Rule Interpretation - Double deck diffusers

[feni_remmen]

So, how far ahead is it possible to create hole in the floor?

Timbo,

I am sure that the hole issue has occurred in the area ahead of the wheel centreline. In the past the area ahead of the diffuser would have been difficult to use for these holes as the general layout of the suspension denied this opportunity + the gains of this layout would've been less differential to a "normal" solution. Unless I have it all wrong, Williams holes (for example) are ahead of the axle line and use the rear leg of the lower wishbone to hide the sprung part of the car above it. The placement of the wishbone lets them use the hole...

Is it possible to create hole somewhere in the middle and vent it to the side of sidepod?
Or is it precisely at the wheel centerline?

If this hole is ahead of the axle line, it does really open a Pandora's box. I think the debate is about to extend to "what is an appropriate to be considered as a sprung part of the car?" I answer to the question about venting isn't a major worry as you would still need to hide the unsprung part of the car, unless it is something like the RB5 had on the weekend.

[feni_remmen]

hi everyone, here is a cool link from marca.com: (spanish), an interactive flash that explains the double deck diffuser, and a comparision (comparativa) between brawn, williams, toyota and renault, hope you like it. cheers

http://www.marca.com/2009/04/15/motor/f ... 25973.html

This is likely quite wrong.

Yes, I think this link is reasonably inaccurate.
The diffuser shown on the Brawn starts at the front of the rear wheels for a start.

These diffusers gain advantage by getting extra air through the holes from under the floor, surely!?

[Metar]

From the FIA ruling:

Brawn GP and Toyota submit that it is obvious from the context what the
reasons for the Contested Decisions were and that those reasons were clear to
the Appellants. Given the confidential nature of the material on which the
Contested Decisions were based, the Stewards were correct to give their
reasoning in broad terms only.

"Yeah, we really do want to make F1 invisible to the fans."


They also make little sense further on:

In this regard, Renault adds that notwithstanding the wording in Art. 2.4 TR
that clarification “may be sought” from the FIA, in reality, it is a requirement
under Art. [Bla Bla Bla gives example of Tuned Mass Dampers]:

[...] it is however necessary, for any future developments that might apply to similar devices, to
refer to Article 2.4 of the Technical Regulations which allows competitors to justify the
innovations which are suggested, and to obtain official clarification from the FIA in this respect[...]

To which the FIA replied with a big "in your face!"

The FIA and the Contested Design Teams contest this argument on the basis
that Art. 2.4 TR is voluntary – it only invites a team to seek the view of the FIA
Technical Department as to the legality of a new design; it does not require a
team to do so.

[kNt]

If I read trough the lines of the full ICA decision(and according to some members here), if you have an unsprung part below the step planeholes above it are permitted.

Are there any regulations restricting unsprung parts of the cars to some area?

If not, one could get rid of the step plane alltogether, fit a large wishbone with sideskirts to the reference plane and the rear wheel (or even to the frontwheel ?) and effectively have a lotus double-floor car. It can't have a wingprofile incorporated but that can be dealt with the diffuser.


I mean I always thought since double-floor cars are illegal also suspension parts below the step plane are illegal. But now it appear such unsprung parts are used to hide the holes in the floor that feed the double-deckers.

[RacingManiac]

These diffusers gain advantage by getting extra air through the holes from under the floor, surely!?

I think not extra air through the hole from under the floor, rather allowing extra air volume from the undertray to be "diffused" into normal flow to make the undertray more effective. Since the whole diffuser dimension deal is to limit the overall volume of the diffuser such that the floor is less effective and cuts downforce, by letting more air from underneath the car expand though effectively a secondary diffuser above the regulated one you are effectively regaining a portion of the lost diffuser volume. Which is why I somewhat doubt that the air is taken from above the floor to drive the diffuser...

[superstring]

hi everyone, here is a cool link from marca.com: (spanish), an interactive flash that explains the double deck diffuser, and a comparision (comparativa) between brawn, williams, toyota and renault, hope you like it. cheers

http://www.marca.com/2009/04/15/motor/f ... 25973.html

This is likely quite wrong.

That's a helpful comment, Gecko Why exactly is it likely wrong? Not just because it's from Marca, surely?

The explanations I've read talk about an extra step or layer in the floor where the diffuser begins. The animations look fine to me.

[Gecko]

Well, throughout this whole thread we were discussing that, for the double decker diffuser to be effective, the air needs to be scooped from the floor and expanded to a larger area. The link shows just the opposite, taking the air from the top of the floor and feeding it into the diffuser.

