Thanks for posting your detailed results, Bob.
Quote:
Originally Posted by donee
My guestimate is that the AirTabs are just too big for the boundary layer thickness on cars. They were designed for 18 wheel truck trailers
|
This is a comment I keep reading, yet the company selling AirTabs markets their product directly to owners of small vehicles as well as large trucks.
As for the thickness of the boundary layer at the trailing edge of the roof, Mitsubishi measured this in their VG development and found it to be approximately 30 mm, which is close to the height of the VGs they used. And which is the same height of the AirTabs style VGs.
It has been speculated that the
style of AirTabs vs. the delta-wing shape used by Mitsubishi could produce different results; the delta-wing presents a much smaller projected area than half an AirTab (which produce two vortices, one on each side).
But again the crucial point is, even though optimized for style/placement, Mitsubishi only saw a .006 reduction in Cd in their model with VG's, which is essentially impossible to detect even in as-controlled-as-possible testing that I tried and Bob also undertook.