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What effect would a spoiler have on a SUV? Now there’s a vehicle that punches a really large hole through the air. I wonder if the front bug shield would have a positive effect on airflow over the vehicle? Bob – Hide quoted text — Show quoted text -> Can anyone give me a technical reason for putting a rear spoiler on a front > wheel drive car? > Wildey Johnson Lerona, West Virginia >A wing can create downforce (and drag) to offset aerodynamic lift >at high speed. Less necessary, perhaps, if the rear tires are not >about to break traction due to engine torque, but it’s still nice >to keep all 4 (or at least 3) contact patches going through high >speed turns. >A spoiler can reduce aerodynamic drag by allowing the air to come >off the rear of the car more cleanly, so less energy is wasted in >creating a turbulent wake as the car moves through the air. >So, the answer to your question is, "yes": >Energy management.
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> Can anyone give me a technical reason for putting a rear spoiler on a front > wheel drive car?
On most production vehicles they don’t do a damn thing even if its rear wheel drive. Driving a car with a spoiler or wing that’s actually tuned to produce affects on the handling makes cars drive a lot less like consumers would expect them to. A prime example are those limited-edition race Vipers. (The white ones with the blue stripes) They’ve got a clone of the wing used on the racing versions of the viper, and its specifically tuned to be as neutral as possible — they admit to being cosmetic only. Cars with heavily sloped rear ends, Taurus’s, J30’s, 911’s and the like tend to often need them. I believe the reason I heard was something about the airflow over the tail of the car shifting around during cornering and the wheels on the rear of the car getting shifting loads making cornering less stable. I assume that’s why the J30t’s spoiler is so non-standard looking, being very close to the trunk lid and more off the back of the car, like the spoiler on the 911’s and Ford Taurus’s. But that’s just from memory, something I thought I read once. – George —
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>Why on any "Street" car? Looks, of course! >Now if you’re going to be driving in the 100 mph range they’ll be for much >more function than form… true, they tend to ad down force as some as air >passes over them, but for most street cars they are for looks, add drag and >decrease gas mileage, just a bit!
Actually, in an environment where car companies put on 1/4 skip shifts, they also pay attention to mileage with spoilers. Most of them on cars actaully do help (slightly) with aerodynamics. Marc
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- Hide quoted text — Show quoted text – > Excerpts from netnews.rec.autos.driving: 27-Feb-99 Re: Spoiler on FWD > e: > >> : Can anyone give me a technical reason for putting a rear spoiler > on a fro > nt > >> : wheel drive car? > >> Appearance. > >To keep it stable at high speeds. Too much lift pulls the car off the > >ground no matter what wheels are driven. > >-s > I usually get this wrong but I don’t think a "spoiler" has much to do > lift. I think it has to with laminar (sp?) flow and "dirtying" that up > some? Chuck? Help? > You’re both right… spoiler reduces lift by breaking up laminar flow. > Basically you’re trading drag for downforce. In theory, anyway; I’ve > seen some cars with factory spoilers that I’m sure were just tacked on > for a performance image.
Some ? Come on Nate, you should know better than that. How about *all* production cars (except the Superbird) come with spoilers for looks only. Jeff
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Which really sheds some light on the whole phenomenon of adding spoilers to cars. If this is true, that the Taurus and Infinity spoilers are truly designed for function, then the theoretical best shape for a car may not match what people expect a spoiler to look like. The thin blade-like thing on the mid-80’s trans-ams comes to mind as one that was designed to match what people percieve a wing should look like- long and thin, to cut through the air cleanly. Most aftermarket spoilers and wings are copies of this shape. Now the public expects that shape to be best, because it just seems to look right. Along comes a proper spoiler, designed for function, and it’s perceived as funny-looking, because it doesn’t match with what we think a rear wing should look like. Jeff – Hide quoted text — Show quoted text -> Hey, has anybody seen the thingy on the back of some of the current > generation Tauruses? Oh my god, it’s so ugly. It doesn’t even *pretend* > to have any sort of functionality. >Actually, that may be one of the functional ones. The spoiler on the >Infiniti J30 was similar – just a little raised lip on the trunklid. It >was put there to induce turbulence over the bumper, making the car a bit >more stable at speed (by creating a stable vortex instead of one that >switches from side to side) and reduce drag. The Taurus’s body has a >pretty similar shape – maybe it’s the same idea. >there was a C/D article about this last year…
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Why on any "Street" car? Looks, of course! Now if you’re going to be driving in the 100 mph range they’ll be for much more function than form… true, they tend to ad down force as some as air passes over them, but for most street cars they are for looks, add drag and decrease gas mileage, just a bit! — Karl Fengler - – - – - – - – - – - – - – - – BRONCO*351 – FXDWG – !! You Have Strayed Upon The Motorway To HELL !! – Hide quoted text — Show quoted text – >Can anyone give me a technical reason for putting a rear spoiler on a front >wheel drive car? >Wildey Johnson Lerona, West Virginia
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> A recent article in an automotive journal quoted some Detroit > engineer, regarding the research and testing performed on spoiler (or > wing) shapes. The question was how much research and testing really > went into testing and developing the shape of the rear appendage to > get the best performance out of it. > His reply was something to the effect of ‘not much’. The marketing > department usually called for the inclusion of the appendage, in order > to give the car the desired ’sporty look’. But often there was no > testing performed to determine if the designer’s effort really > resulted in a performance difference. > I mean really, do you think they’ll spend the money to wind-tunnel > test several iterations of wing or spoiler designs on a foo-foo > stanza?
