OPERATIONS MANUAL
I. INTRODUCTION
A. Purpose of Manual
This manual is designed to serve as a guide in the preparation, launching, and tracking operations of constant-level balloons. In the body of this manual, most of the discussion applies specifically to the 20-foot diameter balloon developed by General Mills, Inc. In Section IX, a brief description is given of the other sizes of balloons used for constant-level flight. The manual is based upon the experiences and investigations of the Constant Level Balloon Project, Research Division of the College of Engineering, New York University. The charts and tables which were developed to use for this work are included in Appendix II of the manual.
B. Principles of Altitude Control
For constant-level work, non-extensible balloons are used for three reasons:
(1) With a given weight of equipment, it is possible to determine before the release of the balloon, the maximum altitude which will be attained.
(2) Without special control equipment, it is possible to maintain a nearly constant altitude for periods from one to six hours, depending upon atmospheric conditions and floating level. Generally, it is not possible to extend such flights through a sunset.
(3) By adding altitude control equipment, it is possible to maintain the balloon at various nearly constant, predetermined levels for periods of much more than six hours regardless of the time of day.
II. GENERAL MILLS 20-FOOT BALLOONS
A. Description
General Mills, Inc. of Minneapolis, Minnesota, has developed a series of non-extensible, plastic balloons. These balloons are tear-drop in shape, made from extruded polyethylene sheet, 0.001" thick. Cells are currently produced with a diameter of 7, 20, 30 and 70 feet. The