mep wrote:Very nice posts 747heavy, =D>
One thing is surprising for me in particular.
In the first paper is written that most race cars have their Centre of pressure (CP) behind Centre of gravity (CG) to have better stability (page 19).
Ok they are talking about stability.
Anyway I got the idea that a CP in front of CG is better for cornering because the front tires need to transmit higher forces to corner the car.
So placing the CP in front of CG should raise maximum cornering speeds.
What do you think about it?
To be honest, I don´t 100% know what he means in this article.
For me it looks like he is talking about CoP in sideview, then what he says and explains makes sense.
And this goes along the lines of what Mystery Steve says.
It´s the "weather vane" (Wetterhahn) effect, which helps with longitunal stability under yaw conditions. Imagine the car goes sideways at high speeds, if you have your CoP behind the CoG, the resulting force will try to straighten the car and makes it a bit understeer. This is a very safe and stable condition, because the effect reduces it´s self when the car straightens out. If you have a CoP before the CoG, the resulting force will increase yaw/turn in the car more, until it travels backwards. That´s a very unstable and difficult to control condition.
You see this in F1 with the extended engine covers. With this concept, you can setup the car a bit more oversteering for the low speed corners, and it will get more neutral/understeering in the medium and fast corners.
Here another explaination from Vasslon:
Toyota used four identical scale models to develop aero parts for the car in its on-site tunnel, and one of the more unusual components that were introduced was the ‘humpback’ engine cover. ‘They are very simple,’ explains Vasselon, ‘it doesn’t bring a lot, it’s just something which improves stability under lateral wind, it has no effect in pure straight line aero. There was almost no aero development on this part, it was just a case of creating surfaces rearward. We went to it after checking there was no unexpected detriment. You see similar concepts on Le Mans cars – you move your centre of pressure rearward, so if you have lateral wind you create a stable car that can brake and steer.’
I don´t think, the guy in the report referes to the vertical CoP (downforce distribution) of the car.
If you have your CoP for vertical pressure (downforce) at your CoG, the car will have the same balance (US/OS) throught the speed range. It´s normally a good starting point.
From here you can use your front wing or rear wing adjustments to move the CoP in relation to the CoG forward or backward, to achieve the desired characteristic.
If you have your CoG wrong (not optimal) you can try to compensate with a different CoP, but this means the characteristic of the car (US/OS) will change with speed.
That´s my take on it, but I could be wrong, and there a probably other members on this forum, which know more about it, and can explain it better, then I can.