IELTS Academic Reading Practice Test 162

The idea of a machine that could climb straight up into the air is older than the engine that made it possible. In the late 1400s Leonardo da Vinci sketched an 'aerial screw', a helical surface that would, he believed, bore into the air like a screw into wood. There was no engine to turn it, so it could not have flown. A simpler version of the idea existed as a toy: a stick with blades that spun when the stick was rolled between the palms. It had been known in China for centuries and had reached Europe by Leonardo's time.

The physical problem was always clear. A wing generates lift by moving forward through the air. A helicopter must instead make its wings travel in a circle, so that the blades keep meeting fresh air while the machine stays in one place. Turning a large disc of blades also produces a powerful twisting force, or torque, in the opposite direction, which tends to spin the fuselage. Every successful design has solved both problems at once.

Early experimenters attacked these difficulties with limited success. In 1907 the Breguet brothers built a machine with four pairs of rotors, which lifted off the ground but was held steady by men and never flew freely. In November of the same year Paul Cornu, a young French mechanic, made what is generally regarded as the first free flight by a rotary-wing aircraft. His twin-rotor machine, powered by an engine of about 24 horsepower, rose perhaps 30 centimetres and stayed in the air for around 20 seconds. It was a historic moment, but the machine was almost impossible to control.

Progress then came from a different direction. In 1923 Juan de la Cierva, a Spanish engineer, flew an aircraft whose wings had been replaced by a rotor that the engine did not drive. Once the machine was moving forward, air flowing up through the blades kept them spinning and produced lift. This 'autogyro' could fly slowly and land in a short space, though it could not hover. Its unpowered rotor also kept turning after the engine stopped, a principle later used to land helicopters safely after an engine failure.

The first machine to combine a powered rotor with real control was German. Heinrich Focke's Fw 61, which first flew in June 1936, used two rotors mounted side by side on outriggers. Because they turned in opposite directions, their torques cancelled and no tail rotor was needed. In 1938 the pilot Hanna Reitsch demonstrated the aircraft inside a large exhibition hall in Berlin, hovering near the ceiling in front of an audience. The Fw 61 is often called the first practical helicopter.

The arrangement most helicopters still use was developed by Igor Sikorsky, a Russian-born engineer who had emigrated to the United States and built large flying boats. His VS-300 made its first flight in September 1939, held by cables, and flew freely the following year. It had one main rotor and a small vertical tail rotor, whose thrust opposed the torque of the main rotor and could be varied to steer the machine. Sikorsky spent months altering the design until the arrangement worked.

The first helicopter produced in quantity was a development of this machine, the Sikorsky R-4, which first flew in 1942 and then entered service with the United States Army Air Forces. It was slow and carried only two people, but it could do things no aeroplane could: take off from a clearing, hover over a damaged ship and land in a small yard. During the Second World War it was used for observation and rescue.

In 1946 a two-seat design by Arthur Young, built by the Bell Aircraft Corporation, became the first helicopter to receive a civil airworthiness certificate in the United States. The Bell 47, with its glass bubble, went on to carry wounded soldiers in Korea and to spray crops. Its piston engine, however, was heavy and unreliable, and the range and lifting power of helicopters remained limited.

The turboshaft engine changed the machine in the 1950s. A turbine produces far more power for its weight than a piston engine and, having no pistons to balance, vibrates much less. The French Alouette II, which first flew in 1955, was the first turbine-powered helicopter to be built in numbers, and it set several altitude records. Larger transport and rescue helicopters soon followed.

Because it needs no runway, the helicopter has become essential where roads are absent or blocked. Ambulance services use it to reach accident sites and to move patients between hospitals; coastguard and mountain teams use it for rescue; and construction and offshore industries use it to lift equipment into places that no crane can reach. Its noise and fuel consumption, however, are far greater than those of a fixed-wing aircraft carrying the same load, and reducing both remains a focus of research.

Flying a helicopter remains demanding. The pilot uses the collective to change the pitch of all the blades together, and so the amount of lift; the cyclic tilts the plane in which the blades turn and moves the machine forwards, backwards or sideways; and pedals adjust the tail rotor. If the engine fails, the pilot lowers the collective so that the blades keep turning in the descending airflow. This manoeuvre, autorotation, allows the machine to glide down and to use the energy stored in the rotor to soften the landing.

