No, a spoiler does nothing else but spoil the airflow. Only a wing (which is basically like an upside-down air plane wing) actively generates downforce to counteract the lift. The spoiler doesn't generate downforce, instead it modifies the car shape in such a way that the shape creates less lift.
No, a spoiler does nothing else but spoil the airflow. Only a wing (which is basically like an upside-down air plane wing) actively generates downforce to counteract the lift. The spoiler doesn't generate downforce, instead it modifies the car shape in such a way that the shape creates less lift.
Don't asume they are cosmetic. I saw a vid about the wrc impreza and the vertical bars in the rear spoiler produced significant amounts of downforce at lower speeds (as I remember it, it was 20% more but i'm bad at remembering numbers) obviously without generating heaps of drag in the process.
The small fins _might_ do wonders with the turbulence, they do have a spiffy name "vortex generator".
But I will not try to cut through gigabytes of marketing speak and journalist bs to find the truth about then as Im not in the market to buy a new evo.
Im seeing the differences between reducing the lift and downforce. but i cant help but think that its the same principles just one is in a stronger amount?
I know this is probably annoying but. Does a wing spoil the airflow?
I know this is probably annoying but. Does a wing spoil the airflow?
Yes, it also spoils the airflow, though in a bit different way than a spoiler does.
It's not the same principles at all.
Yes, a wing could be made to simply spoil the airflow, changing the pressure gradients across the entire car. But it probably wouldn't generate any meaningful downforce that way.
A wing works the local airflow, turning it's motion (relative) to a force acting across it. Whilst it's presence will alter the airflow around the rest of the car, it's in a different way, and a different magnitude.
A spoiler tries to keep the air attached to the vehicle for longer before separation occurs. A wing isn't meant to do that.
Yes, a wing could be made to simply spoil the airflow, changing the pressure gradients across the entire car. But it probably wouldn't generate any meaningful downforce that way.
A wing works the local airflow, turning it's motion (relative) to a force acting across it. Whilst it's presence will alter the airflow around the rest of the car, it's in a different way, and a different magnitude.
A spoiler tries to keep the air attached to the vehicle for longer before separation occurs. A wing isn't meant to do that.
I guessed that it was all the same air pressure type principles. like the spoiler adjust the cross section of the car, which is trying to improve the airflow, much like a wing uses the airflow creating downforce. But the car shape lifts, and it seems the spoilers and whatever on the body kit just reduce lift and give stability, they dont produce any downforces like a pure wing shape does (or diffuser).
ROFL @ This thread 
My face hurts.
Glad to finally see that all the important things have been mentioned. I think magazines and bullshitfolklorepimpdaddytalk sure mess with people's heads about aero. I've seen many articles that would deceive people into thinking that production car X has a net downforce, when I gaurantee all they are talking about is a lift reduction of X at speed Y. As has been stated, spoiler/wing is not the same thing and and spoilers do not produce any downforce, but merely spoil airflow to cause less lift.
If someone states that car X produces 150lbs of downforce at 200km/h, then logic would rightly tell you that the weight at which that "downforce" is acting would be static weight+150lbs right? but no, usually what they mean is that the 300lbs of lift has been reduced to 150lbs, which is deceitful and makes for good reviews, and all sorts of ganstas going "ma ryde gots tuns o DOWNFORCE YO!11" when they buy said car. Then they get high and smash their civs because they can't take a 90 at 220km/h like they figured they could, with their "downforce". But I digress.
Heh, that was comical. I strongly suspect his isn't going poorly
Yay! Perfect.
Late as usual, my bad. Should've gotten in early on this one.
And I'm still holding it against Sam for making that go away, I think he should dig out our relevant posts from that thread so I can remember my train of thought. Still have the images in my head I was picturing, but their context is all fuzzy now. UKCT - friendly my ass
I do agree with you here, but the problem is that manufacturers just deceive people by telling them half the story. You're not going to change the handling of a car that much with a mild reduction in lift. Until the net result is a force into the ground, it just doesn't matter that much. Sometimes this is done by saying "The spoiler on the XXXX produces 150lbs of df at speed blah", when in fact - if it's spoiler, it won't, if it's a wing it will, and does not include the dynamics about the rest of the vehicle. They just want you to feel cool.
Yes, that's where you're wrong as I think you see based on the above post.
My face hurts.
Glad to finally see that all the important things have been mentioned. I think magazines and bullshitfolklorepimpdaddytalk sure mess with people's heads about aero. I've seen many articles that would deceive people into thinking that production car X has a net downforce, when I gaurantee all they are talking about is a lift reduction of X at speed Y. As has been stated, spoiler/wing is not the same thing and and spoilers do not produce any downforce, but merely spoil airflow to cause less lift.
