Things I don't like about RS
03-07-2015, 03:16 PM
#106
Intermediate
Join Date: Oct 2014
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03-07-2015, 06:16 PM
#108
Race Car
Join Date: Jan 2013
Location: The way to hell is paved by good intentions “Wenn ich Purist höre...entsichere ich meinen Browning” "Myths are fuel for marketing (and nowadays for flippers too,,,)" time to time is not sufficient to be a saint, you must be also an Hero
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I don t like
1) The Gearstick
2) Magnesium roof , too expensive for the benefits
3) the rear Turbo fenders
4) the Wing
in general that the car is mainly made for Ring like circuits
i do like
1) It s still a 911
1) Lava orange
2) front Fenders
1) The Gearstick
2) Magnesium roof , too expensive for the benefits
3) the rear Turbo fenders
4) the Wing
in general that the car is mainly made for Ring like circuits
i do like
1) It s still a 911
1) Lava orange
2) front Fenders
Last edited by fxz; 03-07-2015 at 07:09 PM.
03-07-2015, 06:49 PM
#110
Race Car
Join Date: Jan 2013
Location: The way to hell is paved by good intentions “Wenn ich Purist höre...entsichere ich meinen Browning” "Myths are fuel for marketing (and nowadays for flippers too,,,)" time to time is not sufficient to be a saint, you must be also an Hero
Posts: 4,486
Received 441 Likes
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263 Posts
Yeah the Wheel at the end is not too bad despite i would have liked the 4 o clock button
overall i don t like the gearstick it looks like ehm a ***** ?
i can t imagine Rocco how many movie will make on this RS....
The ***** ops the gearstick and the biiig wing uhm i guess he won t miss the Academy Awards
a lot of scripts there
overall i don t like the gearstick it looks like ehm a ***** ?
i can t imagine Rocco how many movie will make on this RS....
The ***** ops the gearstick and the biiig wing uhm i guess he won t miss the Academy Awards
a lot of scripts there
03-08-2015, 12:07 AM
#111
Rennlist Member
Wish the the rear wing plane was left naked Carbon Fiber...versus paint, Like the 997.1RS...a thing of beauty.
Would like full PFC brake system.
PTS!
Would like full PFC brake system.
PTS!
03-08-2015, 01:15 AM
#112
B) You might well be able to achieve as much or more rear downforce as the RS, but unless you do something serious with the front you're not going to be faster that way.
Adding a little bit of rear downforce will help plant the rear. Adding a lot of rear downforce, close to the RS, will be counter productive especially at high speed, resulting in terminal understeer.
You generally want the aerodynamic center of pressure slightly behind the center of gravity for stability. If you've got 62% of the weight in the rear (like the GT3) you might want ~67% of the downforce back there- ~5% more rear downforce than weight bias is a race car rule of thumb.
At 186 mph, the GT3 has:
89 lbs F, 144 R (62% rear)
You'd assume adding an RS wing to the rear would result in:
89 F, 475 R (84% rear)
This would already be near undrivable in a max speed sweeper due to understeer- at high speed it would be as though you cranked in front swaybar and removed the rear, while at low speed it would be fine- handling balance would constantly be changing with speed, and start to change rapidly over ~130 mph.
However the reality would be even worse:
1) The rear wing acts a couple feet behind the rear wheels. Thus for every 10 lbs of downforce you add, you remove around 2 from the front- think of the rear wheels as the fulcrum of a seesaw. This alone would get you to roughly:
56 F, 490 R (90% rear)
2) The rear downforce will compress the rear suspension while the front relaxes. The rake on the car will change, and the downforce made by the splitter and underbody (which is significant) will start to go away. We're just guessing at this point, but ballpark you can expect:
+10 F, 510+ R (102% rear)
The faster you go, the further rearward the center of pressure will move and the worse the car will handle.
At low speeds downforce doesn't make a large contribution, thus even a bad aero imbalance won't be noticeable or might even feel good depending on the setup and driver. As speeds climb, however, it will get to be a very serious issue.
The RS gets around this by adding lots of front downforce to balance the rear, resulting in:
227 F, 475 R (67% rear)
This also means the center of pressure won't move around much, and handling won't change significantly as speeds climb (you'll get mild understeer).
