Hello Everyone,
Since this is my first post I will introduce myself. My name is Jason Roberts, I'm a 5th year student at the University of Cincinnati, primarily responsible for vehicle dynamics.
The question I would like to pose is one of validating carcass overload due to an excess of FZ. Let me elaborate.
In the quest to score more points many teams are running more aero, for obvious reasons. However it seems as though even the top level teams which initially were more reserved on the appeared level of downforce are now beginning to up the anti even more. With initial CFD and physical testing complete on wings we have in house we've arrived at a CL of apprx 3.5 for the total package (front and rear wing only, this is the average value)). This is providing very significant levels of downforce at reasonable competition speeds. The question Im asking myself is, how much is too much?
After diving into our MMM code, which utilizes the TTC data and working with the Pacejka Equations it seems like the 18x6x10x7 R25 B's begin to see negative affects on FY at any vertical load greater than around 2000 newtons per tire (tires at 14psi). This is a rather large assumption as the pajecka equations have to extrapolate to these values however Ill assume accuracy to be around 10%. Either way there will be a normal load in which the carcass will have exceeded its capability and the tire will begin to lose grip.
So back to the statement of how much is too much? It seems as a novice aero team that many other teams would easily be able to match our levels of FZ generated by our aero devices. Many of whom are running the 10" r25b or lc0 which have much less cornering stiffness and vertical stiffness than the 13" tires. So why is it that we see teams like Michigan ann arbor and others putting together packages which seem to me like they would far exceed these FZ values? Im all for putting together more efficient packages by adding a diffuser and other components in order to try and lower the rear wing and perhaps make the elements lighter overall to reduce mass and inertia. But the all out approach seems a bit overkill. But what do I know, Ann arbor was deathly quick in Lincoln this year.
Id be interested to see if any other teams have taken this into consideration during your design phases, if you have seen any adverse affects while testing out on track, and if you have found any way of validating these affects?
As for us where setting this as a basic limit to be safe for now. On to coast down and other testing