So let's say you've mounted your rear wing. What angle do you set it to?
03-25-2011, 11:23 AM
#17
Race Car
Join Date: Apr 2005
Location: With A Manual Transmission
Posts: 4,728
Likes: 0
Received 2 Likes
on
2 Posts
took it down to 10 during my last event. Car was down 7-8 mph from stock wing straight speeds.Just took it down to 5* and added a 10 mm gurney strip. Testing next month.
03-25-2011, 11:39 AM
#18
Rennlist Member
Gurney flap?!...no comment...
There's a neat trick with "juans aero oil" a little jar of tempra paint mixed with oil and dotted on areas you want to study...great telltales that you can measure which gives you direction and relative surface speeds...
Gotta have more cowbell!...
There's a neat trick with "juans aero oil" a little jar of tempra paint mixed with oil and dotted on areas you want to study...great telltales that you can measure which gives you direction and relative surface speeds...
Gotta have more cowbell!...
03-25-2011, 02:03 PM
#19
Rennlist Member
Im curious, I wonder if there is any chance that other factors brought you down by 8mph on your last run. 13degrees down to 10? any idea of the downforce at the top speeds that you were noting from?
Im interested because all the calculations point to about 10:1 L/D ratios. even at 400lbs of downforce, that would be 40lbs of drag and at 100mph , that would be near 8ft-lbs of torque at the engine. (thats the total drag due to downforce, not the change) So, if you chaged the wing angle and lost 100lbs of downforce, that would be 10lbs of drag, and 2ft-lbs of torque at the engine. I dont know if that could be responsible for 8mph slower straightline speed. If it is, I would be interested to see why.
I know there was a lot of mixed messages on the Gurney flap study, but after reading all of them in detail, it seems the net net will be if you put on the GF, now that you turned down your wing, it will be like you turned it back up to the higher AOA again, but at a cost of more drag. Looked like generally, the GF puts back in about 7 degrees more effective AOA, without the AOA. The "no discernable " increase in drag is for the less that 2% GFs. at 5%, which is very common (about .5") the drag is certainly higher for the same downforce setting. (40% higher for the same wing setting that would provide the same downforce)
Anyway, by the charts and experiments of the 3 really good articles posted on GF's. you now going to 5 degrees (8 degrees down from original settings) if you put a 10mm GF on , the wing should make the same Downforce as originally set at 13 degrees, BUT make 40% more drag. It will be interesting how the car reacts to this and if you can notice any difference. Let us know!
Mark
Im interested because all the calculations point to about 10:1 L/D ratios. even at 400lbs of downforce, that would be 40lbs of drag and at 100mph , that would be near 8ft-lbs of torque at the engine. (thats the total drag due to downforce, not the change) So, if you chaged the wing angle and lost 100lbs of downforce, that would be 10lbs of drag, and 2ft-lbs of torque at the engine. I dont know if that could be responsible for 8mph slower straightline speed. If it is, I would be interested to see why.
I know there was a lot of mixed messages on the Gurney flap study, but after reading all of them in detail, it seems the net net will be if you put on the GF, now that you turned down your wing, it will be like you turned it back up to the higher AOA again, but at a cost of more drag. Looked like generally, the GF puts back in about 7 degrees more effective AOA, without the AOA. The "no discernable " increase in drag is for the less that 2% GFs. at 5%, which is very common (about .5") the drag is certainly higher for the same downforce setting. (40% higher for the same wing setting that would provide the same downforce)
Anyway, by the charts and experiments of the 3 really good articles posted on GF's. you now going to 5 degrees (8 degrees down from original settings) if you put a 10mm GF on , the wing should make the same Downforce as originally set at 13 degrees, BUT make 40% more drag. It will be interesting how the car reacts to this and if you can notice any difference. Let us know!
Mark
03-25-2011, 02:27 PM
#20
Scott
03-25-2011, 02:30 PM
#21
Race Car
Oil and/or tufts are useful. But keep in mind that you do not want adhesion over the entire underside of the wing. At least, that's not where you'll be generating maximum lift with the wing. Simon McBeath's book has some good illustrations on this.
03-25-2011, 02:44 PM
#22
The Penguin King
Rennlist Member
Rennlist Member
03-25-2011, 02:48 PM
#23
Rennlist Member
03-25-2011, 03:39 PM
#24
Rennlist Member
03-25-2011, 03:41 PM
#25
Rennlist Member
I just asked this on another thread but I'll drop it in here as well...
https://rennlist.com/forums/racing-a...-uprights.html
Just to add another topic in context. When playing with wing positions / sizes , how do you 'tune' the front end of the car for the balance? How much difference does extending the splitter forwards make when putting the rear wing higher or further back? As you can see in some of the pics in the 'wing upright' thread, there are examples of some wings leaning way back into clean air. It just 'feels' like there is going to be so much leverage applied that something would have to be adjusted to the front to compensate. Well of course this is the case, but do you tune them, together or in isolation?
