Sure, but if your sausage is twisted, you eat it anyway. 
As for the rest, Iâve already said that I think something like this has a one in fifty chance of succeeding. That means a 98% âchanceâ of failure. I have no illusions. I think itâs just a way of trying to improve the original Omnidea concept a bit.
Yes I believe if it gets twisted, you are going to âeat itâ. Or someone or something is. 
I respect your tagging it with a 2% chance of success.
Most people would not be so humble.
I do like the multiple belts idea.
It could lead somewhere - who knows?
Another thing the document would need, would be an insolation map for location, time, and time of year, and calculated or modeled heat loss from the balloon per square meter and in total under different circumstances.
Another drawback any shape for a solar balloon other than spherical would have, but particularly a long cylinder, is that the amount of sunlight hitting it varies dramatically with the orientation it is in, particularly during winter when the sun is low in the sky. Since the prevailing winds mostly are very much not aligned with the sunlight. In winter itâd be better if your cylinder stood upright, also to limit heat loss.
If you had this technology to produce giant rolls of environmentally friendly and durable uv-resistant film economically (ETFE comes to mind but I donât think thatâs economical, or environmentally friendly), there are much better uses for it, that can also be less demanding on the material. The most obvious would be to make domed cities on earth or elsewhere or to make greenhouses.
These will also give you a better understanding of the requirements of the material and the structure, if you do decide to go with the original idea.
Iâd probably go for a partly (parts being transparent) or wholly white dome over a desertified area and make a jungle or farm inside. A main thing that turns deserts into deserts is the high insolation leading to high Evapotranspiration - Wikipedia, and reducing the insolation through shade, raising the relative humidity, and reducing wind would all help with that.
It would be simplest to desalinate the water using reverse osmosis powered by solar, or you could do solar desalination in the same or a separate dome, perhaps moving the moist air to the main dome where the water in it can condense or precipitate.
Food insecurity will increase due to global warming, particularly in hotter and drier regions, this would help with that, as a stopgap.
You donât seem to understand the basic principles of balloons whose buoyancy is provided by the greenhouse effect, including solar balloons. And Iâve just realized that the same applies to the Magnus effect, as Iâve just seen.
Iâve made a few comments on the subject, but apparently to no avail. So Iâm going to adapt my teaching methods. It would be detrimental for readers to read untruths on this subject. It would be a pity if you persisted in torpedoing your own forum.
This means that the balloon is well insulated, but in both directions: it is not heated, and has no buoyancy. A virtually insulated balloon is possible if it is heated by something emitting, for example a burner as for:
As I already suggested: no emissivity means no heating, and no buoyancy. Your mention of emissivity for a solar balloon is quite correct, but the advice to not use it is not.
???
In my comment on Preprint: Towards a gigantic Magnus balloon with motorized belts - #53 by PierreB , I introduced some elements which can help you to understand the basis, above all the text about MIR, which describes how several materials are used to obtain buoyancy by night and by day, according to their respective proprieties.
About aerogel (again): one of the best insulators is air when it is immobile, as in the case of double glazing. A similar insulation is obtained between the black and the transparent envelopes, and could perhaps be improved by connecting them with wires. Aerogel doesnât add anything, but itâs very expensive and fragile: itâs unlikely that we could build an aerostat with aerogel.
The title of the topic is: Towards a gigantic Magnus balloon with motorized belts. By doing this the lift by Magnus effect will go to the left or right depending on the direction of rotation, but not upwards.
We were just watching a show called âEngineering Disastersâ. One segment was on sports stadiums with inflated dome roofs. At the time the show was made, there was only one (1) left. Most were dismantled or replaced with structural roofs. They did show one in Minnesota caving in and dumping snow inside onto a football field. That inflated roof is now gone.
Other segments showed:
In each of these cases, engineers could have, and probably did, warned the projects that they were not building on a solid foundation, etcâŚ
I could just imagine somone who understood high-rise building construction, walking through all the high-rise construction sites in Santos, Brazil, trying to tell people âYou canât build a Hi-Rise Building on mere sand - you have to put in pilings that reach to the bedrock!â
And of course the newbies would not listen.
âIdiots, idiots, idiots!â the experienced building designer probably exclaimed.