Nothing to do with Marca; I'm not British

[RacingManiac]

Btw, whats the rule stopping someone from making a full venturi with a false floor? It probably won't be as effective without the full interaction with a ground plane, but if somehow they can get enough flow from some hole underneath to feed it, it can still do something no? It's basically a more extreme permutation of the setup as seen on the "diffuser gang" right now...

[timbo]

If this hole is ahead of the axle line, it does really open a Pandora's box. I think the debate is about to extend to "what is an appropriate to be considered as a sprung part of the car?" I answer to the question about venting isn't a major worry as you would still need to hide the unsprung part of the car, unless it is something like the RB5 had on the weekend.

Thanks!
So it may appear as if teams would make a very wide wishbone it is possible to create a wide, forward placed hole to feed upper deck of the diffuser.
I wonder would it really drive designers to create something awkward?
Pandora box... quite may be!

[Gecko]

Unless I have it all wrong, Williams holes (for example) are ahead of the axle line and use the rear leg of the lower wishbone to hide the sprung part of the car above it. The placement of the wishbone lets them use the hole

See, this is what puzzles me about the whole ICA case and the actual designs of these diffusers.

Apparently the debate is indeed about the holes ahead of the rear wheel centerline. If the solution was such as was suggested earlier in this thread, namely exactly at the rear wheel centerline, then most of the debate would have been unnecessary.

However, the debate centers on the transition between the reference and step planes, and that applies only to surfaces ahead of the rear wheel centerline (and not necessarily directly on it). Unless the upper surface of the top section of the diffuser is open just above the opening in the floor (which is quite unlikely), then there must be a suspension member directly above the opening that covers the upper diffuser just above the hole if the regulations are to be satisfied.

The question is, why did the ICA not even consider the wording of the regulations where it says that no part of the car be visible through the hole, when other much more clearly written rules have been contested? Or is the new diffuser designed in a way that we don't entirely understand yet?

[PlatinumZealot]

Can somebody show a picture (or sketch) of the step plane please? I want to make sure that it is what i think it is.

[Nat]

But how can you see anything through a vertical hole when looking directly from below?

[kNt]

But how can you see anything through a vertical hole when looking directly from below?

This is where I think "Infinite Precision" comes into play. Claiming that there's infinte precision (so no illegal overlap but also no illegal gap) to circumvent the rules to not have a hole is not ok I think.

[NormanBates]

Unless I have it all wrong, Williams holes (for example) are ahead of the axle line and use the rear leg of the lower wishbone to hide the sprung part of the car above it. The placement of the wishbone lets them use the hole

See, this is what puzzles me about the whole ICA case and the actual designs of these diffusers.

Apparently the debate is indeed about the holes ahead of the rear wheel centerline. If the solution was such as was suggested earlier in this thread, namely exactly at the rear wheel centerline, then most of the debate would have been unnecessary.

However, the debate centers on the transition between the reference and step planes, and that applies only to surfaces ahead of the rear wheel centerline (and not necessarily directly on it).

I'm puzzled by all this too

reading the reasons behind the decision, it seems like the holes are indeed ahead of what I thought, somewhere in the transition between the reference plane and the step plane

I thought that transition was pretty tightly regulated, even maximum radii are set!

in any case, the second sentence of 3.12.3 seems to be the loophole exploited:

3.12.3 The surface lying on the reference plane must be joined around its periphery to the surfaces lying on the step plane by a vertical transition. If there is no surface visible on the step plane vertically above any point around the periphery of the reference plane, this transition is not necessary.

the diffuser teams' defence there is the following:

45. The Contested Design Teams submit that they have shaped the step and reference planes to prevent them from overlapping at various points, so that vertically above these points on the reference plane, the step plane is not visible. As there is no surface visible on the step plane vertically above the periphery of the reference plane at these points, the transition is not necessary and has not been placed. There continue to be transitions joining the points where the step and reference planes overlap.

46. Thus, rather than having just one continuous transition, the Contested Design Concept involves the use of multiple vertical transitions between which air may pass (rather than a single continuous transition through which air may not pass). The spaces between these multiple vertical transitions allow air to be channeled towards an additional diffuser which is not visible from directly beneath the car (as it is placed above the visible lower diffuser).

47. The Contested Design Teams argue that there is no provision of the TR which prevents them from shaping the step and reference planes (provided each surface remains continuous), including by having 'cut-aways’ upon the peripheries of these surfaces. They point to examples of the cut-away or shaping used by all teams at the periphery of the step plane to accommodate the rear tires.

I don't get it, I thought all parts of the car visible from beneath it had to be either referenceplane/stepplane or tyres/suspensions/noseandfrontwing/etc

[Metar]

Can somebody show a picture (or sketch) of the step plane please? I want to make sure that it is what i think it is.

"The step plane must be 50mm above the reference plane."

So, simply, a plane 5cm above the reference-plane.