It is amazing isn't it ? Orville and Wilbur Wright would not have believed
it that over the span of 98 years, their world's first flight on the Kitty Hawk had progressed so much since then.
The Boeing 777 is the latest of the Boeing family that started with the first commercial model, the Boeing 707. Although the Boeing 777 is slightly smaller than the Boeing 747, it is more fuel efficient and has only two engines.
To imagine how heavy 287 tons is, just think of the combined weight of 3250 passengers weighing about 88 kilograms each. The Boeing 777 can carry up to 400 passengers depending on the configuration of the
seating. For comfort, most Airlines reduce the seating to 300 or below.
How it flies ?
How is it able to fly at a speed of about 550 miles per hour (480 knots/900
kph) in the thin air ? Basically, an airplane flies when the movement of air across their wings create an upward force on the wings that is greater than the force of gravity pulling the plane toward the earth.
The science behind this can be attributed to an 18th century Swiss named
Bernoulli. He discovered that the pressure exerted by moving fluid is inversely proportional to the speed of the fluid. In other words, fluid pressure decreases as speed of fluid increase and vice versa.
The same principle applies to moving air. The faster the air moves over the wing, the lower the air pressure is created, and the slower the air moves, the higher the pressure. This pressure differential creates lift.
The
theory of lift can be quite mind boggling to some. Try this
experiment. When someone is driving a car, get him to maintain a speed
of about 100 mph. Wind down the side screen and with your hand
steady, place your palm flat and cut into the air flow at zero angle. You find
that you could probably hold your hand into the air flow but the moment you
increase the angle from zero to some positive value, your hand will gradually
rise due to lift being created. So your palm is almost similar to the cross
section of an aircraft wing, though not that perfect in shape.
The faster the wing moves through the air, the greater the lift becomes, eventually overcoming the force of gravity.
The aircraft then takes off at about 160 miles per hour. It will continue to accelerate as it climbs to its cruising altitude of about 35,000 feet (about 7 miles high). It cruises at between 500 to 550 miles per hour.
During cruise, the weight of the aircraft, (about 280 tons now, due to some fuel being burnt off during the climb) and the lifting force generated by the wings are exactly equal.
What makes the aircraft move forward ?
Most Airlines own aircraft that are equipped with jet engines rather than propellers engines. The engines propel the aircraft to move forward through the thin air. The motion forward through the air generate lift, which enable the aircraft to take off and fly away.
A jet engine takes in air at the front, compresses it into smaller and smaller spaces by pulling it through a series of compressor blades. It then adds fuel to the hot compressed air and ignites the mixtures in a hot combustion chamber. This produces an explosion of extremely hot gases out of the rear of the engines and create a force known as thrust. The thrust then propels the engine, attached to the wings of the aircraft forward.
To
put it very simply, the principle of a jet engine can be described in just
five simple words. They are "suck, squeeze, blow and
go". That is good enough if you have some problem
understanding how the turbines and compressors work.
The most important
product of the jet engine is the 'go' or thrust at the back. Remember, when
you were young. You blew the balloon and the release it after it was
fully inflated. What happened? The balloon flew away. What cause
it to fly away? Well, when the air escaped, it is similar to thrust
being generated by a jet engine.
So with the thrust pushing the aircraft
forward, the speed will eventually increase and cause lift to be generated on
the aircraft wings. When the force of the lift increase to such an
extend that it would overcome the weight of the aircraft, the airplane will
just take off and climb away.
That is how the Boeing 777 is able to fly into the thin air.