Anyway, one thing Iâve been thinking about lately is how all âthe modelsâ for global warming agreed that we should have all boiled off the planet by now, and meanwhile, temps have not changed much, but facts donât matter to some people.
It is as though it doesnât matter how smart or expert people are, sometimes they just donât use the tools or knowledge at their disposal.
So I was imagining a segment of âEngineering DIsastersâ coveriing AWE, and all the millions wasted on nonsense.
A) It could start with Magenn, the original poster-child of AWE - looking ridiculous to anyone familiar with wind energy, looking hopeful to magazines, NASA, etc. Idiots? Yup, Idiots. LOTS of idiots to put Magenn on the map. Magenn was indeed an âEngineering Disasterâ. Based on sheer idiocy. And Magenn was how AWE first got famous. Idiots? yup, Idiots.
B) Next Poster Child: Altaeros - a frail, tubular, buoyant fabric envelope, containing and lifting a Skystream wind turbine. Anyone with a teeny bit of wind energy experience could easily predict at a glance that the envelope lacked the strength to support a Skystream wind turbine, but all the PhD âtalentâ promoting the Altaeros âEngineering Disasterâ thought it was going to work great! From the comfort of their office chairs! Altaeros seemed to be on the cover of so many magazines and websites - highly-celebrated as florward thinking genius! Idiots? You tell me.
C) Next Poster Child: Makani / Google: This is where Iâm a bit perplexed. With so much computer aided design (CAD) and computer modeling power behind it, how could the designers NOT have realized their aircraft would barely be able to transit a circle? It seemed like they all breathed a sigh of relief aftert one bad landing at sea, which allowed them to âthrow in the towelâ and give up. but with all that âIntelligenceâ - whether natural or artificial, how could they have thought it was going to work better than it did? One more âEngineering Disasterâ? Idiots? Well, the results suggestâŚ
d) Then you have âThe Kite-Reelersâ! Most of âthe expertsâ converging on a single basic design. Notice, like the climate âmodelsâ, all these âexpertsâ agreed that kite-reeling was the best way to pursue wind energy, yet their âexpertiseâ turned out to have some serious flaws. Turns out wind energy was more of a challenge than they bargained for, and that simplicity, robustness, and reliability turned out to be more important than they thought.
All those computers, all that âtalentâ, all those âexpertsâ, applying all that âmodelingâ and âintelligenceâ, and yet theyâve come up empty or nearly empty in both cases. More âEngineering Disastersâ? More âIdiotsâ? Well, they should have had a segment on AWE!
For a sphere, the ratio of its surface area and the shadow it casts perpendicular to the sun is a constant
\dfrac{4Ďr^2}{ Ďr^ 2} = 4 , for a cylinder that ratio varies from \dfrac{2Ďrh+2Ďr^2}{Ďr^2} to \dfrac{2Ďrh+2Ďr^2}{2rh} for a cylinder with a length of 10 and a radius of 1, this ratio varies from 22 to 3.46. If the sun is directly overhead and the cylinder is horizontal it is 3.46, if the cylinder is still horizontal and the sun is close to the horizon, and the wind is blowing perpendicular to the sunlight, it is close to 22. Youâd need to design the balloon so that it still flies when the ratio is close to 22, and that in winter with 16 hour nights, and then also not have too much lift in summer when Direct insolation - Wikipedia is higher and more of the horizontal cylinder would be in direct sunlight.
Somewhat differently stated, the enclosed volume for a cylinder that size, letâs say the units were in meters, would be 10\pi m^2, so if the orientation of this cylinder was particularly bad, but there were still no clouds and the sun is still above the horizon, this volume needs to be heated by an area of the envelope exposed to the sun of \pi m^2 and be heated enough by that to lift an envelope with a surface area of 22\pi m^2, plus all the rest.
Yes, I am aware.
For the rest, I hoped that my You also shouldnât go for a solar balloon was enough of a clue that I wasnât talking about solar balloons anymore. It is actually, I posit. You also donât seem to have read my You are misreading the sentence⌠reply to your followup comment.
As your analysis on your own idea is mostly absent, I just like to think of ways on how the analysis and the idea can be improved, by using a electrically heated insulated balloon instead for example, or if youâd still like to explore using a solar balloon, better aligning it with the sun, or all the other pointers I kindly gave you.
