Complementary Contracts:
a. Columbia University
No. W28-099-ac-32
b. University of California at Los Angeles
No. W28-099-ac-228
c. Woods Hole Oceanographic Institution
No. W28-099-ac-227
All contracts on: "Consultation and Assistance in Research on Atmospheric Acoustical Wave Propagation."
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2. Project title: Development of Constant Level Balloons
Project scientist: Dr. James A. Peoples, Jr.
Summary of In-Laboratory Work:
The development of a constant level balloon was at first motivated by the needs of the acoustic upper air sounding program. As it has developed, this balloon is now a principal atmospheric probing tool in its own right. In order to develop this balloon, several special devices have been invented. An Olland cycle pressure indicator, accurate to better than one millibar, has been developed. A device has been constructed which will deflate and bring down balloons in flight either by timing or by pressure activated mechanisms. A balanced flow control valve has been made which gives a constant flow of ballast material proportional to pressure change. Other accessories include a telemetering device to indicate the rate of ballast flow; minimum ballast flow, minimum pressure switches, barographs, and balloon tracking radio transmitters which can be picked up by an aircraft radio compass at a range of 100 miles or more. A sensitive integrating vertical anemometer is now being developed which will aid in the interpretation of atmospheric oscillations.
A thorough investigation of balloon materials and fabrication methods has been conducted, and balloons have been designed suitable for use with the ballasting mechanisms developed. Launching and operational techniques have been developed which permit the launching of balloons in winds up to 20 per hour. Good control of ascent rate and ceiling altitude has been obtained. Constant level flights of several hours duration are now routine and flights lasting up to 5 hours with pressure variations not greater than one or two millibars have been obtained. Simplified control which operate satisfactorily during the day or night are not adequate when sunset occurs during a flight. A system for maintaining constant level thru sunset has been devised and tested in a bell jar, but in actual flight tests have not yet been made. Temperature measurements have been made both inside and outside of balloons to show the effects of super-heat. Temperature measurements have also been made in instrument and battery cases during flight. Measurements to show the actual characteristics of control devices have been made on balloons in flight and simulated in the laboratory. This
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