Quote:
Originally Posted by kach22i
Going off memory, rear underbelly angle of inclination should be limited to 10-degrees.
This is similar to the over the body angle being limited to 22-degrees.
I think with rear diffusers with vertical strakes or fins contain the air and keeps it from wandering or rolling off to the sides.
This containment zone between the fins I believe allows for angles greater than 10-degrees to exist and function as intended for ground effects.
I would think the 3-4 degree thing may apply to the initial curvature upward and not a mandatory angle to be maintained the entire length.
|
That is true USUALLY of 10 degrees to keep the flow from detaching. I have seen much steeper angles than 10 degrees with flow attached however. There are some nifty tricks that can be done
This does make the car more sensitive to ride height and yaw changes though (racecar application only).
He was talking about drag though which doesn't matter. The diffuser will make drag (as an isolated part) at any angle because of induced drag. In a system, it will usually decrease drag even at lets say 7 degrees (especially on street cars).