Flopper stoppers vs gravity

[Sundays_Child]

OK, so everyone knows about the cannon ball and feather in a vaccum and the different weights off the tower of piza....

My question is twofold.

1/ A flopper stopper would work best if the water passing up through it (as it fell) was as unencumbered as possible. My thought here is to use several rows of lighter plastic over a grid, so that there is less falling resistance compared to a larger piece. Is there really any difference? A larger, tougher piece of rubber would react more slowly, but maybe not noticeably?

2/ The above covers the drop-to-pull reaction, but what about the actual drop? Having a slack rope must affect things terribly. So... would having a heavier framework combat the added hydrodynamic friction to any helpful extent? (ie are the rules changed from air to water to the extent as they are from vacuum to air, or more?).

I understand that distance from the centre of roll is as important as anything else.

 

[Nick_H]

I don't think smaller vanes make it sink faster, but I do think they mean you get resistance more quickly on the upstroke, so they are more effective dampers. I think the amount of upward movement of the flopper stopper required to close the vanes, is about half the length of the vanes, so if they are 2 feet wide, you need a foot of upward travel before you get maximum resistance, whereas if they are only 4" wide, you need only 2" of upward travel. I've used this principle on mine.

Yes, for the same effective surface area when sinking, which means the surface area of the structure of the frame, plus whatever portion of the vanes doesn't go completely vertical, then the heavier the frame, the faster it sinks. If you made identical dampers, one with an aluminium frame, and the other with steel, the steel one would sink quicker.

 

[Sundays_Child]

Thank you very much. Very clearly put.

Cheers!