must be compensated for by decreasing the load on the system to prevent descent to the ground.
This decrease of load is carried out by dropping liquid ballast as demanded by a pressure activated ballast control switch. This switch completes a circuit through a relay operated ballast valve whenever the balloon system descends to a region of pressure greater than that of its selected floating altitude. Ballast is thus dropped and the system returned to floating altitude.
On flights made on another project since the termination of the development phase of this project, the ballast control system was standardized to include a pressure displacement switch and an electrically operated ballast valve. The displacement switch (Fig.1) consists of a standard temperature compensated aneroid cell and pen arm from a radiosonde modulator
Fig. 1
Pressure Displacement Switch for Ballast Control