Spoiler Delete=Performance or Cosmetic?
11/26/06, 02:13 PM
#101
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You must certainly have a wind tunnel and know more than the whole SVT engineering team. Why aren't you over there designing cars
Did you forget about the 00 Cobra R? Or even the well publicized high speed instability problems with the Audi TT?
My car has been road raced and drag raced and it is a street car. I drive it daily to work and the car has 27K miles.
Did you forget about the 00 Cobra R? Or even the well publicized high speed instability problems with the Audi TT?My car has been road raced and drag raced and it is a street car. I drive it daily to work and the car has 27K miles.
Instability is not cured by a spoiler/wing creating downforce. That is a design probelm relating to the overall shape. You can treat the symptom by creating more drag and slowing the car down, but that only proves my point. You can create drag without creating downforce.
My car(s) have also been road raced, drag raced, auto-x'd, etc, but even the one with the roll bar is still a street car. There is a certain line before a car actually becomes a race car. Would you consider yourself a "Race Car Driver" too?
11/26/06, 02:22 PM
#102
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Edit: You also posted "Go to your car and press down on the center of the spoiler. Does it flex? Then imagine what REAL downforce (enough to be beneficial in stabilizing a heavy car) would do to our silly spoilers. "
That's a horrible example. A good friend of mine had a 97 Reynard IRL car and it would flex if you pushed down in the center. His Petite LeMans CF spoiler(very light) also does the same thing. Both are highly functional. You are placing load on one specific section, instead of the whole surface area.
But let's go with this. What are the wings mounted to on the Reynard and the LeMnas car? I'll bet they are not mounted via sticky tape and a few nuts onto a flexible trunk lid that is not part of the chassis structure.
Riddle me this:
How much downforce do you think the S197 spoilers generate?
How much force do you think the spoiler can take?
How much force do you think the trunk lid can take?
Do you think this force is beneficial over the amount of horsepower lost to overcome it?
Shees, can we dispense with comparing race cars to street cars?
11/26/06, 02:24 PM
#103
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Cobra R by all admissions is a race car. Limited production, no frills race car. Apple != orange
Instability is not cured by a spoiler/wing creating downforce. That is a design probelm relating to the overall shape. You can treat the symptom by creating more drag and slowing the car down, but that only proves my point. You can create drag without creating downforce.
My car(s) have also been road raced, drag raced, auto-x'd, etc, but even the one with the roll bar is still a street car. There is a certain line before a car actually becomes a race car. Would you consider yourself a "Race Car Driver" too?
Instability is not cured by a spoiler/wing creating downforce. That is a design probelm relating to the overall shape. You can treat the symptom by creating more drag and slowing the car down, but that only proves my point. You can create drag without creating downforce.
My car(s) have also been road raced, drag raced, auto-x'd, etc, but even the one with the roll bar is still a street car. There is a certain line before a car actually becomes a race car. Would you consider yourself a "Race Car Driver" too?
I think Audi would disagree with you (and it's very well documented) that instability isn't cured by a wing/spoiler.
11/26/06, 02:34 PM
#104
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Not as flexible as the street car spoiler I am referring to, and they flex under load (aero) into the position they are designed to work at (air under/air over to create negative lift).
But let's go with this. What are the wings mounted to on the Reynard and the LeMnas car? I'll bet they are not mounted via sticky tape and a few nuts onto a flexible trunk lid that is not part of the chassis structure.
But let's go with this. What are the wings mounted to on the Reynard and the LeMnas car? I'll bet they are not mounted via sticky tape and a few nuts onto a flexible trunk lid that is not part of the chassis structure.
Riddle me this:
How much downforce do you think the S197 spoilers generate? Don't have a windtunnel. I've already said it's probably not anything significant.
How much force do you think the spoiler can take?
How much force do you think the trunk lid can take?
I can answer that if you are willing to buy me a new spoiler and trunk lid I do like the look of the Roush rear spoiler, so I'd be happy to find the point of failure.
Do you think this force is beneficial over the amount of horsepower lost to overcome it?
Refer to the wind tunnel statement
Shees, can we dispense with comparing race cars to street cars?
How much downforce do you think the S197 spoilers generate? Don't have a windtunnel. I've already said it's probably not anything significant.
How much force do you think the spoiler can take?
How much force do you think the trunk lid can take?
