The solar design T-Square is a simple device to represent the sun and greatly aids the design process. My aim is to design better solar cooker reflectors for unattended cooking. I imagine the sun as a giant spotlight shining down. It moves at about 15 degrees per hour across your solar cooker. In a couple of hours the path of the sun is pretty close to a straight line.This means that you can use 2 laser pointers to represent the sun. One is for the sun at the start of the cook time and the other is to represent the sun at the end of the cook time. If you mount the laser pointers on a slider on a T-square, above your model, you can use it to test how the light rays bounce off of every part of your model.
You can then make much better models of your new solar cooker reflectors and use the laser pointers to see where the light ends up after hitting the reflector.
If the light bounces from your reflector and misses the target, it is a relatively easy task to adjust the reflector so that it hits its target.
T-square outlined in orange
The T-Square is outlined in orange, the laser pointers are pointed to with green arrows and a blue arrow points to the target. In this case, the reflector is basically parabolic with strips of material to redirect the light towards the target. The model is almost correct. (The top of the strips should bend and touch the ball, but I could not hold them in place). Other than that, the model is pretty correct and is good for about 2 hours and 20 minuges of unattended cooking! (In theory!)
Dishes designed for unattended cooking with the tsquare are NOT parabolic dishes! It is also possible to design combined troughs where the sun hits a large half trough and the second trough redirects the light to the target. Using the T-Square, it should be relatively easy to design better cookit's and to design whole new ranges of solar cookers to better suit individual requirements.
Clothespeg to keep the laser turned on
The clothespeg is necessary because the cheap laser pointers do not have an on off switch. They have a button that you must keep depressed.
The setsquare has degrees marked on it
I use mylar reflective plastic for the models. the Mylar is "stuck" to a plastic backing (a thin plastic table mat works) with water droplets from the sprayer. that is fairly easy. I also cut it into strips for the upright part that focuses the light further onto the ball. It is quite the task to keep them in place and that is a part that I have not figured out yet.
You can just see a laser dot on the bottom of the setsquare
Here you can see the laser spot at 75degrees
Brian