I have absolutely no way to verify this, but the literature from the manufactuer about my car (which has a spoiler/wing/whatever) claimed that its aerodynamics were tested via computer simulations on a super- computer. Heh. Hey, has anybody seen the thingy on the back of some of the current generation Tauruses? Oh my god, it’s so ugly. It doesn’t even *pretend* to have any sort of functionality. It’s like a blob Play-Doh plopped onto the sheet metal. Yikes. Hmmm… The ones I’ve seen are different from the one pictured in http://www.fordvehicles.com/taurus/exterior3.html. It’s hard to tell since that pic’s pretty useless, but it looks like there’s some space between the spoiler and the decklid, unlike the ones I’ve seen in person. Go figure.
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A recent article in an automotive journal quoted some Detroit engineer, regarding the research and testing performed on spoiler (or wing) shapes. The question was how much research and testing really went into testing and developing the shape of the rear appendage to get the best performance out of it. His reply was something to the effect of ‘not much’. The marketing department usually called for the inclusion of the appendage, in order to give the car the desired ’sporty look’. But often there was no testing performed to determine if the designer’s effort really resulted in a performance difference. I mean really, do you think they’ll spend the money to wind-tunnel test several iterations of wing or spoiler designs on a foo-foo stanza? – Hide quoted text — Show quoted text – >Can anyone give me a technical reason for putting a rear spoiler on a front >wheel drive car? >Wildey Johnson Lerona, West Virginia
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> Hey, has anybody seen the thingy on the back of some of the current > generation Tauruses? Oh my god, it’s so ugly. It doesn’t even *pretend* > to have any sort of functionality.
Actually, that may be one of the functional ones. The spoiler on the Infiniti J30 was similar – just a little raised lip on the trunklid. It was put there to induce turbulence over the bumper, making the car a bit more stable at speed (by creating a stable vortex instead of one that switches from side to side) and reduce drag. The Taurus’s body has a pretty similar shape – maybe it’s the same idea. there was a C/D article about this last year…
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Actually – there have been tests with the early Z-car (240Z), that a 2"-3" rear spoiler at a certain angle (and I forget the angle, but was fairly specific) will actually DECREASE drag while slightly reducing lift – and was proven by having this same car increase its top speed by a few mph (not HUGE gains, but certainly measurable). This is almost certainly the exception to the rule (aren’t there always?). — Dave "Spoiler won’t help my car" Lum – ICQ#2554240 ‘71 Datsun 510 – LIC# 24v 510 http://www.datsuns.com – remove 8 to e-mail - or not. – Hide quoted text — Show quoted text ->Assuming the spoiler is "tuned" properly to the airflow (and this is a HUGE >assumption) about all you are going to get is a lot of drag. Even the slightest >downforce is going to result in huge amounts of parasite drag and lesser amounts of >induced drag. Unless you are a high speed race car, why would you want to
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> Can anyone give me a technical reason for putting a rear spoiler on a front > wheel drive car? > Wildey Johnson Lerona, West Virginia
A wing can create downforce (and drag) to offset aerodynamic lift at high speed. Less necessary, perhaps, if the rear tires are not about to break traction due to engine torque, but it’s still nice to keep all 4 (or at least 3) contact patches going through high speed turns. A spoiler can reduce aerodynamic drag by allowing the air to come off the rear of the car more cleanly, so less energy is wasted in creating a turbulent wake as the car moves through the air. So, the answer to your question is, "yes": Energy management. — – Dave
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Unless you drive at well over 100mph, the wings and spoilers simply don’t generate enough force to be any use. Certainly, they are purely decorative in the US. harbir
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>I mean really, do you think they’ll spend the money to wind-tunnel >test several iterations of wing or spoiler designs on a foo-foo >stanza?
