Rear Wing Position.

[Young Tiger]

This is probably the dumbest question with an obvious answer....Sorry I cannot see it.

Why is the rear wing positioned behind the rear wheels?

I appreciate it is to create down force on the rear wheels BUT as the force acts about 30cm behind the rear wheels there will be a rotational effect around the pivot point which is the road contact strip of the rear wheel. This causes the front wheels to rise. I borrowed my sons' scale model of Schumacher's Ferrari and put pennies on the wing and it lifted the front tyres.

The front wing will obviously counteract that effect BUT if you moved the wing to slightly ahead of the pivot point - would that not allow you to reduce the size of the front wing? The action of the rear wing will be ahead of the rear wheels ground contact and it will benefit both front and rear wheels.

There must be a logical reason as these guys are all a touch on the clever side so I'm hoping someone is able to enlighten me.

[Just_a_fan]

Ultimately the wing is where it is because the rules require it to be in that location. Historically, the wings were attached directly to the wheel uprights. This is the best place to have the wing supported because it means the downforce loads are directed directly in to the wheel and thus the tyre. However, there were a number of failures resulting in some nasty crashes. The rules were changed to prevent the wings being connected to the uprights.

Later, the wings were generally placed above and behind the engine because there wasn't a better place to put it really. Some tried to put it above the centre of the car but it rather got in the way of the driver getting in and out.

One benefit of placing the rear wing behind the car is that you can use the rear wing to help drive the underbody flow which creates much more downforce than the wings alone can create.

As with all things, the position of the wings is a compromise.

[bhall]

There's no such thing as dumb questions; only dumbass answers like the one I'm about to give.

First, teams generally set the rear wing to balance the downforce produced by the front wing. Since the front wing is in ground effect, it doesn't necessarily require a high AoA to make downforce. (This is a gross oversimplification.)

Now think of rear-wing downforce as a force pushing down on a lever. The longer the lever, the less force is required to do work. In the case of F1, in which the work is the force pushing the car down, a wing positioned behind the rear wheels can have a smaller AoA and exert the same force on the car as a wing with a larger AoA positioned directly over the rear wheels. That means less drag. (This is also a gross oversimplification.)

Incidentally, this is why rear wings were moved forward between the 2004 and 2005 seasons; the FIA wanted to reduce downforce on the cars. To counter the rule change, teams simply ran rear wings with higher AoA, which made overtaking even more difficult, because of the increase in "dirty air." (This is the FIA's typical lack of foresight.)

[variante]

Do not confuse Torque with Downforce!
The first goal of an F1 car is the downforce production.
Once the highest levels of downforce are achieved (drag wise), here comes the problem of balancing these forces, thus we start talking of torque: having a wing positioned much further or backward to the wheel does not chance downforce levels, it only modifies torque levels exerted by the wing on the car.

In other words, wing position only influences the Centre of Pressure location (in a semplified situation, obviously).

Why are F1 wings positioned like that? Because this is the best way to achieve the optimal balance (and of course because the regulations state so); generally, the optimal balance is reached when the centre of pressure overlaps the centre of gravity.

[henra]

The front wing will obviously counteract that effect BUT if you moved the wing to slightly ahead of the pivot point - would that not allow you to reduce the size of the front wing?

Which you don't want. You want as big a front and rear wing as allowed within the regulations to have highest possible downforce at the best L/D ratio. (small exception Monza, where you can't use the full allowed area and still effectively exploit DRS)

The action of the rear wing will be ahead of the rear wheels ground contact and it will benefit both front and rear wheels.

That is not necessary. The FW can take care of all the DF you need at the front. You want as much FW and RW as posssible/allowed.
In order for the wings to work best you would want to have the front and rear wing as far away from each other and from flow disturbing bodywork as possible (with the tiny exception that the rear beam wing can help the diffuser if it is in the right position). So in an unregulated world you would probably see the FW and RW even more extended to the front and rear, respectively, in order for them to get as clean air flow as possible.
The real downside to this is the structure required to mount them, so there is a compromise.
That said, in real F1 life, the position especially of the RW is narrowly limited by the regulation.

[Young Tiger]

Thanks very much for the replies - knew it was a prob a dumb question but had to find out why.