My Science School

Seaplanes and flying boats have floats instead of wheels, so that they can land on water. In the 1930s, flying boats were often larger and more luxurious than ordinary aircraft, as they could be made larger without the expense of creating longer runways at airports around the world. Instead, they took off and landed at sea, taxiing in and out of existing harbours.

In aviation, a water landing is, in the broadest sense, an aircraft landing on a body of water. Some aircraft such as floatplanes land on water as a matter of course. The phrase “water landing” is also used as a euphemism for crash-landing into water an aircraft not designed for the purpose, an event formally termed ditching. In this case, the flight crew knowingly makes a controlled emergency landing on water. Ditching of commercial aircraft is a rare occurrence.

Seaplanes, flying boats, and amphibious aircraft are designed to take off and alight on water. Alighting can be supported by a hull-shaped fuselage and/or pontoons. The availability of a long effective runway was historically important on lifting size restrictions on aircraft, and their freedom from constructed strips remains useful for transportation to lakes and other remote areas. The ability to loiter on water is also important for marine rescue operations and fire-fighting. One disadvantage of water alighting is that it is dangerous in the presence of waves. Furthermore, the necessary equipment compromises the craft's aerodynamic efficiency and speed.

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Air traffic controllers have screens on which they can see the planes in their sector. It is their job to see that planes are kept safely apart and guided appropriately during take-off and landing. When aeroplanes are near enough, the air traffic controllers can speak to them directly, but they cannot be expected to speak all the languages of international pilots. For this reason, to make communications as safe and clear as possible, all instructions and discussions take place in English all over the world.

Air traffic controllers use an aircraft’s registration mark when calling it by radio. As one letter can sound rather like another, words are used instead, each one standing for the letter that begins it.

Until controller-pilot data link communication (CPDLC) comes into widespread use, air traffic control (ATC) will depend upon voice communications that are affected by various factors. Aircraft operators and air traffic management (ATM) providers, like pilots and controllers, are close partners in terms of “productivity” for enhancing the airport and airspace flow capacity; operators and ATM should also be close partners in terms of “safety” or risk management.

Communication between controllers and pilots can be improved by the mutual understanding of each other’s operating environment. This briefing note provides an overview of various factors that may affect pilot-controller communication. It may be used to develop a company awareness program for enhancing pilot-controller communications.

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Gliders are so light that the lift created by their wings can overcome the opposing pull of gravity. However, without engines, gliders cannot take off. There are two widely used methods of launching gliders into the air. They can be catapulted upwards from the ground, or they can be towed up by an aeroplane. The cable between the plane and the glider is then released, and the glider can fly solo. A glider flight is an extraordinary experience, as it is almost silent except for the sound of the wind.

The wings on a glider have to produce enough lift to balance the weight of the glider. The faster the glider goes the more lift the wings make. If the glider flies fast enough the wings will produce enough lift to keep it in the air. But, the wings and the body of the glider also produce drag, and they produce more drag the faster the glider flies. Since there's no engine on a glider to produce thrust, the glider has to generate speed in some other way. Angling the glider downward, trading altitude for speed, allows the glider to fly fast enough to generate the lift needed to support its weight.

The way you measure the performance of a glider is by its glide ratio. This ratio tells you how much horizontal distance a glider can travel compared to the altitude it has to drop. Modern gliders can have glide ratios better than 60:1. This means they can glide for 60 miles if they start at an altitude of one mile. For comparison, a commercial jetliner might have glide ratios somewhere around 17:1.

If the glide ratio were the only factor involved, gliders would not be able to stay in the air nearly as long as they do. So how do they do it?

The key to staying in the air for longer periods of time is to get some help from Mother Nature whenever possible. While a glider will slowly descend with respect to the air around it, what if the air around it was moving upward faster than the glider was descending? It's kind of like trying to paddle a kayak upstream; even though you may be cutting through the water at a respectable pace, you're not really making any progress with respect to the riverbank. The same thing works with gliders. If you are descending at one meter per second, but the air around the plane is rising at two meters per second, you're actually gaining altitude.

Newton’s third law of motion states that, for every action, there is an equal and opposite reaction. Based on this law, wings are forced upwards because they are tilted, pushing air downwards so the wings get pushed upwards. This is the angle of attack or the angle at which the wing meets the airflow.

As air flows over the surface of a wing, it sticks slightly to the surface it is flowing past and follows the shape. If the wing is angled correctly, the air is deflected downwards. The action of the wing on the air is to force the air downwards while the reaction is the air pushing the wing upwards. A wing’s trailing edge must be sharp, and it must be aimed diagonally downwards to create lift. Both the upper and lower surfaces of the wing act to deflect the air.

