Halcyon

iTrader: (1)

https://occamsracers.com/results/ope...-and-fastback/


According to that article, open top is 2.5x less effective.
So can I adjust the angle to get to my desired downforce?
For example, with the gtc200. If I want the downforce created at 0 degrees. With an open top can I pitch it at 12 degrees and get close to the same downforce? I’m assuming drag would be about the same as well?

Savington

iTrader: (31)

The wing is less effective because the airflow without a top is incredibly dirty. Dirty airflow across a wing will generate lots of drag and very little downforce. Changing the AOA will add even more drag and not much additional downforce.

Get a hardtop.

Occam’s Racer

I didn’t test the GTC wing, but if you look at my article on NACA wings and do some experimenting on the airfoil tools page, you’ll find that virtually no single-element wing works well at 12 degrees. At that angle, most wings will stall, meaning more drag and less downforce.

https://occamsracers.com/2019/05/23/...airfoil-tools/

Savington may have different data, but my testing didn’t show any increase in drag with the wing and open top, despite the turbulence. In fact the wing was .03 Cd across all tops, and I kind of wonder if the wing might have helped clean up the wake because the open top should have had mode drag. In any case, you can play with the NCrit value to simulate turbulence.

It comes down to this: you need clean airflow under the wing.

Halcyon

iTrader: (1)

Thanks for the response guys.
I enjoy driving at the track with the top down.
But I guess I’ll drag the hard top along and experiment.

flier129

iTrader: (7)

Running the hard-top instead of open-top is 100% the better option. If you didn't have a hard-top then putting the soft-top up would be the way to go.

FWIW 9LR wángs produce the same CFD results in open air as they do on our standard mounts on a NA.

Morello

I find it hard to believe the soft top open (with a roll bar) is better than soft top up...

Occam’s Racer

^ Agree. I'd have to see data to believe otherwise.

flier129

iTrader: (7)

putting the soft-top up ***

Typo! Johnny is rubbing off on me.

LuckyKid

Thanks for posting this. I didn't see that data before. It's helpful to see the data from the fastback. We built ours based off trolling this forum.

Cheers,
LuckyKid
Team PartsBadger