the results are clearly proven because this one performs far better than the original and in this instructable ill try to explain how to build one that will work just as well.
heres a link to a short video i made
Step 1: Design
Step 2: Base
the underside is a piece of white card cut to the same dimensions as the main base with 15 mm extra on all sides. these extra flaps were folded up ready to be glued to the chamfer onn the main piece and a hole punch was used to make some air leaks into the skirt.
this bottom piece should not be glued on just yet, as the linkage for the steering mechanism is hidden between the main basse and the bottom layer.