The amount of lift depends on the speed of the air around the wing and the density of the air. To produce more lift, the object must speed up and/or increase the angle of attack of the wing (by pushing the aircraft’s tail downwards).

Speeding up means the wings force more air downwards so lift is increased. Increasing the angle of attack means the air flowing over the top is turned downwards even more and the air meeting the lower surface is also deflected downwards more, increasing lift. There is a limit to how large the angle of attack may be. If it is too great, the flow of air over the top of the wing will no longer be smooth and the lift suddenly decreases.

Birds and planes change their angle of attack as they slow to land. Their angle of attack is increased to ensure their lift continues to support their weight as they slow down. Wings and tails need to be movable so that their shapes can be changed to control their flight.

Helicopters have rotor blades above them that are aerofoils. When they turn rapidly, they create lift. The blades are tilted slightly, so that they also provide thrust. The helicopter’s tail rotor blades stop the helicopter from spinning and enable it to turn. With this combination of rotors, a helicopter can move in any direction or simply hover. Without long wings, helicopters can manoeuvre in tight places, such as alongside cliff faces, so they are particularly useful for rescue and emergency work.

The science of a helicopter is exactly the same as the science of an airplane: it works by generating lift—an upward-pushing force that overcomes its weight and sweeps it into the air. Planes make lift with airfoils (wings that have a curved cross-section). As they shoot forwards, their wings change the pressure and direction of the oncoming air, forcing it down behind them and powering them up into the sky: a plane's engines speed it forward, while its wings fling it up. The big problem with a plane is that lots of air has to race across its wings to generate enough lift; that means it needs large wings, it has to fly fast, and it needs a long runway for takeoff and landing.

Helicopters also make air move over airfoils to generate lift, but instead of having their airfoils in a single fixed wing, they have them built into their rotor blades, which spin around at high speed (roughly 500 RPM, revolutions per minute). The rotors are like thin wings, "running" on the spot, generating a massive downdraft of air that blows the helicopter upward. With skillful piloting, a helicopter can take off or land vertically, hover or spin on the spot, or drift gently in any direction—and you can't do any of that in a conventional plane.

Aeroplanes fly when two of the four forces acting upon them are greater than the other two. The force of thrust, created by the aeroplanes propellers or jet engines, moves the plane forward. The force of lift is caused by air flowing over the wings. This keeps the plane in the air. The two forces working against thrust and lift are gravity, which pulls the plane towards the Earth, and drag, caused by air resistance, which slows the plane’s forward motion.

Four forces act on a plane in flight. When the plane flies horizontally at a steady speed, lift from the wings exactly balances the plane's weight and the thrust exactly balances the drag. However, during takeoff, or when the plane is attempting to climb in the sky, the thrust from the engines pushing the plane forward exceeds the drag (air resistance) pulling it back. This creates a lift force, greater than the plane's weight, which powers the plane higher into the sky.

If you've ever watched a jet plane taking off or coming in to land, the first thing you'll have noticed is the noise of the engines. Jet engines, which are long metal tubes burning a continuous rush of fuel and air, are far noisier (and far more powerful) than traditional propeller engines. You might think engines are the key to making a plane fly, but you'd be wrong. Things can fly quite happily without engines, as gliders (planes with no engines), paper planes, and indeed gliding birds readily show us.

Newton's third law of motion explains how the engines and wings work together to make a plane move through the sky. The force of the hot exhaust gas shooting backward from the jet engine pushes the plane forward. That creates a moving current of air over the wings. The wings force the air downward and that pushes the plane upward.

Beneath cities are the foundations of large buildings and many pipes carrying water, electricity, gas and telephone cables. Builders have either to tunnel very deeply or to use a technique called “cut-and-cover”, which means that they run the railway under existing roads, so that they simply have to dig a huge trench along the road, build the railway, and cover it up again.

The building method used for many years was a so-called “cut-and-cover” system. It was easier to dig out a large open hole in the road, build the arch of the false tunnel with bricks, and then refill the hole with the dug-out material. As a result, the first underground lines were not very deep, something that tends to be the case with the older underground lines in major cities.

One of the companies of the time, C&SLR, was the first to use electric traction for pulling the trains, as well as a new method for digging circular tunnels, using a technology known as “shield tunneler”, which initially was opearated manually. The front part was used to dig out a circular section and the tunneling machine was called the Greathead Shield. Later on, the shield became mechanical and the machine advanced much more rapidly and could cut through any type of material. Today, these are called TBMs, or Tunnel Boring Machines.