I am sorry, I had did not remark this main element in this post, coming far after other elements about emissivity and âuse solar panelâ expression which seems odd in this context.
This leads me to correct myself for my last post and some other posts, regarding my assessment of your expertise in solar balloons and the like. It should also be pointed out that MIR (infrared) is not considered a solar balloon as such, even though it uses the greenhouse effect. So I wondered for a moment if you were referring to this.
Thus no: it is âheating elementâ.
I had thought of (or rather Peter Sharp had suggested) using the rotation motors to heat the balloon, but this would only be possible with motors installed at the ends as with the Omnidea balloon, and not for the belt motors which are located on the outside (unless there were some means of heat transmission).
I could, however, add two large motors at the ends (as for the Omnidea balloon) and provide most of the rotation and heating power (Joule effect accentuated when poor efficiency). The other motors on the belts would provide the additional energy for rotation, with the wide belts providing the essential support for the large balloon.
Complete insulation of the balloon is therefore preferable, as you indicated. But it is expensive, as for the specific fabric for https://ultramagic.com/hot-air-balloons/eco-magic/ I mentioned above.
But in the end it is probably better than solar balloon, due to the possibility of permanent flight, unlike solar balloons.
The choice remains between two options: vertical reeling mode (with electric (full use) or solar (limited use) heating), or as lifter for wind turbines aloft (with hydrogen or helium because of the weight of the turbines).
Above I said about that, among other things:
Iâd think now Iâd perhaps vote against using concentric balloons. One reason is that the central one, that would have the most volume of humid air, would still need to be quite strong unless it was made larger than necessary and could press against the insulation of the outer envelope, but that would introduce creases and so on. But the main reason would be repearability, as you would only be able to access the inside and outside envelope and not whatâs between them.
I think itâs probably better to add mounting points on the inside of the envelope and attach your modular insulation to that, which probably should be inflatable and have many air pockets, to keep the air inside it as still as possible.
You could probably model the ideal air gap distance (distance between individual layers of the (inflated) insulation) to reduce convection and how that changes as you go through the insulation and as the likely temperature differences between air gaps differs, the number of air gaps, the thickness of the insulation, and the resulting weight and manufacturing difficulty and cost.
You should probably try to do a more thorough analysis on the different options, if youâd like to explore the idea further. For now hydrogen seems most promising to me, but still a bad idea probably, as why would you want to keep something in the air when there is no windâŚ
I like neither of these options.
The reason kites flying crosswind use reeling is that there is, until torque transfer proves it could work, no other way to convert the pull from the kites into rotation of the generator, if the generator is on the ground. And the length of the tether is limited, so generation has to be discontinuous. With a rotating cylinder you already have the continuous rotation that can be converted into continuous rotation of the generator on the ground, or airborne generator possibly. There is no need to have this discontinuity.
Using the balloon as a lifter is weird. You already have this rotating cylinder, why not try using it. You already need to vary the rate of rotation of the cylinder to control its lift. If you already have those things, you already have a working system if you add regenerative braking.
Can you explain this vertical trajectory idea and why it might be better? I assume this is not possible with a fixed tether/belt length? How is a vertical (I assume ascending) trajectory even possible?
Was crosswind flight described in the literature and was that found to be better? How much better, if so?
For launching a heaver than air tethered Magnus effect balloon, I imagine you could ensure that belt tension was high enough while the balloon was on the cradle, spin up the balloon, and then let the balloon pull on the belt and launch. But then in the absence of wind causing drag, would it then not just fly forward and into the ground?
Vertical trajectory concept applies to the pumping (yo-yo) mode, where the tether length varies as for all yo-yo systems. To my knowledge, it has not still be tested. References are given in the preprint. The main explains are on the publication [3], Chapter 13 of the second AWE book:
Milan MilutinoviÄ, Mirko ÄoriÄ & JoĹĄko Deur: Optimization-Inspired Control Strategyfor a Magnus Effect-Based Airborne Wind Energy System.Roland Schmehl. Airborne Wind Energy. Advances in Technology Development and Research, Springer, pp.303-333, 2018, Green Energy and Technology
https://www.researchgate.net/publication/324134888_Optimization-Inspired_Control_Strategy_for_a_Magnus_Effect-Based_Airborne_Wind_Energy_System
PDF available on request.
