Rear spoilers
- Thread starter SuperBuickGuy
- Start date
DJ Dep
refugee from the other place
So you will be driving at the Dayton 500 or at Bonneville or Indy?:amazed:
Twin_Turbo
Der Maulwurf
- Joined
- Mar 5, 2008
- Messages
- 7,575
180? I'm having trouble breaking 150mph w/ a 550HP supercharged GTA on the German autobahm. It's a much more aerodynamically stable car yes it does get scary at those speeds. At those speeds the rear end is the last thing you need to worry about, the front is the 1st problem, you have to keep the air out of it and from under it.
turtlevette
The Turdle
Those big wings must cost a ton of HP. I bet it slows the car down by 20 mph.
MYBAD79
Moderator
Watched the last F1 race ? In India they have a very long straight and they're allowed to open a small slotin the rear wing if they're within a second of the car ahead. The upper wing element can be rotated so it is opening a slot of aprox 3" - when they do that at 150+ mph it's like they suddenly have an additional 200hp or so ... The onboard shots are amazing , you see the white line that indicates where they can open the wing and you see the driver hit a switch on the steering wheel , then the car flies by the car ahead .... Arrodynamics are awesome ....
DJ Dep
refugee from the other place
Nope...he also has dual alternators to offset the HP drain. That way it sucks down less current so the engine actually GAINS power. Probably at least 100HP.
I wonder if DB is following this thread?:amazed:
68L71
Well-known member
- Joined
- May 13, 2008
- Messages
- 747
:lol:
69427
The Artist formerly known as Turbo84
You have no clue how fast, or what kind of cars I've driven. (FWIW I have first hand experience with the aero/handling difference between a non-winged and a winged sprint car. Night and day difference.) And there's no maybe about aero. It's physics and there's no formula that has a velocity constant stating there's noticeable aero effects above that speed, and unnoticeable aero effects below that speed.
Two can play the asshole game here Howard, and I've had plenty of caffeine this afternoon. If you want to talk facts, physics, or engineering, I'm all ears. Or if you prefer to play the game, I'm here too.[/QUOTE]
a winged sprint car weights how much? has tires how wide? has what 850-900hp? and a wing on top the size of a roof and you want to compare that to a Corvette? which is the apple and which the orange?[/QUOTE]
Apples and oranges, huh?
On a road trip today I saw dozens of eighteen wheelers with multiple aero devices. Overcab wind deflectors, tractor side skirts, and even skirts on the trailers. Does anyone here disagree that these trucks are significantly slower than the speeds several of us push our Corvettes on the track? Perhaps another comparison: A Corvette weighs what (compared to an eighteen wheeler)? How wide are Corvette tires (compared to an 18 wheeler's tires)? How much horsepower does a Z06, ZR1, or my ZL1 have (compared to an 18 wheeler)?
And these comparisons mean what? The answer: Absolutely nothing. Air doesn't give a rat's ass how much horsepower a vehicle has. It also doesn't care how much the vehicle weighs or how much tire is on the vehicle.
Air only cares about coefficient of drag (or lift), frontal (or airfoil) area, and velocity.
Apples. Oranges. Lemons.
Two can play the asshole game here Howard, and I've had plenty of caffeine this afternoon. If you want to talk facts, physics, or engineering, I'm all ears. Or if you prefer to play the game, I'm here too.[/QUOTE]
a winged sprint car weights how much? has tires how wide? has what 850-900hp? and a wing on top the size of a roof and you want to compare that to a Corvette? which is the apple and which the orange?[/QUOTE]
Apples and oranges, huh?
On a road trip today I saw dozens of eighteen wheelers with multiple aero devices. Overcab wind deflectors, tractor side skirts, and even skirts on the trailers. Does anyone here disagree that these trucks are significantly slower than the speeds several of us push our Corvettes on the track? Perhaps another comparison: A Corvette weighs what (compared to an eighteen wheeler)? How wide are Corvette tires (compared to an 18 wheeler's tires)? How much horsepower does a Z06, ZR1, or my ZL1 have (compared to an 18 wheeler)?
And these comparisons mean what? The answer: Absolutely nothing. Air doesn't give a rat's ass how much horsepower a vehicle has. It also doesn't care how much the vehicle weighs or how much tire is on the vehicle.
