http://www.rcadvisor.com/
Very Easy to Use Model Airplane Calculator
* powerful EZ Optimizer for creating efficient power systems
* displays 31 graphs that update in real-time
* guides you with 425 ToolTips and 7 interactive tutorials
* flies your model in a virtual wind tunnel
* huge database of preanalyzed airfoils
* shows you the right trade-offs for your scale model
* runs on Windows, Mac and Linux without installation