hardingfv32 wrote:
This is not about the accuracy of the model. It is about the accuracy of the tunnel trying to measure a 100% size F1 car. The size of the test area is the trouble. The walls create issues. A 60% tunnel handles these issue more effectively and provides more accurate results.
This paper out lines the wall issues.
http://thinktech.lib.ttu.edu/ttu-ir/bit ... sequence=1
Feel free to provide contradicting information. I am up for learning something new today.
Brian
Brian that is Texas Tech, and is also over 10yrs old. Technology & construction have come a long way since then. I mean surely you would stipulate that tunnels built 10 years ago are not quite as advanced as the ones now.
You're right, the walls
can create issues, but this is not a given. Teams would certainly test at 1:1 if they could, but the FIA mandated 50% to save costs, then allowed 60%, the same way they would test at full speed if they could.
In the beginnnig, wind tunnel tests were carried out using small models of 1/8th to 1/6th scale, with the tyres fixed and resting on a solid surface. In the mid-70s, the Lotus team started testing on a "moving road plane," which was basically a conveyor belt under the chassis, with the wheels rotating. This simulated the passage of the road under the car.
The results were more accurate than the fixed-wheels/no-moving-road wind tunnels. So what people say, the car is still standing still. True, but as Albert Einstein said, all motion is relative to the observer. In other words, air doesn't care if it's being whooshed past a model or the model is moving through the air, the same displacement happens either way.
The next advancement came in the size of the models. From the 1/8th scale, they went to 1/4 scale, 1/2 scale and possibly 2/3 scale. Teams sometimes even test full-scale cars in the wind tunnel, if they have one large enough.
The reason for this is the "scale factor." As you scale things up, the aerodyamic forces on the model increase exponentially. That includes the "unexpected" forces that can trip up a hypothetically good design when it is built full-scale. The closer you get to full size, the more apparent these unexpected forces become and the more accurate the tests are. <-- What Scarbs mentioned.
In the end, the aim of wind tunnel testing is not so much accurate numbers as a general idea of how the car will perform, and the percent of improvement a change makes over the baseline model.
The bottom line is the closer you get to 1:1 the more likely you are to know or have a better understanding of how the car works & will work when new parts are added. Again if teams could use 1:1 & if they could test at full speed, they most certainly would.
I mean that in a good way btw.