A magazine, I think Car & Driver, tested a recent Mustang with and without spoiler. The spoiler hurt performance. —
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> >Can anyone give me a technical reason for putting a rear spoiler on a front >wheel drive car? > The three responses so far have it wrong. Spoilers don’t produce > aerodynamic downforce (that’s the job of wings). > Spoilers are so-named because they ostensibly "spoil" the vacuum that > forms behind a moving automobile, thereby reducing drag. I don’t know how > often this translates into a significant effect. Rarely, I shall hazard > to guess.
I’d agree, but… that vacuum can also manifest itself on top of the deck lid or rear glass. That produces lift on the rear of the car. Canceling this lift is in effect creating downforce, though we know that the spoiler is not creating actual downforce like an inverted wing. Canceling lift also has the side benefit of reducing drag. Notice the large and steeply angled spoilers in NASCAR? I guarantee you they are primarily there to prevent lift of the rear end at 190 mph rather than to decrease drag. > FWIW, the spoiler on the back of my car is effective at getting the rear > face of the trunklid extremely dirty… so it’s doing *something*.
Like most stock spoilers and wings, the amount of downforce is directly equal to their weight. — Ron Katona
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- Hide quoted text — Show quoted text ->> : Can anyone give me a technical reason for putting a rear spoiler on a front >> : wheel drive car? >> Appearance. >To keep it stable at high speeds. Too much lift pulls the car off the >ground no matter what wheels are driven. >-s > I usually get this wrong but I don’t think a "spoiler" has much to do > lift. I think it has to with laminar (sp?) flow and "dirtying" that up > some? Chuck? Help?
Assuming the spoiler is "tuned" properly to the airflow (and this is a HUGE assumption) about all you are going to get is a lot of drag. Even the slightest downforce is going to result in huge amounts of parasite drag and lesser amounts of induced drag. Unless you are a high speed race car, why would you want to decrease your mileage? Spoilers are placed on cars for appearance. (To those who know about aerodynamics, it just looks silly) We use spoilers on planes when we want to slow down while descending quickly. I’ll take a clean air flow on my car, thanks.
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>> : Can anyone give me a technical reason for putting a rear spoiler on a front > : wheel drive car? > Appearance. >To keep it stable at high speeds. Too much lift pulls the car off the >ground no matter what wheels are driven. >-s
I usually get this wrong but I don’t think a "spoiler" has much to do lift. I think it has to with laminar (sp?) flow and "dirtying" that up some? Chuck? Help?
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Excerpts from netnews.rec.autos.driving: 27-Feb-99 Re: Spoiler on FWD
– Hide quoted text — Show quoted text -> e: >> : Can anyone give me a technical reason for putting a rear spoiler on a fro > nt >> : wheel drive car? >> Appearance. >To keep it stable at high speeds. Too much lift pulls the car off the >ground no matter what wheels are driven. >-s > I usually get this wrong but I don’t think a "spoiler" has much to do > lift. I think it has to with laminar (sp?) flow and "dirtying" that up > some? Chuck? Help?
You’re both right… spoiler reduces lift by breaking up laminar flow. Basically you’re trading drag for downforce. In theory, anyway; I’ve seen some cars with factory spoilers that I’m sure were just tacked on for a performance image. nate
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>>To keep it stable at high speeds. Too much lift pulls the car off the >ground no matter what wheels are driven. >I usually get this wrong but I don’t think a "spoiler" has much to do >lift. I think it has to with laminar (sp?) flow and "dirtying" that up >some?
