@mrwayne. In your last post you told us of the importance of the pod-to-riser diameter ratio.


Question. Please tell us if the ratio of diameter of outer tank to its hight is an important one.

@mrwayne,

I have found that trying to lower the ZED model from it's neutral buoyant condition is very time consuming to calculate.  This is because the volume of the chamber that contains the air and water channels between the Riser layers is also collapsing as the entire Pod and Riser group descends.  This causes the water head in these areas to rise again and buoyancy to rise above neutral for everything except the Pod.

These observations are with an unloaded ZED however; one loaded to 1/3 of ideal only by it's own material weight and additional weights to make it that value.  So the entire system should still sink once loaded to 80% for "production."

All this leads me to believe that the actual working stroke is much less than what I had imagined.  Can you give us an idea how much you are stroking your test set up?

Thanks,

M.

Quote from: mrwayne on June 28, 2012, 01:15:42 PM
One big suggestion - The .20 clearnance is for our 6 and 12 foot tall models.
The pressures adds up inside - but the wall do not have to be stroneger than needed for the head of one layer.
The Pod is a big gain to the system - so look at the ratio from my perspective?
Does downsizing it make it impossible for this relationship?
Thank you again - could I add your work to my journal?

More difficult to build, but yes it can be done.
The acrylic at Lowes are Optix - 20x, Duraplex - 50x, and Lexan-250x (x times glass strength). Each has an increase in price, but not as much as the strength. The easiest technique is to have the 1/4 inch Optix cut at the store and glue (actually plastic welding) them together. 1/8 would not hold up well with this technique. Another technique is the 'Hinge' method where V grooves are cut and they are then folded into a complete box. It requires a router table or a table saw with a V blade. This would work with the 1/8 as the glue surface area is increased. I would only use this to make a four sided box and the top of the riser should be cut separately, as this would not work well for deep boxes. Just google 'acrylic box construction' to see videos.

In the attached spreadsheet, the gap and material thickness is set to .125. The retainer 2 wall would be equal to your 2 riser system shown. Retainer 2 is 10.50 and 8.00 is Pod, or 1.25  to each side of the Pod. I used a computer ruler to take the width relationships off your system and it would be 1.76 to each side, so actually a little better. But if you want the same, a combinations of sizes could be used, like Riser 1/4 and Retainers 1/8. It would also require a thicker material on the top of outer Riser as the total lift force is 221 in a 4 Riser system.

Edit: Just ran another spreadsheet with .25 material thickness and .125 gap and it came out to 1.86 per side. A little over, but close. It seems that just starting with a much wider Pod reduces the relationship issue.

Yes, you or anybody, can add anything I post to whatever you wish.

Regards, Larry

Quote from: neptune on June 28, 2012, 01:26:51 PM
@LarryC. Congratulations on your build. Obviously a lot of time, thought, and calculation went into that. One thing that springs to mind, is that it would be possible to do a hybrid build. By that I mean the use of two different materials, one of which is translucent [see through] and one of which is not. So only the front walls of each compartment are translucent. This would perhaps keep material costs down. It is impressive how the "power output" increases dramatically with a relatively modest size increase, and for a model, as you say it would not need to be very large before things got out of hand. Would it be possible to formulate a rule to show the relationship between size, and lift? Is the lift proportional to the volume of the machine, or combined area of all the risers X pressure, or something else?
       Personally I still think that one of the problems of building a working model is assessing the water level in each compartment. In an earlier post, I suggested loops of translucent pipes running externally, and connected between the top and bottom of each body of water . Wayne says he has used this but it is problematic. It is not totally solved by a transparent machine due to multiple layers.
Wayne has said that a 4 layer machine is not much better than a 3 layer, so is it worth the extra work?

Thanks, actually it was tedious, but all the sizes were taken off the MTO spreadsheets.

Two different materials would not be advised, as the glue actually melts the two surfaces or acrylic welding. But two different size acrylics, 1/4 an 1/8 could be used on each box.

Just use the Travis Effect Calculator spreadsheet to find total force for any combination.

Regards, Larry

Quote from: Seamus101 on June 28, 2012, 03:41:30 PM
To me it sounds like you have invented the equivalent of a longer lever. No mention of the energy involved in this description at all. Force multiplication does not equal extra energy produced unless that force is maintained over an equivalent stroke length. Can we see analysis that integrates both the forces and the distance over which they act, and show that there is a net increase.

Also it is not important that the energy to reset the stroke comes partially from  the other side. This simply represents the oscillation of the stored precharge energy, again with no net increase.

Thanks Seamus,
Study the non linear function of our "Lever" and you will see what you are missing.
Wayne