplane upwards, the front edge of the elevator is raised so as to set it at a greater angle with the horizontal. If the aeroplane's course is required to be downward, the front edge of the elevator is lowered.]
- [FIG 3. Diagram showing the makeup of a biplane (Wright).]
- [FIG. 4. Two methods of controlling the lateral stability of an aeroplane.]
- [FIG. 5. The disturbance created in the air by a square object. The arrow points in the direction of motion. The space in the rear of the object is the scene of violent eddy.]
- [FIG. 6. The disturbance caused by a triangular body moving through the atmosphere.]
- [Plate II.]
- [FIG. 7. Showing the disturbance created by a small spar on the back of a plane.]
- [FIG. 8. Diagram illustrating the ichthyoid shape and how smoothly it slips through the air without creating an eddy.]
- [FIG. 9. Of the three shapes shown above, the round one will slip through the air with the least disturbance and resistance. A bar of wood like (A), 2 inches square, showed a "drift" of 5.16 lbs. when placed in a breeze blowing 49 miles per hour. Turning it as shown by (B) changed the "drift" to 5.47 lbs. A round bar, 2 inches in diameter, like (C) showed 2.97 lbs. "drift" under the same conditions.]
- [FIG. 10. The figures given above each shape show the "drift" in lbs. of wooden bars of those shapes when placed in a wind blowing 40 miles an hour. The bars experimented with had a depth of 9 inches in the direction of the arrows and were 2 inches wide.]
- [FIG. 11. Flat and dihedral planes.]
- [FIG. 12. The action of the air upon a curved and a flat plane. We have seen that by the effects of the resistance of the air, an aeroplane may be sustained in the atmosphere. We must now see in what manner we can use these effects to the greatest advantage.]
- [FIG. 13. Section of a built-up plane showing how a rib is made. When made small, they offer greater "drift" or head resistance than a single curved surface plane and cannot because of the delicate structure necessary to make them light, withstand hard knocks. They have the further disadvantage of being from a constructional standpoint very hard to make smooth and rigid.]
- [PLATE III.]
- [FIG. 14. How ribs may be joined to the long members.]
- [FIG. 15. Form for bending the planes.]
- [FIG. 16. A good method of building a wooden plane.]
- [FIG. 17. Various shapes a plane may take.]
- [FIG. 18. An edgewise view of several planes showing the different ways they may be bent to secure stability.]
- [FIG. 19. The various ways two planes may be combined to secure stability or form a biplane.]
- [FIG. 20. Fins.]
- [FIG. 21. A simple "motor base" or fusellage.]
- [FIG. 22. Paper Tube Fusellage. Part of the tube is cutaway to show the rubber skein inside.]
- [FIG. 23. Two methods of gearing a propeller.]
- [FIG. 24.]
- [FIG. 25.]
- [FIG. 26. Method of laying out a screw propeller, that is, determining the angle of the blades at different points.]
- [FIG. 27. A propeller of the truly helical type delivers a cylinder of air in which all parts move at the same speed as at A. A propeller having blades of the same angle throughout their length throws the air as in B in which the centre of the cylinder moves more slowly than the outside.]
- [FIG. 28. Templets for testing and carving a propeller.]
- [FIG. 29. A simple method of forming a propeller from sheet metal.]
- [FIG. 30. A built-up metal propeller made of aluminum.]
- [FIG. 31. Metal Propeller.]
- [FIG. 32. Method of carving a propeller of the truly helical type.]
- [FIG. 33. Methods of fastening propellers to shaft.]
- [FIG. 34. Method of forming sockets for joining struts, etc., by cutting from sheet metal.]
- [FIG. 35. Bent wood propellers and the methods of fastening them to the shaft.]
- [FIG. 36. Propeller blank (top). Carved propeller (bottom).]
- [FIG. 37. Langley type propeller (top). Wright type propeller (bottom).]
- [FIG. 38. Quasi-helical propeller.]
- [FIG. 39. Blanks for racing (top) and chauviere (bottom) propellers.]
- [FIG. 40. The first step in carving a propeller. The blank. Hollowing the first blade.]
- [FIG. 41. One blade hollowed. Hollowing the second blade.]
- [FIG. 42 Rounding the back of the first blade. Rounding the back of the second blade.]
- [FIG. 43. All carving finished. Sandpapering to secure a smooth surface.]
- [FIG. 44. Varnishing. The propeller finished.]
- [FIG. 45. Accentricity. The effect of placing the center of gravity too low.]
- [FIG. 46. Simplest method of fitting two propellers to a model aeroplane.]
- [FIG. 47. A method of arranging two propellers on the same axis.]
- [FIG. 48. Simple bearings.]
- [FIG. 49. Double bearings.]
- [FIG. 50. Simple thrust bearing.]
- [FIG. 51. Ball thrust bearing.]
- [FIG. 52. Hooks.]
- [Plate IV.]
- [Plate V.]
- [Plate VI.]
- [FIG. 53. Method of holding plane to frame with rubber bands.]
- [Plate VII.]
- [FIG. 54. The Peerless Racer.]
- [Plate VIII.]
- [Plate IX.]
- [Plate X.]
- [FIG. 55. Racing blank and propeller.]
- [Plate XI. Winding a model.]
- [FIG. 56. A winder made from an egg beater.]
CHAPTER I. GENERAL PRINCIPLES UNDERLYING AEROPLANE FLIGHT.
To enter deeply into a discussion of the theory of the aeroplane would not only tire the reader but would waste valuable space in endeavoring to explain that which has been more adequately dealt with in more notable works.
In order to gain a clear understanding of the following chapters, however, it will be necessary to first grasp the elementary principles underlying the flight of an aeroplane. In setting these forth, I shall try, as far as possible, not to hamper or confuse with unnecessary terms or technicalities, except where such might be of worth in rendering a better conception of that to which they apply.
FIG. 1. Diagram showing a kite held in the air by the action of a wind. The dotted lines and arrow heads represent the direction and force of the wind.
An ordinary kite is one of the best examples of the action of an aeroplane. It is scarcely necessary to define the kite; it is a rigid frame of wooden sticks, on which is stretched a surface of cloth or paper. A string attached to the kite by means of a "bridle" serves to hold the apparatus to the ground.
In Fig. 1 is represented a kite against which the wind is blowing as indicated by the dotted lines. The string is so arranged that the kite is inclined at an angle to the wind and thus is sustained in the air by the force of the wind, viz., the molecules of air in striking against the slanting surface exert a pressure upon it which both calculation and experiment show to be perpendicular to the surface and tending to lift it. The kite also exerts a strong pull on the string which holds it in position.
But on days when there is no breeze or when the wind suddenly dies out; what is to be done then?
Wind is not an absolute thing. It is a relative movement of the surrounding air in comparison to a body. The effect is the same, and the relative movement takes place whether the air is still and the body in motion, or the air is in motion and the body motionless.