mini electric ducted fans
The Vasa 55 units are nice units and the diameter of each is only about 2-1/2", so they shouldn't be too large for a 36" WS model.
These units work well with standard Speed 300 6V motors on 7 cells or for a brushless upgrade they really put out with the Model Motors Mini AC 1215/16 Brushless, but at a higher cost.
Mike Hines