In the reading passage, the author puts forward that airships could become popular
again because they offer a number of advantages over airplanes and helicopters.
However, the professor refutes all the possible explanations provided.
First of all, the passage argues that airships use less fuel. In comparison, the professor
challenges this argument by suggesting that airships require the special lighter-than-air
gases. To be specific, two common gases, hydrogen and helium, both have problems.
Hydrogen catches fire easily and resulted in many serious accidents in the past. As for
helium, although it is safer, it is hard to obtain and expensive. Also, it fails to provide
lifting power as much as hydrogen. Therefore, finding a solution that balances safety
and cost is not easy.
Moreover, the passage further suggests that airships can be used in hard-to-reach
locations and can carry very heavy loads. On the contrary, the professor opposes
against this argument by stating that when picking up heavy loads like tree logs in a
forest, it is difficult for airships to keep steady, especially under windy conditions. The
reason is that airships are large and light, and a sudden wind can easily blow the
airships against the forests and damage it.
Lastly, the passage claims that airships could be used to replace satellites. This
argument, however, is directly challenged by the professor in the lecture. The professor
proposes that airships that serve as satellites are about 14 kilometers above the earth
surface, but at that height, there are strong winds. In order to resist the winds and stay
in one place, airships would use up fuel quickly, and have to descend and refuel.