An extra wing to get more downforce

[mycadcae]

Who can use CFD analysis to Lotus F1 rear wing? ...


http://www.f1technical.net/development/283

As the newest of the new teams with just six months to prepare the cars for the first race, Lotus made a good showing. Lotus were alone the amongst the new teams. with both reliability and new developments for the first race. Through out the weekend the T127's ran with mini winglets added to the rear wing. These 15cm wide winglets sit in a zone with the rear wing regulations that allows more than two closed sections. Thus this middle span of the wing comprises both the winglet and a slot in the main plane, totalling five sections in this area. Lotus did try a shark fin briefly on Friday allowed to the winglet but did not continue with it on track.

[volarchico]

I think Virgin can. I hear they're good with CFD.

[autogyro]

I know CFD is a clever discipline and well complicated but with the rear wing elements on the cars above the main airflow of the car, surely it should be possible for Lotus to guess a new rear wing with better results than the current one. After all, even on this site there are enough pictures to use with the FIA regs to build a pretty useful wing with little need to use CFD or a tunnel.
The front wings obviously have a direct effect on the chassis and undertray aero so have to be designed together but I cannot see this as needed for the rear wing and I also cannot see how the rear wing right up high can effect the diffuser that much.

[Mystery Steve]

... I also cannot see how the rear wing right up high can effect the diffuser that much.

The lower rear wing interacts with both the diffuser and the main rear wing. So no, they don't necessarily explicitly interact, but they are part of the same overall package. The upwash and wake produced by the upper rear wing does play a role in the diffuser design as well.

[mycadcae]

I think Virgin can. I hear they're good with CFD.

there and for example

[mycadcae]

I know CFD is a clever discipline and well complicated but with the rear wing elements on the cars above the main airflow of the car, surely it should be possible for Lotus to guess a new rear wing with better results than the current one. After all, even on this site there are enough pictures to use with the FIA regs to build a pretty useful wing with little need to use CFD or a tunnel.
The front wings obviously have a direct effect on the chassis and undertray aero so have to be designed together but I cannot see this as needed for the rear wing and I also cannot see how the rear wing right up high can effect the diffuser that much.

Additionally, an extra slot gap is added in the lower element of the wing to prevent the lower airflow to detach from the wing elements at higher speeds - or steeper angles of attack.

[autogyro]

I know CFD is a clever discipline and well complicated but with the rear wing elements on the cars above the main airflow of the car, surely it should be possible for Lotus to guess a new rear wing with better results than the current one. After all, even on this site there are enough pictures to use with the FIA regs to build a pretty useful wing with little need to use CFD or a tunnel.
The front wings obviously have a direct effect on the chassis and undertray aero so have to be designed together but I cannot see this as needed for the rear wing and I also cannot see how the rear wing right up high can effect the diffuser that much.

Additionally, an extra slot gap is added in the lower element of the wing to prevent the lower airflow to detach from the wing elements at higher speeds - or steeper angles of attack.

Both elements of the wing are high up and should not have a big effect on the diffuser. The rear wing is also in relatively clean air, so why cant the rear wing be designed mostly in isolation from the complete car aero?

[Mystery Steve]

Both elements of the wing are high up and should not have a big effect on the diffuser. The rear wing is also in relatively clean air, so why cant the rear wing be designed mostly in isolation from the complete car aero?

If the lower and upper rear wing are close enough, the upwash from the lower element can affect the upper rear wing. You could evaluate the upper wing separately to simplify things in the component design phase, but you would have to account for the whole package when you put it together. Of course, if the upwash from the lower rear wing isn't strong enough then you would have nothing to worry about.

[autogyro]

Both elements of the wing are high up and should not have a big effect on the diffuser. The rear wing is also in relatively clean air, so why cant the rear wing be designed mostly in isolation from the complete car aero?

If the lower and upper rear wing are close enough, the upwash from the lower element can affect the upper rear wing. You could evaluate the upper wing separately to simplify things in the component design phase, but you would have to account for the whole package when you put it together. Of course, if the upwash from the lower rear wing isn't strong enough then you would have nothing to worry about.

This is exactly what I would want to know.
If the upper part of the rear wing can be designed in isolation then it should be possible to get good results without a tunnel and using easier CFD calculation.
It would also allow for experements with slots and blowing etc without a major CFD run on the whole car.

[Mystery Steve]

The problem is you can't just add an incidence angle the way you would with say two aircraft flying in formation. The lower wing would likely be affecting the back side of the upper wing and actually helping reduce flow separation. You could always do a quick and dirty CFD to see how they interact. You could at least make an assessment on that and decide if a detailed analysis would be required or if you can look at them separately.

[newbie]

mini wings like these point to an obvious lack of downforce on the Lotus car. cranking up the rear wing or adding short-span elements like this mini-wing do bring increases in downforce but at a pretty severe drag penalty.

[wesley123]

i doubt the drag penalty, it is kinda similair with the double deck front wing, creates little drag but lots of extra downforce. If it would lower L/D im sure teams would have doubts of putting it on