I realized I forgot to link these up on my blog:
Grassroots Mapping PDX 6/26/2010: helium flight from mathew lippincott on Vimeo.
Grassroots Mapping PDX 6/26/2010: Solar Hot Air flight from mathew lippincott on Vimeo.
Grassroots Mapping PDX: flight images
I still haven’t stitched together a map from my helium flight on 7/9, but here are some great aerial photos:
From the solar balloon flights. I really wish I could send these balloons above 150ft, as is RJ and I we only got shots of the beach.
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this is a great shot of me and robby kraft inflating a solar balloon on 7/27, taken by Samantha Mitchell. We never got into the Sauve Island airspace though, the Sheriff told us to stop. He was jovial, but wouldn’t give us a charge or cite what statute we were violating. I actually had to chase him down and harangue him before he conceeded that he’d ticket us for “harassing wildlife.” The only wildlife we harassed was the pig tooling around in a pickup truck. We had the decency to walk into the refuge on foot.
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Helium Flight
I’ve got over 800 photos that need stitching from this one, my dad and I went to a little over 1000 ft on the beach at Seaside, OR.
Grassroots Mapping PDX: test conclusions
With help from my Dad, RJ Steinert, Samantha Mitchell, Robby Kraft, and Molly Danielsson, I’ve been flying balloons most weekends since the workshop in June, gathering lift and flight data on helium and solar hot air balloons.
Solar Balloons:
Regular charcoal sucks, no matter how finely ground. In my tests over this month I couldn’t get it to coat the balloon well. My previous successes were with Char-Kole brand compressed charcoal, ground up. Jeffery Warren copied my building instructions and tried charcoal in Georgia (EU) without success.
I still want to test lamp black, but Cabot pigments STILL hasn’t sent me samples (ordered them the 2nd week in June). Go with iron oxide black (sold as tempura pigment, or from industrial suppliers). Iron oxide black consistently generates roughly 500g of excess lift from a 12-foot tetrahedron. the easiest way to test the lift of a balloon is to tie a water bottle to it and empty out the water until the balloon is airborne.
Use a mattress blower to disperse the pigment when the balloon is mostly full. It pulverizes and disperses, and possibly, through proximity to the motor, charge them a bit.
I stand by my dislike of black HDPE, because it is weak and tears easily when hot.
Helium
My balloons have, until now been all solar, so these were my first helium flights. Helium is great. it rides proudly in the wind, owing to a favorable ratio of static lift to surface area/drag. But helium is expensive. I spent four times as much on helium as I did on all other supplies. After flying my very thin HDPE .3mil balloons and watching the helium leak out over a 3 hour period, I think a more substantial balloon aught to surround such an expensive gas.
I might try some PET film, which retains helium better, but it’s cost ($15 vs $0.50) makes me averse to it.
Or I might switch to hydrogen. I’m excited about this method of urine electrolysis. Apparently it’s far more efficient than water, and I’m already carrying it around!
GrassrootsMappingPDX: Heat Seaming
Here’s the instructional video from the workshop on heat seaming balloons. If you have the space and equipment, this will produce a lighter, more air-tight balloon.
Grassroots Mapping PDX 6/26/2010: heat seaming from mathew lippincott on Vimeo.
Grassroots Mapping PDX: Taping up balloons
I’ve finally collected and edited the workshop’s videos and instructions:
Taping Instructions
Follow the first two pages of my Balloon Building Guide to make a tetrahedron balloon. Tape carefully.
My balloon guide’s rigging is for short flights in confined urban areas. We’re going to use a different rigging for aerial photography.
One corner of the balloon is used for filling, and is tied off, like a trash bag. A second corner is re-enforced, and a loop of tape attached. To the tape is tied a short length of line. The knot used is a Bowline.
Grassroots Mapping PDX 6/26/2010: Rigging a balloon for flight from mathew lippincott on Vimeo.
attach a swivel to the balloon so that any spinning won’t twist the line or the camera.