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How does the engines make an airplane move?

How does the engines of an aircraft make the aircraft move when the aircraft weighs more than the total thrust? For example, let's say that an aircraft weighs 500000 pounds and has 2 engines producing 80000 pounds of thrust each. How does 160000 pounds of thrust move a 500000 pound aircraft? I'm so confused...

Posted by Mary Stegg on

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  • James M Knox
    James M Knox Jan 11, 2018

    Powered aircraft are pure Newtonian devices. That is, if you push against something, that something pushes back against you. A jet engine produces thrust by shoving air out the back at high velocity. As it pushes the air backwards, the reverse force pushes the plane forward. [This is not that different from blowing up a balloon and releasing it. Air escapes out one direction, and the balloon is forced the other.]

    As for how it works when the total engine thrust is so much less than the max gross weight of the aircraft - remember, it is not trying to LIFT the entire weight of the aircraft with the engine force. Think of your car out there in the relatively flat driveway. It may way between 1 and 2 tons - but you can still push the car. You can even get it going several miles per hour - as long as you keep pushing. [The force you apply by pushing is cumulative (minus losses).]

    By the same means, that jet thrust starts the plane rolling down the runway, faster and faster. The engines are NOT producing lift - just push. But the resulting airflow over the wings produces lift (why? different topic), and that causes the aircraft to climb. Engines continue to produce thrust, plane goes faster and faster, and plane climbs more.

    BTW, there ARE planes where the jet thrust is equal or greater than the weight of the plane. Advanced fighter jets are frequently almost all engine - have a thrust to weight ratio that is greater than 1.0, and can (for a while, at least) climb straight up.

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  • sherlywang
    sherlywang Jun 27, 2019

    As all we know, when we take by airplane, we see airplane is very big, and there many people in airplane, but why airplane can move, maybe many people has this confuse.
    If an object wants to fly, it must first have its own power system, and secondly, it must use upward thrust from the air. So airplane also needs these two conditions.
    The power system of an aircplane is the engine it carries. The engine provides power support to the airplane by burning chemical fuels.The design of airplane wings can help the airplane gain an upward thrust with the help of air.The streamlined design of the fuselage also helps to reduce the air resistance of the airplane as it flies forward in the air. When the airplane is ready to take off, the engine starts, giving the airplane a forward thrust and accelerating forward motion.
    Because the wing of the airplane is designed to be straight under the bend above, there will be a relative velocity between the wing and the air when the airplane moves forward, and the air will be divided into two streams by the wing.
    According to Bernoulli's principle, the airflow velocity passing through the surface of the wing is small and the airflow velocity passing through the flat surface under the wing is large. At this time, the airflow under the wing pushes the wing upward more than the airflow above the wing pushes the wing downward, thus giving the aircraft an upward force. And the greater the speed, the greater the difference between the two, and the greater the upward force. So when the speed of the aircraft forward to a certain extent, the upward force will be greater than the gravity of the aircraft, the aircraft will then start to fly upward.

    So there are many factors about airplane can move, such as diesel engine, the design of airplane itself, air conditions etc. More question about diesel engine, maybe you can see at:https://www.dieselgeneratortech.com/dies...

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