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[FerrariFan63]

Looking further into it, there are two possibilities if the assumption that it's an open duct that feeds air from the back to the front are correct.

The duct might be physically closed when DRS is not engaged, and the movement of the DRS wing element (or other physical parts of the system) may open the duct.

Or, the duct may be permanently open. But, when DRS is not engaged there isn't sufficient air pressure feeding into the duct to have an effect at the front of the car. But when DRS is engaged, the different airflow means that there is sufficient pressure feeding into the duct to make a difference.

We have this from Charlie Whiting.

"At the beginning of last year, with engineers being unable to unlearn things, they wanted to try and get the effect via different means, and they talked about opening and closing a duct by having interaction with the suspension. We said no, you cannot do that because that is not the primary purpose of the suspension system – which is to insulate the car from undulations in the road.

"There was then a lengthy discussion in the TWG at the beginning of last year about that, to make sure everyone was clear about it. It seems a couple of teams went away from that meeting with the impression that F-ducts were banned in general. Whatever an F-duct is. But they are not."

Whiting would not reveal further details of how the Mercedes system works, but said that he viewed it as completely passive.

"What it appears some teams are doing is that when the DRS is operated, it will allow air to pass into a duct and do other things," he explained.

If it was an active opening of the duct, then I can't see how CW could both say that suspension couldn't drive such a duct, but the DRS could. Note in particular CW's use of "primary purpose".

This to me suggests a permanently open duct but which is fed with low pressure when DRS is not enabled, and high pressure when DRS is open. Even if a physical movement that opens the duct was the movement of the wing element end-plate, there's no way that a duct that is physically opened by movement is "completely passive". A permanently open duct could be. Air-flow around the rear wing should change significantly when DRS is engaged making a passive duct feasible.

Edit: Are these "slots" under the front of the Mercedes wing?

http://www.suttonimages.com/searchresul ... us3467.jpg

[bud]

But if the DRS wing opens making available airflow to the duct behind the wing then really the DRS wing isn't actually interacting with the duct. The duct is just passive as in it's not interacting with anything like a suspension version would.

[LRW]

Edit: Are these "slots" under the front of the Mercedes wing?

http://www.suttonimages.com/searchresul ... us3467.jpg

Yeah, that's where the machine guns come out.

Nothing in the rules saying no machine guns.

[FerrariFan63]

But if the DRS wing opens making available airflow to the duct behind the wing then really the DRS wing isn't actually interacting with the duct. The duct is just passive as in it's not interacting with anything like a suspension version would.

In the case of a purely passive duct that's open all the time, but receives high or low pressure depending on DRS position, then I'd agree that's legal.

If the wing element end-plates, when they move, act as a tight fitting physical lid or cap on the duct, such that the physical movement of the wing physically opens and closes the duct, then I don't think it's correct to describe the duct as "passive", and I don't personally think it's legal.

There is of course a continuum between the wing acting as a tight fitting cap, and the wing element being physically quite removed from a permanently open duct such that remote pressure changes are what activates and deactivates the duct.

This photo is supposed to show the open duct, but I'm not sure I can identify the duct opening itself.

http://img1.auto-motor-und-sport.de/Mer ... 579917.jpg

Overall I think Charlie Whiting's language suggests no close physical interaction between the moving wing element and the duct. Otherwise how could he describe it as completely passive? But, the FIA has quite frequently done very odd and inexplicable (barring conspiracy theories) things in the past.

[bud]

you can see the duct here.

[andrew]

It's been declared legal. The other teams just have to dry up and get on with it.

That it's been declared legal doesn't mean that it actually should be legal given the rules. We have many example of things that have been declared legal, then declared not legal. E.g. mass dampers and brake steering. There is a lot of interesting discussion on this in the comments for the article I link to, but I haven't read enough of them to come up with a firm opinion. And the article is still making guesses about how the system actually works.

