Maximum (minimum) Coefficient of lift

[Jreyenga]

Hey guys, former FSAE guy here. I'm designing a wing for an autocross streetmod car. I'm limited to only a two element wing. Using real CFD (i.e fluent and not the crap that is javafoil) I've generated a 2D model that has a CL of -3.4 at 40mph. As a drive of whether or not to refine the model more, I'm trying to gauge how "good" that is. I've heard that F1 wings for Monaco get in the -4 range, but I can't hope to develop a wing that good(I realize that's probably also measured, where my '-3.4' will lose a bit due to 3d effects).

Unfortunately I slept through a lot of my aero classes so I don't have a good intuitive feel for how to improve a wing.

If I add a gurney flap, should it be vertical on the last profile or perpendicular to profile? (I'd guess vertical)

For those of you that have done some serious aero work, what kind of Coefficients of lift are you looking at?

Thanks and good luck to all of you at competition this year.

[Jreyenga]

Hey guys, former FSAE guy here. I'm designing a wing for an autocross streetmod car. I'm limited to only a two element wing. Using real CFD (i.e fluent and not the crap that is javafoil) I've generated a 2D model that has a CL of -3.4 at 40mph. As a drive of whether or not to refine the model more, I'm trying to gauge how "good" that is. I've heard that F1 wings for Monaco get in the -4 range, but I can't hope to develop a wing that good(I realize that's probably also measured, where my '-3.4' will lose a bit due to 3d effects).

Unfortunately I slept through a lot of my aero classes so I don't have a good intuitive feel for how to improve a wing.

If I add a gurney flap, should it be vertical on the last profile or perpendicular to profile? (I'd guess vertical)

For those of you that have done some serious aero work, what kind of Coefficients of lift are you looking at?

Thanks and good luck to all of you at competition this year.

[HenningO]

I'd say that you CL is in the right neighbourhood. I would spend too much time to get those extra 5% in CL, better that sanding you final wings.. Will probably get more!

The guerney flaps should be perpendicular to the last wing section, what the flap does is that it creates a vertex behind the flap which helps the flow stay attached longer.

Using endplates will reduce the 3D effects on your wing.