Tim.Wright wrote:You have two unknowns in one equation being the friction coeff and the downforce.
Exactly like this.
With 2 unknowns left we have already reduced the problem to something we can handle. Well there is another unknown which is the car weight.
So we need to find ways to get a good guess for the 2 unknowns left(friction coeff, car weight).
For car weight it is rather easy because we know the minimum weight. So we just have to figure how much fuel was in the car. In case we are talking about a qualy lap we can be sure the car was almost empty. Also the fuel usage per lap is known for every track so we can get a really close estimation of car weight. It doesn't matter if it was a kilo more or less in real life because we will still be close.
Friction coeff. is much more difficult to figure out. You are right Tim that this causes some problem because it can bring a big failure tolerance to the result.
However we can do some research about friction coeff. figures. By this we might find out that they are located in a special area. As far as I know is 1.4 a good figure but lets say we want to but some focus on the fact we don't actually know it and give the figure a tolerance rate of +-0.2. Notice that the range of 0.4 can be the difference between dry and wet road so it is a lot and we should be safe with it.
So ok lets assume we have a 700kg car going trough a 4g corner.
This will mean we have a downforce of around 1820kg with a tolerance of +-140kg.
By this we got a idea in which area the downforce is located including a error tolerance. For me it is better to make a rough estimation but having something in my hands than saying there are to many unknowns to say anything at all about the issue.
The more time is investigated into the topic the closer the input figures will come to reality. The next thing we can do is taking acceleration or braking datas of the car and check if it’s possible to get such accelerations with the chosen friction coeff.
You realize now why I give the recently published telemetry sheet such a high value. It is because we have a complete lap on one paper even more important because this year we have a mandatory weight distribution. Now we know lots of the frame data like weight distribution, engine power, and wheelbase. The ones we don’t know like friction coeff, coeff of downforce and drag can be calculated more exactly by the driving characteristics now.