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Figs. 9-10-11-12. Showing the Use of Elevators in Changing Angle of Incidence. - Machine Shown in Four Principal Attitudes of Flight. As the Body and Wings Are in a Single Unit, the Body Must Be Turned for Each Different Wing Angle.

In Fig. 11, the large angle (i’) is still maintained, but the load is reduced to the value given in Fig. 9. With an equal load, an increased angle of incidence causes the machine to climb, as along the new flight line f-f. With the load (W) equal to that in Fig. 9, the angle of incidence will still be (i) but this will be along a new flight line if the large angle (i’) is maintained with the horizontal as shown by Fig. 11. With the wings making an angle of (i') with the horizontal, and angle of incidence (i) with the flight line, it is evident from Fig. 11 that the new flight line f-f must make an angle (c) with the original horizontal flight line F-F. This shows how an increased angle with a constant load causes climbing, providing, of course, that the speed and power are maintained. With a given wing and load there is a definite angle of incidence if the speed is kept constant. Should a load be dropped, such as a bomb, with the wing angle kept constant, the new path of travel will be changed from F-F to f-f.