Quote:
Originally Posted by JulianEdgar
The strakes I trialed are 410mm apart. I've seen production cars with strakes as far apart as the full diffuser width, all the way to being only about 75mm apart. In my book, page 95 and pages 183 - 185 have some good views of strakes in diffusers of production cars.
The plywood (both strakes and base) is 3mm thick. I didn't bother describing the assembly because it's shown in the third post in this thread - https://ecomodder.com/forum/showthre...tml#post622797
When it was in position, it was taped around all edges. The sheet was sized to be the same as the rear diffuser, which in this part is flat (ie not curved). I would guess the boundary layer as being something like 10mm thick at this point, so I can't see small discontinuities making much difference to anything. At their maximum, the strakes are 90mm deep. |
So 410mm is a little over 16", wider then "norm" by my definition IMO, I also suspect many strakes on today's road cars/SUV's are often more cosmetic , kinda like the wings mounted an inch above the "boot". I also believe strakes more then two, are mainly to enhance DF goals, rather then reduce drag (when used for a performance goal not cosmetics), I don't know precisely.
Would a curved piece of PW been a more proper fit? I get that almost all testing accepts some compromises.
I totally agree 3mm would be hard to image as great impediment on this application, but also remember in aircraft wing tests, bug splatter is even detectable. The tape was visible in posted pics, so it was apparent you were likely trying to minimize any "discontinuities".
Regardless, something caused the increase in measured air pressure, and I can't still conclude it was only caused by the three strakes.