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Now this one, along with the coffee can muffler actually makes 63 more horsepower and adds 300 lb/ft of downforce to keep that baby stable at 162mph.
Thursday humor guys.......
Now this one, along with the coffee can muffler actually makes 63 more horsepower and adds 300 lb/ft of downforce to keep that baby stable at 162mph.
Thursday humor guys.......
Now this one, along with the coffee can muffler actually makes 63 more horsepower and adds 300 lb/ft of downforce to keep that baby stable at 162mph.
Thursday humor guys.......
A Spoiler and a wing are two different things.
Try telling that to the world in general.
A "Spoiler" spoils/defeats drag at the rear of a car and most resemble a "Duck Tail".
A Wing creates down force at the rear of a car and is elevated off the rear deck and resembles a "Wing".
Sorry I don't know what wing would work better.
You are correct they are different things, but both create downforce. NASCAR guys rely on spoilers to create downforce all the time.
The difference is just that wings are much more efficient at doing it (drag vs downforce).
You can, obviously, set up a spoiler to produce nearly zero downforce and it will lessen drag significantly over not having one there, which is what you're essentially referring to. It helps smooth out the low pressure area behind the car and allow the air traveling under/around the car to reintegrate with the air travelling over the top of the car without causing so much turbulence.
The problem is that when you have a very tall spoiler with a high plane of attack, the high pressure area in front of the spoiler actually will push the car down and cause downforce. The trade off is that hte more downforce you make, the more turbulence you create behind the spoiler and drag increases up quickly.
That's why for pure downforce, most people will install wings in competition environments. Nearly every racing series where people use regular duck bill type spoilers is because they are restricted to those via the rules.
Also, fluid dynamics is very complicated, and while some things are understood, these aerodynamic problems get VERY complex very quickly when talking about interactions of airflow across various bodies and around things and even computer simulations are not always completely accurate to real world behavior. Things like splitters and diffusers play a role as well and we're quickly getting into areas that my intuition can steer me wrong in, so Im going to stop there. Im not a fluid dynamics engineer. Just be aware this is a problem that almost requires HUGE budgets, wind tunnels, and very expensive high level modeling software to actually calculate, so the resources to figure out this stuff are limited to OE mfr's and very well funded high level race teams. Everyone else just builds off of what is known and experiments.
Lastly, from what I understand, the factory GM 82-86(and 91-92) spoiler actually DOES create some amount of downforce... It's not a lot... but allegedly GM wind tunnel tested it and it produced some non negligible amount at high speeds. Less than 100 lbs at 100+mph I know that. (your windshield creates more) But it also reduces drag and increases fuel economy - which is probably the actual purpose for its installation beyond styling. But as Ron usmc said... they do decrease drag, and I imagine meeting cafe regs was the primary reason GM did the wind tunnel testing on them in the first place. It just so happens that the best compromise of styling and drag ended up producing some amount of downforce at high speeds.
I believe the 87-90 Trans Am Spoiler (or one of them? Im not super familiar wit hthose) has been proven to be very effective in bonneville speed record competition. This is the first stock bodied car to ever break 300mph. Note it's a 91-92 TA with an 87-90 wing on it.
Gale Banks also had an 88 Firebird he used for high speed runs. But he used an aftermarket (maybe a Mecham?) spoiler. SImilar to what was used in Trans Am in 82-84.
One is lift, as in an airwing, but designed upside down.
The second it wedge, as in NASCAR, which is like putting your arm outside the window doing 80mph. It doesnt use physics like Bernoulli and is probably not 'the best' but it appears to work.
The wedge, to my thinking, just catches air like a parachute. And the weight of doing that forces the rear of the car down. Alot more crude/brute and I cant imagine it being as smooth in ride characteristics, having as high of an output, nor would I think it leaves the wake of air behind you as clean as an upside down wing.
Maybe our terminology results in disambiguition.
Wedge (can be called a spoiler) is just panel that doesn't cut thru the air and is not aerodynamic, but will catch the wind and push the bumper down.
Diffuser- a device used under the car to break up vortices, turbulence and underbody lift.
Wing (can be called a spoiler)- what a Boeing 747 uses to get you in the air....but turned upside down to force the car into the ground for high speed stability, traction, and probably other benefits.
