Why is the leading edge of a rear wing curved up?

[flynfrog]

http://www.grc.nasa.gov/WWW/k-12/airplane/foil3.html
you can play with it in foil sim

[marekk]

I thought so, but perhaps it's even interesting to have flow seperation there, reducing the amount of generated downforce and drag at higher speeds. Just guessing though...

No flow separation on high pressure side, sorry

[machin]

I've seen some cfd plots before showing flow pattern... with a "conventional" horizontal nose configuration, the flow which goes under the wing actually arrives from significantly above the wing... the flat nose causes the flow to separate from the wing as it travels around the nose (the flow tries to turn through too tight an angle)... By turning the wing's nose upwards it allows a much more gradual direction change for the flow going under the wing...

[Richard]

Isn't this the same as the leading edge slats on aircraft? Its all about maximising angle of attack.

Slats are aerodynamic surfaces on the leading edge of the wings of fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of angle of attack and speed, so by deploying slats an aircraft can fly at slower speeds, or take off and land in shorter distances. They are usually used while landing or performing manoeuvres which take the aircraft close to the stall, but are usually retracted in normal flight to minimize drag.

http://en.wikipedia.org/wiki/Leading_edge_slats

.... and the slat leads us to the slot as seen on the Ferrari side pod to ensure better flow over the top of the side pod.

A leading edge slot is an aerodynamic feature of the wing of some aircraft to reduce the stall speed and promote good low-speed handling qualities. A leading edge slot is a span-wise gap in each wing, allowing air to flow from below the wing to its upper surface. In this manner they allow flight at higher angles of attack and thus reduce the stall speed

http://en.wikipedia.org/wiki/Leading_edge_slot

So just like Tomba, I'd love to see an aerodymacist's explanation of what is going on with these leading edges. Thanks to Machin for helping us along that path.

[marekk]

Isn't this the same as the leading edge slats on aircraft? Its all about maximising angle of attack.

Not exactly the same, both slats and flaps are separate airfoils with own circulation, but generally speaking the idea is the same - to increase the camber and lift/downforce of the wing, even at low AoA.

.... and the slat leads us to the slot as seen on the Ferrari side pod to ensure better flow over the top of the side pod.

Clever way of adding 2 small additional wings to the car. Shorter sidepods behind the slot, with fresh boundary layer and lower speed of incoming air, can help to keep flows attached all the way to the beam wing.

[shelly]

See mp4-27

[hardingfv32]

With the slat design, lift comes with a very high drag penalty. This Ferrari wing is for a low drag Monza setup.

There is something else going on here.

Brian

[Just_a_fan]

The Ferrari sidepod slot is a cooling outlet. It's an idea borrowed from last year's McLaren (and probably other before that).

[andylaurence]

It looks to me like both teams have approached the DRS solution differently. Does the Ferrari main plane stall without the DRS flap in place? It's heavily cambered and I wonder if it requires the flap to use the energised air passing between the main plane and the flap to keep the air attached to the underside of the main plane. The effect being that a good deal of downforce is generated in normal operation thanks to the heavy camber and steep flap angle but when the DRS is enabled the main plane stalls, reducing its drag and the flap goes horizontal, reducing its drag too. The other wing uses the main plane in a conventional manner and the DRS doesn't affect it so much. Drag when DRS is enabled will be lower than the Ferrari design, but downforce when DRS is not in use will be substantially lower.

[horse]

Like Marekk says, highly cambered aerofoils have a decent lift coefficient at low angle of attack. It will have a tad more drag than a less cambered wing, aka the Virgin.

The reason why that doesn't matter so much is because the wing is operating at such a low angle of attack and the majority of the force on the wing is directed straight down.

Remember, this is a two element wing, also, and the second element will help in keeping the flow attached.

Here is a link to a paper with some high camber aerofoils.

when the DRS is enabled the main plane stalls, reducing its drag

I'm not sure that would be the case in this situation andy, I think a stall would increase drag at low AoA.

[marekk]

With the slat design, lift comes with a very high drag penalty. This Ferrari wing is for a low drag Monza setup.

There is something else going on here.

Brian

It's common belief for unknown reasons, but it's not true. L/D for slats + main plane system is always better then for clean wing alone. In other words - for a given amount of lift/downforce, slats, flaps, any mulitelement system in fact, if properly designed, will give you lower drag numbers. There is a very good paper on this linked on wiki page for leading edge slats (numer 3 on reference list).

[volarchico]

I think some people may be greatly over-complicating a very simple cambered wing aligned to local flow...

EDIT: Not referring to horse. It took me awhile to post and I hadn't seen what he wrote. I actually agree with his post entirely.

[hardingfv32]

"I think some people may be greatly over-complicating a very simple cambered wing aligned to local flow..."

Roughly what would be your estimate of the alignment of local flow in the region of the rear wing?

Brian

[hardingfv32]

"It's common belief for unknown reasons, but it's not true. L/D for slats + main plane system is always better then for clean wing alone."

Then correct statement should have been that a clean (one element?) high lift wing comes with a high drag penalty?

Brian

[ringo]

ringo, the lowest pressure line is near the leading edge even for a cambered wing. Forget Venturi.

No. This is not a plane wing.