Why do some teams not use blown diffusers?

[MIKEY_!]

Most teams are now running these coanda/downwash trick exhausts but we still have three fairly quick cars (lotus, mercedes and williams) which don't feature them. My question is; is there something that sets these cars apart that means exhaust blowing is of no use? Do they have some alternative diffuser sealing that is harder to spot (eg fancy brake duct fins like what I have been experimenting with)? Or have these teams just not got the trick exhaust to work yet?

[hardingfv32]

It would seem to indicate that flow over say the beam wing or top of diffuser is just as effective as flow to the edge of the diffuser.

Brian

[Nando]

Why would RBR go to such great lengths then?

[JohnsonsEvilTwin]

Why would RBR go to such great lengths then?

They know the value of it, and they are also the masters of it.
Look how they have used their resources to get back the loses of 2011, breaching regulations in the process.

We may now find that those blowing the outer edges, as per red bull, will be hampered by the ruling, even of its a tiny amount.
Mercedes where around 0.5 seconds off the ultimate pace at Germany ... Lotus about the same at 0.4.
We will see how it transpires in Hungary, but maybe the circuit isn't indicative of most other tracks we will see after.
We could see teams reverting to Sauber/Mercedes/lotus style exhausts as a result.
All depends in the losses.

[hardingfv32]

Why would RBR go to such great lengths then?

Because they have 'faith' that they can make this style of exhaust substantially better than the other. Unfortunately, with all the other updates going on, we will never know if the have succeeded.

Brian

[n smikle]

I think Evil twin has it right. They have mastered it in a way, so they can predict what it will do in a given situation. However, the advantage of Blown diffuser is significantly diminisged with this year's regulations making it aninvestment risk for lesser teams. It is hard to say whether 2012 blown diffusers are costly or cheap. I guess it is ironic that teams like Caterham and Marussia are able to develop the blown diffuser.

[Cam]

For the RBR EBD it was certainly to help Vettels driving style. This was shown by his utter dominance last year and why the year previously and this year, Webber has been much closer, if not better, than Vettel.

I imagine a great team will design the car to the feedback of it's drivers. Vettel (the reigning 2 x WDC) likes to get on the throttle early and the EBD actually makes more traction when there's gas there - ergo, jump on the throttle, more gas, more downforce. It makes sense for the team to try to tailor the car more to his style and we saw evidence of this in China(?) where they ran two completely different cars.

Different drivers have different styles and some may not like the way the EBD works, which I think Webber does not and it's probably true that other drivers do not either. With the tyre situation, being easier on the tyres simply through better driving, may actually be better than trying to force grip through downforce tricks.

[Cam]

Here's a really nice video comparison of Webber and Vettel in Turkey 2011 - the height of EBD goodness. At about 1:20 you can see how Vettel is on the gas way earlier and he generally carries more speed. The EBD was his stairway to heaven.

http://the-kerb.com/wp-content/uploads/2011/05/polelap2.mp4

But that was just his style that liked it. Remove the EBD, what do you have? It comes back to driving style that can adjust.

[Nando]

Thanks guys. It really does give you an impression that it doesn´t really matter where you put your exhausts this year but maybe that is simply masked with the Pirellis.

[MIKEY_!]

EBD teams are still having to deal with balance issues while non-EBD teams don't have as much grip on corner exits perhaps?

[skgoa]

'12-spec EBD gives a tenth of the benefit they got from last year's EBD. I can't say anything about Lotus(although their diffusor seems unusual and might have characteristics that prohibits an EBD), but Mercedes is pretty obvious in their focus on getting air over the beam wing, the top of the diffusor and through the starter hole/their mini-DDD. They might very well have looked at EBD in CFD/wind tunnel and found that they would simply loose to much in those regions, if they were to switch.

[n smikle]

There is no mini double diffuser at the starter hole.. really now.. The Air-flow througth the starter hole just helps the diffuser a little bit but most of all helps flow in the coke bottle zone. But where are these mini double diffuser claims coming from?

[MIKEY_!]

they have been around since the start of the year, scarbs had an article on it i think, or check through the early days of the MGP W02 thread

[skgoa]

To expand on this for a bit: the "mini double diffuser" is the part of the diffuser roof that below the rear crash structure. They abuse the starter motor hole rules to essentially create a bigger diffuser in that section.

[Javert]

Williams aero is so nice, so clean that putting the external exhausts would hamper that, ruining the performance.

Mercedes are trying to understand the tires (they haven't still done) and so they don't want to change exhausts

Lotus wants to focus on the basic downforce as it seems that nose / exhaust regolations of 2013 will be perfect for E20 so they can just make slight changes to the chassis and win the WDC