What Is An Aerostat?

A TCOM aerostat is a pressurized, completely flexible structure. Its hull is filled with the inert lighter-than-air, non-burning gas helium. Inside the lower part of the hull is an air compartment called a ballonet. An automatic system of sensors, switches, blowers and valves controls the super-pressure within the hull to maintain the external aerodynamic shape. There is associated power and housekeeping equipment. The hull is an aerodynamically-shaped balloon up to 71 meters in length, fabricated from a high-strength multi-layer fabric and designed for long term use in all types of environments. Thermally bonded together, the completed flexible structure exhibits an exceptionally low helium loss rate. The multi-layer laminate provides significant resistance to ultraviolet radiation, chemicals and oxidation, while offering a field-proven life expectancy of 10 plus years with minimum maintenance.

During the aerostat ascent to altitude, expanding helium forces air from the ballonet chamber to the atmosphere through automatic valves. As the aerostat is retrieved from altitude, the helium contracts, reducing hull pressure. This triggers an automatic mechanism that pumps air into the ballonet compartment to compensate. Aerodynamic shape is thereby maintained at all times.

An automatic system continuously monitors all vital aerostat data, including altitude; hull, fin, and windscreen pressures; helium and ambient air temperatures; blower and valve status; and aerostat pitch and roll. This information is relayed to the ground via radio or through fiber optics within the tether.

Although aerostats generally operate in a fully automatic mode, commands can be sent from the ground to control all blowers and valves. Similarly, all aerostat-borne payloads are controlled and monitored by the telemetry and command system.