5.
(Type E preferred); a rotating commutator of two segments, an insulator and a conductor; a six volt 1 rpm motor; and a shelf for the pen arm. In calibration, the aneroid cell is moved across the base by means of a screw which allows selection of various altitudes for control.
Initially the pen arm rides on the shelf during ascent so that the circuit to the valve remains open until the balloon approaches floating altitude. Several thousand feet before ascent is completed the pen arm falls off the shelf closing the ballast circuit (Fig. 2) and causing ballast flow during the final period of ascent. When the balloon reaches control
[figure]
Fig. 2
Ballast Control Circuit