I have to go to an expert on this one: Paul Van Valkenburgh’s _Race Car Engineering and Mechanics_, Ch. 6, "Aerodynamics". "The simplest solution [for rear lift] is to mount a vertical lip at the extreme rear edge of the upper body surface. This has the effect of generating a high pressure area ahead of it, which acts downward on the body. But surprisingly, it doesn’t necessarily add drag to the body as a whole, unless it adds to the frontal area. If there is a rearward-sloping body surface ahead of the lip, the positive pressure area can also act to push the car forward. So the lip contributes both to increased downforce and decreased drag until it reaches a height where the negative pressure at the rear cancels out those effects". He goes on to say that the better solution, where practical (or allowed) is a separate wing mounted well above the rear body work, because a wing’s lift-to-drag ratio is higher than a spoiler’s. As for breaking up laminar flow, I vaguely remember from fluids classes that it is sometimes desirable to force the airflow to become turbulent along the tapering rear surfaces of a vehicle. Apparently, if the air remains laminar along the tapering surface, the surface pressure will be lower (good for lift, bad for drag) than if the flow were turbulent. IIRC, one use for that property is in "Kamm-backed" vehicles. Basically, if the rear end of the vehicle has to taper fast enough (due to length constraints) that air flow will separate (and become turbulent) over the rear surface, you might as well lop off the body work after the separation point. I think that explains the Corvette C5’s big ol’ butt (hey, nothin’ wrong with that 
They cleaned up the airflow as much as possible within the length available, then they sliced off the body cleanly at the rear. If you look at a C5 that has dried out after cruising on a wet/salty road, you might see that the top and sides of the rear bodywork are relatively clean, washed off by streams of water pushed by laminar flow. In constrast, the rear of the car is almost uniformly filthy, as a salty/dirty mist kinda settled in the "dead air" beyond the cutoff point. My C4 has a similar effect, but the C4’s clean/filthy transition zone is quite a bit wider than the C5’s. — Chuck Tomlinson
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Can anyone give me a technical reason for putting a rear spoiler on a front wheel drive car? Wildey Johnson Lerona, West Virginia
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: Can anyone give me a technical reason for putting a rear spoiler on a front : wheel drive car? Appearance.
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> Can anyone give me a technical reason for putting a rear spoiler on a front > wheel drive car? > Wildey Johnson Lerona, West Virginia
Perhaps it is to give better traction at 200+ MPH. Kev — To reply, replace "NOSPAM" in return address with "eatel" http://www.eatel.net/~kevinm/homepage.htm Kevin Mouton – Automotive Technology Instructor "If women don’t find you handsome they should at least find you handy!" Red Green of Possum Lodge
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>Can anyone give me a technical reason for putting a rear spoiler on a front >wheel drive car? >Wildey Johnson Lerona, West Virginia
Same reason you’d put a rear spoiler on a RWD car: to keep the rear end on the ground at high speed. Even though you are driving the front wheels, if the rear wheels lose contact with the ground at high speed, the car will become quite unstable. Regards, Bill Bowen Daly City, CA
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> : Can anyone give me a technical reason for putting a rear spoiler on a front > : wheel drive car? > Appearance.
To keep it stable at high speeds. Too much lift pulls the car off the ground no matter what wheels are driven. -s
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>Can anyone give me a technical reason for putting a rear spoiler on a front >wheel drive car?
The three responses so far have it wrong. Spoilers don’t produce aerodynamic downforce (that’s the job of wings). Spoilers are so-named because they ostensibly "spoil" the vacuum that forms behind a moving automobile, thereby reducing drag. I don’t know how often this translates into a significant effect. Rarely, I shall hazard to guess. FWIW, the spoiler on the back of my car is effective at getting the rear face of the trunklid extremely dirty… so it’s doing *something*. Steve — i am stv-at-ot-dot-com.
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The vast majority of spoilers and wings found on street vehicles are purely cosmetic. However, a functional spoiler would serve the same purpose on a FWD car as it would on a RWD car–it would break up the airflow that otherwise creates a low pressure area behind the car and slows it down. A wing, which has a different purpose than a spoiler, would also work on a FWD car. The wing acts as an inverted airfoil to create downforce on the rear of the car. FWD cars can have just as much rear end lift as RWD cars; while drive wheel traction would be unaffected by rear lift in a FWD car, its presence would still cause the rear end to become "loose," and make the car more susceptible to oversteer. In fact, given that FWD cars often have a substantial front end weight bias, a functional rear wing might be more important in a FWD car than in a R- or AWD vehicle. – Hide quoted text — Show quoted text – > : Can anyone give me a technical reason for putting a rear spoiler on a front > : wheel drive car? > Appearance.
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> : Can anyone give me a technical reason for putting a rear spoiler on a >front > : wheel drive car?
I think spoilers are there to do more than just increase traction on rear tires. Doesn’t the shape of a car act as a wing at high speeds? I think the spoiler (an inverted wing) is there to counteract any upward forces acting on the car as a result of lift. In fact, I remember a story about one of those fellows who one a Darwin award. He attached a jet engine to his car (an older model without a spoiler) and achieved such great velocity and lift that he ended up embedded in the side of a cliff…
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> : Can anyone give me a technical reason for putting a rear spoiler on a front > : wheel drive car? > Appearance.
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