Quote from richy :

Aircraft can fly at some pretty slow speeds, if a plane can lift off at those speeds then surely a car can be pushed down at those speeds? Some light aircraft take off around 60mph because of their shape, surely the shape of a car comes into play at the same speeds?

You have to take into account the surface area's of the wings. For example , an escort cosworth is about the same weight as a cessna 182. The surface area of the aerodynamic elements of the cossie can't be anymore than a couple of square feet at most (pure guess). The cessna has a wing span of 36 feet, with a total area of 16 square metres.

So in other words, if you bolt a set of cessna wings to a cossie then it will take of at 60-70 mph (remember James Bond, "The Man with the Golden Gun" ?) and conversely if you put the wings on upside down then yes you'd get downforce or reverse lift. But what kind of a numpty would put 36 foot wings on his escort ?

Quote from Mazz4200 :

But what kind of a numpty would put 36 foot wings on his escort ?

Harjun?

"pretty much" meaning they do but not enough for you to call it downforce? Or straight simply, they produce lift and no downforce?

I never claimed to be an expert :P

Quote from richy :

"pretty much" meaning they do but not enough for you to call it downforce? Or straight simply, they produce lift and no downforce?

Some parts of the car produce lift, other parts produce downforce. If you add everything together, the net result is that production cars produce lift.

Knowing peak power is useful.
Peak torque (on it's own) is fairly meaningless.
Knowing both of those above is very useful.
Knowing the whole torque curve is ideal.

It's impossible, without playing with the cars in a windtunnel yourself, or discussing with someone who has, to differentiate between the lift and downforce of a car. all you can do is look at the net result.

Most road cars end up with lift. They might create their own weight in lift as a basic shape, and generate vast amounts of downforce that nearly cancel it out (although this is rubbish). What is more likely is that most of the car produces some lift, and some areas of the car (if it were possible to consider them in isolation) might make a bit of downforce. But the final force is nearly always lift rather than downforce.

Civics = net lift. MX-5 = net lift. Starion = net lift. F430 = net downforce

Quote from tristancliffe :

Harjun?

BIG ROFFLE,

Erm, off topic but, anyone know if hot coffee can damage an LCD monitor, mines now covered in the stuff

but if comparing say, all roads cars that produce lift, then the difference is downforce? Right?

Quote from tristancliffe :

F430 = net downforce

Has anyone seen numbers on this? Ferrari told us this too but their telemetry data (apparently, I've not seen it personally) shows constant peak lateral gs at any speed.

Quote from richy :

but if comparing say, all roads cars that produce lift, then the difference is downforce? Right?

No, still lift. Essentially less lift = more downforce but I'd reserve the term downforce for when absolute lift is negative rather than relative lift.

Edit: Hah, I won this time!

No.

Downforce is the term given to a net download at speed.
Lift is the term given to a net upload at speed.

The difference between the lift values of different cars is called "The difference between the lift values at speed".

Also don't forget the Audi TT as a prime example. Before the little spoiler was added, several people died because the half-egg shape of it produced so much lift at the rear that the car became uncontrollable at autobahn speeds. The spoiler fixed this by changing the shape of the car so it produces less lift at the rear now.

Quote from Bob Smith :

Has anyone seen numbers on this? Ferrari told us this too but their telemetry data (apparently, I've not seen it personally) shows constant peak lateral gs at any speed.

I haven't, I'm just going on what data we have. So many supercars claim downforce at speeds (perhaps only in a straight line :schwitz that I think it would be silly to discount it. If anything, it serves a purpose in this thread

I've yet to hear Hyundai claiming downforce figures for the Accent, so it probably doesn't.

So what question will be next to push this thread up to 50 posts per hour?

but if you add downforce that reduces the lift?

I did find the numbers for the 612 Sca...<italian sounding thingy> gilette thingy.. I forgot of course, but its mostly at the rear of the car for sure.

If you'd pull the same lateral G at any speed, that might well indicate a bit of downforce as my - based on no real data at all - thinking was that tyres loose a tad of their grip at higher speeds?

Yes.

Quote from richy :

but if you add downforce that reduces the lift?

What's so hard to understand that we look at the end result? Yes SOME parts of the car produce downforce. ALL parts of the car together still produce lift.

Quote from Niels Heusinkveld :

Same with downforce; Since when do people actually believe that road cars produce downforce? Only a handfull do, and those are the 'supercars', certainly not your Civic! And even those few like the Ferrari 430, specify downforce at 300km/h, choosing this extreme speed to make the numbers two or perhaps juuuuuuuuuuuuuust 3 digits in kilos.. At 100 or 150km/h the numbers would be pretty pathetic..

end of semi mild shrug type semi rant.

Well this is the topic right?

Think of lift and downforce as the difference in 'weight' the car would put on the scale at 0km/h and at 'speed'..

So if your car is 1000kg , and you'd weigh it at 200km/h it would only register 900kg, that means there is 'lift'; the wind pushes the car up a bit.

If the car would put 1100kg on the scale though, you'd have 100kg of downforce.

But comparing the same car with a wing and without 1 would have more downforce than the other even if both are producing lift overall. 1 would be heavier. Right? Thus producing more downforce than the car next to it.

Quote from Bob Smith :

So what question will be next to push this thread up to 50 posts per hour?

I'll try...

What's the point of those spiky affairs that they now put on the rear of the roof of Evos ?

According to Jeremy Clarkson they must've been some random Halfords bist that stuck to the car as it drove straight through the shop.

I can't imagine them doing anything significant, especially at normal speeds <150km/h. (Yet of course in all those reviews they'll rave on how much stability it adds..)

Quote from Bean0 :

What's the point of those spiky affairs that they now put on the rear of the roof of Evos ?

Hey it's her server, she paid for it, she can have whatever hairstyle she wants....oh, i see

Got any pics so we know what you mean ?


oh bollocks, to slow again.

Quote from richy :

But comparing the same car with a wing and without 1 would have more downforce than the other even if both are producing lift overall. 1 would be heavier. Right? Thus producing more downforce than the car next to it.

Well, yes, if you're being pedantic. But what is accurate would to say one produces less lift than the other. Neither 'car' actually produces downforce still.