These tunnelling machines made it possible to dig under the city at a greater depth and create new underground lines on another level: they could dig under buildings and keep away from electricity lines, sewers and other infrastructures. They could even dig under the Thames.

Fast forward 155 years to our times. A massive new rail undertaking spanning over 100 km, more than 40 km of which run below the streets of London, connecting with the underground network at some points.

The world’s first city underground railway line was opened in 1863 in London. It was called the Metropolitan. The London Underground (also known simply as the Underground or by its nickname the Tube) is a public rapid transit system serving London region, England and some parts of the adjacent counties of Buckinghamshire, Essex and Hertfordshire in the United Kingdom.

The Underground has its origins in the Metropolitan Railway, the world's first underground passenger railway. Opened in January 1863, it is now part of the Circle, Hammersmith & City and Metropolitan lines; the first line to operate underground electric traction trains, the City & South London Railway in 1890, is now part of the Northern line. The network has expanded to 11 lines, and in 2017/18 carried 1.357 billion passengers, making it the world's 12th busiest metro system. The 11 lines collectively handle up to 5 million passengers a day.

The system's first tunnels were built just below the ground, using the cut-and-cover method; later, smaller, roughly circular tunnels—which gave rise to its nickname, the Tube—were dug through at a deeper level. The system has 270 stations and 250 miles (400 km) of track. Despite its name, only 45% of the system is underground in tunnels, with much of the network in the outer environs of London being on the surface. In addition, the Underground does not cover most southern parts of London region, and there are only 29 stations south of the River Thames.

A cowcatcher is a V-shaped metal part on the front of a train, designed to push obstacles — including cows! — Off the line before the wheels hit them. The American Denver and Rio Grande steam engine has an example.

Cowcatchers were wooden bars added to a metal frame and fitted to electric corporation trams in cities across Britain as they were set up in the very early 1900. A cow catcher is a device attached to the front of a train or tram in order to clear obstacles off the track.

Invented in 1838 by British engineer Charles Babbage, this device is now used mostly in North America, as modern European railway systems tend to be fenced off and less susceptible to the danger of foreign objects on the track. In the locomotive industry, a cow catcher is more commonly referred to as a pilot. A cow catcher is typically a shallow, V-shaped wedge, designed to deflect objects from the track at a fairly high speed without disrupting the smooth movement of the train.

The shape serves to lift any object on the track and push it to the side, out of the way of the locomotive behind it. The first cow catcher models were constructed of a series of metal bars on a frame, but sheet metal and cast steel models became more popular, as they work more smoothly. When steam-powered locomotives became more common, the cow catcher was often supplemented with a drop coupler.

The front coupler, a device used to attach railroad cars to each other, was fashioned to hinge up and out of the way in order to prevent its catching on obstacles. Another bygone pilot model is the footboard pilot, which featured steps on which railway workers could stand and catch a ride.

In the 1960s, these pilots were outlawed and replaced with safer platforms on the front and rear of the locomotive. Today, people in the railroad industry frown upon the term "cow catcher," but the pilot is still in use. Today's pilots are much smaller and shallower than their predecessors.

Since diesel locomotives feature front cabs carrying crew, the pilot must be constructed to prevent the cab from being struck by objects deflected from the road. A separate feature known as an anticlimber is typically installed above the pilot to protect the cab.

The intersections that allow a train to move over onto another track are called switches or points. Short pieces of rail are able to move across to bridge the gap between the two tracks, so that the train’s wheels cross over as smoothly as possible.

To make a train change its track, a special mechanical arrangement is made. This arrangement is known as a railroad switch and it consist of pair of rails, known as switching rails or points that are linked to one another. As the name suggests, the switching rails can direct or guide the train, either on straight path or on the diverging path which is established by a curved rail line.

The railroad switch can only be in one of the two positions at a time. If it is locked the train will change the track. If it is open, it will go straight-through. Here is animated rail-road switch demonstrating the principle and operation.

It is very important that the switch is set up carefully. Most train derailments take place at the point when it goes from one track to another track. A loose set up is a guarantee of making train jump off the track, a disaster. However, a railway authority, not only in India, but around the world has expertise the art of train track changing. Most times the process is so smooth, that one even doesn't notice it. However an experienced traveler can make out with the sound of the train, that indeed the track is changed.

Sometimes tracks are changed at the last moment to change the platform at which the train arrives. An Indian railway is overly notorious in this regard. So many times people are caught napping when they would be waiting for train at one station only to hear a last time announcement that the train is arriving at the other platform. This is especially problematic if the halt of train is of couple of minutes only, on a specific station.