Edit: If the benefit of the system is that the front wing is stalled when DRS is open, maintaining the balance of the car, then there is little benefit when the car is moving in a straight line. If that's the case, then the system should be of very little advantage in the race, as the DRS overtaking zones tend to be straights, aren't they?

Charlie Whiting is pretty clear this:

What it appears some teams are doing is that when the DRS is operated, it will allow air to pass into a duct and do other things.... That is all I can say - you will probably have a pretty good idea of what it might be doing, and other teams will as well. But it is completely passive. There are no moving parts in it; it doesn't interact with any suspension. No steering, nothing. Therefore I cannot see a rule that prohibits it.

Link

[What's Burning?]

A lot of hair splitting going on, passive yes, but in the end it's the driver pressing of a button that activates the duct. So the rules can be interpreted many a ways...

[scotty]

If it passes scruitineering then it is legal at this time, by definition. I believe it is passive myself, and can't personally see the argument. The moving parts are all in the wing element itself, so how can the system be banned under these technical regualations, without stopping the rear wing being able to move via DRS - it can't.

[andrew]

Mercedes' Brawn hits back over F-duct controversy

[madbrad]

If some team came up with some aero device that altered its behaviour or properties when the front wheel of each side is on an angle because the driver is turning right or left, is that considered something that's the result a a motion from the driver too?
Should steering and stepping on the gas pedal or the brake pedal be outlawed because it is a driver input that changes what the car is doing?
Should starting the engine be outlawed because it changes the state of the engine?

[vaptin]

The DRS is allowed to be driver operated, the driver changing the DRS system is what effects the F-duct, so the F-duct itself is passive is my interpretation (of Mercedes's argument). Clever.

F-ducts were never banned, the driver moving to change the state of the F-duct was banned, but presumably there isn't any qualms about the DRS system as that's meant to be a moving aerodynamic device, it's an existing exception to the rule and Mercedes have built on that.

---

Also, if it is found to be illegal, the FIA will probably retrospectively punish Mercedes (as long as its not outside the time limit to alter race results). They did it to Sauber last year. Although I just assumed the FIA would be consistant

Andrew Benson It states that with the exception of DRS, "any car system, device or procedure which uses driver involvement as a means of altering the aerodynamic characteristics of the car is prohibited".
They argue that as the driver is pressing the DRS button to activate the device, and that the device is not the specific rear-wing flap designed to be used by the DRS, then it is illegal.
McLaren team boss Martin Whitmarsh, though, said he thought it was legal. "I do, yes," he said, "because there is an exception for DRS mechanisms and I think it's part of that."

http://www.bbc.co.uk/sport/0/formula1/17412581

[What's Burning?]

It's a non issue, let Merc enjoy the fruits of their labor, and in two races, Red Bull, Ferrari, McLaren and Renault will all have it, the rest within 4 races, HRT and Marrusia, not so much.

[bud]

Also, if it is found to be illegal, the FIA will probably retrospectively punish Mercedes (as long as its not outside the time limit to alter race results). They did it to Sauber last year. Although I just assumed the FIA would be consistant

Sauber didn't pass scrutineering and were out by mm on their wing construction. Not the sme thing, if it is banned later I don't see any retrospective points deduction.

[killem2]

I think it is pure genius myself.

[geetface9]

If I remember correctly, bob varsha said something to the effect that the f-duct still receives air while the wing is down, but once it opens, obviously gets a lot more and has a more dramatic effect. If this is the case, then it is taking air in all the time, but just more while DRS is open, so I believe that would be legal purely on the grounds that it is passively taking air in all the time. It only has enhanced effect with the wing open during DRS zones. Essentially, using DRS doesn't "activate" it, it merely enhances it's effects. Just my opinion on the issue, and bold on the last sentence because I think that could be a main talking point for mercedes GP to keep it legal.

In the case of a purely passive duct that's open all the time, but receives high or low pressure depending on DRS position, then I'd agree that's legal.

As would I !!