Charging an electric car is slow. Even at a rapid charger, a typical model needs twenty minutes or more to take on enough energy for a long journey, and the fastest chargers are not available everywhere. Battery swapping offers an alternative. Instead of waiting for the pack in the vehicle to fill, the driver visits a station where machinery removes the depleted pack and fits a fully charged one, a process that can take less time than filling a petrol tank. The idea has been tried, abandoned and revived several times, and it now occupies a distinct and growing place in the market.

Mechanically, a swap is a precisely choreographed operation. The vehicle stops on a platform, and cameras and lasers measure its position so that the pack lines up with the lifting machinery within a millimetre or two. Bolts that hold the pack release, and the pack is lowered into the station. A charged replacement is raised into place, and the connections are remade: heavy electrical contacts, communication cables and the pipes that carry coolant to keep the cells at a steady temperature. Each connection must be watertight and secure, because a pack that worked loose at speed would be catastrophic.

The first large attempt to build a swapping network was made by Better Place, a company founded in 2007 by the Israeli entrepreneur Shai Agassi. It raised hundreds of millions of dollars, built stations in Israel and Denmark and persuaded Renault to produce a car designed around a removable pack. The idea attracted enormous publicity, but the arithmetic was unforgiving. Each station cost far more than a charger and served only a handful of cars, because few drivers had bought the one model that could use it. In 2013 the company went bankrupt, having sold far fewer cars than it had planned. Tesla, too, demonstrated a swap in 2013, showing a Model S exchanging its pack in about ninety seconds. The demonstration was impressive, but the company chose to invest in its own network of rapid chargers instead, and the swap was never offered widely to customers.

The most successful version of the idea is Chinese. The manufacturer NIO has built more than two thousand swap stations, most of them in China, and sells its cars with the battery excluded from the purchase price. Owners pay a monthly subscription that covers the use of a pack of the size they need and can upgrade for a long trip. Because the company owns every pack, it can decide how each one is charged and when it is retired. Swapping also lets NIO sell a car more cheaply than a rival with a comparable battery, since the most expensive component is not included.

Smaller vehicles have adopted swapping even more widely. In Taiwan, the company Gogoro operates a network of several thousand cabinet-sized stations where riders of its electric scooters exchange a flat battery for a fresh one in seconds. Similar systems have spread through cities in India, Indonesia and East Africa, where electric motorcycle taxis are used intensively and a spare battery can be carried by hand. For a rider who earns a living from the vehicle, ten minutes spent waiting at a charger is ten minutes of lost income.

Taxis, delivery vans and buses run almost continuously and return to a depot at night, so a station can serve many vehicles in turn. Their batteries can be charged slowly, when demand for electricity is low and prices are lowest, rather than at the high power that degrades cells. A station can also act as a store of energy, buying power at night and, in some designs, feeding it back to the grid when demand peaks. Because each pack spends hours in the station, its health can be monitored, and failing units withdrawn before they cause a breakdown.

The obstacles are considerable. A station must keep a stock of expensive packs, perhaps twenty for every ten cars it serves, and that capital sits idle for much of the day. Manufacturers build packs in different shapes and sizes, with different chemistries and cooling systems, so standardisation across brands has proved difficult; a station that serves only one model has a small market. The vehicle itself must be designed around the swap, which constrains its structure and crash protection. Rapid charging has also improved: a modern charger can add most of a battery's capacity in the time it takes to eat a meal.

Research is directed at these weaknesses. Several manufacturers are experimenting with packs built from smaller, standardised modules that can be handled by lighter machinery. Better sensors and data analysis allow a station to predict which packs will fail and to schedule their charging around the price of electricity. Regulators are beginning to require transparency: under European Union rules, each battery must carry a digital passport recording its history. For heavy trucks on fixed routes, where batteries are huge and downtime is costly, several companies are now testing swap stations.

