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Is it possible for an airplane to fly as it compress the atmospheric air during flight?

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    $\begingroup$ Sure, but how does the air come to be compressed? Compressing air requires energy of some sort and "fuel" happens to be a particularly efficient form of energy storage, especially when you're interested in getting the most energy per pound. There was an early (1879) model airplane with a compressed air engine and small compressed air model rockets are certainly possible. There are a lot of practical concerns with filling a large airliner on the ground with enough compressed air for a flight. $\endgroup$ – Zach Lipton Feb 29 '16 at 8:11
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    $\begingroup$ Yes. The problem is that you cannot compress a gas to store anywhere near as much energy as petrol or diesel. $\endgroup$ – Simon Feb 29 '16 at 8:11
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    $\begingroup$ related: aviation.stackexchange.com/q/17648/1467 aviation.stackexchange.com/q/14710/1467 $\endgroup$ – Federico Feb 29 '16 at 8:14
  • $\begingroup$ we use electric motor installed in the jet engine. we use the same jet engine layout but without fuel and combustion chamber. $\endgroup$ – Ziyad Razali Feb 29 '16 at 8:20
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    $\begingroup$ So basically you're describing an electrically powered aircraft (like the prototype Airbus E-Fan, which uses two electrically powered ducted fans and a motor-driven wheel on the gear to help with takeoffs). There's no reason for it to be a jet at that point, it's just a motor turning a fan. This leads to the next question: where does the electricity come from? It has to be generated and stored somewhere. And jet fuel stores far more energy per pound than any available battery technology. $\endgroup$ – Zach Lipton Feb 29 '16 at 8:33
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First of all, where does the compressed air come from? Is it stored in big tanks, or do you compress it as you fly?

Assuming you use the second way (the first would be quite inefficient), you need to power the Air Compressor, which means you need to generate energy.

If you do not want to use fuel, then it has to be powered by electricity, i.e. an electric plane. This is basically how the Airbus E-Fan works, using two ducted fans powered by electricity (as @Zach Lipton said in the comments)

So to answer your question, yes, your theory works. There are already a few prototypes using it.

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  • $\begingroup$ yes, the second option, thanks $\endgroup$ – Ziyad Razali Feb 29 '16 at 17:33
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    $\begingroup$ Yes, but by the time you're to the point of the E-Fan or a similar aircraft, you're not really talking about an aircraft powered by compressed air anymore. You've just got a fan, and that's no different from every prop out there. $\endgroup$ – Zach Lipton Feb 29 '16 at 17:34

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