I'm quite certain you don't have the wing angle adjusted to make anything like this type of downforce on your car currently. If you'd like to take full advantage of the downforce the wing can make you need to look at adding significantly more downforce to the front (splitter, etc). Otherwise you're limited to making a little more downforce than stock, but not a lot, before you start running into problems as above.
Last edited by Petevb; 03-08-2015 at 01:57 AM.
03-08-2015, 01:58 AM
#115
Three Wheelin'
A) You can't accurately estimate peak downforce based on the wing's size. Airfoils vary too much for that.
B) You might well be able to achieve as much or more rear downforce as the RS, but unless you do something serious with the front you're not going to be faster that way.
Adding a little bit of rear downforce will help plant the rear. Adding a lot of rear downforce, close to the RS, will be counter productive especially at high speed, resulting in terminal understeer.
You generally want the aerodynamic center of pressure slightly behind the center of gravity for stability. If you've got 62% of the weight in the rear (like the GT3) you might want ~67% of the downforce back there- ~5% more rear downforce than weight bias is a race car rule of thumb.
At 186 mph, the GT3 has:
89 lbs F, 144 R (62% rear)
You'd assume adding an RS wing to the rear would result in:
89 F, 475 R (84% rear)
This would already be near undrivable in a max speed sweeper due to understeer- at high speed it would be as though you cranked in front swaybar and removed the rear, while at low speed it would be fine- handling balance would constantly be changing with speed, and start to change rapidly over ~130 mph.
However the reality would be even worse:
1) The rear wing acts a couple feet behind the rear wheels. Thus for every 10 lbs of downforce you add, you remove around 2 from the front- think of the rear wheels as the fulcrum of a seesaw. This alone would get you to roughly:
56 F, 490 R (90% rear)
2) The rear downforce will compress the rear suspension while the front relaxes. The rake on the car will change, and the downforce made by the splitter and underbody (which is significant) will start to go away. We're just guessing at this point, but ballpark you can expect:
+10 F, 510+ R (102% rear)
The faster you go, the further rearward the center of pressure will move and the worse the car will handle.
At low speeds downforce doesn't make a large contribution, thus even a bad aero imbalance won't be noticeable or might even feel good depending on the driver. As speeds climb, however, it will get to be a very serious issue.
The RS gets around this by adding lots of front downforce to balance the rear, resulting in:
227 F, 475 R (67% rear)
This also means the center of pressure won't move around much, and handling won't change significantly as speeds climb (you'll get mild understeer).
I'm quite certain you don't have the wing angle adjusted to make anything like this type of downforce on your car currently. If you'd like to take full advantage of the downforce the wing can make you need to look at adding significantly more downforce to the front (splitter, etc). Otherwise you're limited to making a little more downforce than stock, but not a lot, before you start running into problems as above.
B) You might well be able to achieve as much or more rear downforce as the RS, but unless you do something serious with the front you're not going to be faster that way.
Adding a little bit of rear downforce will help plant the rear. Adding a lot of rear downforce, close to the RS, will be counter productive especially at high speed, resulting in terminal understeer.
You generally want the aerodynamic center of pressure slightly behind the center of gravity for stability. If you've got 62% of the weight in the rear (like the GT3) you might want ~67% of the downforce back there- ~5% more rear downforce than weight bias is a race car rule of thumb.
At 186 mph, the GT3 has:
89 lbs F, 144 R (62% rear)
You'd assume adding an RS wing to the rear would result in:
89 F, 475 R (84% rear)
This would already be near undrivable in a max speed sweeper due to understeer- at high speed it would be as though you cranked in front swaybar and removed the rear, while at low speed it would be fine- handling balance would constantly be changing with speed, and start to change rapidly over ~130 mph.
However the reality would be even worse:
1) The rear wing acts a couple feet behind the rear wheels. Thus for every 10 lbs of downforce you add, you remove around 2 from the front- think of the rear wheels as the fulcrum of a seesaw. This alone would get you to roughly:
56 F, 490 R (90% rear)
2) The rear downforce will compress the rear suspension while the front relaxes. The rake on the car will change, and the downforce made by the splitter and underbody (which is significant) will start to go away. We're just guessing at this point, but ballpark you can expect:
+10 F, 510+ R (102% rear)
The faster you go, the further rearward the center of pressure will move and the worse the car will handle.
