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[[balance]] of forces on the mechanically propelled airship, suggest themselves as a suitable form of relation. 

As the propelling force is counter-balanced by the resistance of the hull and its accessories, the speed at which an airship of given size can be driven by the horse-power installed depends on the efficiency of conversion of that power available at the crankshaft into useful thrust and on the quality of the airship with regard to drag. This quality is affected only by the drag coefficient, which like the efficiency of conversion of power is non-dimensional. If put into mathematical form the forces acting on an airship in motion may be written as follows:

Airscrew thrust in kg. P - 75 E x N / v

Resistance in kg. W - D-c x Y/g x J 2/5 x v2

where 
v is the velocity of the airship in meters per second, 
N    the total horsepower available at the crankshaft,
E    the efficiency of the airscrew and the transmission gear, 
J    the volume of the airship in cubic meters,
D-c  the drag coefficient of the hull and accessories.

As the forces P and W must be in equilibrium, the above equation may be reduced to the following:

E/D-c - Y/g x J 2/3 x v3/75 N

which represents the efficiency of propulsion. It shows the degree 

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Transcription Notes:
---------- Reopened for Editing 2024-04-27 23:47:53