Posts

WORLD WAR II AIRCRAFT - INFO

-
Image
  WORLD WAR II AIRCRAFT WHEN WORLD WAR II began in 1999, air forces had already replaced most of their fabric skinned biplanes with all metal, stressed-skin monoplanes Aireraft played a far greater role in military operations during World War II than ever before, The wide range of sireraft duties, and the introduction of radar tracking and guidance systems, put pressure on designers to improve aircraft performance. The main areas of improvement were speed, range, and engine power. Bombers became larger and more powerful - converting from two to four engines in order to carry a heavier bomb load: the US B 17 Flying Fortress could carry up to 6,2 tonnes (6,1 tons) of bombs ver a distance of about 3,200 km 2.000 miles), Some aircraft increased their range by using drop tanks (fuel tanks that were jettisoned when empty to reduce drag). Fighters needed speed and manoeuvrability: the Hawker Tempest shown here had a maximum speed of 700 kph (36 mph), and was one of the few Allied aircra...
Post a Comment
Read more

AMERICAN FOOTBALL - INFO

-
Image
  AMERICAN FOOTBALL AMERICAN AND CANADIAN FOOTBALL, the object of the game is to get the ball across the opponent's goal line, either by passing or carrying it across (a touchdown), or by kicking it between their goalposts (a field goal). An American football team has 11 players on the field at a time, although up to 40 players can appear for each side an a single game. The agile "offence" tries to score points, and the heavy Hitting defence holds back the opposition. When in possession of the ball, a team has four chances ("downs"), to move it at least ten yards (in metres) up the field to make a "first down". The opposition gains possession if they fail, or by tackling and intercepting the ball, Canadian football is played on a larger field, with 12 men on each side. A team has only three chances to achieve a first down. Otherwise, the game is very similar to American football. Helmets, face masks, and layers of body padding are worn by the playe...
Post a Comment
Read more

TABLET COMPUTER - INFO

-
Image
  TABLET COMPUTER BY THE EARLY 1990s electronic circuitry had been miniaturized to such an extent that it was possible to make small handheld computing devices. The first of these was the Personal Digital Assistant (PDA), which offered features including an address book, calendar, and notepad. In recent years, PDAs have been overtaken by smartphones with Internet and email access (see pp. 588-589). A related product is the e-book reader, which stores books in digital form and uses "electronic paper" to mimic the appearance of ink on real paper. An e-book reader no bigger than a thin paperback can store several thousand digital books in its memory. The most recent handheld computing device is the tablet computer. This looks like a thin flat display, but it is actually a complete computer. Tablet computers are typically controlled by a touch-sensitive screen and have a wireless link to other computers and the Internet. They run software applications, or apps, downloaded fro...
Post a Comment
Read more

LIGHT AIRCRAFT - INFO

-
Image
  LIGHT AIRCRAFT LIGHT AIRCRAFT, SUCH AS THE ARV SUPER 2 shown here, are small, lightweight, and of simple construction. More than a million have been built since World War 1, mainly for recreational use by private owners. Virtually all light aircraft have piston engines, most of which are air cooled, although some are liquid cooled. Open cockpits, almost universal in the 1920s, have today been replaced by enclosed cabins. The cabins of high wing aircraft have one or two doors, whereas those of low-wing aircraft usually have a sliding or hinged canopy. Most modern light aircraft are made of aluminium alloy, although some are made of wood or of fibre reinforced materials. Light aircraft today also usually have navigational instruments, an electrical system, cabin heating wheel brakes, and a two-way radio.
Post a Comment
Read more

COMPETITION MOTORCYCLES - INFO

-
Image
        COMPETITION MOTORCYCLES THERE ARE MANY TYPES of motorcycle sport and in each, a specialist machine has evolved to perform to specific requirements. Races take place on roads or tracks or "off-road", in fields, dirt tracks, and even the desert. "Grand Prix" world championships in road-racing are contested by three classes: 125cc, 250cc two strokes; the top class of 500cc two-strokes; and 900cc four-stroke machines. The latest racing sidecars have more in common with racing cars than motorcycles.  The rider and passenger operate within an all-enclosing, aerodynamic fairing. The Suzuki RGV500 shown here, like other Grand Prix machines, carries advertising, which helps to cover the cost of developing motorcycle technology. In Speedway, which originated in the US in 1902, motorcycles operate without brakes or a gearbox. Off-road competition motorcycles have less emphasis on high power output. In Motocross, for example, which is held on rough terrain, they m...
Post a Comment
Read more

MOTORCYCLE ENGINES - INFO

-
Image
           MOTORCYCLE ENGINES MOTORCYCLE ENGINES must be light weight and compact, and have a good power output. They have between one and six cylinders, can be cooled by air or water, and the capacity of the combustion chamber varies from 49cc (cubic centimetres) to 1500cc. Two types of internal combustion engine are common: the four-stroke, which is used in cars (see pp. 342-343), and the two-stroke. A basic two-stroke engine has only three moving parts - the crankshaft, the connecting rod, and the piston - but the power output is high.  The engine fires every two strokes (rather than every four), giving a "power stroke" every revolution (see p. 343). Power is conveyed from the engine to the rear wheel by the transmission system. This usually consists of a clutch, a gearbox, and a final drive system. Clutches are multiplate devices, which run in oil. Gearboxes have five or six speeds and are operated by foot pedal. Shaft and belt drive systems are us...
Post a Comment
Read more

MOORING AND ANCHORING - INFO

-
Image
      MOORING AND ANCHORING FOR LARGE VESSELS IN OPEN WATER, ANCHORAGE IS ESSENTIAL. By holding a ship securely to the seabed, an anchor prevents the vessel from being at the mercy of wave, tide and current. The earliest anchors were nothing more than stones. In later years, many anchors had a standard design, much like the Admiralty pattern anchorshown on this page. The Danforth anchor is somewhat different. It has particularly deep flukes to give it great holding power. On large sailing ships, anchors were worked by teams of sailors. They turned the drum of a capstan by pushing on bars slotted into the revolving cylinder. This, in turn, lifted or lowered the anchor chain. In calm harbours and estuaries, ships can moor (make fast) without using anchors. Berthing ropes can be attached to bollards both in board and on the quayside. Berthing ropes are joined to each other by bends, like those opposite TYPES OF ANCHOR ● Close-stowing anchor ● CQR anchor ● Admiral...
Post a Comment
Read more