DBF Workshop Session 1 - Aerodynamic Study of Model Plane (Part 1)

Hi there,
My query is with regard with calculating the areas of the projected planes.I downloaded the geometry to find the above values in my cad software,but the file being a .STL file does not show the tree to select individual features and evaluate its properties. Is there any other format which i can download? As of now,I am using the values mentioned in the tutorial above.
Thank you.