Download or read book Modified Gas Valve for Improved Balloon Descent Control written by George F. Nolan and published by . This book was released on 1980 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to control balloon descent rates has been improved through use of a modified gas valve which has a range of openings. The descent rates obtained with this valve are more constant than those obtainable with the standard gas valve. Atmospheric temperature lapse rate and other thermal and aerodynamic influences are unquantifiable factors affecting balloon vertical motion, but are better compensated for when use is made of a variable opening gas valve. Even with this valve, slow descents on the order of 200 fpm or less will have oscillations with short periods of time when ascents and leveling off will occur. (Author).