Air only cares about coefficient of drag (or lift), frontal (or airfoil) area, and velocity.
Apples. Oranges. Lemons.
69427
The Artist formerly known as Turbo84
turtlevette
The Turdle
here's a graph i found. I would have thought the slope would have been greater. Its a squared function.
at 60 mph (100 km/hr) it shows 100 Newtons or about 22 pounds downforce. That's pretty insignificant.
at 120 mph (200km/hr) it shows 380Newtons or about 80 pounds downforce. Nothing to write home about.
The formula for downforce of a wing is given by:
Where:
D is downforce in newtons
WS is wingspan in metres
H is height in metres
AoA is angle of attack
F is drag coefficient
ρ is air density in kg/m³
V is velocity in m/s
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redvetracr
Well-known member
[/QUOTE]
Apples and oranges, huh?
On a road trip today I saw dozens of eighteen wheelers with multiple aero devices. Overcab wind deflectors, tractor side skirts, and even skirts on the trailers. Does anyone here disagree that these trucks are significantly slower than the speeds several of us push our Corvettes on the track? Perhaps another comparison: A Corvette weighs what (compared to an eighteen wheeler)? How wide are Corvette tires (compared to an 18 wheeler's tires)? How much horsepower does a Z06, ZR1, or my ZL1 have (compared to an 18 wheeler)?
And these comparisons mean what? The answer: Absolutely nothing. Air doesn't give a rat's ass how much horsepower a vehicle has. It also doesn't care how much the vehicle weighs or how much tire is on the vehicle.
Air only cares about coefficient of drag (or lift), frontal (or airfoil) area, and velocity.
Apples. Oranges. Lemons.[/QUOTE]
I see so what your saying is that great big wing on the roof of a winged sprint car is there to make the sprinter more aerodynamic but the side skirts on a semi trailer are there for downforce? I can`t wait to see your car with it`s World of Outlaws hydraulic roof wing, and please let us know how much it reduces your lap times...and when you win your first race in the Corvette...
Apples and oranges, huh?
On a road trip today I saw dozens of eighteen wheelers with multiple aero devices. Overcab wind deflectors, tractor side skirts, and even skirts on the trailers. Does anyone here disagree that these trucks are significantly slower than the speeds several of us push our Corvettes on the track? Perhaps another comparison: A Corvette weighs what (compared to an eighteen wheeler)? How wide are Corvette tires (compared to an 18 wheeler's tires)? How much horsepower does a Z06, ZR1, or my ZL1 have (compared to an 18 wheeler)?
And these comparisons mean what? The answer: Absolutely nothing. Air doesn't give a rat's ass how much horsepower a vehicle has. It also doesn't care how much the vehicle weighs or how much tire is on the vehicle.
Air only cares about coefficient of drag (or lift), frontal (or airfoil) area, and velocity.
Apples. Oranges. Lemons.[/QUOTE]
I see so what your saying is that great big wing on the roof of a winged sprint car is there to make the sprinter more aerodynamic but the side skirts on a semi trailer are there for downforce? I can`t wait to see your car with it`s World of Outlaws hydraulic roof wing, and please let us know how much it reduces your lap times...and when you win your first race in the Corvette...
redvetracr
Well-known member
please do enlighten us of your vast racing experience...
SuperBuickGuy
Well-known member
here's a graph i found. I would have thought the slope would have been greater. Its a squared function.
at 60 mph (100 km/hr) it shows 100 Newtons or about 22 pounds downforce. That's pretty insignificant.
at 120 mph (200km/hr) it shows 380Newtons or about 80 pounds downforce. Nothing to write home about.
The formula for downforce of a wing is given by:
Where:
D is downforce in newtons
WS is wingspan in metres
H is height in metres
AoA is angle of attack
F is drag coefficient
ρ is air density in kg/m³
V is velocity in m/s
and suddenly, out of the rainstorm of pissing matches; solid information... thanks turtle :thumbs:
DJ Dep
refugee from the other place
I heard if you mount a slide rule on the roof, you get tons of downforce. Of course, it depends on the angle of deflection and the length and width of the slide rule. But at least they are adjustable. 
phantomjock
Well-known member
Back to the issue at hand...
