During a climb, what is the main concern if damper valves are not closed?

If damper valves are not closed during a climb, the primary concern is that excess air might enter the envelope. This influx of air can create additional drag on the lighter-than-air vehicle, leading to a lower rate of ascent. Lighter-than-air vehicles, such as airships, rely on buoyancy provided by the lifting gas, and maintaining the right balance of internal pressure is crucial for effective climbing. When the damper valves remain open, it disrupts this balance, potentially leading to insufficient lift to achieve the desired ascent rate, which impacts overall performance and maneuverability.

While other factors like engine overheating or increased fuel expenditure may also be concerns in certain situations, they are not the primary issue directly related to the state of the damper valves during a climb. The immediate effect of excess air is the most significant factor influencing the rate of ascent.