(e) Take-Off 

Yv’hen the ship is in the hangar it is norl!lally J..cept under proper pressure by means of a ground blower. As the ship is taken out of the hangar, v;ea ther condi tion3 may be such as to cause a change of the temperature of the gas. 

If the temperature is increased, air will be released automatically by the air valves. If the temperature is de- creased, air may have to be blo~~ into the system to keep up the pressure. This may be done by opening the scoops and the air dampers, and speeding up the engines or it may be done by means of the auxiliary blower. 

NOTE: The dampers can be kept continuously open while air is blown occasionally in the system by man› euvering the throttles, the check valves pre› venting loss of air when the engines are idle. Under normal conditions, however, it is best to keep the dampers closed when not pumping air. 

(f) Climb 

As soon as the ship begins to rise, the problem is no longer one of feeding air to the system, but one of releas- ing air to maintain a constant differential pressure between the gas in the envelope an.d the decreasing atmospheric pressure. This is done automa tically as outlined above, by the <>-ir valves. The air valves and ducts can prevent the pressure from rising above 2.5 inches of water when the ship is rising a t a speed of 2400 ft. per minute. 