As I know it, downforce only comes from a wing. It is the opposite of lift.
Last edited by mjoekingz28; 05-01-2016 at 01:06 AM.
I can't speak for wings, since I've never had a car that had a wing. Typically, a wing on a pure Street car is about as useful as drag slicks on the rear of a Honda Civic.
I do, however, have an adjustable duck-tail spoiler on my bird. I don't race, so can't say what effects it would have in that realm, but I can say it has a noticeable effect on street driving. Mines setup for efficiency, though.
It's bolted to the rear of the hatch and sits rearward at about 45° angle, though is adjustable to a wider range. It was done using CFD data and wind tunnel data off similar bodied cars, as well as some home/kind of backwoods style testing as well.
Using just that spoiler, with no other changes, my mpg bumped from 18.7 mpg (no spoiler or wing) to 20.2 mpg. This is with a stock cam 305 carb car.
As far as stability goes, unless you're in a racing class that has restriction, a wing with a moderate-high angle of attack would give plenty of downforce, but at the expense of plenty of drag, along with every other riceburner will want to "race" haha.
Downforce doesnt need a specific type of idealized structure to create it. It is merely the net effect of positive and low pressure areas around an object that creates a net downward force.
An angled barn door moving through the air creates downforce, even if it's not what you would think of as a wing... because the shape doesnt matter to create downforce, it still creates positive and low pressure areas on opposite sides. That's what wings do. Ground effect (what the plastic appendages on our cars are named after, not the other way around) creates downforce. Venturis and splitters and diffusers in flat bottomed race cars create huge amounts of downforce.
There's a LOT of very complex theory behind that, and the Bernoulli equations play a role in lift, but not the way it's usually explained.
Note the date - 2012. This is common knowledge before this, but this is a really well done experiment to prove it.
Here is what is going on... as simply as it can be put.
1. There's air flowing over and under a wing. The wing ends below the split point (not always, but in cases where this is a designed in mechanism to create aerodynamic force, this is true), therefore there is a net upward force on the wing. This creates high pressure under the wing and low pressure above it.
2. The air deflected over the top of the wing "jumps" over the curvature of the wing, creating a low pressure area below the air flowing over the wing. This creates lift.
There are MANY other things going on, but those are two simpler, yet significant factors.
This is why you can also have completely flat wings:
Here's the tricky part... we're applying this to vehicles... these are not wings. THese are just giant heavy blobs of moving parts moving through the air.
You see all that turbulence behind the car? That's air rushing back into where it was displaced from, like the wake of a boat, because that's a low pressure area.
Now the problem is that there are all kinds of vortices in the air behind a car as the air tries to recombine. The size of these are somewhat hard to predict and are very hard to visualize and have drastically different effects depending on their size. They can be used to generate all sorts of air-induced forces. Diffusers and venturis on racecars are used to intentionally create vortices. Same with those tiny little fins they put on jet liner wings.
What people dont realize is a spoiler that is angled upwards creates LOW PRESSURE behind it. But not only that, it means there is a LARGER low pressure area behind the car. It prevents air that went under the car and air that went over hte car from rejoining as quickl and thus further imbalancing the pressure on top and bottom of the car, or it can be specifically designed to smooth their rejoining (This reduces drag). Think about the drag racing tea tray spoilers. Those significantly reduce drag because they allow the air from under the car to stay separated from the vortices that would be created by air flowing over the car. When they rejoin, most of the turbulence from the car on the bottom is handled, and they can much more smoothly rejoin the airflow. This doesnt create much downforce, but it hugely lowers drag. It still creates some downforce, however, as long as it rejoins ABOVE THE AVERAGE AIR SPLIT point ahead of the car. This is why we have splitters! You split the air low, force it to rejoin much higher. This is a net upward force on the air the car is flowing through, creating a net downward force on the car.
The point of all this, is i want you guys to understand that typical duck bill spoilers arent standalone wings. They use your car as an airfoil. They create lift by affecting airflow over your car as a whole. The wings you see create lift independently of the car and are structurally mounted. Their effects (massive low pressure area below them) will cause air flowing over the back of the car to jump upward, but that's a side effect, and it is generally more beneficial to have them farther away from the car to reduce drag and get them in cleaner (denser, calmer air) than it is to keep them low where they play a role in the aerodynamics of the car body as a whole.
