How do 747 engines work

In both of these types of engines, you need to get the main shaft spinning to start the engine. This starting process normally uses an electric motor to spin the main turbine shaft. The motor is bolted to the outside of the engine and uses a shaft and gears to connect to the main shaft. The electric motor spins the main shaft until there is enough air blowing through the compressor and the combustion chamber to light the engine.

Fuel starts flowing and an igniter similar to a spark plug ignites the fuel. Then fuel flow is increased to spin the engine up to its operating speed. If you have ever been at the airport and watched a big jet engine start up, you know that the blades start rotating slowly. The electric starter motor does that. They used less fuel. And they were much quieter than the old turbojets.

Early operators frequently used the upper-deck space aft of the flight deck as a premium-class Qantas' luxurious Captain Cook Lounge, pictured here, was particularly popular with travelers. The was arguably inadvertently responsible for the demise of supersonic transports SSTs like the Concorde. The was envisioned as only an interim intercontinental subsonic substitute before being replaced by SSTs.

In the late sixties, the next generation of SSTs was thought to be close to taking over the global aviation market. Once passenger SSTs were flying globally, Boeing was planning on primarily marketing the as a cargo freighter.

But it was the that was the big hit of the Paris Air Show. Ironically, at the time, even Boeing had some supersonic skin in the game. The Concorde also had range and capacity problems. It could barely accommodate passengers and its range limited it to crossing the North Atlantic. In contrast, the fledgling U. As the hot air blasts backwards through the nozzle the plane moves forward. Henri Giffard built an airship which was powered by the first aircraft engine, a three-horse power steam engine.

It was very heavy, too heavy to fly. In , Felix de Temple , built a monoplane that flew just a short hop down a hill with the help of a coal fired steam engine. Otto Daimler , in the late 's invented the first gasoline engine. In , American Hiram Maxim tried to power his triple biplane with two coal fired steam engines.

It only flew for a few seconds. The early steam engines were powered by heated coal and were generally much too heavy for flight. American Samuel Langley made a model airplanes that were powered by steam engines.

In , he was successful in flying an unmanned airplane with a steam-powered engine, called the Aerodrome. It flew about 1 mile before it ran out of steam. He then tried to build a full sized plane, the Aerodrome A, with a gas powered engine. In , it crashed immediately after being launched from a house boat.

In , the Wright Brothers flew, The Flyer , with a 12 horse power gas powered engine. From , the year of the Wright Brothers first flight, to the late s the gas powered reciprocating internal-combustion engine with a propeller was the sole means used to propel aircraft. It was Frank Whittle , a British pilot, who designed and patented the first turbo jet engine in The Whittle engine first flew successfully in May, This engine featured a multistage compressor, and a combustion chamber, a single stage turbine and a nozzle.

At the same time that Whittle was working in England, Hans von Ohain was working on a similar design in Germany. The first airplane to successfully use a gas turbine engine was the German Heinkel He , in August, It was the world's first turbojet powered flight. It was the XPA experimental aircraft that first flew in October, The basic idea of the turbojet engine is simple.

Air taken in from an opening in the front of the engine is compressed to 3 to 12 times its original pressure in compressor. The resulting hot air is passed through a turbine, which drives the compressor.

If the turbine and compressor are efficient, the pressure at the turbine discharge will be nearly twice the atmospheric pressure, and this excess pressure is sent to the nozzle to produce a high-velocity stream of gas which produces a thrust. Substantial increases in thrust can be obtained by employing an afterburner. It is a second combustion chamber positioned after the turbine and before the nozzle.

The afterburner increases the temperature of the gas ahead of the nozzle. The result of this increase in temperature is an increase of about 40 percent in thrust at takeoff and a much larger percentage at high speeds once the plane is in the air.

The turbojet engine is a reaction engine. In a reaction engine, expanding gases push hard against the front of the engine. The turbojet sucks in air and compresses or squeezes it. The fan blades for the Pratt engines are made with high-strength aluminum alloy with a titanium leading edge. Other jet-engine makers use hollow titanium blades or blades wrapped with carbon fiber.

Fun fact: the fan blades themselves are mini wings, generating lift. One thing you notice when you get near the engine is just how close the fan tips are to the engine casing. The tolerances must be incredibly small. In flight, the fan blades spin at around 3, RPM.

Any higher and the fan tips start to run supersonically, making a huge amount of noise in the form of a piercing drone. One shaft turns the low-pressure turbine, low-pressure compressor and the fan, which you can see on the diagram above.

Another shaft turns the high-pressure turbine and the high-pressure compressor. Each component needs to rotate at different speeds for each stage. These additional stages add weight and negatively affect fuel efficiency. The current gear box is around pounds; the first attempts were closer to pounds. The gear reduces the rotation speed three to one. If the low-pressure shaft is running at 10, RPM, the gearbox will act to reduce the fan itself to 3, rpm but — critically — without adding more lower-pressure stages.

Pratt has been working on it since Speich joined the company, and actively for 20 years of testing. In turn, you need fewer stages of low pressure — and less component weight — to run the fan at that slower speed.

They were also made with steel fan cases and forged steel components, which was quite heavy. Compare that to the GTF engine, which boasts a bypass ratio of 12 to 1. And in case you were wondering, the little swirl in the middle of the nose of the engine is to let anyone know — visually — whether the fan is spinning or not. Terms Apply. Disclaimer: The responses below are not provided or commissioned by the bank advertiser. Responses have not been reviewed, approved or otherwise endorsed by the bank advertiser.

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