Then page 2 of the preprint:
A vertical trajectory is visualized on the Fig.12.23 [7] in the end of the publication.
Reference [7] of the Chapter 12 of the same book:
Ahmad Hably, Jonathan Dumon, Garrett Smith, Pascal Bellemain: Control of aMagnus Effect-Based Airborne Wind Energy System.Roland Schmehl. Airborne Wind Energy. Advances in Technology Development and Research, Springer, pp.277-301, 2018, Green Energy and Technology, 978-981-10-1946-3. 10.1007/978-981-10-1947-0_12 hal-01759173
https://www.researchgate.net/publication/324134958_Control_of_a_Magnus_Effect-Based_Airborne_Wind_Energy_System
PDF available on request.
That said this chapter is also available on https://hal.science/hal-01759173/document. The same Fig. is Fig.1.24, representing a vertical trajectory. See also the conclusion including an estimation of the power/m² (1.48 kW/m²). In my preprint I did not use this estimation, preferring to base myself on Omnideaâs experiments, then extrapolate in vertical trajectory, based on the Chapter 13. As a result the spin ratio is far lower, as for the power/m² (about 400 W, roughly as for the Mutiny power kite [reference 4 in the preprint], assuming a same wind speed of 10 m/s.) I think high spin ratios above 2 are not achievable due the power consumption by the cube of the tangential speed of rotation.
In few words I think (but explains are better in the chapter 13) the vertical trajectory far from the winch (as noted in the chapter 13) is more efficient than the basic oblique downwind trajectory, because a crosswind component is added, and the balloon does not go downwind. It is a little (but not quite) as if you fly a power kite vertically in reel-out phase.
Yes (no reference in the preprint), crosswind eight-figure trajectories were studied:
Modeling and control of a Magnus effect-based airborne wind energy system in crosswind maneuvers
PDF available on https://www.researchgate.net/publication/320495787_Modeling_and_control_of_a_Magnus_effect-based_airborne_wind_energy_system_in_crosswind_maneuvers
If I remember correctly, the numbers given seem to lead to a power/m² being 2 times higher than for vertical trajectory. WindFisher uses this crosswind trajectory.
Yes: I prefer the motors are close to the balloon is such a way the respective belts are sufficiently tight all round. That said launching a heaver than air tethered Magnus effect balloon can be difficult or even impossible due to stability issue: in flight, perhaps the weight of the belt motors below the balloons can improve stability, but this is a point to be verified. If electric heating appliances are added in the ends of the balloon, combined with an insulating envelope, some neutral to light buoyancy can occur. But all this has to be studied deeper. Hydrogen or helium should be avoided.
The centrifugal force by rotation will project colder and heavier air against the internal walls of the envelope. As a result the hotter air would remain in the middle of the balloon, benefiting from insulation. So, perhaps the far less expensive current fabrics (ripstop) could be sufficient. But this is still a point for investigation.
A way to design this could be to dropstitch the inner and outer membranes. So you get both sturdiness and fixed distance for insulation.
Complicated though.
Anyhow, the design should come from requirements. Right now we are grasping at straws because we have no idea how strong it must be, and which weight and so on
Or, not as a stopgap, it would be a very good way to do Carbon dioxide removal - Wikipedia I think this has a much better chance of success than the original idea of this topic. It is not competing with already established solar and wind, it is probably easier and more easily scalable and cheaper than techniques that donât rely on growing plants, so there is relatively little competition, if you grow economically viable products like bamboo, you should be able to survive without external funding, you can start pilot projects as small as you like, and you can start anywhere you like, but probably close to a source of (sea)water and in a warm climate.
To a very limited degree I think. I donât think the boundary layer will be very high as the inside of the envelope will probably be smooth and air is not very dense or viscous, and you wanted a large radius cylinder. How high do you need to go in a large open field like an airfield before the wind speed is almost equal to the free stream?
Convection should play a much bigger role. Because of the large radius and relatively slight temperature differences compared to say a hot air balloon though, I suspect convection will be relatively lackadaisical. You could try to add horizontal surfaces to try to limit that further. There are also no point sources of heat in a solar balloon to drive convection. And any insulation should also decrease the temperature differences inside the balloon, and with that also limit convection.