What about a high mounted rear foil on a C3?
I offer the following:
This image was lifted from a VetteWeb article on 1980s Kevlar bodys for Greg Picket. This particular image was identified as being one of, "A wide variety of "aero" devices were evaluated in order to determine the optimum shape for the 1980 race car. Courtesy of Dr. Kevin Cooper, NRC."
It appears not to be fastback (mirrors don't look right, not a 78 escutchion - so maybe a 76?) - so if it is a 'notch-back - it answers the original postings.
Unfortunately I find no details (lift/drag/downforce/velocity/etc)- but what you see. Kevin Cooper has done a lot of research in aero devices, he is an award winner at SAE, and has worked on "near surface (ground) flow." Most recent work appears to be in the area of rear diffusers.
Nice splitter too.
Cheers - Jim
What about a high mounted rear foil on a C3?
I offer the following:
This image was lifted from a VetteWeb article on 1980s Kevlar bodys for Greg Picket. This particular image was identified as being one of, "A wide variety of "aero" devices were evaluated in order to determine the optimum shape for the 1980 race car. Courtesy of Dr. Kevin Cooper, NRC."
It appears not to be fastback (mirrors don't look right, not a 78 escutchion - so maybe a 76?) - so if it is a 'notch-back - it answers the original postings.
Unfortunately I find no details (lift/drag/downforce/velocity/etc)- but what you see. Kevin Cooper has done a lot of research in aero devices, he is an award winner at SAE, and has worked on "near surface (ground) flow." Most recent work appears to be in the area of rear diffusers.
Nice splitter too.
Cheers - Jim
This chart shows that aero doesn't "kick in" (also shows who the half assed engineer is).
GT Machine?
What about to the luggage rack? I used to be all turned on w/Pro Touring.
What happened to the Touring part? How long would you want to drive a
750 hp race car that does everything better than a stk w/o trunk or rack. At the expense of comfort and damm the cost!
I called my car semi-pro touring, now I'm thinking of the older Grand Touring
cars a model.
Anyway, what about a 8-10 in spoiler set at about 60* from vert?
I'm waiting for some enterprising member to do some testing w/spoiler
extension and yarn.
I think that getting downforce in the rear w/o massive drag will be more difficult that in front. I noticed that I have a few things hanging under the car, looks like the heater core hose is a bit low.
R
What about to the luggage rack? I used to be all turned on w/Pro Touring.
What happened to the Touring part? How long would you want to drive a
750 hp race car that does everything better than a stk w/o trunk or rack. At the expense of comfort and damm the cost!
I called my car semi-pro touring, now I'm thinking of the older Grand Touring
cars a model.
Anyway, what about a 8-10 in spoiler set at about 60* from vert?
I'm waiting for some enterprising member to do some testing w/spoiler
extension and yarn.
I think that getting downforce in the rear w/o massive drag will be more difficult that in front. I noticed that I have a few things hanging under the car, looks like the heater core hose is a bit low.
R
SuperBuickGuy
Well-known member
I hate reinventing the wheel, but it appears my research (read, I googled) prior to posting concludes that no one has shared their actual data on rear spoilers... sounds like it's time for tape, yarn, my gopro, the tank installed in my car and a day without precipitation.
I'll work on snapping that 180 picture (lol). (troll answer - on) No one said I was going 180, the implication was I'm designing for that point.... (troll answers - off)
and one more thing: lol
This car is a fun car that autocrosses, does open track days, and gets driven a lot. If I can avoid a radar arch (spoiler), I will; however, if I do have one on the car it will be because it needs it to overcome what I presume is a pretty substantial low-pressure area behind the rear window.
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Research!
SBG: Someone on CF has done some yarn testing. I believe it was to do some Mythbuster type testing on a hood/windshield. They were trying to prove or dis the low pressure area at the base of the windshield being of benifit to performance.
The evidence was interesting, but by no means conclusive.
If your testing can really prove the wing is significantly better for downforce w/o big increase in cda, I'm happy to consider it.
I'm waiting for George to jump in.
R
SBG: Someone on CF has done some yarn testing. I believe it was to do some Mythbuster type testing on a hood/windshield. They were trying to prove or dis the low pressure area at the base of the windshield being of benifit to performance.
