Red is planning a sequel, for after validation, including an epilogue of recent 'oh so simple face palming' improvements & efficiencies.

This will be called "ZED's for Zombies".

Quote from: TinselKoala on October 04, 2012, 04:10:13 PM
@AmoLago:
Thanks for doing that demonstration and documenting it so well. A ruler somewhere in the picture, next to the tank, would help; one could go over the still pictures with dividers or calipers and get good measurements that way. But it's not really necessary for what you are showing, which is that the water levels will equalize and the system will end up back where it started.

Hi TK,

Thanks for the kind words, much appreciated, I'll bear the ruler idea in mind for next time.

Quote from: TinselKoala on October 04, 2012, 04:10:13 PM
But the situation you have demonstrated isn't what Seamus 10n was talking about, I don't think. It looks to me like what he finds objectionable is the situation that the pod _starts out floating_ above the bottom, then sinks back all the way down to the bottom at the end. In your demo the pod starts on the bottom, and winds back up there. If you started with just a bit more water in the system to begin with, so that the pod started at, say, 1 cm high, then that is where it would wind up, not all the way down at the bottom.
So you are both right: If you are adding nothing and subtracting nothing and your input winds back up at the same place where you started.... so will your output.

You know what, I went back and re-read his post again and I see what you're saying:

Quote from: seamus103
I would expect it to remain floating as the water surface equalizes on both sides.

So apologies Seamus, yes of course, the pod will remain floating while the tank drains and once the water is completely balanced again, only then will the pod be back at base. Maybe that wasn't as clear as it should have been within the spreadsheet, but it was certainly the intention.

Quote from: TinselKoala on October 04, 2012, 04:10:13 PM
To answer this question, imagine a string attached to the top of the pod. What force would you have to pull upwards with to prevent the pod from starting to sink?
Or, conversely, imagine that you are taking work from the water pressure as it flows during the pod sinking. This is equivalent to pushing against a little bit of elevated head. So, to simulate this, don't put the input reservoir back down completely on the table at the "recovery" but rather elevate it, by say, 1 cm. Now where do the water levels and pod wind up?

Hmm, this is where I fall down. I'm all good at playing with numbers, but the practical part eludes me, certainly as far as what is considered "work out" anyway.

So, String theory! (pun intended)
I would think that initially very little force would be required on the string to stop the pod sinking, but as the tank drained you would need more force to hold it in the same position. As we hold it in place, the pod is not sinking with the water, so the water would eventually equalise at a slightly lower point in the two tanks (no mass of the pod to cater for), until we let the pod go, which would cause the two water levels to rise back to the, in this case, start position at the 40% mark on the pod.

To the second point, I will try later cos it's fun to play, but I would think that the water levels will equalise at a higher point and thus the pod doesn't sink to the bottom. I also would think that how far off the bottom the pod will be is going to be determined by the ratio of the area of the fill tank and the gap around the pod. This would mean that further work would would be required to complete the cycle - probably approximately what we just took out of the system

Alright, to leave this post on a more positive note (for myself at least), the spreadsheet's calculations do appear to be correct, even if it might not be possible to use the full or indeed any of PE difference of teh sinking pod. This at least gives me confidence to push on to adding risers/layers to see if there is a benefit to that. And reading Wayne's last post, I think I also need to look in to controlling the stroke height rather than letting the pod float to it's full potential.

Amo

Amolago ..

EDIT: you just squeaked in while I was writing 

Thanks also for taking the time to document a simple experiment of POP.

Further to what TK & Seamus have said, I would add that ...

Logic should show without calculations that the Input should equal the Output, if the complete cycle is mapped from start to end - the end condition must be all components returned to start conditions.

I gather that your Pod has just enough water surrounding it to cause it to 'float', just above the bottom of its tank floor - this is where water levels are equalized & is the starting condition.

It might be beneficial to view your system from a slightly different perspective - that is, that with the Pod just floating you have shown a good example of Archimedes Floatation Law - where the weight of the Pod [374 g] is exactly equaled by the equivalent weight of water displaced by the Pod below & up to the water line.

