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Portable Heliostat

Small sun tracking mirror, for pranks / vandalism
 
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First, the mirror: Instead of being made of heavy glass, it's a thin sheet of metalized Mylar, stretched over an airtight drum. Moving air into or out of the drum changes the mirror between flat and concave. When concave, the mirror isn't a parabola, but it's close enough to one for our purposes. The mirror's diameter should probably be about two feet (60 cm).

For aiming, the drum holding the mirror has a pair of pins, about which the drum can rotate, providing one degree of mechanical freedom. These pins fit into a circular track, and can move within that track, providing a second degree of mechanical freedom. The track itself can also tilt relative to the base, providing a third degree of mechanical freedom.

Each of the three angles is automatically adjusted throughout the day, so as to aim the light of the sun that reflects off of the mirror at a particular target.

Uses range from heating one's solar oven, to warming up the neighbor's front walkway (to give him a hotfoot when he comes home), to vandalism.

goldbb, May 24 2010

solar film reflectivity http://www.reflecte....com/technical.html
[afinehowdoyoudo, May 26 2010]

[link]






       why not on a particulary hot summer, late friday night paint your neighbors house flat black completely including windows, then not only will he think its earlier than it is when he wakes and will sleep in, by noon itll be over 100 degrees regardless of air conditioning. mind you this is just a mental exercise.
Arcanus, May 24 2010
  

       To apply paint to one's neighbor's home, one needs to enter his property, vastly increasing the risk of being caught. Not to mention the amount of time it would take to do so, the telltale splashes of paint on one's clothes, etc..   

       The heliostat, however, could be left almost anywhere, so long as it will get good sunlight and a straight line-of-sight to whatever target you want heated up.   

       "Almost anywhere" even includes locations a mile or two away, allowing significant getaway time.
goldbb, May 24 2010
  

       "... And unless you deliver to me 12 Billion Dollars, we will vandalise the tool shed... ah... hahahaa .... MUAHAHAHAHAHAHAHAHAHA..."
FlyingToaster, May 24 2010
  

       "Do you expect me to talk ?"

"No, Mr. Bond, I expect you to ... well ... hop around a bit, cursing and rubbing your foot ..."
8th of 7, May 24 2010
  

       20Q, spelling corrected.   

       FT, unless you pay me X million dollars, I will use my heliostat to burn a hole in your Bugatti Veyron. Or in your Lamborghini Reventon, or your McLaren F1, etc..   

       8/7, It's a bit of a cliche for an evil villain to threaten to drop the hero into a fire, or lava pit... but it would be novel for the hero to be trapped in a room whose floor was being heated to a red hot glow. There's probably a reason... maybe it's not dramatic enough?
goldbb, May 25 2010
  

       //providing a third degree of mechanical freedom// Why?
mouseposture, May 25 2010
  

       For third degree burns of course.   

       Oh, I see. I thought maybe [goldbb] was a libertarian.
mouseposture, May 26 2010
  

       So, the base thing isn't the idea here, though. It's this stretchy metallic mylar that has how much reflectivity? Is that a property? How hard is it to bend? I guess power requirements aren't the issue here, huh. It's the damn base thing.
daseva, May 26 2010
  

       Make it look like a controllable satellite dish on the roof of your house, and no one will suspect a thing...
hippo, May 26 2010
  

       .... until their cat suddenly bursts into flames, MUHWHAHAHAHAHA !   

       Ahem.
8th of 7, May 26 2010
  

       Patent it and make your kids charge 5 bucks for a glass of instant sun tea at the curb.   

       Also, [8th], how daftly you choose your squabbles. Are cats superior on another planet somewhere?
daseva, May 26 2010
  

       It's like Klingons and Tribbles. It's a Borg thing, you wouldn't understand.
8th of 7, May 26 2010
  

       mouseposture, technically, you only need one automated degree of freedom; if the heliostat is going to be adjusted manually just before use, then aligning the axis of rotation of the mirror with the earth's axis of rotation, and adjusting for the time of year can be done manually. In this case, the heliostat doesn't even need to sense the sun's light -- it could move using a cheap clockwork mechanism.   

       Or, you could have two degrees of automated mechanical freedom, in which case both axes would need to be continuously adjusted to follow the sun. Of course, when the sun moves behind clouds, the device ceases to be aimed in the right direction; it needs to "catch up" after the sun comes out from behind the clouds.   

       With three automated axes of rotation, two would be adjusted in response to sunlight, while the third would be a (much cheaper) clockwork mechanism. The light-tracking motors would move once when the device is turned on (or at dawn) and perhaps once or twice during the day, while the (cheap, durable) clockwork motor would run continuously. By not moving often, the light tracking motors last longer than they otherwise would, and if they fail... well, we can still adjust manually. And if by chance the clockwork motor fails, it can be replaced with the clock movement from any 24 hour analog clock.
goldbb, May 26 2010
  

       //both axes would need to be continuously adjusted to follow the sun// This is essentially how modern telescopes work, I believe. Even hobbyists' telescopes, so how difficult can it be? Seems simpler than designing a multi-degree of freedom light-seeking servo. (On the other hand, the servo sounds like more fun, plus, you could use it on other planets.) (On the third hand, your neighbors could spoof it into giving *you* a hotfoot.)
mouseposture, May 26 2010
  
      
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