SIBAP

[hartiberlin]

No,
actually not.
This is the hydrostatic paradoxon..

It does not depend on the diameter size of the hose,
it does only depend on the height (or deepness in water ) of the hose...
unfortunately....

I'm not sure this is entirely true as there is air friction that may be more noticable in a smaller hose(say 1/4 inch) compared to a hose that is 1 inch. just try blowing thru a piece of  automotive brake line then thru a garden hose.  big difference.

Well, the volumes or air transported are different, but the air pressure you need to do it are equal !
Just blow and hold the pressure, so that the water goes one 1 meter below
surface and then hold the water  there in the tubes...

You would need the same pressure on both different  hose or tube diameter sizes
to hold the water there 1 Meter below the surface.

[fletcher]

IMO Stefan's absolutely right - if the end of the air hose has a flap valve of some sort the water pressure will hold it closed so no water leaks into the hose - in order to open the valve to let air bubble up into the piston you have to provide enough force [pressure] to open the flap valve - the deeper the valve the greater the hydrostatic pressure your weight needs to overcome.

Perhaps you could think about using a flexible hose that went up inside the hollow piston to the top & traveled with the piston up & down ?

[dirt diggler]

No,
actually not.
This is the hydrostatic paradoxon..

It does not depend on the diameter size of the hose,
it does only depend on the height (or deepness in water ) of the hose...
unfortunately....

I'm not sure this is entirely true as there is air friction that may be more noticable in a smaller hose(say 1/4 inch) compared to a hose that is 1 inch. just try blowing thru a piece of  automotive brake line then thru a garden hose.  big difference.

Well, the volumes or air transported are different, but the air pressure you need to do it are equal !
Just blow and hold the pressure, so that the water goes one 1 meter below
surface and then hold the water  there in the tubes...

You would need the same pressure on both different  hose or tube diameter sizes
to hold the water there 1 Meter below the surface.

I totally agree, the pressure after stabilizing would be exactly the same, but in a system like this where speed is critical, the pressure build up with a small line would be considerable.

[BasementExperiments]

All very good and valuable points to consider. I'm going to test a few things this weekend to see how possible this really is.

Would it help if the air was helium? Say, for example this contraption was placed inside an airsealed container, recycling the same helium over and over.

Also, as far as SPEED being critical, I dont see it as being a primary step initially. Getting something to move perpetually is the first important step. IF it is possible then testing friction on the machine would be part two. Although in the end it is important, I'm not worried about the energy usage at this time.

When I complete som testing I will get back to this thread.

[hartiberlin]

Yes, please do a few test, so you can see, how much pressure you need
for different hose diameters to press air e.g. 1 Meter under water through the hose.
Maybe it could be good to use very small needle type hoses and press the air through it in
pulses, like letting a weight fall onto the airbulg connected to this hose...

Many thanks.