In poor countries solar cooking saves the forests. Box cookers are a bit slow but are reliable. Parabolic cookers are fast and unreliable. Perhaps they need something in between the 2? The jig in the videos below gives you "scallop shaped" reflectors that could go like 2 ears onto a box cooker to give greater power. the jig is pretty simple and it uses 2 laser pointers ($1.50 each in the dollar store) to represent the sun at the start and at the end of the unattended cooking period. thought it might be a good project for engineers. (I do not have the patience)
I put 2 videos on youtube to further explain what I am trying to do. They are
formatting link
formatting link
you are short on time, just watch the first 5 minutes of the second video. Brian
If only I had a fiver for every time I`ve heard that, I could pay someone to cook for me.Come to think of it I already have,that is,until she sees this. Mark.
Why not leave you parabolic reflector for 20 minutes and see how good and "reliable" its focus is? (This off focus effect is quite dangerous if it hits your eyes). And off focus parabolic reflectors also have a second order "focus" that can burn stuff yards away from the dish. Would you think it "reliable" if your barbecue burnt down your garden shed every few years? I am not sure how that fits in with the term "reliable" in your eyes. A parabolic solar cooker is only "reliable" if it has constant accurate tracking.
99% of parabolic solar cookers do not have that feature. I hope we get a few mature responses from now on. I am not in the mood for this level of comment.
46 degrees of seasonal movement is one of the problems, The parabolic focus does not corespond to a center of gravity. So you cannot balance the dish on the gimbal for more than a few days. I have been playing with this problem for 3 years and reading the solar cooking groups for about that long too. The problems with parabolics are very real.
I am not doing anything commercial. It is a charity project and I get abuse, not money. I have not figured out how to keep the strips in place when making the model. If anyone else does it, they get the credit not me. If one of you invents a new scallop shaped solar cooker (using the jig), and shows it to the world, you get the credit, not me. It might be a great thing or it might end up as a dead end. Perhaps worth a try and rewarding for someone? Brian
No, it was huffy because the subject is unattended solar cooking and parabolics are a little better than useless for that. And parabolics are dangerous. But someone HAS to go and steer the thing off track. I am an amateur too. I do not have skills in model making. I thought some of you might be interested in making an impression AND helping people in far off lands. People give money to charity, why not time? Right now, carbon credits are being used to pay for making parabolic solar cookers in India, and even used to pay people to use them! (To save the forests) And users are saying "my skin is getting burnt", "My eyes feel like hot coals", "I got sunstroke cooking dinner". But are the carbon credit people listening? Are the cooker makers listening? Nope. It is a good game for them. They make their money. There are several answers. One answer is cheaper tracking. (I have worked on that) Another is reflectors designed for unattended cooking. (This can be addressed somewhat with this project) Several of my free solar cooking ideas are on the net in solarcooking.org I do not get a cent for them. There is nothing commercial about my interest in solar cooking. Why do people dig in their heels when they hear new ideas?
20 minutes with the jig and you will be saying, "holy crap, he is right" but instead a few people act like a gang of thugs and intimidate everybody. Parabolics are only good if they have all day everyday tracking. At other times they are an eyesite and fire hazard. Tracking for solar cookers is just not as simple or as cheap as people seem to think. If you do not want to make the model, that is fine with me, but why do you think you speak for an entire group? Brian
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.