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Sorry, another brain fart from poor English : shoud say bearing ball , or steel ball above instead of ball bearing.

Thanks, gentlemen. I came up with an hysteretic mechanism, but appreciate your inputs. ----> A plastic pipe with a ball bearing inside and weak magnet end caps.

..."Whelks, in my opinion have very little taste and lots of texture. Not good eating.".... Didn't anyone tell you to eat only what is inside of the shell ?

Thanks Marc for your elaborated and thoughtful post using purely delta temperature and fluid contraction. Deserves all the merit. Maritime environment as you say, is very agressive and there is never enough precautions in redundant sealing. Been a scuba diver for 30 years and experienced several unexpectations. Currently, am evaluating components sourcing to build the key buoyancy part of the contraption on two or three different schemes, test them as standalone (tether yes !) and much later to see housing in a PVC pipe fuselage. Something I must also consider is the delta T may not be enough at all locations the glider encounters while travels, as delta depths could be restrictive. So the contraption may work in open seas but to reach there from a 'shallow' waters launch will pose a challenge.

Thanks ! Contacting the private technology contractor should be a much better approach option. Will do.

In the name of science and technology, not warfare; what would be the correct way to find/approach a chief engineer involved with the military to propose improvements/modifications/changes to a current project ? Is anyone here in the forums working with the military forces, that could know or suggest proper contact paths ?

Because of the abundance of what you would call 'bad' foods. Any predator animal will eat first the most energy supplying parts of the killed victim, and leave the rest of the carcass for second thoughts -or next needs- if no other victims are found soon. The same predator, will go for broccoli to avoid starvation if nothing else is available. What you name 'good' foods can be a label pushed by nutritionists and not reality.

I do not think three dimensional works. Sound perceived from above and below cannot be achieved by synthesizing a psychoacustical illusion from only two speakers. Virtual surround illusion can be created by processing audio from only two channels, but that is not 3D, it is 2D Several companies have their own processing methods to the virtual surround.

Is there any new breaktrough development of a material for better containment of helium in weather balloons ? Beyond mylar, with more durable containment, perhaps from nanothechnology ? Or,.... is there any new larger molecule gas, lighter than air which will not escape trough current porous materials in balloons ?

Hi Marc. Having difficulty to discern solids which show significant expansion. If you have suggestions, please come forward. The force exerted by this one at a delta of ~20 degrees Celsius may not be useable to force enough expansion. http://i00.i.aliimg.com/photo/v0/449280688/Bi_metal_thermostat_spiral_coil_on_silicone.jpg Please comment on post #14 above.

See no botanics or agricultural or gardening in the forums, so am planting it here... What happens or not happens in a plant growing upside down that seems not to affect its development, growth and productivity, while being so unnatural ? Getting ready several 3 litre soda bottles and a few commercial brand planters to experiment in the coming spring, and compare with the normal upside up in my vegetable garden. Tomatoes and strawberries are on mind, I would post progress pictures periodically. If there is a plant choice that you know would be more successful than others, or interesting to try, please suggest.

Hi. In an attempt of exploring less complexity and difficult solid materials, let me make a parenthesis at this point, will return to the main solids expansion later. What is your opinion on following the electric route, and as bubbling from electrolysis is not promising, what about using ethanol or an even better behaving liquid in a thermally insulated sealed bellows. Heating it up will become gas causing expansion and buoyancy. Something like 'hand boiler' toys. A volatile liquid that can be easily gasified with little energy from a battery powered heating element. Which could be as simple/available or better performing enthalpy of evaporation than ethanol ? Propane, Acetone, Ethane, Carbon tetrachloride, Chloroform, Ether, Methane .... ? Under depth pressure of ~ 7atm = ~200 feet Will be back...

Thanks again, Marc. Am thinking on your good suggestions, will be back. So far I see a problem with your paragraph " If the bladder is located before the wings, its volume change will not only provide the net up or down force, it will also put the nose up or down." The air volume change due to depth pressure or lower temperature in the nose bladder would not provide surfacing force, as the pressure will reduce the volume, making it dive instead. -----> The root of the problem is that at depth, there is lower temperature, and that causes air volume reduction, sinking it more, and; at depth, there is high pressure, and that causes air volume reduction, sinking it more. Then, to my poor brain, depth pressure and temperature are not useable to provide air expansion to rise to surface. We need the opposite action. I came up with an hysteretic mechanism for nose up/down : A long sealed pipe lengthwise to the fuselage, with a ball bearing inside and weak magnet end caps. Seems to me, sealed bellows are preferable to piston/cylinders. Will be back after digesting your post and evaluating the availability of fancy materials with expanding when cold property.

