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The Solar Death Ray
Ant writes the "Solar Death Ray is made of 112 mirrors mounted on a platform 4 feet wide and 6 feet tall. Each mirror is a square roughly 3.5 inches on edge. All these mirrors focus the sun to a single spot 5 feet, 6 inches from the mirror platform. A wooden fork extends from the mirror base to the area near the focus and serves as a mounting point for Solar Death Ray targets. The mirror platform is mounted to the support frame on a pivot that allows the platform to be angled. The whole system is mounted on a set of wheels. The goal of the Web site was to show the results of the targeted items when the solar death ray was used."
Wonder how much juice you could generate if you were to mount a stirling engine at the end of this sucker. Seems like it'd be a lot cheaper/easier to implement than normal high efficiancy solar cells if you could work out a reasonable and reliable sun tracking system.
Every year during my review, I just pray the words "slashdot.org" aren't mentioned.
THIS is a solar death ray: 10 metres of high-precision parabolic polished aluminium. (And there are bigger ones out there in the world too.)
I've observed there. Because it is radio astronomy, we could observe before sunset and after sunrise, but for some reason we had strict instructions to never let the sun fall on the dish. (That includes the back, but that was to do with thermal distortion of the dish, rather than frying the focus.)
I also used my HP48SX calculator (running a terminal emulator) to command the telescope to slew. Because of this, I claim the CSO as world's the largest and most expensive peripheral for a pocket calculator.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Larry Niven invented the "flashmob" years ago. Now, it looks like someone has come up with something similar to his Ringworld "Sunflowers", which consisted of petal-ringed mirrors which could focus on prey and turn it into ash fertilizer.
Don't blame Durga. I voted for Centauri.
Yes.
The claim was that Archimedes thought up having 1000+ soldiers use their reflective bronze shields to shine sunlight on enemy ships. Thus igniting and incinerating them.
They tried this on MythBusters and it didn't work. But they don't always do a perfect job on that show, and since armies were huge back in the day....I wouldn't be surprized if it worked.
The government has a defect: it's potentially democratic. Corporations have no defect: they're pure tyrannies. -Chomsky
This one is a bit bigger!
The parabolic reflector gaves at the focal point a maximum flux of 1000 W/cm2. The experimentations takes place at the focal zone (18 m in front of the paraboloid. The range of available temperature is from 800 to 2500 C (the maximum reachable temperature is 3800 C) for a maximum thermal power of 1000 kW.
(Did someone just say holy fucking shit?)
Picture of the Odeillo Solar Furnace
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Given that he was able to set a rag on fire, I'm guessing that the Mythbusters team did something incorrectly regarding the focusing of their mirrors. And your link says they used a circular configuration which is only good in limited cases since the light is focused in a line (which isn't really focus) rather than a point. This was parabolic setup which is why he was able to melt plastic and set a rose on fire.
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Wired article as proof
Maybe not igniting them directly, but...
How about blinding the sailors on board, who then run around in a panic and knock over the pot of charcoals used for igniting the flaming arrows? Carcoals ignite the ship's deck instead, or someone's clothes, the fire spreads, voila. No more battleship.
I surrender.
Under perfect conditions, you should be able to reach the surface temperature of the sun - about 5600 C. This will be reduced by atmospheric absorption, imperfect reflectivity of your mirrors, etc.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Tip it up at a higher angle.
The sun is just about as strong in Scotland as at the equator. It's just that the angle of incidence to the ground is larger. sin 90 vs sin 30.
This is why domestic solar can work in the UK. Put the panels on the roof at the angle which'll maximise the energy collection. Hell if you can plumb, you can make a solar panel for peanuts, e.g. http://www.bigginhill.co.uk/solar.htm
Government of the people, by corporate executives, for corporate profits.
Stuff burns when it gets real hot.
Supposedly the inventor Archimedes during the siege of Syracuse by the Romans used large mirrors that focused/concentrated sun light into an intense enough laser beam that it burned invading Roman ships. There was an episode of Myth Busters on this subject (Season 2 Episode 4).
Here's what the Myth Busters guys did to test the theory:
- The crew build half a trireme and balanced it in the water.
- The crew built 400 sq ft mirror built from 300 individual mirrors. They were arranged in a cicle and were all focused at the same point.
- They aimed the giant mirror such that the focal point of the indvidual mirrors was directly on the trireme.
- They were only able to get the temperate up to 280 degrees even with all of their efforts.
- They just couldn't get the ship to burn, so they used Molotov cocktails instead just so they could destroy something.
Simply put, this is a myth. It is very unlikely it happened.
Pankaj Arora
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This is a solar furnace, of which there are many in use today. The biggest one in the world is the Odeillo Solar Furnace located in Odeillo, France. The top 3 in use in the United States are at Sandia National Labs, Georgia Tech and the White Sands Missile Test Range. Awesome stuff!
One amusing side note is that Frank Gehry's popular postmodern buildings have been noted to act as solar collectors, effectively frying people passing by on the sidewalk.
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(Hopefully someone that took some optics (physics) or astronomy) ...or high school physics.
i forget
Take a microscope and set it to 500X. Point the objective at the sun. Do you death rays spewing from the eyepiece? (Answer: no).
A while back I was at an observatory and the guy in charge said never to point a telescope at the sun. To demonstrate, he turned the telescope (10.5" refractor) toward the sun. We could see a beam of bright light coming out the eyepiece. He put a piece of paper in the middle of the light and it ignited into flames almost instantly.
Yes, telescopes and microscopes are not the same thing, but aren't they similar? What caused this? No, I am not a physicist, and don't know about optics and all that beyond what they taught me in college.
24 beers in a case, 24 hours in a day. Coincidence? I think not!
Finally something I can contribute to slashdot!(says the optical engineer working late): The collection of mirrors used here is actually a piecewise-flat approximation to a large magnifying mirror, and does magnify the sun, within a margin of error. Augustin Fresnel invented this concept in 1822 for use in lighthouses. http://www.lanternroom.com/misc/freslens.htm If you look at the array of mirrors used here, the outer ones curve increasingly inward, just as as if it were a sigle curved mirror that had been cut up and rearranged to fit on a flat board. Any small part of a large curved lense is approximately flat anyway. It is not generally called "magnification" because that is used to talk about enlarging images, and this type of lense, being approximate and cheap, yields pretty blurry images. Still, works great for spotlights and solar concentrators. Here is another example: http://ravenrocks.org/Mook/
"I love his boyish charm, but I hate his childishness" - Leela
How about a board of little mirros on motor-controlled pivots. If you point the board directly at the sun, with a single command from a controlling computer you could redirect all of the mirrors to any point in your firing arc at any distance.
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Sorta, anyway. This is a link to the UNLV Solar Project, a project playing with new ideas in solar energy such as focus the light to a specific point (roughly, of course) to increase the uptake of energy by the receptors. I drive by these bad boys everyday. UNLV Solar
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Myth Busters tried this one too to duplicate something Pythagoras (I think) was supposed to have done.
Archimedes. You're talking about using mirrors to set fire to the sails of attacking ships, right?
David Gould
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