2009 Testing - March (Jerez & Barcelona)

[vyselegend]

Seems like Rosberg crashed the same place Alonso did Sunday... I guess that's the end of the day for Williams.

[meves]

Thanks for the insight kilcoo316, it sounds quite likely as they are looking at the flow around the sidepods and the top of the tray from air flow off the front wheels. A sudden change in downforce from unexpected flow from the front wheels could be the cause of Hamiltons excursions.

Does anyone with any 'insight' know if McLaren are using this now to gain extra information and take new parts to Australia with them?

[Moanlower]

I wonder what explanation the Piquet critasters will have now...

Possibly the same explanation with Brawn Gp doubters and Lewis Hamilton followers: non-comparable as in different weight, day, car ie..

Ofcourse it's still testing, but if you look at the pecking order topic almost everyone put Alonso near the top and Piquet at the back of the list. And yes, no exact comparison because of different track- and air temp although the condition are practically the same as yesterday. And I can't state it as a fact but i'm quite sure both set these times with practically the same fuel load and setup. Fact is he not off by 3 seconds as some believed.

[Keir]

The CFD code doesn't really care what you plug into it.

Unfortunately, no, it really, really, really cares what you put into it.

Should someone with the knowledge comment on the differences to run CFD now and previous years?

Its all in the boundary conditions you use.

As I said earlier, I'm suspecting the tyres, as they are the biggest change from last year to this - modelling how the tyre deforms under load/unload is critical to good aerodynamics - and it is also far more complex than modelling a deforming wing.

Look how Renault went horribly wrong in 2007 - there is history for it - and I *believe* it is where McLaren's problems lie.


Note also - incorrectly modelling the tyre deformations will affect the wind tunnel* as well as CFD - which is why the tunnel didn't pick up on the problem until the car was on track.


* the tyres in a tunnel are independent of the chassis aero loading - so the teams control how they react through the stings.

This is exactly where my thoughts were heading, albeit in a slightly less technical, more ignorant way.
There is previous with regard to changes in tyres bringing massive benefits/problems on several occasions before.

There is the McLaren and Renault situation in 2007.
McLaren bolt the Bridgestones on the 2006 car and instantly go quicker, Renault do the same and go the same chunk slower.

Also thinking back to BAR/Honda in 2004, their switch from Bridgestone to Michelin yielded positive results whereas the switch back in 2007, well, we all know about Honda in 2007.
Might it have been that their rear end instability (the same problem now afflicting McLaren I would suggest) was caused by the different aerodynamic properties of the Bridgestone tyre?

I would surely go as far as suggesting that it is obvious that the problems they are encountering are based on the different properties of the new slicks, which they have thus far failed to understand.

[McMacca]

Paintball again for McLaren

[i70q7m7ghw]

I'm not sure what it's called but the element that connects the rear wing end plates to the crash structure has changed. It now curves over the rear crash structure.

[scarbs]

Revised diffuser from yesterday. The middle tunnel has the extra vane running through it (but still closed off at the top. Then the outer edges of the side tunnel are bowed out. Plus a new beam wing reminiscent of the 1994 Benetton & Williams F1 cars.

[zgred]

Paintball again for McLaren

I have problems with my eyes or there are two different exhausts?

Edit: Different angle.

[vall]

good point. Need more pictures to be sure. In one of my previous posts I noted then the exhaust pipes of Macca are different from the rest of the cars. They go out of the body more. Now they may be trying different solutions, but to run two different configurations at the same time makes sense only to see how the air flows (with paint) not check the performance? Such a car should be un-drivable, shouldn't it?

[twoshots]

Just looks like the angle of the photo to me.

Edit after zgreds edit: definitely looks different on the second one, interesting...

[Tbox]

Paintball again for McLaren

I have problems with my eyes or there are two different exhausts?

It certainly looks like it. Quite a good idea - paint both sides of the car with paint, fit asymmetic bits to it - compare and contrast flow patterns.

I'm pretty sure I've spotted them running an asymetric underfloor as well... Can't find the picture now.

[noname]

what is more accurate today? A well done calculation or a 60% model ?

if we take out "today" from this question the answer would be: there is no difference. today's CAE packages and powerful computers allow us to build and solve huge models but our ability to really simulate REAL PHYSICS has not increase due that and is poor.

if the CFD method would be so good we would not need the tunnels.

after this, maybe too long, introduction answer to your question: it depends who is doing the job (both CFD and tunnel's test). at the time being both method are glued together - first you perform numerical simulations and then you go with pre-tested ideas to the tunnel. do not expect miracles if you screwed up the first part

[peroa]

Regulations updated today.
http://www.fia.com/en-GB/sport/regulati ... nship.aspx

Anybody got the old versions for comparison?

[Keir]

Regulations updated today.
http://www.fia.com/en-GB/sport/regulati ... nship.aspx

Anybody got the old versions for comparison?

Interesting that there are changes to 3.10 which concerns the diffusor does it not?

3.10 Bodywork behind the rear wheel centre line :

3.10.1 Any bodywork more than 150mm behind the rear wheel centre line which is between 200mm and 730mm
above the reference plane, and between 75mm and 355mm from the car centre line, must lie in an area
when viewed from the side of the car that is situated between 150mm and 350mm behind the rear wheel
centre line and between 300mm and 400mm above the reference plane. When viewed from the side of the
car no longitudinal cross section may have more than one section in this area.

3.10.2 Any bodywork behind a point lying 50mm forward of the rear wheel centre line which is more than 730mm
above the reference plane, and between 75mm and 355mm from the car centre line, must lie in an area
when viewed from the side of the car that is situated between the rear wheel centre line and a point
350mm behind it. When viewed from the side of the car, no longitudinal cross section may have more than
two closed sections in this area.

[CHT]

Suspect Mclaren is running out of time to fix their aero problem and they are now trying to maximise their track time by running asymmetrical aero on the car.

pretty smart idea, if it works.