At low speeds downforce doesn't make a large contribution, thus even a bad aero imbalance won't be noticeable or might even feel good depending on the driver. As speeds climb, however, it will get to be a very serious issue.
The RS gets around this by adding lots of front downforce to balance the rear, resulting in:
227 F, 475 R (67% rear)
This also means the center of pressure won't move around much, and handling won't change significantly as speeds climb (you'll get mild understeer).
I'm quite certain you don't have the wing angle adjusted to make anything like this type of downforce on your car currently. If you'd like to take full advantage of the downforce the wing can make you need to look at adding significantly more downforce to the front (splitter, etc). Otherwise you're limited to making a little more downforce than stock, but not a lot, before you start running into problems as above.
Pete,
FLT's Crawford wing was designed and built by Max Crawford, specifically for his car. It isn't a "guess". It isn't a CF "bodykit" to make it look cool. Crawford took the time to design it, and FLT took the time to take his car to them to create it. Crawford has a lot of race credibility when it comes to designing rear wings (check out the Tudor car series). I am by no means challenging the physics of what you have put forward, but I have yet to see a 186 mph sweeper at a typical track, unless it is a banked oval turning left. What many of us early 991 GT3 track enthusiasts have noticed, is an unsettling of the rear when speeds reach 140 mph or so, under braking and in high speed sweepers. FLT reports snap over steer as well (I haven't experienced that). FLT's track happens to be Sebring, and he is well versed in how HIS car handled there with the OEM wing, as well as the Crawford wing. He reports faster times, significantly so, and has not reported any added understeer (as everyone fears). Of all the track mods I have seen so far, I think this "motorsports derived" wing is great. It is a true airfoil wing, not the attempt at an airfoil the OEM has put on the GT3. Before bashing the Crawford wing, I would think one would actually contact Max Crawford, and ask him about how he choose the design, what CAD/CAM design did he consider, what knowledge from motorsports did he utilize when creating it, etc, etc, etc. With his reputation and motorsports background, he wasn't likely just looking to make a buck by selling a "poser" Cf wing or bodykit. Just saying.....
03-08-2015, 03:10 AM
#116
Pete,
FLT's Crawford wing was designed and built by Max Crawford, specifically for his car. It isn't a "guess". It isn't a CF "bodykit" to make it look cool. Crawford took the time to design it, and FLT took the time to take his car to them to create it. Crawford has a lot of race credibility when it comes to designing rear wings (check out the Tudor car series). I am by no means challenging the physics of what you have put forward, but I have yet to see a 186 mph sweeper at a typical track, unless it is a banked oval turning left. What many of us early 991 GT3 track enthusiasts have noticed, is an unsettling of the rear when speeds reach 140 mph or so, under braking and in high speed sweepers. FLT reports snap over steer as well (I haven't experienced that). FLT's track happens to be Sebring, and he is well versed in how HIS car handled there with the OEM wing, as well as the Crawford wing. He reports faster times, significantly so, and has not reported any added understeer (as everyone fears). Of all the track mods I have seen so far, I think this "motorsports derived" wing is great. It is a true airfoil wing, not the attempt at an airfoil the OEM has put on the GT3. Before bashing the Crawford wing, I would think one would actually contact Max Crawford, and ask him about how he choose the design, what CAD/CAM design did he consider, what knowledge from motorsports did he utilize when creating it, etc, etc, etc. With his reputation and motorsports background, he wasn't likely just looking to make a buck by selling a "poser" Cf wing or bodykit. Just saying.....
FLT's Crawford wing was designed and built by Max Crawford, specifically for his car. It isn't a "guess". It isn't a CF "bodykit" to make it look cool. Crawford took the time to design it, and FLT took the time to take his car to them to create it. Crawford has a lot of race credibility when it comes to designing rear wings (check out the Tudor car series). I am by no means challenging the physics of what you have put forward, but I have yet to see a 186 mph sweeper at a typical track, unless it is a banked oval turning left. What many of us early 991 GT3 track enthusiasts have noticed, is an unsettling of the rear when speeds reach 140 mph or so, under braking and in high speed sweepers. FLT reports snap over steer as well (I haven't experienced that). FLT's track happens to be Sebring, and he is well versed in how HIS car handled there with the OEM wing, as well as the Crawford wing. He reports faster times, significantly so, and has not reported any added understeer (as everyone fears). Of all the track mods I have seen so far, I think this "motorsports derived" wing is great. It is a true airfoil wing, not the attempt at an airfoil the OEM has put on the GT3. Before bashing the Crawford wing, I would think one would actually contact Max Crawford, and ask him about how he choose the design, what CAD/CAM design did he consider, what knowledge from motorsports did he utilize when creating it, etc, etc, etc. With his reputation and motorsports background, he wasn't likely just looking to make a buck by selling a "poser" Cf wing or bodykit. Just saying.....