I think as there are no point sources of heat, there also will be very little convection and there will be just different layers of air above each other, from cold at the bottom to hot at the top. If the balloon is very well insulated the layers will perhaps equalize in temperature, if it isnât, the loss of heat from the envelope, and the addition of heat from the envelope, would drive convection.
For a solar balloon yes, I think thatâs a good idea. The launch is probably the most difficult so you only really need the balloon to be lighter than air then.
If there is no sun, or if youâre using an insulated balloon, while on the cradle you could inject heat and steam into the balloon using a probe through a valve, and you can drain condensation. Youâd have some intermittent operation perhaps if you need the balloon to be LTA after launch, but also a much simpler and somewhat lighter balloon.
7 posts were split to a new topic: Lackadaisically and Intermittently Throwing Darts at a Surprisingly Resilient and Long-Lived Bubble, With the Bubble Fighting Back | An experiential experience on the lasting effects of US media global warming misinformation in the minds of its recipients
For a moment I thought weâd lost our way, but thereâs no denying that the expression âa bubbleâ takes us back to âourâ balloon, which is certainly cylindrical rather than bubble-shaped.
Iâd like to thank @Windy_Skies, @tallakt , @dougselsam for your present and future contributions to this topic.
Iâve made a few changes to the preprint: as I donât think helium and hydrogen are feasible, and indeed not useful, since only a little buoyancy is needed, barely above the mass of the balloon. So for the moment Iâm opting for electric heating appliance so as to also have stable buoyancy, knowing that the irregularities of the weather would be absorbed by the aerodynamic lift (by Magnus effect) up and down. Solar heating would lead to high buoyancy ranges, thus difficulties to control the pumping mode operations.
Drop stitch technology should only be used on the discs (or crowns) where the belts run, where the forces are concentrated. The rest of the balloon could be made of simple ripstop: of course, more insulating fabrics would be preferable, but we need to look at their respective higher costs and weights.
Iâve roughly estimated the mass of a 1 km balloon (note, among the countless criticisms, I havenât yet received the one about these incredible dimensions, but that shouldnât be long 
) at 100 tons, and the heating power required at a few MW for a few degrees more, for an expected (only on the paper) average power of 80 MW with a wind speed of 10 m/s.
Iâm not claiming that this system could be viable, but on the other hand, single-unit AWES that claim scale utility should outperform single-unit conventional wind turbines, which is next to impossible, even if it is essential. The reason is as follows: when you enter a wind farm, you can walk around, there may be activities; if by chance you try to enter an AWES park, especially crosswind ones, you will see that it is not possible and probably prohibited. I experimented this with a small AWES in crosswind operation. With a Magnus balloon, it would be the same. So the possibility to go large is the only way.
OK Pierre, how about a black weather balloon that starts traveling upward in the morning, with a flight time lasting until late afternoon, pulling upward the whole time? This is also reminiscent of the âsolar chimneysâ surrounded by a collection zone of dark-colored material - using solar power to create wind, extracting energy from that wind.
Now, weâve heard about more than one of these âsolar chimneyâ-powered wind turbine sorts of projects.
They got a lot of attention at the time.
Seems like the bloom is off the rose on them lately though - I havenât heard about one in a few years.
Last I remember, at least one was slated for completion and operation fairly soon (at the time).
Of course we know how these surefire-success slam-dunk new forms of wind energy projects normally go - they are abandoned as level-headed people slowly figure out how unworkable they really are, but they make a big splash on magazine covers for a timeâŚ
But still, a single black weather balloon, pulling upward all day - how much power could it produce?
Hi Doug, Iâve just written that Iâm leaving out solar heating, and why, as youâve just quoted.âHigh buoyancy rangesâ expression means that the power is too fickle, between day and night, sun and cloudâŚI noted that âonly a little buoyancy is needed, barely above the mass of the balloonâ, âIâm opting for electric heating appliance so as to also have stable buoyancyâ. Please reread my post.
Oh OK Pierre, Iâll let everyone know, youâre going with electric heating. Forget all the other crazy ideas. youâve got it all solved. Sorry if I didnât grasp the importance of that executive decision right away. I stand corrected.