None of this means that swapping will replace charging. The two solve different problems, and for a private car parked at home overnight a plug is hard to beat. But where vehicles run almost continuously, where charging is slow or unavailable, or where a battery is too costly to buy outright, exchanging it may be the better answer. The technology is unlikely to become universal; it is likely, instead, to settle into a niche, or rather several niches.

When the internet began to reach ordinary homes in the 1990s, it was widely described as a great leveller. Anyone with a connection, it was said, would have access to the same libraries, markets and audiences as anyone else. The phrase 'digital divide' entered policy language at about the same time, used to describe the gap between those who had access and those who did not. Three decades later the gap has narrowed dramatically but has not disappeared. The International Telecommunication Union estimated in 2023 that some 2.6 billion people were still offline, roughly a third of humanity.

The first version of the divide is the easiest to measure, and the easiest to fix. Most of the world's population now lives within reach of a mobile broadband signal, and the price of data has fallen sharply in most countries. What remains is a stubborn minority in places where there is no reliable electricity, no mast nearby or no affordable device. Here the obstacles are material: a phone costs money, a monthly allowance costs money, and a family with one handset between five people cannot treat it as a private connection. Progress has been real, but it has been slowest where poverty is deepest.

Access, however, was never the whole story. In the early 2000s the sociologist Eszter Hargittai drew attention to what she called the second-level digital divide: even among people with the same equipment, the benefits they obtain differ enormously, because using a computer well requires skills that are learned rather than bought. A patient who can navigate a health service's website, a student who can judge whether a source is trustworthy and an adult who can attach a document to an email are doing very different things with the same connection. Surveys consistently find that education, age and language predict these abilities more strongly than the presence of a device.

A rural clinic with a satellite connection but no trained staff gains little, while a well-educated family in a city can turn a slow connection into income. The pandemic made this interaction visible. When schools closed, children with a laptop, a quiet room and a parent at home continued to learn, while others shared a single phone with several siblings. The divide, in other words, is not a line between the connected and the unconnected but a series of steps, and people stand at different heights on them.

This matters because the cost of being offline is rising. Banks close branches, employers accept applications only through a website, schools post homework on a portal, and governments move services online in the name of efficiency. When a service becomes digital by default, the people who cannot use it are not merely inconvenienced; they are excluded from something they have a right to. The exclusion is quiet, because it happens in homes and queues rather than in visible protest.

Policymakers have often preferred simple technological answers, and these have a poor record. The best-known attempt to put a laptop in the hands of every child in the developing world began in 2005 and distributed machines in dozens of countries. Independent evaluations found disappointingly little effect on learning, largely because hardware without trained teachers, reliable power and suitable materials changes very little. When an Indian regulator banned differential pricing in 2016, it was not rejecting the desire to connect the unconnected but the terms on which the connection was offered.

The counter-argument is that the divide is closing by itself. Smartphones are now made in enormous numbers, and second-hand handsets circulate widely, so that even poor households often have one. But a phone is not a smaller version of a computer. Studies of 'smartphone-only' users find that they perform fewer tasks online: they read, watch and message, but rarely write a curriculum vitae, complete a tax return or manage a business's accounts. The device that connects them is also the device that limits what they can do.

If the divide is not simply about wires, neither is it only about skills. Affordability remains decisive. The United Nations has set a target that entry-level broadband should cost no more than two per cent of average monthly income, and in many low-income countries it costs several times that. Women are less likely than men to own a phone in parts of South Asia and sub-Saharan Africa, and the gap is widest among the poorest. A household budget under pressure will pay for food and school fees before it pays for data.

What works, then, is less glamorous than a new device. Competition between network operators has driven down prices wherever regulators have allowed it. Public access in libraries, schools and post offices gives people without a connection somewhere to go. Training for older people, content in local languages and services designed to work on cheap handsets all help. So does the decision to keep essential services available offline, through paper forms and telephone lines, until everyone can reach them online.

My own view is that the divide will not be closed by any single product, and that framing it as a gap in hardware has wasted a good deal of money. Connectivity is now a form of infrastructure, as necessary to a modern economy as roads and electricity, and it should be planned and subsidised as such. But infrastructure is only the beginning. The harder and slower work is building the skills, the affordability and the confidence that allow a connection to become a capability.