The evidence was interesting, but by no means conclusive.
If your testing can really prove the wing is significantly better for downforce w/o big increase in cda, I'm happy to consider it.
I'm waiting for George to jump in.
R
phantomjock
Well-known member
Class is in Session
Testing is always useful.
Gene has done some tuft testing as I recall, and another member was working testing on velocity change through a radiator.
Another approach; base a design on sound theory, set out a hypothesis, and then do some experimentation. Analyze results and repeat as necessary. (I'm sure someone can Google that series of steps and point out a few missed steps - BFD, you'll get the idea.)
If you are interested in some theory, I'll offer the following invaluable texts for low speed aerodynamics, theory and application - depending on the text:
Ing S.F. Hoerner - Fluid Dynamic Drag, and the companion book Fluid Dynamic Lift. Abbot and Doenhoff, Theory of Wing Sections; Geoffrey Howard, Automobile Aerodynamics; a translated Japanese text published by Car Styling, Automotive Aerodynamics, SAE Papers - Vehicle Aerodynamics (a collection of papers), New Directions in Race Car Aerodynamics: Designing for Speed by Joseph Katz, and Simon MacBeath, Competition Car Downforce: A Practical Handbook. These are all part of my growing Low Speed/Aero Library. I'm going to post a section from Simon MacBeath's Competition Car Downforce in the downloads - for those interested. It's a nice piece and useful for some of what you're looking for - if I read and understand your stated needs correctly.
Hopefully you'll find it interesting. It is a pdf and requires TT or BBShark to upload - so it will be a bit. Meanwhile, I offer a few jpgs of the appendix on WINGS (the correct name is WINGS, after all - spoilers are there to KILL lift! -- these WINGS just generate lift DOWN.):
Another approach you see more these days is the Cellular Wing -- witness the posted A-Mod Autocross/Hillclimb car (which is so cool I want to build one next.) I did MS work using Cellular Wing Theory it and a presentation at AIAA regionals - back in the very early 70s. It was also a key to our Uni study for a Man Powered Aircraft. No, we didn't build it - but would have been a player! McCreedy had the funds - we were poor students - and could only afford to build a HG instead - 50 bucks - and it flew.
Hope you enjoy.
Cheers - Jim
Class adjourned.
Testing is always useful.
Gene has done some tuft testing as I recall, and another member was working testing on velocity change through a radiator.
Another approach; base a design on sound theory, set out a hypothesis, and then do some experimentation. Analyze results and repeat as necessary. (I'm sure someone can Google that series of steps and point out a few missed steps - BFD, you'll get the idea.)
If you are interested in some theory, I'll offer the following invaluable texts for low speed aerodynamics, theory and application - depending on the text:
Ing S.F. Hoerner - Fluid Dynamic Drag, and the companion book Fluid Dynamic Lift. Abbot and Doenhoff, Theory of Wing Sections; Geoffrey Howard, Automobile Aerodynamics; a translated Japanese text published by Car Styling, Automotive Aerodynamics, SAE Papers - Vehicle Aerodynamics (a collection of papers), New Directions in Race Car Aerodynamics: Designing for Speed by Joseph Katz, and Simon MacBeath, Competition Car Downforce: A Practical Handbook. These are all part of my growing Low Speed/Aero Library. I'm going to post a section from Simon MacBeath's Competition Car Downforce in the downloads - for those interested. It's a nice piece and useful for some of what you're looking for - if I read and understand your stated needs correctly.
Hopefully you'll find it interesting. It is a pdf and requires TT or BBShark to upload - so it will be a bit. Meanwhile, I offer a few jpgs of the appendix on WINGS (the correct name is WINGS, after all - spoilers are there to KILL lift! -- these WINGS just generate lift DOWN.):
Another approach you see more these days is the Cellular Wing -- witness the posted A-Mod Autocross/Hillclimb car (which is so cool I want to build one next.) I did MS work using Cellular Wing Theory it and a presentation at AIAA regionals - back in the very early 70s. It was also a key to our Uni study for a Man Powered Aircraft. No, we didn't build it - but would have been a player! McCreedy had the funds - we were poor students - and could only afford to build a HG instead - 50 bucks - and it flew.
Hope you enjoy.
Cheers - Jim
Class adjourned.
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