So, in a sense, you can forget about the Pod itself when it is 'floating' - as far as the tank is concerned the density of the water inside the tank is uniform up to the water line i.e. the weight of water in an identical tank without a Pod would rise to the same water line height & have uniform density etc.

When you release the Pod it rises because its virtual density is less that the water medium for its real displacement volume, until displacement volume in water weight equals 374 g.

N.B. See3d could also use this 'control experiment run mode' approach quite realistically to test & cross check the integrity of his code & sims - IOW's don't lock down the Pod & Risers etc then release them to do Work - just let them float up unrestricted - when the Input & Output sums equalize to zero [assuming no losses] then you have created a floatation experiment adjusted for water transfer.

The question then becomes ...

Does or Is the Work Done capability [Output] of the Pod acting as a piston [rather than slowly floating up & down via water transfer in this simplified approach] greater in one scenario over the other ?

IF locking down & releasing of the Pod shows a clear advantage in the energy equations then something new has definitely been discovered & it doesn't depend on number of risers or differential pressures etc.

IF there is NO advantage to be seen here then the Travis Effect is related to number of risers & pressure differential & is not a function of a Pod acting as a piston rather than floating up as water is transferred back & forth etc.

........................

The skeptics here categorically feel there isn't any advantage to be had in a short displacement stroke because whilst the force is variable for the TE the Work capability is solely related to the Water Volume increase under the Pod as it rises, whatever distance that might be !

Quote from: mrwayne on October 04, 2012, 09:24:37 PM
My thoughts were to offer the book after the Validation.
We are concerned that it would send mixed signals releasing it before.
Thanks for asking - Michel put a lot of work into it.
Wayne

Sounds good Wayne, looking forward to it 

Quote from: fletcher on October 05, 2012, 12:56:58 AM
..............................................
IF locking down & releasing of the Pod shows a clear advantage in the energy equations then something new has definitely been discovered & it doesn't depend on number of risers or differential pressures etc.

IF there is NO advantage to be seen here then the Travis Effect is related to number of risers & pressure differential & is not a function of a Pod acting as a piston rather than floating up as water is transferred back & forth etc.

The skeptics here categorically feel there isn't any advantage to be had in a short displacement stroke because whilst the force is variable for the TE the Work capability is solely related to the Water Volume increase under the Pod as it rises, whatever distance that might be !

Hi Fletcher & all,
In comparison to the Travis device, locking the pod at the end of stroke distance, as I see it, has to do with removing the load and maintaining the stroke head, the head maintains the pressure. To maintain the pressure has a greater benefit in the dual zed setup by its capability to equalize both zed’s, than the gain would be if extracted and later to be inputted.  Also it is easier to recover the energy of a steady pressure volume than that of a receding one, a situation you would have if a float up would be allowed after removal of the load.  The zed described by Wayne is customized for a dual balanced setup,  a single zed wouldn’t do without alternative recovery measures (which would equal the dual zed in any case).

       "The Travis Effect is related to number of risers & pressure differential & is not a function of a Pod acting as a piston rather than floating up as water is transferred back & forth etc."
The Pod as a piston can not float up without all risers floating up also, the pod is part of the riser assembly, all need to act in unison,  so the whole contraption must be seen as one.  The uniqueness of the pod (area) is the single point of control for the whole device, the pod water does serves 3 functions,  the pod head controls the pod (for lift) and all the riser heads (total lift) since it is located at the bottom of the water column. The third water function is volume injection at stroke pressure to fill-in vertical lift space created by the stroke.

The skeptics are right in general that there is no advantage in a short stroke. The reason for short stroke is a requirement due to the physical properties of the multilayer buoyancy device.  This is the only way to minimize water input cost.  The more layers, the more this (short stroke) becomes an advantage. This is a main Travis effect pillar towards OU.  This has been discussed previously, I don’t remember on which page, so for details pls look back into the pages for a more detailed explanation.

Regards, Michel