I've seen this type of spoiler on a lot of fuel efficient cars, my Prius included. This Miata hardtop spoiler looks similar and I kind of like the looks of it. Would it in any way be functional on a Miata? Comments from the hive appreciated.
I've seen this type of spoiler on a lot of fuel efficient cars, my Prius included. This Miata hardtop spoiler looks similar and I kind of like the looks of it. Would it in any way be functional on a Miata? Comments from the hive appreciated.
The rear window of a Miata should be a sufficiently shallow angle that the air is following the roofline and detatching at the top edge of the trunk. If the window stays reasonably clean, then this is true. If it is dirty all the time, like a hatchback or minivan or SUV, then the air is sometimes/always detaching at the roof.
If the air detaches consistently at the roof (old Rabbit), then the spoiler does nothing aerodynamically.
If the air detaches at the roof, but not consistently (pre-spoiler Scirocco), then the spoiler will cause the air to detach at the roof consistently and will reduce drag.
If the air detaches at the trunk, then the spoiler will cause the air to detach at the roof, increasing drag noticably and making a slight reduction in lift.
Generally, anything steeper than 32° from horizontal will detach at the roof. Less than 28° will follow the window. Between 28° and 32° gets messy. These generalizations apply to "car shaped objects" and not always to what happens to a pick-up cab or the roof of an MR2 or Del Sol.
Now the real experts can check my answer and hopefully I will learn something, too.
Good info! Thanks. That leads me to another question: Would it benefit a wing?
The spoiler would "spoil" the the vaguely clean air headed to the wing and significantly reduce the effectiveness of the wing.
If you look at some of the WRX Subarus, you can see various attempts to get the air to follow the window even more (vortex generators, or wing-like items bending the air path to encourage the air to follow the profile of the window). Those efforts can reduce drag at the edge of the roofline, but increase lift. If they help the air stay clean enough for the wing on the back, then the wing can give more benefit in downforce than the extra doo-dads cost in lift.
Makes sense!
You'll need to log in to post.
