OVERVIEW

The experiments with the Plane-Dropper in the preceding chapter give the soaring speeds of wind-planes of different shapes set at varying angles, and enable us by the use of a fundamental formula of mechanics to make a provisional computation of the work expended per minute in their uniform horizontal flight, neglecting frictional resistances.

Among several conclusions, one of prime importance, namely, that in such aerial motion of heavy inclined planes the higher speeds are maintained with less expenditure of power than the lower ones, presents an appearance so paradoxical that, in view of its obviously extraordinary importance, I have endeavored to establish it independently wholly by experiment, without the use of any formula whatever. For this purpose it is desirable to measure by means of a suitable dynamometer the number of foot-pounds of work done in overcoming the resistance to advance when a wind-plane is driven at soaring speeds ( i. e., speeds at which it maintains a horizontal course by virtue of the vertical component of pressure, which in this case is just equal to the weight), by means of the whirling table, yet under conditions strictly assimilable to those of free flight, in the case of an actual aerodrome propelled by its own motor.

After much study and much experiment, I gradually perfected an instrument (that described here as the Component Pressure Recorder), to be used in connection with the Dynamometer-Chronograph in recording the speed, the resistance to forward motion at the instant...