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Since atmospheric pressure is very large, so we just have to create vaccuum on one side of the transport to make it go to that side by a large force. And, the size of the vaccuum doesn't even matter. A few millimeters thick vaccuum would lose the contact of atmosphere from one side of the vehicle. I hope some vaccuum creating devices have been invented by now. Now, those devices have to do work on air to move it by a few millimeters and create vaccuum there. We'll derive that energy required by the device from the kinetic energy of the vehicle itself.

Suppose we create some initial vaccuum on top of the vehicle upto a few meters by spending some energy. The vechicle will move up and will require some kinetic energy. And, we'll give some of this kinetic energy to the vaccuum creating device to produce some more vaccuum. I hope machines have been invented to convert kinetic energy of the vehicle to heat to give to the vaccuum creating device. And once the vehicle has acquired some kinetic energy from the initially created vaccuum, the vaccuum creating device has to maintain a 1mm vaccuum for the rest of the journey, the energy for which it will acquire from the kinetic energy of the vehicle itself. And, work done to move air through some millimeters against atmospheric pressure should be less than the kinetic energy of the vehicle if the lower cross sectional area of the vehicle is large.

And once the vehicle has acquired a convenient height, we'll somewhat let the air fill in the space above it to the extent that the lower atmospheric pressure balances its weight. And then we'll create vaccuum towards one of its horizontal faces to move it horizontally.

What are the flaws in the idea?

I have used the word 'vaccuum' while writing all this. But we don't even need complete vaccuum. Atmospheric pressure is very large. So, even removing 50% of the air above should give a good pressure difference.

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  • $\begingroup$ Creating vacuums isn't easy, from both a energy perspective and from a structural perspective. You wouldn't be able to really save energy by doing this. I'd say it's likely more efficient (and definitely far easier) to positively pressurize the fluid behind instead of negatively pressurizing the fluid in front. $\endgroup$
    – JMac
    Jan 20, 2017 at 11:50
  • $\begingroup$ Note: For lifting it is enaugh to make the density of your veichile less than that of air. This could be done for example with large helium baloon. When you achive suficient height you just let some helium out to balance the lift with weight. $\endgroup$ Jan 20, 2017 at 11:57
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    $\begingroup$ When I saw the title I just thought - sailboat. $\endgroup$
    – M. Enns
    Jan 20, 2017 at 12:02
  • $\begingroup$ @NonStandardModel- yeah, that's good but I'm talking about an atmospheric preasure driven vehicle, not some balloon. The vehicle will ve heavy and you would require large helium balloons to displace air of that much weight. Even then, the acceleration would be much less for the helium ballon and even less due to viscosity. $\endgroup$
    – Dove
    Jan 20, 2017 at 12:34

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It is not possible without any fuel.

Creating vacuum needs energy. A part of that energy gets transferred to the vehicle as kinetic energy - the remaining part is transferred to air as kinetic energy, too, or wasted as head. If you take again kinetic energy from vehicle to make more vacuum again, you will have lost part of the initial energy making less vacuum each time. You can try to be very efficient and reduce all energy losses, but according to first law of thermodynamics you will never achieve continuous movement without fuel.

If you can use fuel it's different: there are devices to move vehicles by creating a relative vacuum. In fact, they lover pressure in one side of the device and increase it in the other side, therefore getting a differential of pressure (or a differential of vacuum) that pushes the device and the vehicle. The most common of such devices are propellers and wings.

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