On a balloon equipped with a blast valve, what is the primary use of the blast valve?

On a balloon equipped with a blast valve, what is the primary use of the blast valve?

• A. Altitude control
• B. Emergency venting only
• C. Temperature control
• D. Ground speed control

Answer: (A)

The blast valve is used to change altitude quickly by rapidly venting hot air from the envelope. When you open it, hot air bursts out, reducing buoyancy and allowing a rapid descent or a faster adjustment of the flight level. Heating with the burner controls ascent, while the blast valve provides a swift way to shed buoyancy when you need to drop altitude or make a precise altitude change. It isn’t intended as a temperature-control device, since venting hot air mainly changes weight and buoyancy, not the overall temperature you’re maintaining. Ground speed is governed by the wind, not by the blast valve.

The blast valve is used to change altitude quickly by rapidly venting hot air from the envelope. When you open it, hot air bursts out, reducing buoyancy and allowing a rapid descent or a faster adjustment of the flight level. Heating with the burner controls ascent, while the blast valve provides a swift way to shed buoyancy when you need to drop altitude or make a precise altitude change. It isn’t intended as a temperature-control device, since venting hot air mainly changes weight and buoyancy, not the overall temperature you’re maintaining. Ground speed is governed by the wind, not by the blast valve.