Originally Posted By: paul
WOW !!!

so in this closed container ( the pipe ).
air will only move in one direction?


Ahh, I see - your pipe is the closed system, and doesn't exhaust into the ship?.

If that's the case, it doesn't help you any. Same problem, only confined to a smaller space.

Originally Posted By: paul
so after all the air has been released out of the tank there will be a 1000 cu ft block of 100 psi air at the end furtherest from the nozzle.


I'm not 100% sure I've understood your engine. I am assuming:

1) There is a pipe, sealed on one end
2) There is a pressure tank on the other end
3) You release the air in the pressure tank into the pipe

Regardless, the math is the same. In this situation you'll release the air, and it will flow into the pipe until you reach a pressure equilibrium - i.e. the pipe and tank are all at the same pressure; no pressure gradient.

The initial movement of the air from the tank into the pipe will create a force that will move the ship forward. However, that force will be exactly countered by an equal and opposite force created by the air coming out of the tank interacting with the pipe itself and any air in the pipe.

Net result - no thrust.

Originally Posted By: paul
I said a believable calculation.


That's the science of it. Whether you "believe" science or not isn't my problem. Momentum, kinetic energy, potential energy and force are all well established physical concepts. If you can find some math that allows for those to move a closed system, let us know - that would be nobel-prize kind of work.

Originally Posted By: paul
in my world , the air at the other end of the pipe will slowly compress along with the rest of the air in the pipe.


Nope. The air in the pipe will be compressed equally as air moves in from the tank - gasses naturally fill a void in order to generate an even distribution. You may have a slight imbalance if you release the air quickly enough, but this will only exist for a short period of time.

Originally Posted By: paul

lets take your assumptions even further.

lets place air pressure guages on every square inch of surface area outside the pipe.

according to your comical assessment the pressure guages will all keep reading 14.7 psi , except the ones located at the end of the pipe.


Nope, they wouldn't. I think the issue here is we're sealing up different parts of the system.

I was describing the case where the pipe is open to the inside of this ship. In this case the pressure of the whole ship would increase.

I now think you're describing a case where the pipe is closed, and thus the pressure in the pipe increases, while the remainder of the ship stays the same.

In either case, the net thrust is zero - the initial momentum provided by the movement of the gas from the tank into the pipe or ship will be exactly countered by the interactions of that moving air with the stationary pipe (if the pipe is sealed) or ship (if the pipe is open).

Net thrust, in either case, is zero. Newtons laws - every action has an opposite and equal reaction.

After all, if it worked the way you think it does, NASA would have no trouble sending people to Mars. Just recycle you propellant back and forth.

They don't - strange, isn't it. That the rocket scientists at NASA don't know about this imaginary physics you have created...

Bryan
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