I appreciate the info and ideas. I quite like that Ford Fusion.
Tired of my own guesswork and theorizing, I broke out the yarn and tape. I made a spoiler from cardboard that follows a shallow angle starting at the base of the trunk lid and ending at the rear, that has a height of maybe 3 inches.
I noticed a lot more pressure on the rear (the tufts are flowing much faster), and the tufts spun and fluttered all over the place. I’m not sure if that’s good or bad, but that seems bad.
The stock rear end seems to have pretty good flow. The C-pillars have a poor transition to the rear windshield and from what I can tell that is causing two vortices to fall off them; culminating in a separation bubble at the base of the trunk’s centre.
So, maybe that’s the wrong way to go. I have considered extending the sides up to create a wall all around the spoiler; like the “bird bath” on the Walkinshaw.
But given that flow seems to be attached for most of the windshield, I think I’ll try out the spoiler on that 999 LSR Fusion. Very similar to the first spoiler I ever built for this car.
