Another wiew on gravity wheel - vacuum controlled under-water wheel

[Low-Q]

Thanks for the reply @TinselKoala. You are right about the greater pull force at the bottom compared to the one on the top.

Say we have two cylinders placed right across eachother. Each cylinder displace 5cm³ each when the alignment is vertical. Say there is 10cm between the surfaces of the diaphragms, and the diaphragm area is 1cm².

Each diaphragm in air will provide 1 kilo pull, but there is two opposite forces, so the net pull force is zero.

In water, there will be approx 1 % more pull on the bottom diaphragm than the top diaphragm. The difference in pull force in grams is 10 grams.

Say the max displacement of water is 10cm³ (5 + 5 vertical, or 0 + 10 horizontal). this is a weight of 10 grams too. Just enough to make the wheel stay still in any position.

What if it's possible to keep the design except increasing total water displacement? What will then happen?

If the water displacement is greater than the 10g of pull force difference, shouldn't then the wheel start running?

So the next question is: How to design such wheel? Is it possible to increase water displacement without increasing the distance between each diaphragm, and witout increasing diaphragm area? Which means, increasing the diaphragm stroke only.

Br.

Vidar

[Low-Q]

OK,

Lots of replies from myself here, but I would again like to challenge the reply from @TinselKoala with a drawing.

This drawing shows two identical cylinders, in the same depth in a water tank. It also shows two ways to construct the piston that keeps the vacuum inside. The difference here is in what hight in the water the main surface area of the piston is present. They are 10cm apart in hight.
Say that both pistons (ALL the blue parts) have the same weight.

The question:
We know that in these two examples, the pull force is vertical. We also know that the pressure in water is greater at greater depths. So, taken into account that both cylinders of vacuum is at the same depth, what piston have the greatest pull force - A or B?

Br.

Vidar

[TinselKoala]

It seems to me that the "pull" force will be greater on the B side.
In response to your question, let me ask you one: which one of your cylinders will experience the greatest relative change in its buoyancy?
All the blue parts may have the same weight (a neat trick, but OK), but the water they displace doesn't.

[Low-Q]

Here is the idea, that came out of the previous picture.
The idea is to have a linear travel of all pistons, and where there is no atmospheric pressure or water pressure that acts on the pistons differently depending of depth in the water.
All cylinders are fixed to another wheel which is not showing in the drawing.

Now @TinselKoala, what do you think?



Br.

Vidar

[TinselKoala]

I think it's getting pretty complicated.

You make nice drawings, though. I wonder if it could be animated?
Do you know about Phun?
http://www.phunland.com/wiki/Home
You might be able to get this working in Phun, if you play around a little.

I still don't think it will work in real life, though, because I don't think the overbalanced (or overbuoyant) condition will continue all the way around the wheel. There will be a point (several actually) where all forces  balance and the wheel will stop, because inertia won't be able to carry it past that point.

I see that CLaNZeR is building a similar idea on another thread. If anybody can get one working, it will be he.

(EDIT to add there isn't going to be much power available from buoyancy changes, as you no doubt have already calculated. All that complex mechanism, and the drag of pulling stuff through the water, subtracts a lot of power from the system, and the bigger (more buoyant) it gets, the more drag there is...)