In India there are mostly two railway tracks that you'll see running parallel to each other. One is known as the 'up' track, and other is 'down' track. But as soon as any railway station comes, there are plenty of tracks that one can see. This is where the train wills starts climbing from one track to another to get to the platform from where it is scheduled to leave.

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A Locomotive is an engine that can travel under its own power, not pulled by horses, for example. But we usually think of it as running on tracks, or tramways, as they were first called. In 1804, Richard Trevithick (1771-1833), an English inventor, designed a train to pull coal wagons in a Welsh colliery. Trevithick was convinced that steam engines had a great future and later travelled to Peru and Costa Rica, where he introduced steam engines into the silver mines.

In 1802, Richard Trevithick patented a "high pressure engine" and created the first steam-powered locomotive engine on rails.  Trevithick wrote on February 21, 1804, after the trial of his High Pressure Tram-Engine, that he "carry'd ten tons of Iron, five wagons, and 70 Men...above 9 miles...in 4 hours and 5 Mints."  Though a ponderous-sounding journey, it was the first step toward an invention that would utterly change man's relationship to time and space. 

George Stephenson and his son, Robert, built the first practical steam locomotive.  Stephenson built his "travelling engine" in 1814, which was used to haul coal at the Killingworth mine.  In 1829, the Stephenson built the famous locomotive Rocket, which used a multi-tube boiler, a practice that continued in successive generations of steam engines.  The Rocket won the competition at the Rain-hill Trials held to settle the question of whether it was best to move wagons along rails by fixed steam engines using a pulley system or by using locomotive steam engines. The Rocket won the £500 prize with its average speed of 13 miles per hour (without pulling a load, the Rocket attained speeds up to 29 miles per hour), beating out Braithwaite and Erickson's Novelty and Timothy Hackworth's Sans Pareil.  The Stephenson incorporated elements into their engines that were used in succeeding generations of steam engines.

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The gauge of a railway is the distance between its rails. At one time, the standard gauge in several countries was 1.48m (4ft 10.25 in), which was thought to have been the width of Roman chariot tracks. Today, many different gauges are used.

In rail transport, track gauge or track gage is the spacing of the rails on a railway track and is measured between the inner faces of the load-bearing rails.

All vehicles on a rail network must have running gear that is compatible with the track gauge, and in the earliest days of railways the selection of a proposed railway's gauge was a key issue. As the dominant parameter determining interoperability, it is still frequently used as a descriptor of a route or network.

In some places there is a distinction between the nominal gauge and the actual gauge, due to divergence of track components from the nominal. Railway engineers use a device, like a caliper, to measure the actual gauge, and this device is also referred to as a track gauge.

The terms structure gauge and loading gauge, both widely used, have little connection with track gauge. Both refer to two-dimensional cross-section profiles, surrounding the track and vehicles running on it. The structure gauge specifies the outline into which new or altered structures (bridges, lineside equipment etc.) must not encroach. The loading gauge is the corresponding envelope within which rail vehicles and their loads must be contained. If an exceptional load or a new type of vehicle is being assessed to run, it is required to conform to the route's loading gauge. Conformance ensures that traffic will not collide with lineside structures.

Steam locomotives are described by the arrangement of their leading, driving and trailing wheels. In fact, only the driving wheels are connected to the cylinders that provide the engine’s power. So a 2-8-2 has two leading wheels, eight driving wheels and two trailing wheels.

Under the Whyte notation for the classification of Steam locomotives, 2-8-2 represents the wheel arrangement of two leading wheels on one axle, usually in a leading truck, eight powered and coupled driving wheels on four axles and two trailing wheels on one axle, usually in a trailing truck. This configuration of steam locomotive is most often referred to as a Mikado, frequently shortened to Mike.

At times it was also referred to on some railroads in the United States of America as the McAdoo Mikado and, during the Second World War, the MacArthur.

The notation 2-8-2T indicates a tank locomotive of this wheel arrangement, the "T" suffix indicating a locomotive on which the water is carried in side-tanks mounted on the engine rather than in an attached tender.

The 2-8-2 wheel arrangement allowed the locomotive's firebox to be placed behind instead of above the driving wheels, thereby allowing a larger firebox that could be both wide and deep. This supported a greater rate of combustion and thus a greater capacity for steam generation, allowing for more power at higher speeds. Allied with the larger driving wheel diameter which was possible when they did not impinge on the firebox, it meant that the 2-8-2 was capable of higher speeds than a 2-8-0 with a heavy train. These locomotives did not suffer from the imbalance of reciprocating parts as much as did the 2-6-2 or the 2-10-2, because the center of gravity was between the second and third drivers instead of above the centre driver.

