McLaren MP4-28 Mercedes

[Pup]

“That was another thing that caused this: we’re always looking at the correlation between full-scale windtunnel and CFD, and there’s always an offset between those, and we work on that.

“That was another thing that has exacerbated this situation. The real [2012] car was actually better than the windtunnel [model].”

I've always suspected that the wind tunnel correlation problems we hear so often about aren't so much about problems with the tunnels themselves, but rather with designs that don't scale well from the tunnel to the full sized car. This sounds like a confirmation of that.

[Holm86]

“That was another thing that caused this: we’re always looking at the correlation between full-scale windtunnel and CFD, and there’s always an offset between those, and we work on that.

“That was another thing that has exacerbated this situation. The real [2012] car was actually better than the windtunnel [model].”

I've always suspected that the wind tunnel correlation problems we hear so often about aren't so much about problems with the tunnels themselves, but rather with designs that don't scale well from the tunnel to the full sized car. This sounds like a confirmation of that.

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

[beelsebob]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max. What he means is that air behaves differently over a 60% model than it does over a full sized car. They can do all kinds of things to try and make it behave as similarly as possible, but ultimately they can't make it exactly match how the car will make the air behave.

[Javert]

They probably changed too much and need to recalibrate many parameters

If they started MP4-28 production with the data they have now, they would have done much better imho
(also with front pull rod and "unified" rear suspension!)

[Holm86]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max. What he means is that air behaves differently over a 60% model than it does over a full sized car. They can do all kinds of things to try and make it behave as similarly as possible, but ultimately they can't make it exactly match how the car will make the air behave.

Okay. I just read that it was full scale. So I thought it was full scale. Didn't know it was illegal to have full scale windtunnels. I just thought they used scaled versions to keep costs down. But yes scaled versions will not affect the airflow in precisely the same way as a full scale model.

[Pup]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max...

I do think they can test individual pieces at 100% - wings and such - just not the car as a whole. I could be wrong - those rules were written too long ago for me to remember.

But I think the confusing part of the quote is that there should probably be a comma in there; i.e., "correlation between full-scale, windtunnel and CFD". That's how I read it, at least.

[Holm86]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max...

I do think they can test individual pieces at 100% - wings and such - just not the car as a whole. I could be wrong - those rules were written too long ago for me to remember.

But I think the confusing part of the quote is that there should probably be a comma in there; i.e., "correlation between full-scale, windtunnel and CFD". That's how I read it, at least.

That could be the case

[Huntresa]

Teams can trade straight line test for 100% scale wind tunnel testing, like Lotus did last year or year before.

[beelsebob]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max...

I do think they can test individual pieces at 100% - wings and such - just not the car as a whole. I could be wrong - those rules were written too long ago for me to remember.

But I think the confusing part of the quote is that there should probably be a comma in there; i.e., "correlation between full-scale, windtunnel and CFD". That's how I read it, at least.

Nope, sporting regulation 22.9:

With the exception of the full scale testing permitted in 22.4(h)(ii) above, no wind tunnel testing may be carried out using a scale model which is greater than 60% of full size.

The full scale testing permitted in 22.4(h)(ii) allows the team to take straight line test days and substitute them with 4 hours of full scale wind tunnel testing instead.

[smr]

I keep reading articles about Jenson saying Mclaren will be much improved for Spa, potentially fighting for a podium finish. Why is this exactly? What is it about the upgrades Mclaren have placed on the car which instils this confidence within the team to the extent that they reckon they'll be much more competitive for Belgium?

Sincerely hoping this hope will come to fruition!

[Pup]

Apart from the track suiting the car, my only guess is that after the young driver test, they feel they have a better understanding of the car, and have planned upgrades for the race. Supposedly they are supposed to have some 2014 relevant parts that will find their way onto the car this season - something about a 'radical' new wing, which in McLaren-speak probably means that it's installed with different bolts.

[Pup]

Nope, sporting regulation 22.9...

Thanks - no idea how I got that into my head. Yet, there it sits.

[adrianjordan]

Apart from the track suiting the car, my only guess is that after the young driver test, they feel they have a better understanding of the car, and have planned upgrades for the race. Supposedly they are supposed to have some 2014 relevant parts that will find their way onto the car this season - something about a 'radical' new wing, which in McLaren-speak probably means that it's installed with different bolts.

I heard similar. Instead of mid-aluminium coloured bolts, they will be using the all new slightly-darker-mid-aluminium coloured bolts...

[turbof1]

Nope, sporting regulation 22.9...

Thanks - no idea how I got that into my head. Yet, there it sits.

To be honest, I heard about it to. The word of the regulation does not disallow full scale testing of individual parts per se.

I do hope this doesn't get removed from here; it's pure for conversational reasons: I came across this
http://www.ebay.com/itm/Ferrari-Formula ... 0597978763

Apperently back in the 90's they also used 50% scale models. What that tells me is that scale certainly wasn't always a problem. In mclaren's case the troubles go way deeper then just scale.

[godlameroso]

What do you mean by scaling of design?? If you look at the bit you quoted yourself it says full-scale windtunnel. So its not a downscaled version.

Teams are not allowed to operate full scale wind tunnels, only 60% at max. What he means is that air behaves differently over a 60% model than it does over a full sized car. They can do all kinds of things to try and make it behave as similarly as possible, but ultimately they can't make it exactly match how the car will make the air behave.

Wind can also work differently if you don't have programs and algorithms to account for the pressure distortion that occurs when wind interacts with the walls of the tunnel.

Perhaps some teams had better correlation with smaller models because there wasn't as large air displacement that could possibly interact with the tunnel walls.