"Compound" parabolic solar cooker, make a template with technical drawing

Step 5 How do we test a compound parabolic shape for effectivness?

This is part of my continuing attempts to understand what I am doing!
Below are pictures of a 60 degree compound parabolic model that I made around January 18th 2009
As you can see, depending on the angle at which the picture was taken, the reflection of the apple or little ball was very different. (The apple happened to be closest to the size of the distance between the focus and the bottom of the dish). I think the photos are a clue to how effective the dish can be.
I also used a lazer spot to test its effectiveness.
I have not done anything scientific just yet but it is a start! As you get closer to directly over the dish, you get an increase in the size of the reflection that probably coresponds to how effective the dish will be when the sun is in that posititon.
Brian

Comments

[danno]

Nothing in your instructions showed how you made the base for the reflective strips..... There's a huge leap from drawings to finished bowl to glue reflective strips to

[gaiatechnician]

Yeah, sorry. I made a template and rotated it in the middle of the bowl filled with wet clay. The reflective strips were stuck on by squirting a plant mister on the clay and sticking the mylar directly on to the wet clay.
It was really more to show myself and other people what happens with off focus paraboloids and other shapes.  YOU are the SUN and the reflection you see is the same size (pretty much) as the area that reflects onto the target.
I spent ages trying to do this in software. It ended up being the basis for the solar design T-square idea.