freedom_honda wrote:what do you think about this new movable rear wing?
[youtube]
http://www.youtube.com/watch?v=73-3epSENYg[/youtube]
while looking at this video, i was just wondering shoudlnt they increase the AOA for the outter wheels instead of the inner wheels since most of the weight of the car is on the outter wheels therefore the inertia of the car is pushing the car outwards thus more grip on the outter wheel is required to keep the car on the road?
Don't confuse mass and load. What changes the inertial properties of the car is the mass.
Thus in this case we want to know the mass transfer.
In addition to that mass transfer we also have a loading transfer, born with the torque created by the plan of action of cornering forces and CG height.
The actual mass transfer is very low in comparison with the load transfer.
A typical value of shift of mass for cars is around 2% as compared to a load transfer that can range as high as 20-30% shift.
The mass transfer is then not so important there.
If you visualize the situation, the outer wheels are actually loaded, that is they have a force acting on them. That force doesn't increase any inertial property and thus represent a bonus grip.
However the fact that tyres lose their capacity with load applied onto them makes that the total grip is lower.
let me explain you: let's say Four wheels have 300kg of load onto them.
The car turn right. The load transfer will increase the load on the outer wheels, decrease on the inner.
Let's say the load is 100Kg. Thus the outer wheels now have 400kg onto them, while the inner have only 200kg.
If tyre's did not grip less with load increase we would stick with the same balance, the problem is that with 400kg onto them the tyres actually lose grip.
It results the total grip aviable is lower than the non loaded case.
If we refer to a steady state analysis, that's why the inner part of the wing LOADS the inner tyre, in fact it loads the inner suspension to correct the load transfer.
The goal is simply to go back to the neutral balance (in our example 300Kg).
freedom_honda wrote:
and after watching the video for a few times, why are they even splitting the rear wing? wouldnt it be better if BOTH rear wheels get more downforce instead of just the inner(or outter?) rear wheel? plus the supporting element of the wing is positioned very close to the centre. so is the "extra" downforce created for the inner wheel REALLY going to help pushing the inner wheel to the road?
See above, you need to have the most neutral balance possible and the purpose is not really to push the tyre on the road but rather to go back to the neutral load.
freedom_honda wrote:
one final question, if they can get the rear wing to change its AOA, why dont they just increase the AOA of the whole rear wing in the corners, and decrease the AOA on the straights?
The car you see is an autcross one, the speeds are usually not much than 60mph so there's no significant drag.
In an application like a F1 car, yes it would be useful.
thanks,
Jonathan
ps. by the way, im not sure if this thread is meant to be in the section, so feel free to move it.[/quote]