If someone states that car X produces 150lbs of downforce at 200km/h, then logic would rightly tell you that the weight at which that "downforce" is acting would be static weight+150lbs right? but no, usually what they mean is that the 300lbs of lift has been reduced to 150lbs, which is deceitful and makes for good reviews, and all sorts of ganstas going "ma ryde gots tuns o DOWNFORCE YO!11" when they buy said car. Then they get high and smash their civs because they can't take a 90 at 220km/h like they figured they could, with their "downforce". But I digress.
Heh, that was comical. I strongly suspect his isn't going poorly
Yay! Perfect.
Late as usual, my bad. Should've gotten in early on this one.
And I'm still holding it against Sam for making that go away, I think he should dig out our relevant posts from that thread so I can remember my train of thought. Still have the images in my head I was picturing, but their context is all fuzzy now. UKCT - friendly my ass
I do agree with you here, but the problem is that manufacturers just deceive people by telling them half the story. You're not going to change the handling of a car that much with a mild reduction in lift. Until the net result is a force into the ground, it just doesn't matter that much. Sometimes this is done by saying "The spoiler on the XXXX produces 150lbs of df at speed blah", when in fact - if it's spoiler, it won't, if it's a wing it will, and does not include the dynamics about the rest of the vehicle. They just want you to feel cool.
Yes, that's where you're wrong as I think you see based on the above post.
And now were right back in the discussion BBT and I started months ago, and were stopped half way though thanks to either Sam or Ben.
Anyway my take on this is that a spoiler can in fact generate downforce as long as it sits at about the highest point of the car and ensures that the stream above the car separates from the body flowing up. This should in principle mean that the car acts like a large V shape pushed though the air. This is more or less the basic shape of all modern Ferraris neither of which has a wing to my knowledge (360 430 and the Enzo ... obviously their underbodies help a great deal too).
It´s actually more than marketing mumbo jumbo and in fact a real technical term.
What a vortex generator does is just what the name implies, it creates a vortex sort of like a miniature hurricane flowing across the surface of the wing or underbody the generator is placed on.
The big idea here is that the eye of the vortex, or in fact the entire vortex looked at as a distinct entity, will move across the surface at roughly the same speed as the rest of the flow. Additionally to that though the air also circles round the centre of the vortex faster than the speed it would move at as a linear flow without the vortex generator.
According to Bernoulli a faster flow has less pressure so the vortex itself becomes a pocket of low pressure air moving across the wings surface creating downforce.
Obviously it will also create additional drag due to the energy needed to fuel the vortices.
I always thought it did the exact opposite in that it forcefully disconnects the airflow from the cars body at a hard edge in a defined manner mainly to keep the upper body airflow from rejoinging with the lower one, at least as far as non economy increasing spoilers are concerned.
Depends on which way you look at it I guess. To me 150lbs more load on the tyres means a lot, but then again I live in a country where going 200+ kmh is something you might do every day depending on how you commute to work.
You´ll need a strong knife to cut though the marketing rubbish of course but on some cars those aero devices are rather effective. Thanks to my 190e enthusiastic friend I know of at least one car where taking them off at one end will invalidate the TÜV (german MOT ... lot harder to get too) tag, due to the large imbalance in lift caused by it. Ironically leaving the wing on will get you stopped by just about every police car that sees you driving around and you´ll grow plenty of gray hair trying to explain to them, that the wing is factory standard, and, that you do not have a certificate for it because of this.
Well....this thread has officially given me a headache. Not because of tristan of BBT, or any rational thought. It was my mind trying to figure out how Richey couldn't seem to grasp the idea as a whole, and how much more complicated he was making it all on his own.
I need a nap now.
I need a nap now.
As most spoilers are on the far end of a car, I'd say Tristan is right... The air has to flow over the additional length of the spoiler, thus keeping the airflow a bit longer at the car... And disconnecting the airflow from the car's body would create an area of low pressure right behind the car = additional drag...
1) i hate you guys
2) the torque vs power thing simple, and it drives me nuts how badly people misunderstand it. to say that power affects top speed, and torque affects acceleration is stupid (sorry to say, but it's true). torque measures how much push is generated by each firing of the cylinders. power is obtained by multiplying the torque by the rotational velocity (revs), basically adding up all the little pushes into a big push. so, as the OP stated, a high torque, low rev engine and a low torque, high rev engine will perform identically (assuming they are geared properly). the thing to note is that if you are caught out in the wrong gear with high rev 4 banger, then you will have low torque AND low power, and get left in the dust. a big V8 wont suffer that weakness. so if there is a single quality of torque that makes it desireable in a car, it's the ability to accelerate from anywhere in the revs, not just in the top end.