I can answer that if you are willing to buy me a new spoiler and trunk lid
I do like the look of the Roush rear spoiler, so I'd be happy to find the point of failure.Do you think this force is beneficial over the amount of horsepower lost to overcome it?
Refer to the wind tunnel statement
Shees, can we dispense with comparing race cars to street cars?
11/26/06, 03:01 PM
#105
Team Mustang Source
Thread Starter
Perhaps a better function of the rear spoiler is not so much to create downforce, but rather to help redirect the airflow for better/different aerodynamics. If the airflow is "spoiled" by the spoiler, what effect does this have on the handling at high speeds?
For example, any convertible owners (had an 89 vert prior to my 06 coupe) know that when the windows are up at cruising speed, the soft top is being pulled upwards due to the airflow going over the top of the car. This is negative downforce, and it works the same on hardtops, it just is not noticable because the roof is solid. When you roll down a window, the soft top sags down (and flaps around a little) due to the open window "spoiling" the airflow. Maybe the spoiler does something similar to this, in that not only does it produce downforce by itself, but reduces negative downforce on the rest of the car? Just a thought...
For example, any convertible owners (had an 89 vert prior to my 06 coupe) know that when the windows are up at cruising speed, the soft top is being pulled upwards due to the airflow going over the top of the car. This is negative downforce, and it works the same on hardtops, it just is not noticable because the roof is solid. When you roll down a window, the soft top sags down (and flaps around a little) due to the open window "spoiling" the airflow. Maybe the spoiler does something similar to this, in that not only does it produce downforce by itself, but reduces negative downforce on the rest of the car? Just a thought...
11/26/06, 03:16 PM
#106
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The angle, of say, the Audi TT's rear spoiler vs. the Mustang GT's is vastly different as are their shapes - the Audi's is a "lip" or "ducktail" and the Mustang GT's is a "wing"/"airfoil" at (close to) neutral. So while the Audi's is effective and admittedly necessary for stability at high speeds, the Mustang's is not - notice how the Cobra R's spoiler is placed in an area of higher/cleaner airflow. The same can be said of Maximum Motorsports' development car and countless other race cars - from rallying to F1. Also remember that the surface area, along with angle and its position in the airflow also affects the amount of downforce or lift generated. In this case, the Mustang GT's is pretty small. One can argue that a Champ/Indy car in oval track configuration has some pretty small wings, but no street-driven Mustang GT will ever see sustained speeds at 180+ into the 200's. Plus they're set up for minimum drag at those rarefied speeds.
I'll submit this again, Ford's FR500C (a race car) does not use the GT spoiler, neither does the Shelby GT500 (a street car) - SVT wanted one that worked in terms of looks and effectiveness. The same could also be said of the last-gen Mustang GT vs. the SVT (Terminator) Cobra's rear spoilers.
I'll submit this again, Ford's FR500C (a race car) does not use the GT spoiler, neither does the Shelby GT500 (a street car) - SVT wanted one that worked in terms of looks and effectiveness. The same could also be said of the last-gen Mustang GT vs. the SVT (Terminator) Cobra's rear spoilers.
11/26/06, 08:20 PM
#107
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You missed the point entirely. Does the Z06 need downforce? Why isn't there a spoiler or wing on the back of it? Answer: because it is unecessary even for a lighter car with more power. Let me know at what speed the rear end of a slug street Mustang becomes light enough to require downforce. Mixing race car talk and street car talk is silly.
If you want to believe that your 3500+ lb street car benefits from a spoiler that can deflect under the force of a blow dryer, then by all means keep believing. Go to your car and press down on the center of the spoiler. Does it flex? Then imagine what REAL downforce (enough to be beneficial in stabilizing a heavy car) would do to our silly spoilers.
You are right that downforce creates drag, but so does neutral and that is what our spoilers are. Sorry to burst your race car dreams, but spoilers and wings on street cars are just for looks.
Do you really think auto manufacturers give a rats @#@$% about creating downforce on a street car? You've said it yourself that downforce = drag, but what does drag equal? Drag eqauls requiring more power to overcome. More power means worse gas mileage. In the realm of auto manufacturers (especially American V8) gas mileage is a huge concern, downforce on a 3500+ lb street car that will most likely never see triple digits is not.
