#video #toread about radio-controlled #drones #flying with circular wings
#video of Bach’s Toccata and Fugue in D Minor on an accordion. #music
#faircompanies #video of 360-acre Ozark homestead #dwelling by military veteran concerned about facing hard times #toread
#video #toread about an e-bike trailer for #dwelling that is apparently illegal. 95 minutes
#Concept-Crafted-Creations #video about a #solar #energy collector based on the James Webb Space Telescope with 18 mirrors costing US$5 each, each mounted on three springs with screws in a giant flower, with a dual-axis solar tracker. It yielded only 924 watts out of 1.31m².
#Concept-Crafted-Creations #video about #manufacturing the #solar-energy collector based on the James Webb Space Telescope with 18 mirrors costing US$5 each. Explains that the JWST uses gold so it can do better infrared imaging. He made some small concentrating mirrors by letting heated plexiglas discs sag into a mold made with #3D-printing, which seems like an interesting technique for #optics in its own right, though possibly not imaging optics. Rather than for the final solar concentrator, this was used for a goofy invalid experiment to compare “silver” and “gold” which were represented by colored spray paint, and the “#energy” gathered was measured by some unknown kind of light sensor #electronics. For his big collector, he used not just 3-D printing but also #laser-cutting on wood and assembly with screws. He also used a laser-cut alt-azimuth wood base with a giant gear for #solar tracking. He explains the three-point screw-and-compression-spring mounting that makes each of the 18 mirrors alignable, using TPU accordions for the compression springs; the mirrors themselves are laser-cut plexiglas with reflective window film stuck to it. He was hoping to sag these plexiglas hexagons into a mold in the same way as for the small test mirrors, but his microwave oven (which must be what he used for the others) damaged the window film, so he ended up heating them to only 100° or 120° and clamping them into a mold (with a laser-cut custom clamp) instead of just letting them sag under their own weight. His aluminum collector plate with coolant grooves running through it cost him US$171 for #PCBWay to custom-machine, making this a very expensive solar collector, though he thinks it’s cheap. Also he’s in the Netherlands, where it’s cloudy a lot, especially in winter. Comments mention that blackening copper with liver of sulfur makes a good solar-collector material.