Aerostats: Frequently Asked Questions

Despite the exponential growth of global interest in the use of aerostats for a wide range of activities, there remains a gap in the understanding of some clients in their capabilities and strengths. These FAQs aim to clarify both the capabilities and the limitations of aerostat systems.

Aerostats use helium as their lifting gas.  Helium is not flammable. While hydrogen has been used, and might be used again in the future, it requires different materials and construction techniques to avoid generating static that might ignite the gas.

Conventional Aerostats can fly at up to 20,000ft  Above that altitude requires some modification to the pressure management system. The higher you want to go, the bigger the Aerostat needs to be.

One cubic metre of Helium can lift 1kg at sea level at standard temperature/pressure.  That volume of helium has to lift the weight of the Aerostat itself, the payload and the tether. As a rule of thumb, an Aerostat weighs around one third of its volume.

There are four main factors that affect the size of the Aerostat.  The weight of the payload, the length and weight of the tether that holds it, the altitude at which you want to fly, and the climate you will fly in. The more you want to carry, the higher you want to fly and the hotter it is, the bigger the Aerostat you will need.

Aerostats usually carry cameras, radars and electronic communication or monitoring devices.  The more you want to carry, the bigger the Aerostat required.

When flying at 1,000ft (300m), a camera mounted on an Aerostat will have a view to the horizon of over 38 miles (60km).  The better the camera, the further it can see clearly, but the heavier it will be.

Yes. With the right camera, you can observe oil pollution and algae blooms.  The best camera for the job will include HD day (EO) and night (IR) video, ultra violet (UV) and a stills camera. This sort of camera will weigh about 30kg.

Depending on its power consumption, you can use batteries carried on the Aerostat, or conductors built into the tether.  Both will add some weight to the system.

For security, you can use a tether with optical fibres built in, or use an encrypted radio or Wi-Fi/WiMAX solution. The quantity of data and the security required will determine the best solution.

Yes.  With the right communications devices, Aerostats can be part of a much wider communications system sending their data across the world.

An Aerostat can usually fly in windspeeds up to 60-80mph.  However, to launch or recover an Aerostat, the wind speed must be lower.  As with an aircraft, take-off and landing are the most critical stages of flight.  Aerostats are usually launched and recovered at a time of day when the wind is calm.

All Aerostats must have a means to deflate themselves if the tether breaks.  There are several ways of doing this using valves, cutting or burning a hole in the skin, or opening up a special deflation panel. This can be activated by GPS ring-fencing, pressure or altitude sensing.

Yes and no.  An Aerostat won’t burst, but enough bullet holes will allow the helium to escape over time, bringing it down slowly.  Usually the loss of lift is detected and the Aerostat is brought down for repair and topping-up.

Helium is a very slippery gas, so there is always some gas loss through the skin, depending on the materials and construction methods used.  A well designed and built Aerostat can accommodate between a week (for a small one) to a month (for a larger one) without needing to be topped up.

Yes you can. However, on anything but the smoothest ground and under the most favourable conditions, the system must be designed to accommodate the lumps and bumps in the terrain that will add shock loads to the tether, which might risk a break-away.