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cabling should have a breaking strength of at least five times the maximum gross load that is suspended on the cables. This must include sand ballast, as well as the weight of the gondola, the occupants, and all supplies and equipment. For hydrogen systems, the cabling must be electrically conductive. For ammonia systems, the cables should be long enough to separate the occupants of the gondola from gas fumes coming out of the appendix. 

The bottom end of the cabling is gathered at a load ring which acts as the interface between the envelope and the gondola cables. The load ring also serves as the system’s strong point for attachment of inflation harnesses or trail ropes. 

## Equipment 

Equipment carried varies with the purpose of the flight. A minimum equipment list should include an altimeter/ variometer, compass, global positioning system (GPS), aircraft position lights, several flashlights (for night flights), oxygen (for high altitude flights), aircraft radio, and aircraft sectional maps for navigation and communication. [Figure 11-6]  Other items which may be included for safety and occupant comfort may include: a first aid kit, adequate food, water, warm clothing, and toilet facilities for both the planned flight and for the postflight period before the recovery crew arrives. 

<img src='content_image/602422.jpg'>

## Theory of Gas Ballooning 

Complete books have been written on the theory of gas ballooning and a full discussion of the topic is not possible here. At the very least, three topics must be understood by the competent gas pilot: physics, weather aspects, and the significance of different lifting gases. 

## Physics of Gas Ballooning 

Four main factors are instrumental in determining lift: 

1. Type of lifting gas used (e.g., helium, hydrogen, or anhydrous ammonia) 

2. Amount of lifting gas in the envelope (usually equal to the envelope’s total capacity) 

3. Outside air temperature 

4. Ambient barometric pressure (which is directly related to altitude and local weather conditions). 

## Lift at Sea Level 

The generation of buoyancy (commonly referred to as “lift”) in a gas balloon is somewhat different from that of a hot air balloon. The basic principle is the same, but for different reasons. 

One cubic meter of air weighs 2.702 pounds at sea level under International Standard Atmosphere (ISA) conditions (29.92 inches of mercury ("Hg) and 59 degrees Fahrenheit (°F) at sea level). At the same time, and also under ISA conditions, a cubic meter of helium weighs 0.3729 pounds. The difference between these two numbers, 2.329 pounds, is the gross lift of a gas balloon with a volume of one cubic meter. To determine the gross lift under ISA conditions, it then becomes a simple multiplication of 2.329 pounds times the volume of the envelope. For the standard 1,000 cubic meter gas balloon, the gross lift is 2,329 pounds. 

The above calculation is valid for helium. If, however, hydrogen is used as the lifting gas, the factor is 0.189 pounds per cubic meter; anhydrous ammonia’s weight is 1.583 pounds per cubic meter. As compared to helium, hydrogen has 8 percent more gross lift per cubic meter, while ammonia has approximately 50 percent less lift than helium under ISA conditions. 

## Lift at Altitude 

As a balloon ascends, it is generally true that temperature, atmospheric pressure, and gross lift all decrease. Gross lift decreases as pressure decreases, but increases as temperature decreases. Thus, as a gas balloon rises in the atmosphere, the decreasing pressure and temperature oppose each other. The decreasing temperature increases lift while the decreasing pressure decreases lift. Atmospheric pressure changes are more significant than temperature changes. Thus, net lift decreases as altitude increases in a standard atmosphere. 

