February Test Thread

[djos]

It looks like the option tire this year will have a aqua stripe:

[ESPImperium]

I am really concerned about some of the teams progress so far, most particularly Renault. They seem to be chasing relyability, but i think they are going in the wrong direction, thats why i feel they are taking next week off to make shure a good redesigned front end comes out fighting at least.

Another team im concerned about is McLaren. They are using the 2008 rear wing, somthing says to me they have some rear stability issues and arnt getting enough downforce in that car. From a couple of pictures im seeing so far they have a new diffuser as well.

But one thing im concerned about is the fact alot of teams have the resource only to test one car concurently, i think they would make more progress with 2 cars running at once. Or is there some rule that stops this???

And id like to see Buemi in the STR3 do some tests with Webber or Vettel in the RB5 just to test out its KERS and how well it takes the wake of other cars, even tho it may not be totally scientific, i think it may work, BMW Sauber did that at the end of last year with 2 intrim F1.08s.

[Fil]

Just remember what state BMW was in this time last year. That may ease your worries a little..

[ESPImperium]

Just remember what state BMW was in this time last year. That may ease your worries a little..

True, true.

[slimjim8201]

McLaren's explanation:
"This is what we call a 'flow vis' (visualisation) - where we take a paraffin-based light solution and apply it to the car."
"The solution is light enough to flow over the car, drying quickly to determine the airflow over the bodywork."

At what point in the lap does it 'dry'?

What are the ambient conditions at the time it 'dries'?

Note - use of the word dry in inverted commas - as the viscosity will be changing right up to the point of 'drying' (i.e. eventually so viscous it ain't going nowhere anymore).

There are just so many variables to this testing 'method' that it reeks of desperation or a flat out decoy.

McLaren explained this is a routine operation. "This is a common occurrence when testing new cars and is used to confirm the wind tunnel readouts."

*snigger*

A common occurence when something is FUBAR.

What do they determine from that - there is indeed a front wing wake at approximately 5 degrees (give or take 2 degrees - or something similarly ludicrious!).

Without having exact control over the boundary conditions, the explanation given is bull. You'll verify f**k all in the way of wind tunnel tests from some paint streaks on a surface that changes direction all the time.

For instance - what happens when the car is going laterally at 3g? Is the paint not expected to move towards the outside of the car?

Perhaps it doesn't dry at all. Being parafin based, its probably not even paint. It's a coating that spreads out on the car surfaces, highlighting areas of flow impingement and near-surface flow fields. Over the course of a few laps, the combination of many cycles of left and right turns, rapid accelerations and decelerations and umpteen other variables will cause the parafin to spread out to wherever it's going to spread out. Someone may look at the car after and see that there is a particularly high amount piling up in a certain spot. A spot that shares the EXACT same stagnation pressure value as many other spots from CFD and wind tunnel testing.

In reality, we all know so little about this stuff because we didn't see it put on, we didn't see where it started, and we certainly don't have ultra detailed images of where it all ended up. Who are you to say that it is worthless and their CFD/wind tunnel programs are FUBAR? Judging by your short-sighted posts, I'd actually venture a guess that you are more or less unqualified to make the assumptions you have made.

There is a chance that this stuff doesn't provide them with any additional useful information about the airflow around the car. It could mirror what the wind tunnel and CFD results show to within 99.9%. In addition to that, it might not highlight anything that the other testing methods haven't already highlighted. In that case, wouldn't it still be valuable? Wouldn't it confirm that their testing procedures are spot on and give the CFD guys, technical director, entire team confidence?

[kilcoo316]

Who are you to say that it is worthless and their CFD/wind tunnel programs are FUBAR?

No, I'm not saying both are FUBAR.




As you well know, you cannot exactly extract hard numbers from this kind of stuff (paint).

Now, all that means is you can perform qualitative comparisons (I assume you are well aware of qualitative and quantitative comparisons yes?).


You know about CFD - for example if your model is predicting a separation bubble at 15% cord length with reattachment at 40% chord length, while experiments say 10% and 30% - you can live with that, its not great, but at least your physics are right. [That is a (very) rudimentary quantitative comparison]

Now, if your model is not predicting separation at all... while these paint tests predict there is separation, you'd be a very worried man, and rightfully so [qualitative comparison - the physics between prediction and reality has changed].


I'm saying that if they have wind tunnel/CFD problems, and these crude (and they are crude) tests show qualitative differences - they are deep deep deep in the brown stuff.


But if you are a mclaren fan - I would be worried - does the presence of the paint tests indicate the suspension deflections at speed (aero load) are very far from what the wind-tunnel said the aero load would be?

Maybe they are grand and all this is mclaren throwing a few people off the trail, but if they are truly worried enough to try and check their wind tunnel accuracy with this...

[kilcoo316]

A spot that shares the EXACT same stagnation pressure value as many other spots from CFD and wind tunnel testing.

