Lighter-Than-Air Aircraft are aircraft that rise and remain suspended by using contained gas weighing less than the air that is displaced by the gas.

Lighter-Than-Air Aircraft are aircraft that rise and remain suspended by using contained gas weighing less than the air that is displaced by the gas.

• A. True
• B. False
• C. Only for hot air balloons
• D. Only for airships

Answer: (A)

Lighter-than-air craft rise and stay aloft because the gas inside the envelope is less dense (weighs less per volume) than the surrounding air. When a volume of air is displaced, Archimedes’ principle says the craft experiences an upward buoyant force equal to the weight of that displaced air. If the weight of the gas inside the envelope is less than that displaced air, the buoyant force exceeds the gas’s weight, producing lift. This fundamental idea applies to all LTA types—hot-air balloons, helium/hydrogen balloons, and airships alike—so the statement is true. It isn’t limited to just hot air balloons or just airships.

Lighter-than-air craft rise and stay aloft because the gas inside the envelope is less dense (weighs less per volume) than the surrounding air. When a volume of air is displaced, Archimedes’ principle says the craft experiences an upward buoyant force equal to the weight of that displaced air. If the weight of the gas inside the envelope is less than that displaced air, the buoyant force exceeds the gas’s weight, producing lift. This fundamental idea applies to all LTA types—hot-air balloons, helium/hydrogen balloons, and airships alike—so the statement is true. It isn’t limited to just hot air balloons or just airships.