Sunday, April 12, 2009

Solar Success and Set Backs - a Garbage Bag Balloon and Windshield Shade Cooker Follow-Up

Finally, a sunny day! Of course, since it was Easter, we were tied up until about two in the afternoon, so we missed most of the really good sunshine for our solar experiments. However, after checking the forecast for the next week, and realizing we're probably going to be socked in with clouds and rain all next week, we decided to make use of what sun we could.

First off, we set out our solar cooker (look back a few posts to see our original trial), with our modified pan set up. Instead of using a cast iron pan in a cooking bag, we used a black bread pan set atop the black base of a spring form pan, and topped with a clear glass mixing bowl. We just put water in the pan this time. Our hope was to see it boil.

Things started off well. The temperature rose to 250 degrees Fahrenheit within an hour. Then disaster struck. A strong gust of wind tipped the shade enough to make the rack tilt, and the pan and bowl slid off, spilling most of the water onto the ground. We had weighted our pail down with rocks to keep it from tipping, but this did not protect the upper portion of our cooker.

We started over, but by this point we were into the late afternoon sun. Our cooker touched 250 degrees again, but then rapidly declined as the sun moved lower in the sky. Wind and poor weather seem to be very major negative factors for solar cooking. However, we have watched too many videos on YouTube of people bringing there food to steamy perfection in their own homemade solar cookers to give up yet. When the sun returns, so will we!

While we were waiting for our water to boil, we did manage to get our garbage bag balloon in the air. Heated nicely by the sunshine it rose quickly. I'm quite confident it would have risen to a significant height if we had not kept it moored to the ground by a thread attached to one end. The thread threw off the weight and balance of the balloon a bit, causing it to move erratically in the wind, like a Chinese dragon on the loose. It was excellent fun!

With a little modification (like attaching thread to both ends), this could be an excellent kite for days with little to no wind. It requires very little breeze to move the balloon once the air inside has been heated by the sun. Since we are one of those families you might see trying to get a kite to fly on a windless day by running frantically down a hill - this invention could be a great asset to us.

It's great to be a homeschooler!

No comments: