Cup lip and Gurney flap seem to work.
03-10-2011, 08:15 PM
#32
Rennlist Member
well you are half right, it is 2 to 5% of the cord length, but what it buys you is MORE drag for a give lift for the aero device. what this means is that, unless you are lift (downforce) limited with your current wing angles, then the gurney flap is a waste of time and money. if you ARE limited, then its a damn good idea. you get basically 25% more drag for the same downforce is if you increased the angle of attack of the wing. if you have a fixed wing, then its a god send, because now, if you want more angle, you cant without adding a gurney flap.
Facts:
1. based on the charts, for a given lift or downforce, the gurney flap produced more drag.
2. if you are maxed out at AOL, it can increase downforce by 20%.
summary, use the wing angle until you are maxed out and then add a gurney flap, or a larger wing!
I never heard of any one gainnig 1 second truely by increasing their wing angle alone, by 4-5 degreees. I think most of that would be placebo. but I agree. put the gurney flap on. try and run as fast as you can, take it off and repeat. data logging will tell most of the story! one thing i found when racing with no aero (recently did this because the car wasnt finished yet) is that it felt squrimey, and i knew i had no wings, so I was more cautious. times were 1.5 seconds slower, but that is without ANY aero.
Facts:
1. based on the charts, for a given lift or downforce, the gurney flap produced more drag.
2. if you are maxed out at AOL, it can increase downforce by 20%.
summary, use the wing angle until you are maxed out and then add a gurney flap, or a larger wing!
I never heard of any one gainnig 1 second truely by increasing their wing angle alone, by 4-5 degreees. I think most of that would be placebo. but I agree. put the gurney flap on. try and run as fast as you can, take it off and repeat. data logging will tell most of the story!
one thing i found when racing with no aero (recently did this because the car wasnt finished yet) is that it felt squrimey, and i knew i had no wings, so I was more cautious. times were 1.5 seconds slower, but that is without ANY aero.
03-10-2011, 09:33 PM
#33
Then you have to compare the difference in gurney vs. no-gurney lap times vs. the within-group standard deviation of lap times.
... and then I'm sure some statistician will still find fault with the data!
03-11-2011, 09:50 AM
#34
Rennlist Member
Thread Starter
That sounds like a lot of work. I did enough testing to know it works and I am too lazy to rip it off and re-glue it on.. I already know it is faster, I really did not think about the flap when I went faster:
I have no idea how much down force the lip and flap make.
I agree the difference is big.
It's not even 2 minute lap:
Session 2 I did steady 12 laps, all 1:21's 1x 1:221 and 1x 1:208. Session after no changes at all besides adding the lip and flap and maybe 1/4 tank less gas. I drove hard, pushed like hell.
1 1/2 hour later, pushed like hell: 11 laps, all 4x 1:19 4x 1:20 and 1 1:21 (Traffic).
Same driving, not more confidence, either the car slides or it does not..
I agree the difference is big.
It's not even 2 minute lap:
Session 2 I did steady 12 laps, all 1:21's 1x 1:221 and 1x 1:208. Session after no changes at all besides adding the lip and flap and maybe 1/4 tank less gas. I drove hard, pushed like hell.
1 1/2 hour later, pushed like hell: 11 laps, all 4x 1:19 4x 1:20 and 1 1:21 (Traffic).
Same driving, not more confidence, either the car slides or it does not..
03-11-2011, 11:00 AM
#35
Drifting
Slow.. Where did you get that Gurney Lip?? I like that..
03-11-2011, 11:20 AM
#37
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03-11-2011, 01:06 PM
#39
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03-11-2011, 02:50 PM
#43
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Found this link on another site. Good read if you can make it thru the techno speak - http://www.aoe.vt.edu/~mason/Mason_f/AIAA2007-4175.pdf
https://rennlist.com/forums/racing-a...lap-study.html
03-11-2011, 05:30 PM
#44
Rennlist Member
Thanks but this study is the reason why this thread was bumped.. : )
https://rennlist.com/forums/racing-a...lap-study.html
https://rennlist.com/forums/racing-a...lap-study.html
Last edited by ATL Fahrer; 03-11-2011 at 05:48 PM.