Instead I'm attempting to correct your misconception of what it does and can do. The most basic misconception is that more downforce is better. It is not. You need properly balanced downforce to be useful. You're not going to get properly balance downforce by putting 500+ lbs at the rear of your GT3 as you suggested above, and if you try at some speed physics is going to rear its ugly head.
I have no doubt you're feeling a real benifit by increasing rear downforce slightly. However if you're not getting understeer when you don't change the front the increase in rear downforce is relatively slight, by definition. You're getting a small fraction of the GT3 RS aerodynamic benefits with a rear wind only, and suggesting, as you did above, that you're getting GT3 RS type downforce at the back at the angle you've set is not correct.
I'd suggest you discuss with Max, point him at these posts if it's useful, and see if he agrees. Then perhaps talk with him about a front splitter and what benefit it might bring.
03-08-2015, 06:07 AM
#117
Race Car
A) You can't accurately estimate peak downforce based on the wing's size. Airfoils vary too much for that.
B) You might well be able to achieve as much or more rear downforce as the RS, but unless you do something serious with the front you're not going to be faster that way...
B) You might well be able to achieve as much or more rear downforce as the RS, but unless you do something serious with the front you're not going to be faster that way...
Thanks for posting
03-08-2015, 12:12 PM
#120
Rennlist Member
Any one read the degrees of adjustability on the RS wing?
The 997 RS has 2 positions only and I added the CUP splitter, canards (on 3.8RS) and gurney flap. On all tracks I always ran max wing. This added about .5 seconds per mile of track with high speed corners. Tested it back to back.
Although the same wing the 3.8RS wing was something like 3 to 6 degrees but on the 4.0 it was up to 9 degrees or something and that's why the car also had helper springs.
I also added the Baron taller uprights, felt the same to me but I could see out the rear window..
I think Baron matched the adjustability of the 4.0 uprights.
Not sure how the helper or progressive? Springs affect the car but I never liked the rear on the 4.0 the 3.8 rear grip always felt better at Sebring. Another 4.0 changed his springs to 3.8 springs as well.
I don't have a full understanding of setup but for ME the car was always better for me with big wing and stiffer sway bar, I guess that's only to the point you need to stiffen the rear springs and add ride height to compensate for it and that may be counter productive on a bumpy track like Sebring.
The 4.0 was more sensitive to rake lowering the car overall, it needed more height in the rear and that was also how the factory specked it in the manual.
So more of the same in the new RS?l
Anyway for us weekend drovers it's easy to screw up the car weekend after weekend screwing around with all the adjustability. Downforce increases the problem exponentially.
The 997 RS has 2 positions only and I added the CUP splitter, canards (on 3.8RS) and gurney flap. On all tracks I always ran max wing. This added about .5 seconds per mile of track with high speed corners. Tested it back to back.
Although the same wing the 3.8RS wing was something like 3 to 6 degrees but on the 4.0 it was up to 9 degrees or something and that's why the car also had helper springs.
I also added the Baron taller uprights, felt the same to me but I could see out the rear window..
I think Baron matched the adjustability of the 4.0 uprights.
Not sure how the helper or progressive? Springs affect the car but I never liked the rear on the 4.0 the 3.8 rear grip always felt better at Sebring. Another 4.0 changed his springs to 3.8 springs as well.
I don't have a full understanding of setup but for ME the car was always better for me with big wing and stiffer sway bar, I guess that's only to the point you need to stiffen the rear springs and add ride height to compensate for it and that may be counter productive on a bumpy track like Sebring.
The 4.0 was more sensitive to rake lowering the car overall, it needed more height in the rear and that was also how the factory specked it in the manual.
So more of the same in the new RS?l
Anyway for us weekend drovers it's easy to screw up the car weekend after weekend screwing around with all the adjustability. Downforce increases the problem exponentially.