Public Lab comments[edit source]

These comments were ported from https://publiclab.org/notes/mathew/5-29-2012/solar-hot-air-balloons

  • thanks for this. I wonder whether this would work in Louisiana marshes in the summer--lots of sun. May have to make multiple tether points for the wind, though. --eustatic
  • This is so great. Mathew - how many flights is 1lb of pigment good for? I have the 1lb jar you gave me, will probably try it this summer, but am happy to ship anyone some amount of it if they like. If this starts to really become popular, we could buy a 50lb bag and resell, i suppose. Do you happen to know the cost of the 50lb bag? BTW I love that their product image on the pigment website is of a pigment molecule. Talk about open source... lol --warren
  • The pigment doesn't really wear off and I don't have to re-coat the balloon between flights. Next time I make one I'll have to weigh the balloon before and after coating, but my impression is that each balloon takes much less than an ounce of pigment. Volumetrically it only takes about a tablespoon. That said, its hard to coat the balloon unless its filled with a good quantity of pigment to work around; just throwing a tablespoon in doesn't work very well. When Molly brought me the first pigment sample, it was less than a 4 volumetric ounces,, and that served to make 3 twelve foot balloons and 5 seven foot balloons, with some left over and about half of it recklessly spilled. I'd bet that a pound could be divided into 20 or more packets each good for a few balloons. --mathew
  • The phone number for BayFerrox is updated to 800-526-9377. --liz
  • Hi, This is really interesting. Do you know if you can fly solar ballons over New York City, or Staten Island? If so, are there height restrictions in this area (especially Staten Island)? Many thanks
  • the flight restrictions are going to be the same everywhere-- stay away from the airport and under 300 feet. These balloons ARE large enough to be regulated. be careful, and keep the local FAA number handy if it gets loose. --mathew
  • Great set of instructions but ... the heat seaming video is sort of done from the wrong angle so you can't see what's happening. Any chance of posting one showing precisely where you put the iron? Do you put it on the metal rule and slide the rule down, or on the plastic directly? How long do you make contact? I've tried melting plastic and just ended up making a mess. Heating the metal rule, the heat dissipated and had no impact on the plastic. Guidance much appreciated. :(
  • Directly onto plastic will get you a melted mess. Put down silicone parchment paper (for baking cookies) and use an iron on top of that. Use the tip or edge of the iron. I have good luck using irons sideways. If you need a protective surface underneath, try butcher paper. I'd start by turning the iron all the way up, and pressing hard into the plastic. The straight-edge/form is just a guide. --mathew
  • Updated link to Bayferrox pigment: http://bayferrox.com/fileadmin/pdf/IPG/00672017_000_BF-330-ENG.pdf --Juan
  • Ramiro on the KAP forums has posted a whole system of spreadsheets and software for making spherical gores: http://arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/5133/solar-balloon-how-to-go-from-txt-to-drawing also, check out the Jake III from bovineaerospace. http://bovineaerospace.wordpress.com/2012/05/26/jake-iii-the-successful-launch-of-a-20-ft-solar-balloon/ --mathew
  • more on heat seaming http://publiclab.org/notes/elainechoi89/8-3-2012/solar-balloon-heat-seaming-process --mathew
  • As a pigment, can we use charcoal as mentioned in the annotated kiss balloon pdf? As charcoal is easily available anywhere so i was hoping if i could use it? Has anyone tested with charcoal, do you recommend using charcoal? --suman
  • Also what's the current progress in this solar heated balloons in public labs. I just came to know that it topic is 5 years ago. Please share any progress, if any --suman
  • Hi, @suman - this is a great question and I've had some not great experience using coarse charcoal briquettes (the balloon did not fly very strongly). But maybe vine charcoal or art charcoal would be better. If you'd like to post this question to the whole community, try https://publiclab.org/questions --warren
  • Hi Suman, I haven't really worked on solar hot air balloons for a while. Hot air balloons, and solar hot air balloons especially, are not great for flying on strings. They don't have enough lift to resist even the slightest wind. it is a good strategy for free flight balloons. In terms of balloon fabrication I haven't seen any new developments, but the Aerocene project is making some great strides on flight prediction software: http://aerocene.org/ Pigment: A solar balloon doesn't need pigment to fly, but the pigment significantly increases solar absorption. Charcoal will work to get a pale grey color. it needs to be ground very finely. We did a series of tests back in 2010 of different pigments. The type of charcoal doesn't seem to matter much: https://groups.google.com/forum/#!topic/grassrootsmapping/qdzH9mnfUo0 One thing I haven't seen tried-- static charging either the balloon or the charcoal/carbon black particles. This has been suggested a few times. I'm not sure how to do that. good luck! I hope to see you flying. --mathew
  • Hello Mathew, Thanks for sharing some of your insights of solar heated balloons. I totally agree with you that wind is one of the major limitations. I have been working on the design to withstand the wind. My mission is to fly in the morning time usually (9-11 am ) which has normally less wind. Also, this time is also the best time for flights with an NDVI camera as the sun is nearly at Zenith. I designed a model of solar heated balloon with payload of 100 gm which can embed Modified Mobius Action Cam. Regarding pigmenting, i have tried charcoal mixture which subsequently increased the solar absorption rate. Similarly, the rope configuration that i designed seems to be slightly more withstanding wind speed than the normal configuration. I will share the design in the public labs soon within a month as i have other deadlines coming very soon. I too haven't tried static charging the balloons or charcoal but i would love to try it out. Can you share me some more contents on it. My main vision behind solar heated balloons is to make a more scalable model that can be integrated to light weight action camera modified for infrared spectrum and together with automatic image recognition and image processing pipelines; provide a cheap affordable precision agriculture tool for farmers belonging to developing countries like Nepal, India, Tanzania, etc. Lets keep in touch, share and make the discussion going. I would like to apologize for my late response. Best, Suman Ghimire Nepal --suman
  • Hello, I know that this thread is quite inactive but maybe still someone with experience is hanging around. My question is about the mentioned problem on navigating the balloon in wind. I fully understand, that this is a problem having the balloon attached to just one line. What about attaching the balloon to three lines to keep the balloon in place? Spreading these three lines apart on the ground would limit the balloons movement in the horizontal. I understand, that this limits the possible height as distance of corners on the ground needs to be adjusted to the height but would that be possible? Or is the balloon changing height during winds, so it sinks rapidly? Do I miss something in my thoughts? Naturally three lines would add more load... Thanks for any explanation! --thom_heinze
    • Thom, A "tripod" of lines may help stabilize the balloon somewhat, and is a good idea. However, the problem of balloon stability is not just about the lines, but also about the forces acting on the balloon, specifically the wind and the lift of the gas. A solar balloon has very limited gas lift for its volume, and a large surface area affected by the wind. In practice, this means that even a very slight breeze (i.e. 2-3mph, 3-5kmh) can drive a tethered solar balloon to the ground. A solar balloon is best flown an an extremely still, windless and sunny day. I will usually identify the slight breeze that exists and plan the travel path of the balloon around the breeze. I'll start on the windward side of the site and walk downwind with the balloon until the edge of my site is reached. Then I'll take the balloon down, move to a new upwind location, and repeat. --mathew
  • Hello, I know this thread is quite inactive but maybe someone with experience is still hanging around. I have a question regarding navigating the balloon during slight winds. Would it work to attach the balloon to three lines that are spread to a triangle at the ground to limit horizontal movement of the balloon? I know that this would add more load and limit possible heights as the spreading on the ground needs to be larger than the height but still.... Am I missing something in my thoughts? Thank you for any explanation! --thom_heinze
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