In 2006, Science Olympia had a trial event called Balloon Launch Gliders. Since it was a successful event last year, they decided to make it a Division B event in 2007. The 2007 Balloon Launch Rules are at: http://www.soinc.org/events/sample/index.htm or at http://www.soinc.org/events/blg/BLGlider-B-07.pdf
In the 2007 event, the rules are slightly different than they were in 2006. The biggest change appears to be the model’s minimum weight, which has been raised from 1.5 grams to 2.0 grams. The BLG plans on this website were designed for the 2006 rules and the desired weight of the model is list at 1.5 grams, not 2.0 grams.
I have not designed or built a model to the 2007 rules, nor do I plan to do so. Simply use the plans posted on this website and just build the plane a little heavier or add ballast. The model will still perform well, but I predict about a 25% loss in duration time from the same model which weighs 1.5 grams.
Another option would be to make a new design specifically for the 2007 rules. I believe a better design can be developed in the basic construction of the model. To achieve the minimum weight of 1.5 grams (old 2006 rules) I constructed a built-up wing to make minimum weight. Please note: You’re not required to make minimum weight, but the lighter the plane, the better time it will turn.
The rules have added .5 grams to the minimum weight. In my opinion, developing a wing made from solid material, like balsa or foam could be another option. Building a model out of solid material allows better airfoil shaping. Also, the airfoil will not change during the flight, where as wings that are covered with covered with plastic or tissue will change. Solid wings typically produce less drag, and it's in your best interest to keep the drag minimal. Some simple testing and calculations predict that an extra 20% gain in time could be achieved by choosing the best airfoil and building the wing out of solid material like balsa. In my opinion, the “best airfoil” is something similar to what the low ceiling indoor catapult and hand launch glider use. There are examples of these airfoils on this website in the plans for the Time Machine and the Slow-Cat. The challenge will be to construct a plane just at 2.0 grams using solid materials like balsa or foam. If you can’t build it at 2.0 grams using solid materials, you are better off constructing a built-up wing.