Multiple element wings

[PlatinumZealot]

Unless I am missing something, the drag of an F1 wing has relatively little to do with the frontal cross section (more or less equal in all cases) and skin drag and the such. F1 wings do not work like plane's wings, witness the almost vertical fences that we call rear wings.
These wings are designed to capture as much air as possible, and push upwards not only the air they cross, but, as much as possible, they try to capture air around them and send it upwards too. A wing affects air well beyond its cross section. The more air yo send upwards, and the faster upwards you send it, the more downforce you get.
Now, it is not like the wings are magically creating upwards thrust in the air like a rocket, they capture air moving horizontally relative to the wing, and send it out as vertically as possible. The total speed of this air (relative to the car) is not going to increase, and hence, air sent upwards has been redirected more than anything else and has lost most of its horizontal velocity.
All that air sent upwards in the name of downforce is being stopped horizontally, that is, pushed forwards, that is, the car has been pushed backwards, that is: drag.
So to me, in a good and efficient design, the more downforce you make, the more drag you will have. Because, except from the diffuser, this downforce comes from slowing air to send it upwards. That's why a stalled wing has less drag, as it has stopped pushing air upwards, it also has stopped decelerating it horizontally.
As far as I know, a three element wing (an efficient one), simply manages to capture more air and expel it at a more vertical angle than a two element wing.

You are implying that all the force from the wing comes from impulse. That's not true you know. You have pressure differences creating downforce and there is some coming from the reaction of the air after it accelerates from the wing.

[PNSD]

Amazingly how lift is generated is still an unknown, circulation theory seems to fit well but there is still not yet 100% accepted answer... then again will aerodynamicists ever agree :p?

[marekk]

@hollus,
actualy no more then 10% of lift/downforce results from dynamic pressure (molecules of air hiting surface), 90% from static pressure differences between upper and lower surface.
It helps to think of airfoil more as vacuum generating device - and all of earth air weight above it trying to push your wing back into this vacuum.
F1 wings are just this - airfoils.
And if you compare F1 rear wing to 747 in landing configuration (flaps and slats fully extended, about the same speed) it's not even that "vertical".

[ringo]

For a given plan area, a multi element wing theoretically makes less downforce because of less surface area. simple as that.Extra slot gaps take up room that could be used for producing downforce, but they also greatly reduce seperation on backside of wing hence they stall less.

You sure about that?

It does not make less down force. The lift coefficients can be drastically higher than 1 or 2 elements. Surface are is not the main decider in down force generation.

The limitation is the strength of the element and the construction itself.

Pure, simple but wrong.

Yupp

[ringo]

sorry guys if it were that simple why on earth would it take years to go from 1 plane to multiple plane wings.
Ferrari were the first to introduce more than one flap on each side of the front wing if I´m correct and it took the rest of F1 quite a while to follow that route..
so to say more flaps is better per se cannot be universally true.And please explain why 3 flaps won´t be even better going along that logic?

regulations.

[marekk]

Amazingly how lift is generated is still an unknown, circulation theory seems to fit well but there is still not yet 100% accepted answer... then again will aerodynamicists ever agree :p?

Don't think so. Lift results from turning of fluid flow in one direction (Newtons third law in work). There are some tricky details (vortexes, turbulent flows, boundary layers - to name the few), but basics are quite clear.

[ringo]

That's why a stalled wing has less drag, as it has stopped pushing air upwards, it also has stopped decelerating it horizontally.
As far as I know, a three element wing (an efficient one), simply manages to capture more air and expel it at a more vertical angle than a two element wing.

Not in all cases does a stalled wing have less drag. Wings can have different stall behavior. Especially if the continue to rotate through angle of attack after stalling.
for an extreme example, if a wing stalls and continues to pitch to 90 degrees before it stabilize, you will basically have a barn door at that angle with massive drag.

[godlameroso]

The way F1 cars generate downforce is by spoiling the air over the car slowing it down relative to the underside. To demonstrate hold a piece of paper vertically so that it is parallel to your chest, then blow across the surface nearest to you. Make sure that you don't blow directly on the surface of the paper but rather across it's surface. You will notice that the paper moves closer to your body, this is because the pressure on the opposite surface of the paper is higher, than on the side you are blowing across. The harder you blow the more the paper moves towards your chest.

[horse]

I've not got much to add here, but I thought perhaps multi-element wing doesn't clearly describe the front wing well enough. Bi-multi-element-wing maybe?

Agreed that the main plane is now usually a multi-element setup, but there is also the second upper plane. I was reading a bit about bi-planes, and the relative positioning of the upper and lower planes can make a difference to the aero of the combined system.

Voila:



Regarding the Mercedes, it's hard to believe they've got this part of the car wrong, given they had a strong front wing setup in 2009. Where did it go wrong?

[volarchico]

The way F1 cars generate downforce is by spoiling the air over the car slowing it down relative to the underside. To demonstrate hold a piece of paper vertically so that it is parallel to your chest, then blow across the surface nearest to you. Make sure that you don't blow directly on the surface of the paper but rather across it's surface. You will notice that the paper moves closer to your body, this is because the pressure on the opposite surface of the paper is higher, than on the side you are blowing across. The harder you blow the more the paper moves towards your chest.

I never realized how simple an F1 car really is...it's just like a piece of paper! Glad we finally put to rest all this nonsense about Newton, static pressure, and turning flow.

[shelly]

In the picture of the redbull front wing posted above we can appreciate the twist of the last element: almost vertical before the wheels and far less aggressive on the inside.

Also the extra elements upfront are divided in two parts, with a fence dividing them: a bigger and more aggressive double element on the outside, and a smaller double element on the inside.

The transition from low-loaded parts, to high-loaded parts and then to no part(wing has ended) that takes place travelling from the centerline to the outside of the wing, generates a vortex pattern which has to be:
- exploited on the wing, in order to generate more downforce
- managed on the parts downstream, in order to reduce losses.

For example, it is important to have a wing designed so that the outer, lower vortex (the one that starts entrapped in the lower arch of the endplate) passes outside the front wheel, both in a straight line and steered position of the wheel.

[marcush.]

The maximum height of the front wing is fixed in the regs so you will not be able to exploit the angle of attack beyound some angle without reducing wing planview,that was my point.

[shelly]

@marcush: the picture of the redbull front wing tells different: the outide part of the trailing edge of the last element is almost vertical

[segedunum]

Multi-elements do not give more downforce. The figures will always tell you that simpler, larger elements will give more downforce because of greater surface area. That changes in pitch and under braking. The car starts to behave differently closer to the ground making the car have less front end grip, despite the raw figures telling you otherwise. It's also long been possible to add downforce to a car and make it undriveable and sluggish to turn into corners. You want a quick turn in and change of direction and then you want the downforce to take effect. I suspect that's why Renault's front wing is so complex.

You have to fully understand what's going on and the variables involved. All the teams have suffered with many of them changing two and three element wings on Friday last season, but Mercedes seems to be the team most perplexed.

[shelly]

@segenundum: I think previous posts have made clear not only that surface is not the point but also that even if it would be, three-elements wing have more surface than two-elements wing.

I agree on the fact that prediction of the behaviour on track of a front wing is a big challenge, because it involves a lot of issues which can not effectively be tested in windtunnel or in cfd. I take two examples:
- even now it is very difficult to model the shape of the real wheel as it is deformed in action(braking, cornering)
-vortex stability is very difficult to predict