Note how the whole car functions as a wing? Note how the car is not, externally wing shaped? THe air doesnt care if a car looks like a wing or not. It just needs to function like one. This is what duck bill spoilers do. http://www.projectm71.com/lotus2_s.jpg
Or if you prefer, imagine this wing as your car body, and the gurney flap as your spoiler:
The difference is that wings have better downforce vs drag ratios. Thats it.
But this is a SUPER complicated topic, and that's why peopel get paid BIG money to understand this well.
I never really considered the front of the car. I see some have an airdam, but I thought it was to direct air to the radiator or serve as some sort of shield. You used to hear them go crunch when someone pulled to close to the parking space barrier.
I really appreciate the photos on the above post that show the attitude of the car with differing set-ups. I wonder why all cars wouldn't all have both front and rear spoilers. Maybe cost, maybe some drivers do not car, or limited body parts? I don't know
Dont over think that. The 69 Camaro was designed before they really paid that much attention to aerodynamics. Our cars have integrated chin spoilers. They dont function as wings so much as they function as splitters to split the air over and under the car. Cars are designed today to be efficient and stable. Not to create downforce. Just to be stable. The more modern the car, the more attention they paid to this for the most part. Especially the high performance German cars that live on the autobahn.
The spoilers on a 69 Camaro were afterthoughts tacked onto a design they thought looked good. They did not design the front end to work with a spoiler, nor did they design the spoiler to work with the front end.
Our air dam creates a low pressure area behind it which causes air to rush up through the radiator to get to it. It is not there for aerodynamic reasons - it's there for radiator cooling reasons as our cars are designed to breathe from the bottom. Think about why they would design a car to breathe intake and radiator air from the bottom. It means you dont have to have a huge radiator opening on the front of the car. This means you have a lot more freedom with how aerodynamic the front of your car can be and you can design in some amount of front end downforce to make sure the car is stable.
Also, understand, these cars are not designed to go 150mph. They are just designed to be aerodynamic for fuel mileage/styling reasons. If you want the car to be 150+ mph stable you're going to have to get creative with the air flowing through the radiator. I think you'd need a splitter and a heat extractor in the hood to keep radiator air from getting trapped in the engine bay and pushing up on the hood. Also, this is not something that will matter unless you're building a 700+ hp silver state classic race car.
Another bit of food for thought. The original DeTomaso Pantera and the original GT40 were known to create lift at high speed. Thats because back then cars werent designed to be stable so much as they were designed to be slippery. They didnt understand as much then as they do now. The GT40 was quickly redesigned (GT40 Mk1 and Mk2 show obvious differences) and the Pantera got a bunch of fancy stuff added to it over the years.
Cars from the 80s onward tended to have more thought put into that from the start, but even then, a cheap performance car from 1985 was not designed with the intent to create tons of useful downforce in a balanced way at 200mph. Just know that the Firebirds do work well for that and the 85-90 spoiler is proven to be successful for such endeavors.
1965-1970 was the aerodynamics revolution in racing... That finally trickled down to being integrated into new car designs in the 80s, of which our cars are a prime example.
1962 AC Cobra
1965 Cobra Daytona:
1966 GT40:
1967 Ferrari 312:
1969 Ferrari 312:
1966 Porsche 906:
1970 POrsche 917:
Wings didnt appear in F1 until 1968. So this stuff was VERY VERY early when GM started talking about spoilers on Camaros. They were used more because they were known to work a little rather than as part of some deliberate engineering intention and understanding. 1965-1970 was when this exploded. Look at an F1 car from 1967 and 1972 and the differences are staggering. This was a time when power outputs were far outpacing tire technology, and once the aero cat got out of the bag they went hogwild with it and experimented with all kinds of crazy things, hitting an experimentation crescendo in the mid 70s, and by the 80s we had started to settle on certain things being probably the best, and from there it was a lot of refinement ever since.
Last edited by InfernalVortex; 05-02-2016 at 05:30 PM.
03-12-2016, 01:27 AM