How important are Canards and how much bearing do they have in all this?
https://rennlist.com/forums/racing-a...-uprights.html
Just to add another topic in context. When playing with wing positions / sizes , how do you 'tune' the front end of the car for the balance? How much difference does extending the splitter forwards make when putting the rear wing higher or further back? As you can see in some of the pics in the 'wing upright' thread, there are examples of some wings leaning way back into clean air. It just 'feels' like there is going to be so much leverage applied that something would have to be adjusted to the front to compensate. Well of course this is the case, but do you tune them, together or in isolation?
How important are Canards and how much bearing do they have in all this?
03-25-2011, 04:11 PM
#26
Rennlist Member
Havng gone through this exercise myself, it seems the entire idea of tuning is really left for the rear wing, with a few things you can do up front, if you have an adjustable front splitter that comes forward. (Ive seen one on a BMW racer)
Mostly, you put as much downforce as you need up front and then match the wing in the rear, FOR the track. As Scott says, many have thought about increased drag, so they take out wing, only to lose entrance, corner,and exit speeds down the follwing straight. as long as you know what your drag and downforce numbers are, you can approximate the drag down a main straight. it might be worth it to keep the drag, if you have the power to overcome it.
(think of the drag on the wing as 10% of its downforce, generally, and then 25% of that would be the effect at the wheels in Ft-lbs at near 100mph)
dive planes are great for adding additional downforce, but not as efficiently as a wing or canard (small forward mounted wings) on a F1 car would be.
You are right, as you see the wings moving rearward, it increases the leverage proportioally. raising it might not do much, as it depends on the roof line flow.
So, as I said on other posts, i added a pretty standard cup wing. then spent the next few race weekends adding on larger and larger splitters, hood vents and taking wing angle out to find balance. in the end, the car was much better.
Mostly, you put as much downforce as you need up front and then match the wing in the rear, FOR the track. As Scott says, many have thought about increased drag, so they take out wing, only to lose entrance, corner,and exit speeds down the follwing straight. as long as you know what your drag and downforce numbers are, you can approximate the drag down a main straight. it might be worth it to keep the drag, if you have the power to overcome it.
(think of the drag on the wing as 10% of its downforce, generally, and then 25% of that would be the effect at the wheels in Ft-lbs at near 100mph)
dive planes are great for adding additional downforce, but not as efficiently as a wing or canard (small forward mounted wings) on a F1 car would be.
You are right, as you see the wings moving rearward, it increases the leverage proportioally. raising it might not do much, as it depends on the roof line flow.
So, as I said on other posts, i added a pretty standard cup wing. then spent the next few race weekends adding on larger and larger splitters, hood vents and taking wing angle out to find balance. in the end, the car was much better.
I just asked this on another thread but I'll drop it in here as well...
https://rennlist.com/forums/racing-a...-uprights.html
Just to add another topic in context. When playing with wing positions / sizes , how do you 'tune' the front end of the car for the balance? How much difference does extending the splitter forwards make when putting the rear wing higher or further back? As you can see in some of the pics in the 'wing upright' thread, there are examples of some wings leaning way back into clean air. It just 'feels' like there is going to be so much leverage applied that something would have to be adjusted to the front to compensate. Well of course this is the case, but do you tune them, together or in isolation?
How important are Canards and how much bearing do they have in all this?
https://rennlist.com/forums/racing-a...-uprights.html
Just to add another topic in context. When playing with wing positions / sizes , how do you 'tune' the front end of the car for the balance? How much difference does extending the splitter forwards make when putting the rear wing higher or further back? As you can see in some of the pics in the 'wing upright' thread, there are examples of some wings leaning way back into clean air. It just 'feels' like there is going to be so much leverage applied that something would have to be adjusted to the front to compensate. Well of course this is the case, but do you tune them, together or in isolation?
How important are Canards and how much bearing do they have in all this?
Last edited by mark kibort; 03-25-2011 at 08:34 PM.
03-25-2011, 04:28 PM
#27
Rennlist Member
Thread Starter
Any idea what weight oil to use?
03-25-2011, 04:35 PM
#28
Race Car
Yeah, and the BMW actually has some pretty sophisticated aero.
You can see that even if you put the wing five feet above the roof, you still wouldn't have horizontal-to-ground airflow.
You can see that even if you put the wing five feet above the roof, you still wouldn't have horizontal-to-ground airflow.
03-25-2011, 07:26 PM
#29
Addict
Rennlist Member
Rennlist Member
Some of your replies are hilarious! Drive behind a 951... 
It works like a charm and it is used on the pro circuits more than they'll accept.
As to weight, we use what we run (Valv racing 20/50).
It works like a charm and it is used on the pro circuits more than they'll accept.
As to weight, we use what we run (Valv racing 20/50).
03-27-2011, 11:19 PM
#30
Rennlist Member