3) downforce. meh. afaik, any negative lift is downforce, even if it is less than 100%.
4) did i mention that i hate you guys?
2) the torque vs power thing simple, and it drives me nuts how badly people misunderstand it. to say that power affects top speed, and torque affects acceleration is stupid (sorry to say, but it's true). torque measures how much push is generated by each firing of the cylinders. power is obtained by multiplying the torque by the rotational velocity (revs), basically adding up all the little pushes into a big push. so, as the OP stated, a high torque, low rev engine and a low torque, high rev engine will perform identically (assuming they are geared properly). the thing to note is that if you are caught out in the wrong gear with high rev 4 banger, then you will have low torque AND low power, and get left in the dust. a big V8 wont suffer that weakness. so if there is a single quality of torque that makes it desireable in a car, it's the ability to accelerate from anywhere in the revs, not just in the top end.
3) downforce. meh. afaik, any negative lift is downforce, even if it is less than 100%.
4) did i mention that i hate you guys?
And what, exactly, is 100% negative lift?
Ok so im back again, curious as usual. Yes I know it did nothing for the cat.
If I am in my road car travelling behind another car on the motorway at say 100mph, in the slipstream, would I essentially get more grip since the car isnt lifting? I assumed that the car would go more lighter in that situation, or do you only lose grip in slipstreaming if you car has wings?
Sorry.
If I am in my road car travelling behind another car on the motorway at say 100mph, in the slipstream, would I essentially get more grip since the car isnt lifting? I assumed that the car would go more lighter in that situation, or do you only lose grip in slipstreaming if you car has wings?
Sorry.
Probably depends on your car and the car you're following, but yes it could be that you actually gain grip behind a car due to a reduction in lift - not that it really matters because at those speeds and distances you'll be on a motorway where grip isn't really an issue, and the additional grip is likely to be pretty minimal.
These threads are usually fun, reading now.
Only very downforce dependant race cars suffer from slipstreaming or "dirty air" downforce loss.
Regarding your example, at 100mph slipstreaming effects are, especially for road cars, rather minimal. To get a real effect, you'd need to follow the car in front really closely, like only a few feet behind. If you ever do that on a public road/highway, you deserve to get your license taken away for a long time.
Any grip change due to the slipstream on a non-downforce road car would be negligible. In theory, you have less air around you, lowering the lift slightly. Then again, the slipstream mainly affects the front of your car, so also the opposite could happen; you lose the downforce the front provides while the back is barely affected and still produces the lift, increasing the total lift. Though it's all very theoretical and you should never ever even think about trying this anyway.
Regarding your example, at 100mph slipstreaming effects are, especially for road cars, rather minimal. To get a real effect, you'd need to follow the car in front really closely, like only a few feet behind. If you ever do that on a public road/highway, you deserve to get your license taken away for a long time.
Any grip change due to the slipstream on a non-downforce road car would be negligible. In theory, you have less air around you, lowering the lift slightly. Then again, the slipstream mainly affects the front of your car, so also the opposite could happen; you lose the downforce the front provides while the back is barely affected and still produces the lift, increasing the total lift. Though it's all very theoretical and you should never ever even think about trying this anyway.
richy, maybe you are confused by the difference between downforce and weight. Weight is the "downforce" caused by gravity acting on the mass of the car, downforce is the force that gets added to the weight by aerodynamics, not the net total of the downwards force acting on the car.
And about torque and power. The way I make sense of the common "torque means great low end acceleration" half-knowledge (does that term exist in English?) is that when you are comparing two similar engines with similar max power and you know that one engine has more max torque than the other, then you can assume by probability that the engine with the higher max torque is likely to also have a wider power band, meaning more power than the other one at low revs --> better acceleration.
Looking at it that way catch phrases like the one posted by Rizzo make kinda sense.
And about torque and power. The way I make sense of the common "torque means great low end acceleration" half-knowledge (does that term exist in English?) is that when you are comparing two similar engines with similar max power and you know that one engine has more max torque than the other, then you can assume by probability that the engine with the higher max torque is likely to also have a wider power band, meaning more power than the other one at low revs --> better acceleration.
Looking at it that way catch phrases like the one posted by Rizzo make kinda sense.
Nah think I was just wrong about the aero of a car adding downforce.
but this hasnt proved that wings on road cars or body styling is useless and just for manufacturers to sell vehicles.
anti lift, drag reduction and stabilising is still good right?. Just technically the term downforce is incorrect and shouldnt be used.
but this hasnt proved that wings on road cars or body styling is useless and just for manufacturers to sell vehicles.
anti lift, drag reduction and stabilising is still good right?. Just technically the term downforce is incorrect and shouldnt be used.