Thanks, Michel. Your correct wording made a world of difference ! Great help !

Hi. Did not pay enough attention when a 10,000 sq.ft. freezer was added at a facility I worked at many years ago. ...Remember a reinforced concrete slab poured on the ground, then a ~8" layer of styrofoam, and another reinforced concrete slab on top. Forklifts danced all over that floor with no problem. Am I missing details?; what is the building technique to avoid cracking/collapse with such styrofoam sandwich ? How is it done properly int the civil engineering world ?

Thanks, Enthalpy. Very interesting. Such depth pressure piston actuated bimetal dome could shift the ballast position for nose up when a depth is reached, to reverse its action for nose down when reaching zero pressure at surfacing. Nice and 'simple'. The buoyancy cycling is left to deal with. If solar cells on wings/fuselage of the glider charge a battery, could bubbling at an electrolysis chamber triggered by a depth switch work? * ; purging them when reaching surface is sensed , enabling next dive. Surfacing at night, halts everything if battery sensors do not detect full charge. Unless other opinions come up with a bubbler/expanding chamber actuated by depth/temperature/light deltas. *Would bubbling volume by electrolysis be seriously impaired at depth, as to not consider such method ?

Is there any commercial device used in industry, equivalent to mechanical hysteresis ? A device that snaps mechanically or hydraulically, to two states like a toy clicker, or a 'klixon' thermal switch ? -A mechanically bistable device like a wall switch, unstable at its center position-

Thanks. It does not always show the "Attach this file" capability. [image below] This time did ¿? See attached. Retrying... perhaps will attach. Seems does not work on 'quick' replies...

Hi. OK, call it engine. No problem there. But the word 'pixies' does not click in my poor English. An underwater contraption that will travel powered by delta pressure, delta light, delta temperature, delta whatever supplied by sea environment. To simplify, to come up with a device that endlessly dives and surfaces periodically by some clever automatism using the above deltas. I believe would take a 'snap' hysteresis action mechanism triggered from the delta extremes. Like a liquid that vaporizes under pressure and liquifies when not pressurized, as ideal dream. The 'snap' 'toggling' action is what I believe would make it work. Nitinol, solar cells and electrical actions, pressure driven actuators, anything in that line. Sample attached. But open to any suggestions Edited. Unable to attach a picture. Will retry. Edited2 : Lost in space on how to attach a picture on this new forum format. It was just a 'party clicker' image.

Hi John. There is no need to have an engine to propel it forward. The sinking action with nose slightly down will make it advance forward. Same when rising, the nose slightly up will make it to continue advancing forward. Like an airplane with no engine (glider) The mechanism to make it buoyant and nose up could be an electrolysis bubbler running from a seawater battery. When the craft surfaces, bubbles bleed by either a solenoid or a needle valve held closed by its own float, repeats the cycle starting to dive. But there have to be other ways... http://i588.photobucket.com/albums/ss323/Innernet/P1010038_zps089b92e7.jpg

Hi all. Picture a glider model, ballasted to stay near horizontal and near neutral buoyant when placed in the sea. When placed in the warmer water surface, with daylight and little depth pressure, some mechanism makes the nose go down, slightly decreases buoyancy and advances while dives. When reaches a set depth pressure, darkness and cold water, those cause the mechanism to toggle back towards being slightly buoyant and tilt nose up. It will rise and advance. When surfaces, little depth pressure, daylight and warmer sea temperature cause the mechanism to toggle towards slightly decreased buoyancy and nose down. It will sink again and advance. Repeat and repeat... The lengthwise center of gravity shifting and the buoyancy are the mechanisms that can be actuated by solar cells, pressure collapsible chambers/piston, temperature actuators, or whatever else you think may work . Some mechanism that increases buoyancy with cold/depth pressure/darkness/hitting bottom would be needed. Bubble generation and purge... or other clever methods. Come up with ideas,,,

Or, put them all 24 / 7 into calculations to find the next winning lottery numbers. And I expect my percentage of wins, not of the power bills... !

There is no trick, and 19 is wrong because it is wrong, being mathematics an exact science.

28 bottles come in seven promotional packs of three + one free; which is buying 21 and getting 7 free ?

Are +/- 90 north/south latitude degrees, +/- East/west 180 longitude degrees, 24 hours per revolution; 60 minutes and seconds subdivisions being used when exploring and charting other planets ? Is the absence of the decimal system being carried to other worlds exploration in favor of the senseless duodecimal / sexagesimal / dozenal and earthly time divisions ? Would it be better to start using a rational decimal system for -say 100 hours with decimals time- per revolution; dividing a circle in 'new' 100 degrees with decimals ? Why yes and why not ? <Sorry. title should spell 'committed'>