On completion of the survey of balloon materials other orders will be placed for experimental intermediate balloons.
As soon as a series of successful flights are obtained, it is planned to procure balloons of about 8 times the displacement of the intermediate size for tests as the model to solve the problem. These larger balloons would be about 30 feet in diameter.
Altitude Control
Mr. Goudy of the Kollsman Instrument Division of Square D Corporation was contacted to determine the feasibility of:
(1) An accurate pressure-actuated liquid ballast dropping device.
(2) A motor-switched modulator for the standard Army radiosonde AN/SMT-1. The standard pressure-switched modulator would be of little value in determining the height of the constant level balloon after it leveled off on a constant pressure surface.
On a subcontract Kollsman undertook to build a pressure actuated "dribbler" or ballast dropping device as follows:
Mechanically Controlled Dribbler
To consist of a diaphragm operated needle valve which will allow no flow for a 2 mb. increase in pressure on the diaphragm over pressure of which diaphragm is sealed but will allow a flow of 40 grams/minute under 1 foot of lead for a 5 mb. increase in pressure. Petroleum ballast with a density of about .775 gm/cc is to be used.
Diaphragm to be open to the atmosphere until it is sealed off by the radiosonde pressure switch at a preset altitude.
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