I'm sorry but all i have is GCSE Physics and even i "get" this...
The Spoiler on the XRT - I'd assume that LFS gives the car drag of x (0.35 iirc), and an overall Lift (or negative downforce, or whatever) statistic based on both the lift and downforce of the car.
IIRC the road cars in LFS all have the same drag and downforce.
The Spoiler on the XRT - I'd assume that LFS gives the car drag of x (0.35 iirc), and an overall Lift (or negative downforce, or whatever) statistic based on both the lift and downforce of the car.
IIRC the road cars in LFS all have the same drag and downforce.
When i first wrapped my head around the concept of spoilers vs wings I though about planes. Imagine a car's cross section as a wing. Just like on your average Cessna. See the similarity? Ok.
Now, imagine another, smaller wing, mounted on top of the wing, but turned upside down, so the flat part is turned upwards. The main wing will lift, the little wing will push down on it.
Now, remove the small wing, and add a spoiler instead. Now, on planes, a spoiler is a small plate that rise from the wing surface to break the airflow over it, effectively stalling it. That is exactly what a spoiler on a car does too, it 'stalls' it, so it creates less lift. See the difference? One create a separate force acting opposite the lift, the other destroys the lift of the original shape.
Now, imagine another, smaller wing, mounted on top of the wing, but turned upside down, so the flat part is turned upwards. The main wing will lift, the little wing will push down on it.
Now, remove the small wing, and add a spoiler instead. Now, on planes, a spoiler is a small plate that rise from the wing surface to break the airflow over it, effectively stalling it. That is exactly what a spoiler on a car does too, it 'stalls' it, so it creates less lift. See the difference? One create a separate force acting opposite the lift, the other destroys the lift of the original shape.
Dunno about the Cw values of the different cars, but all LFS road cars neither have lift nor downforce. As far as I can remember, Scawen said a long time ago that he simply doesn't have access to good real life figures for similar cars to the ones used in LFS, so he just left the lift at zero. The benefit for us is that the road cars handle a bit better at speed then they should
Downforce exists at 1mph just as it does at 300mph but Niel, most of the people (except us LFS'ers ofcourse) don't know jack**** about cars. They just like Vauxhalls and Fords and don't really seem to know anything.... They usually support Manchester United or Chelsea too.
) don't know jack**** about cars. They just like Vauxhalls and Fords and don't really seem to know anything.... They usually support Manchester United or Chelsea too.Anyway.
If a car was a wedge shape like this.
Does that shape produce lift? Its sort of like a wing in reverse. faster air over the top right? Or would that produce a downwards force into the ground since the air is being pushed upwards?
or is it just anti lift shape? lol
If a car was a wedge shape like this.
Does that shape produce lift? Its sort of like a wing in reverse. faster air over the top right? Or would that produce a downwards force into the ground since the air is being pushed upwards?
or is it just anti lift shape? lol
That's not very nice :sadbanana:
Actually, it's very simplified but not as stupid as first glance would indicate. Power IS directly related to top speed, actually, since it's really just an indication of torque delivery at higher rpms. All other things being equal, a higher HP engine will push the same car to a higher top speed - so that's not really "stupid" to say.
Also, to say torque affects acceleration is also not stupid, unless you think F=MA (or A=F/M) is stupid, and most people don't think that. For a given set of gears, the greatest acceleration numbers occur at the engine's peak torque area. So, that's not really stupid either is it? Incomplete, yes, but not stupid.
Since you have such a great understanding of this simple topic (by your own profession), please answer me in detail the following question:
The definition of 1HP = 550ft/lb per sec
Take a power curve, and plot the HP values at various places on the curve. Of course, the most amount of work is being done at the horsepower peak. Say the engine makes 300hp at 6000 rpm, that's 165,000 ft/lb/s of work being done, whereas for example at 4000rpm, the engine makes peak torque but only say 270hp which is 148,500 ft/lb/s. So we can see that more work is being done at peak HP, BUT, the problem is that max wheel torque is experienced at 4000rpm, where the engine's torque peaks. This is all, of course, in the context of a single gear ratio.
Please explain why this seeming dichotomy exists, and specifically why work is a useless concept in this situation, in terms of how fast the car would accelerate. Since it's so simple, and everyone else is a moron, and you hate us, please oblige with the all encompassing truth about the matter.
Would that cheese car be right on the ground like that or would it be off the ground; because that would have a big effect.
Torque and 'downforce' common misconceptions
(164 posts, started )
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