One of my old partners in crime visited me a few weeks ago, and brought with him my second attempt at building a solar balloon. I’d sent it to him for launch in Minnesota, but he wasn’t able to get it off the ground. But together, he and I patched it up, attached a second, clear balloon to the top, and set it free in Chapel Hill, North Carolina. It was carrying an Android phone transmitting GPS coordinates and pictures, and also a paper bag filled with messages in bottles. We were hoping to make the Atlantic Ocean…instead we made it about 6 miles (but we did almost land in a lake!).
I started making solar balloons in Spring 2012. My first attempt was a 5 footer that was way too heavy to get off the ground. So I bought a bunch of 0.5 mil black plastic trash bags and spent weeks ironing them together to make a 13′ spherical black balloon (the bottom balloon in the above photo). I took it outside for a test in some extremely windy conditions (i.e. winds in excess of 5 mph) and it ripped at the seams almost immediately. What a piece of junk. So I repaired it and sent it to my friend Paul, thinking that he’d have better luck in Minnesota…but he didn’t. Meanwhile, I built and launched a spectacular 20′ solar balloon made from paint dropcloth-and I swore I would never make a balloon from trash bags again. That’s because the paint dropcloth balloon took only a couple of days to make and every single seam held.
But we still had this 13′ garbage bag flying disaster. So when my friend flew out to visit, we decided to launch it. In my infinite wisdom I thought it would be a good idea to splice a 10′ clear dropcloth balloon on top of the garbage bag balloon for extra lift. For payload, we had an Android phone that my friend programmed to send GPS positions every minute as well as take send pictures. I also made 10 bottles with messages in them in case the balloon landed in water.
Armed with a hair dryer, we headed out to the local park and started inflating just as a big elementary/middle school soccer tournament was getting started. We had lots of questions from curious (and suspicious) passers-by as we filled up the balloon.
We had everything ready to go when the seam between the top clear balloon and the bottom balloon ripped and the whole thing lost air. After frantic taping we got everything together. The wind was rising and a soccer game was in progress, and we needed to get this thing off before conditions deteriorated even more. Despite the nearby pine trees I made the executive decision to launch. Jake IV actually took off a lot faster than Jake III (the 20′ dropcloth balloon) probably because the hair dryer had already filled it with hot air. But Jake IV looked really, really weird:
We tracked up to around 3000 ft elevation, then lost cell reception. To our disappointment, the pictures weren’t transmitting, but we were just glad to get the balloon into the air. About forty five minutes later, my friend wanders over and says “it came down.”
Solar balloons aren’t supposed to come down till sunset, so I was pretty surprised. I figured that the seam between the two balloons had come undone, and the whole thing just fell from the sky. The upshot was that if we could recover the balloon, we’d be able to get the pictures off the cellphone.
Google Earth told us that the landing site was a brushy area just shy of Jordan Lake. We headed out and half an hour later, we were staring at a wall of thorn bushes. No solar balloon in sight. We spent another fifteen minutes getting scratched to hell, wondering how we could have lost a 23 by 13 ft solar balloon in a 50 yard circle, when I came upon the payload hanging right in front of me. The balloon had come down in a small tree and was easily recovered. Here’s a picture the cellphone took after the balloon landed:
But to our disappointment, every single picture taken in flight looked like this (yes, there’s a picture right below this):
It’s so washed out you can’t tell any detail. I’m not sure what happened. Somehow the air photos were completely saturated.
After extracting the balloon from the tree, I checked it for holes and burst seams…and found no evidence that the balloon ripped open during flight. I was very surprised to see this. So really this leaves two possibilities: either there was a rip that I didn’t find, or the sun went behind a cloud and the balloon came down.
We then realized that the cellphone actually had been sending us pictures, but they’d just ended up in a different directory on our computer. So it “worked” but the pictures were crap.
To top it all off, hundreds of tick larvae hitched a ride on my boots and ended up all over the dogs, me, my wife, and our house.
1. Don’t make a double decker balloon. The neck between the balloons has a lot of stress on it and will rip open easily. Plus the black balloon did not transfer much hot air to the upper balloon, and the increase in surface area made the whole thing lose heat a lot faster. Complex balloon geometries are a bad idea: stay simple and you’ll fly better.
2. Don’t make a balloon out of trash bags…make it out of paint dropcloth and darken it with charcoal powder (see my post here).
3. Test any camera you’re going to send up. We thought the Android would take nice pictures, but instead they’re horribly washed out.
4. Remember that stuff can go wrong, so try to launch your balloon so that it goes over open land (i. e. no urban areas, airports, or other sensitive areas).
5. Solar balloons are still awesome…and as my friend pointed out “any launch is a beautiful launch.” Recalibrate, and launch again!