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Compound parabolic solar cooker from petal template. Want to try one?

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Posted by brian white on December 30, 2008, 11:48 pm
 
I made a compound parabolic solar cooker in September 2008 and it worked
well. Most people would lot like to repeat my method (I made a Dome and
used it as a mold) and they asked for a template instead.
The first link shows how to make a mold for a compound parabolic solar
cooker (using technical drawing to design the "petals" to stick together
to make the reflective dish).
http://www.instructables.com/id/Compound_parabolic_dish_making_a_template_with_te/
and the bottom link has more details about what they are and how they
work. Perhaps some of you would like to try? I have no good sun till
about march because my lot slopes to the north.

http://www.youtube.com/user/gaiatechnician
Thank you
Brian White

Posted by Father Haskell on December 31, 2008, 1:50 am
 

dish).http://www.instructables.com/id/Compound_parabolic_dish_making_a_temp ...

Is this the same idea as used to design Direct TV dishes?
I see these things on the curb awaiting the trash company.

Posted by brian white on December 31, 2008, 10:19 pm
 No it has a different curve to it. Thanks
Brian
Father Haskell wrote:



Posted by Father Haskell on December 31, 2008, 10:27 pm
 
Multiple focal points?



Posted by brian white on January 3, 2009, 5:20 am
 Nope, it has a focal area. A parabolic dish has a focal point but only
when it points DIRECTLY at the sun. Get a concave mirror or a magnifying
glass and  make a focus with a light in your room or with the sun. Now
twist the glass or mirror a bit to model the sun as it moved for an hour
or 2. No more point of light! It spreads into a focal streak! The idea
with a compound parabolic dish is to start off with a focal "ball"
(Perhaps as big as a soccer ball) and 2 hours later still have the same
focal "ball"! Place a cooking pot the same size as the ball in the focal
ball area and you are in business.
  Although you do not get the same concentration as a dish, you get
something much more usable. Now you set up the dish, stick on you food
and come back to a cooked meal! This is not possible with a parabolic
dish because you have to move it so often.
I do not know the exact shape of the "Ball" because I cannot do the math
but I am pretty sure how big the area that contains the "ball" is. It is
called a "Caustic curve" and very complicated to model exactly.
Father Haskell wrote:


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