I'm not sure if this is pressure paint though. I think it is applied uniformly over the body and then changes colour dependant on airflow incidence through oxygenation.



Agreed that pressure paint is very useful - but I *think* they have to be used in a controlled environment with detailed light sensors to be of use.

Even then - there can be large errors within those tightly controlled environments (i.e. clean wind-tunnels with zero outside influences) - imagine what they would snowball to on a track!

[slimjim8201]

Who are you to say that it is worthless and their CFD/wind tunnel programs are FUBAR?

No, I'm not saying both are FUBAR.




As you well know, you cannot exactly extract hard numbers from this kind of stuff (paint).

Now, all that means is you can perform qualitative comparisons (I assume you are well aware of qualitative and quantitative comparisons yes?).


You know about CFD - for example if your model is predicting a separation bubble at 15% cord length with reattachment at 40% chord length, while experiments say 10% and 30% - you can live with that, its not great, but at least your physics are right. [That is a (very) rudimentary quantitative comparison]

Now, if your model is not predicting separation at all... while these paint tests predict there is separation, you'd be a very worried man, and rightfully so [qualitative comparison - the physics between prediction and reality has changed].


I'm saying that if they have wind tunnel/CFD problems, and these crude (and they are crude) tests show qualitative differences - they are deep deep deep in the brown stuff.


But if you are a mclaren fan - I would be worried - does the presence of the paint tests indicate the suspension deflections at speed (aero load) are very far from what the wind-tunnel said the aero load would be?

Maybe they are grand and all this is mclaren throwing a few people off the trail, but if they are truly worried enough to try and check their wind tunnel accuracy with this...

I think you are coming at this from the assumption that their CFD wind tunnel tests aren't good/valid. I don't think they are using this method of flow visualization for anything other than to have another method of flow visualization. There are no big secrets here, they aren't trying to throw off other teams or lead them to believe that they are up a creek with their non-track testing.

The results here are 100% purely qualitative. Numbers can't really be gathered by this sort of a test. But neither can you gather much useful number data from a smoke bar in a wind tunnel test. The more data they have about this stuff, whether raw numbers from CFD or flow visualization techniques, the better.

Imagine this scenario...their CFD tests are perfect. Their windtunnel tests match their perfect CFD tests. What do they have to lose by putting parafin on the car and having more data to work with? Nothing. Nothing at all. No smoke a mirrors here, just parafin.

[Shaddock]

Torpedoes away !!!

[slimjim8201]

A spot that shares the EXACT same stagnation pressure value as many other spots from CFD and wind tunnel testing.

I'm not sure if this is pressure paint though. I think it is applied uniformly over the body and then changes colour dependant on airflow incidence through oxygenation.



Agreed that pressure paint is very useful - but I *think* they have to be used in a controlled environment with detailed light sensors to be of use.

Even then - there can be large errors within those tightly controlled environments (i.e. clean wind-tunnels with zero outside influences) - imagine what they would snowball to on a track!

This is not pressure paint. Pressure paint is applied evenly to all surfaces of the object and then must be analyzed with filtered cameras.

It's simply a substance that stays put under high static pressure and moves under high shear stress.

[ben_watkins]

The green stuff on the Macca is oil..

http://www.f1technical.net/news/11238

"Also note the the test car is sprayed with green oil paint to mark the airflow around the car's bodywork. This method is often used to verify simulations from the wing tunnel and CFD tests and indicates McLaren's desire to clearly understand how the new front wing influences the car's airflow."

[slimjim8201]

Torpedoes away !!!

Would everyone agree that the car would actually look decent, and perhaps even good if they got rid of the undernose bulge and diffuser-like vanes? Amazing how one area can make the entire car look bad.

Also, what if it works? What if their testing issues are related to slick tires and not aerodynamics? I'm anxious to see how this car performs in a few weeks...

[xpensive]

Sometimes you are perhaps a little to fast for yourself kilcoo, what's your Phd about anyway?

[djos]

Would everyone agree that the car would actually look decent, and perhaps even good if they got rid of the undernose bulge and diffuser-like vanes? Amazing how one area can make the entire car look bad.

Not to mention the fat bodywork around the rear end!

[myurr]

Yep, the Macca has its '08 wing on again:

http://74.125.19.113/translate_c?hl=en& ... 4picOtx9xw

I can't understand why they would do this in good weather? last time their excuse was because of the bad weather.

They might want to check the differences to better understand what is caused by the '09 wing and what is caused by other changes.

What we do in law stuff sometimes, is to compare the regulations in different countries to better understand the differences. It might be just the same in terms of technical / aerodynamical developement and understanding.

Or they might be anticipating an extension of the diffuser producing more downforce and so are testing with a simulated configuration to see what difference it makes. Do we know for sure that they are only running the 08 wing today or have they been switching between the two. Was their best recorded time set with the 08 or 09 wing? If we don't know that how can anyone jump to the conclusion that they're up a certain creek?