(2) Air System  The air system comprises a forward and an aft  ballonet, a system of scoops, ducts, valves and air chambers.  Air is taken in at scoops located in the port and starboard  motor outriggers and is led through a check valve of the  butterfly type into an air chamber.  From this chamber, two  air ducts lead, one  to  the forward and the other to the aft  ballonet, through  ma~ually  controlled dampers.  An automatic  valve is connected to each ballonet system and is set to  release air automatically when the pressure reaches a pre› determined value.  In  airships K-3 thru K-98, a blower with  a gasoline power plant is provided in the cabin to supply  pressure to the air system when the pressure from the regular  system becomes inadequate.  In airships K-99 and future, an  electric blower is provided.  The construction of the system  is described in full detail in the "Descriptive Specifications  Manual."  The operation of the system is considered further  below:  As mentioned above, air is collected by scoops located  in the port and the starboard outrigger and is led to an air  chamber through check valves.  This air chamber can be con› nected to either or both ballonets by means of two manually  controlled dampers.  The air pressure in the ballonets can  be adjusted within certain limits, as described further on,  by regulating the opening of the scoops.  (a) Scoops  -23-