## A. FLIGHT CHARACTERISTICS 

The lift of an airship is made up of two components -› the static lift and the dynamic lift. These two components have different physical origins and require separate treat› ment. 

## (1) Static Lift 

The static lift is that component of lift which is due to buoyancy and which iS independent of any motion of the ship with respect to the air. 

The gross static lift of an airship is the difference between the weight of the air displaced and the weight of the lifting gas. 

The net lift is the difference between the gross lift and the gross weight of the ship. 

The ship is said to be "light" when the gross lift ex› ceeds the gross weight. The ship is said to be "heavyn when the gross weight exceeds the gross lift. 

In calculating the gross lift of an airship both the gas volume and the lift coefficient of the helium, or lift per 1000 cubic feet, must be knovm. 

The lift coefficient c.an be computed, as indicated be› low, when various conditions of the atmosphere and of the helium are known. 

The gas volume, however, can be determined accurately only when the ship is fully inflated. Calculations of gross lift are largely limi t •ed, therefore to full inflation. 

