Now turn to section 4. Section 4. You will hear part of a lecture about balloons and airships. First, you have some time to look at questions 31 to 40. Now listen to the lecture and answer questions 31 to 40.
Now, balloons and airships are worth consideration because while on the one hand they represent humans' first successes at air flight, after centuries of less than successful theory and experimentation, they also, on the other hand, continue to be used today. We may have appeared to have moved on to jet planes and space rockets, but you can still see these more primitive flyers in the skies. Okay, gas balloons first.
France saw the first balloon flight in 1783, and this began a process of development. By 1862, in the Civil War in the United States, we find Thaddeus Lowe replacing spies with balloons to go behind enemy lines. The success of this led to the continued use of balloons in peacetime, and they were employed in the creation of maps.
And such applications continue to this day, with balloons assisting in increasing our knowledge and understanding of the world we live in. Unmanned balloons are still widely used to collect data to inform scientific research of various kinds. You'd be surprised at how much contribute.
All sorts of instruments can be mounted in a balloon, and ongoing investigations into climate benefit from the information that can be gathered from a flight. Well, that's gas balloons. Now, the increase in the popularity of ballooning as a sport or leisure activity has been mainly due to the development of the modern hot air balloon, being cheaper and safer than the gas balloon.
Heating air rather than using potentially explosive gas is what makes these rise, although the process doesn't generate as much lift as with gas balloons. But this is a small price to pay for its other benefits, and this type of balloon is no doubt here to stay. Airships are also fairly old in their origins.
The idea for a balloon that could be powered and steered was first published in France in 1784, although 1852 was the date of the first successful airship flight. The first airships, like the first aircraft, didn't provide any weather protection for their crew, so it must have been rather uncomfortable up there. But designs continued to develop in sophistication.
It was realised that the ships would drift about if they weren't strengthened, and that to work effectively, they would have to have a framework. Once design started incorporating this, flights became longer and more reliable. Airships were deployed for various uses in the First World War, and once peace returned, designers began to turn their attention to ambitious plans for regular intercontinental flights.
However, in the 1930s, this programme more or less came to an end. For one thing, the speed and popularity of airliners meant that the airship appeared superseded – they just couldn't compete. And as if that weren't enough in itself, another factor in the decline of the airship was an alarming number of crashes, and this of course put people off.
Nevertheless, several countries have continued to build smaller airships for various uses, such as naval observation or publicity purposes. In fact, their popularity seems set for a slight revival, and in the past few years, there has been renewed attention paid to the possibility of using them to transport cargo. Who knows, maybe the 21st century will be the age of the airship.
Now, if you look at your handouts, you'll see that I've included some information. That is the end of section 4. You now have half a minute to check your answers.