contribution of physics in the aviation industry before situation
Answers
Answer:
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Explanation:
Once upon a time, air travel was risky, costly and highly polluting. But these days modern airliners are the safest way to travel long distances, as well as being cheaper, quieter and more fuel-efficient than their predecessors. If you need to cross the US, a seat on an Airbus will get you there on less than half the fuel of an average American car – and save you three days.
Unfortunately, this efficiency is a double-edged sword, encouraging more and more people to fly or send cargo by plane. Aviation’s contribution to the world’s CO2 emissions has risen from zero to 2% within the last century despite the fact that the litres of fuel burned per passenger-kilometre has plummeted – from 10.3 l/100 passenger-km for the De Havilland Comet 4 in 1958, when commercial flight with jet engine aircraft was new, to 2.42 l/100 passenger-km with today’s Airbus A330neo-900. Furthermore, with around 107,000 commercial flights taking place every day prior to the COVID-19 pandemic, noise pollution from airports is a huge concern.
Aviation’s contribution to the world’s CO2 emissions has risen from zero to 2% within the last century despite the fact that the fuel burned per passenger-kilometre has plummeted
Green solutions
So, what can be done to make aviation greener? Well let’s consider Boeing’s 787 Dreamliner – a modern airliner that looks much like its noisier, less-efficient ancestor, the 707. Each has a cylindrical fuselage with a square-root-of-x nose profile, wings swept back about 35°, and jet engines sticking forward from under the wings. This shape is set by the laws of mechanics and by compressible fluid flow.
Look closer, however, and differences emerge. The Dreamliner’s engines are fatter in front, so they have a high “bypass ratio” – they put less kinetic energy into the airstream for the same amount of thrust. The engine exhaust nozzles are scalloped with a chevron shape, which creates vortices in the exhaust fumes. When high-speed exhaust mixes with the slower-moving air, the vortices make less noise than the chaotic mixing of earlier engines.
More subtly, the leading edge of the 707’s aluminium wing is straight but the Dreamliner’s is curved, which reduces fuel-wasting drag. Although the shape is too complex to be affordably built with aluminium, it is made possible thanks to a composite material – carbon-fibre-reinforced plastic (CFRP). Besides allowing aircraft components such as the wings, tail and fuselage to have a wide variety of shapes, CFRP is stiffer and has a higher strength-to-weight ratio than aluminium or steel. These factors make the aeroplane lighter, so less fuel is needed to get it off the ground and keep it airborne.
One challenge of CFRP is in the factory, where it starts as a flexible fabric or tape infused with uncured epoxy resin. This is laid on moulds by hand or by automated tape-laying machines. To make it rigid, it then has to be “cured” or baked in an autoclave at temperatures of up to 180 °C, depending on the blend of CFRP. The problem is that ensuring that every region of the part stays at exactly the right temperature is tricky, calling for careful process control and sometimes for instruments embedded within the fabric. To verify that every ply of material (there can be as many as 100 layers) lies smoothly on the one below it with no wrinkles, voids or delaminations, aircraft manufacturers use inspection methods, such as machine-vision, for automatic checks while the tape is being applied, and X-ray and ultrasound to verify each part before it’s built into a larger structure.
Physics allows us to explain how engines work, both piston and gas turbine; how airplanes and helicopters fly; and countless other things related to the field of aviation and aerospace. In addition to allowing us to explain the operation of the things around us, it also allows us to quantify them.
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