The first 2-8-2 locomotive was built in 1884. It was originally named Calumet by Angus Sinclair, in reference to the 2-8-2 engines built for the Chicago & Calumet Terminal Railway (C&CT). However, this name did not take hold.

The wheel arrangement name "Mikado" originated from a group of Japanese type 9700 2-8-2 locomotives that were built by Baldwin Works for the 3 ft 6 in (1,067 mm) gauge Nippon Railway of Japan in 1897. In the 19th century, the Emperor of Japan was often referred to as “the Mikado” in English. Also, the Gilbert and Sullivan opera The Mikado had premiered in 1885 and achieved great popularity in both Britain and America.

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The first public railway in the world to run a regular service was opened on 27 September 1825. It ran between Stockton and Darlington in the north of England. A steam train called The Locomotion pulled 34 wagons, some of which carried coal, while others were adapted to carry passengers. Both the locomotive and its track were built to the design of George Stephenson (1781-1848). Stephenson’s background was in mining engineering. Coal mines had long used tracks to move wagons of coal, and it was with steam engines for these wagons that Stephenson first experimented.

“The world’s first public railway to use steam locomotives, its first line connected collieries near Shildon with Stockton and Darlington… The movement of coal to ships rapidly became a lucrative business, and the line was soon extended to a new port and town at Middlesbrough. While coal waggons were hauled by steam locomotives from the start, passengers were carried in coaches drawn by horses until carriages hauled by steam locomotives were introduced in 1833". 

One of the significant results of the success of the Stockton and Darlington project was the extent to which it gave support to plans for building a railway between Liverpool and Manchester.

 

Two areas of car design have been researched very thoroughly in the past few years. One of these concerns fuel consumption and exhaust gases, as the realization grows that the world’s fossil fuels are polluting the atmosphere. The other is safety. It is likely that future cars will be able to prevent some accidents by assessing - the distance to an obstacle and taking evasive action without prompting from the driver.

After decades of auto technology that had evolved only marginally since the mid-20th century, experts say we’re now seeing a super-fast shift that's comparable to the industry's early days. “In the last 30 to 40 years the way cars were manufactured didn’t change much,” says Ozgur Tohumcu, CEO of the car-tech company Tantalum. “But now things are fundamentally changing — and very quickly.”  Quickly, indeed. Here's a look at some of the cool innovations we're likely to see in the next generation of cars.

Voice commands for your car

High on the list of innovations is the introduction of Alexa-like personal assistants. “You’ll be able to interact with your car through voice command,” says Tohumcu. One scenario: You might be driving and looking for a parking space. All you’ll have to do is say “Find parking,” and your vehicle will navigate you to the closest, least expensive, safest garage, based on your programmed preferences, and then pay the fee with your credit card.

Mechanic on wheels

Cars will be able to diagnose their own mechanical problems. “If it’s a software fix that’s needed, you’ll get an upgrade,” Tohumcu says. If you need to take the car to a mechanic, the car will research the options and book itself an appointment. (It will be able to renew its own insurance and look for better deals, too.)

More map options

As navigational maps get overlaid with more data, you’ll be able to choose your route based on a broadening array of criteria, including “least polluted.” “People will be taken from point A to point B through better air-quality routes,” Tohumcu says. “If you’re an older person or you have chronic asthma, this becomes a real benefit.” Other possibilities: “safest route” and “most scenic.”

Custom-designed vehicles

Using 3D printing technology, Arizona-based Local Motors is 3D-printing cars. “They work with pre-determined engine types and 3D print cars on top of those engines,” Tohumcu says. “You can pick and choose features from different cars to create your own.” That means we may see all kinds of interesting-looking cars on the street, he says. “These cars won’t be cheap, but if you really want to stand out it’s one way to go.”

Shared autonomous vehicles

Self-driving cars are already here and doing well in safety tests, says Alan Brown, executive vice president at NuVinAir, an automotive-industry startup, who previously spent 27 years with Volkswagen. The twist he predicts: People will be able to share these cars. “Cars today sit unused 80 percent of the time,” he says. “If the car is self-driving, we have a wonderful opportunity for people to co-own it and pay only for the portion of the car they use.” He sees the potential, in particular, for younger people who may not be able to afford their own vehicle, people with disabilities who aren’t able to drive, and older people who may need to stop driving.

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