The rear wing on the new Mercedes W03 Formula 1 car has been declared legal. It is great to see the innovation of the Formula 1 teams and I wonder how many points of drag this apparent stall system reduces.
The image shows a close up, best I could find at the moment, of the rear wing of the W03 Mercedes 2012 Formula 1 car. The area I have highlighted is where the small top wing comes into contact with the rear wing end plate (the bit with aabar written on it – same on both sides).
The reason for highlighting this area is because the little wing is what rotates open when the DRS* system is activated.
It seems that as the little wing (or flap) opens, it is revealing a hole that channels air through the rear wing end plate. This air flow is apparently being used for other beneficial purposes.
This seems to either be to further reduce the aero drag being caused elsewhere on the rear wing (most likely on the beam wing for example) or, and possibly more far fetched, to reduce the lift on the front wing, by channelling air back up from the rear to the front of the car …
The rear wing benefit is fairly straightforward – just reducing straight-line drag giving you more acceleration potential when using the DRS.
The front wing benefit is possibly more involved. One idea is to re-balance the car in high speed corners so that the DRS can be used more often in corners on a qualifying lap. I am not sure about this, as really on corners you want as much downforce as possible. It is however an interesting train of thought.
Possibly a more likely benefit would be in reducing high-speed ride-height variation at high speed.
The car often changes ride-height quite a lot at high speed because of the down force generated by the wings. The downforce is really for the corners; on the straights its not as important. However, the car will run the lowest at the end of the straights as this is typically the fastest point on the track.
The cars are typically set-up so the front is lower than the rear. This is called rake angle and what was used to good effect by Red Bull last year.
The cars also have a limit on how low they are allowed to run. Go with me on this if its new to you but the lower the cars the better.
What happens is that the front wing generates downforce and pushes the car into the track. The faster the car goes the low it gets to the road.
This is all great until that lower limit comes into play. That limit is controlled by-the-way by an extremely sophisticated (!) blank of wood under the car. It starts life at 10mm thick. After a race it can’t be less than 9mm thick; with one notable German having previously been disqualified for planing his plank too low.
Anyhow, so what the engineers have to do is something like this:
1) Work out the fastest speed the car is likely to be travelling at any point on the circuit.
2) Work out how much the front wing will be reducing the ride height of the car at that speed.
3) Then set the ride heights so that they don’t plane the plank. (There’s got to be a better description than that but anyhow …)
Now clearly this leads to quite a few compromises which I won’t go too into here, but includes things like choosing appropriate suspension spring solutions to trade off high stiffness suspension and low stiffness suspension. Again, something for a future post …
The idea I think they are trying to get to is that if they can reduce the front wing downforce on the straights, they can run the car at a lower overall ride height.
A lower overall ride height would have quite a big benefit all round.
It’s an idea anyhow. The issue is that this would be great in qualifying but then you can’t change the ride-height (officially) before the race. In the race you’re not going to be in control of when you use the DRS so you’d end up planing the plank as before.
Now if the front wing worked on its own and just stalled all the time at high speed, through the pressure differential air switch, discussed here and here. Then that would give you the reduced ride height variation and the ability to run lower overall.
And …
If the rear beam wing stalled when the DRS was opened, through the channelling of air from the little exposed hole in the end-plate, then you’d reduce the drag and go even faster on the straights.
Phew.
There a clever lot these F1 guys.
Of course there is another theory, that the air is being channel down the end plates to create a curtain between the wheel and the difusser, therefore improving the effectiveness of the diffuser in qualifying …
All just ideas but its fun guessing.
Comments welcome as ever.
Notes:
There are some good pieces on the written Mercedes wing ideas here:
http://scarbsf1.wordpress.com/2012/03/14/mercedes-f-duct-front-wing-operated-by-the-rear-wing-drs/
*For those unsure about DRS, check out this video. Mark Webber explains the Formula 1 DRS system with some nice animated graphics. Scroll to about 1m25 for the DRS bit.
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