Spoilers/wings on race cars = useful
Spoilers/wings on street care = looks
A street car driven on a race track != a race car
If you want to believe that your 3500+ lb street car benefits from a spoiler that can deflect under the force of a blow dryer, then by all means keep believing. Go to your car and press down on the center of the spoiler. Does it flex? Then imagine what REAL downforce (enough to be beneficial in stabilizing a heavy car) would do to our silly spoilers.
You are right that downforce creates drag, but so does neutral and that is what our spoilers are. Sorry to burst your race car dreams, but spoilers and wings on street cars are just for looks.
Do you really think auto manufacturers give a rats @#@$% about creating downforce on a street car? You've said it yourself that downforce = drag, but what does drag equal? Drag eqauls requiring more power to overcome. More power means worse gas mileage. In the realm of auto manufacturers (especially American V8) gas mileage is a huge concern, downforce on a 3500+ lb street car that will most likely never see triple digits is not.
Spoilers/wings on race cars = useful
Spoilers/wings on street care = looks
A street car driven on a race track != a race car
11/27/06, 06:48 AM
#109
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ANY amount of downforce (un-needed down force) will be negated by the huge amount of drag created by extending the body upward into the air flow and increasing the coefficient of drag (Cd), thus eating more horsepower.
11/27/06, 06:57 AM
#110
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Silly! the three cars you posted for your theorem position! are street cars !! and apparently you live in vacuum! Since automobiles have been built there has been street cars adapted for the track ! and race car technology used on street cars depending on the handling carsteristics one wanted to achieve! do you see GT on the side of the car whats that mean! Grand Touring! not street racer not 1/4 mile dragster, no GT on the side of the cobra GT500 Why! set-up for different principal uses! thus different spoilers! Most spoilers do flex you better hope they do! push on the hood of your car it flexes too! and has hundreds of pounds of down force exerted on it at speed! As in another post ! pointed out the GT spoiler has over and under flow! a point I thought was understood by you! to help enhance stability! not necessarily to create earth shaking differences! But to enhance handling characteristics! As far as the rear GT spoiler deflecting from the use of a blow dryer, I DON'T KNOW WHAT YOUR DRYING YOUR HAIR WITH BUT STOP! while you still have some hair on your head! by the way why! are you blow drying your car! spend more time driving it and you might understand what I'm talking about..
Your hood has downforce on it? You must have the special "Defy Physics" version of the Mustang. Here is a pic'y for you to look at since the big words are not helping:
The spoiler helps does it? For it to help it must be up in the clean flow, not the flow over the car. The spoiler increases the drag created by the rear of the car (solid green area in pic).
I don't think you understand what you are talking about
11/27/06, 07:38 AM
#111
Shelby GT500 Member
Fellas,
If you'd read about the "history" of the S197, you'd find that Hau Tai Tang designed it without the spoiler. Only marketing wanted the spoiler on the car, but Hau objected.
The spoiler delete option was the compromise.
If you'd read about the "history" of the S197, you'd find that Hau Tai Tang designed it without the spoiler. Only marketing wanted the spoiler on the car, but Hau objected.
The spoiler delete option was the compromise.
11/27/06, 08:23 AM
#113
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Notice this picture! Mr.2MFF see the GT spoiler Incorporated into the rear of the car! is it above the roof line ! no its not...now if you will follow the arrows of the picture you drew in your therapy session! notice how the the air flow fallows the contour of the roof line! even thou your picture has the arrow dynamics of a rock! those arrows move across the back of the car! signifying air flow! right Mr. Blow dryer! since you might not recognize a car thats not drawn with crayons! this is a 2005 Porsche Carrera GT list price $440.000 arguably the best automotive engineers in the world designed this automobile and I guess you think they just stuck it on the rear of the car for looks.I've been racing for over thirty years slick! and your talking sideways out of your blow hole! 
11/27/06, 03:09 PM
#117
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HTT didn't do much for aerodynamics. Just take a quick peek at the surfaces of the front. Our cars are like bricks. IIRC the CD is something like .36. My brother's 350Z has a CD of .29 and most new cars are in that range.
11/27/06, 04:44 PM
#118
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blkstang06? The Carrera GT's spoiler automatically deploys higher from that position past 70mph into better airflow above the rear deck.
11/27/06, 04:46 PM
#119
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I've got cars in the garage for that!
11/27/06, 04:59 PM
#120
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PS: I realize the spoiler on PC GT does deploy but its elevation still doesn't clear the roof line!