Weight distribution

just read an article about car weight and wanted to ask a question about aerodynamics. If car weight distributions is ideal say 50:50, how would rear spoiler affect it's balance? Or by putting rear spoiler you have to work on front end too? If weight distribution is 52% front 48% rear, can rear spoiler help it balance closer to 50:50? I think yes, but how to calculate all this?

Thanks

http://grassrootsmotorsports.com/articles/understanding-corner-weights/

You're right, it does affect balance, but only by imparting a downward force at speed. So you could balance your hypathetical 48/52 car, but only at X speed. To calculate it you've got to know the forces of the wing.

To complicate it a bit, a wing mounted aft of the rear axle also creates wee bit of lift on the front due to leverage around the rear axle.

50/50 weight distribution doesn't impart handling magic. That magic comes from total design. A 40/60 car with a well designed suspension for that distribution will out handle a 50/50 weight balanced car with a mediocre suspension.

Yeah I think foxtrapper covered most of it - and it would be better to accept an imperfect weight balance, set up your suspension for it, and try to keep downforce as even as possible. Unbalanced downforce becomes more unbalanced (in terms of lbs front vs. rear) as speed increases.

The concept of "perfect" 50/50 balance is simply because as humans, we like nice round numbers. It is a good starting point if you are constrained to running the same exact tire on the front and rear on a reasonably-or-less-powered car. If you have control over the suspension pickup points, you can really make any weight distribution handle well (see Mini vs. DeltaWing). Even without that control, you can do a lot with multi-way adjustable dampers, springs, and anti-roll bars.

It must be said that spoilers and wings are two very different things. The purpose of a spoiler is reduce drag by breaking up the laminar flow and leveling out the transition slope behind the vehicle. Ever wonder why the Prius has a spoiler? In many cases they can actually end up increasing rear lift. A wing's purpose is to create downforce and push the tires into the ground. Generally wings create drag.

A large aerodynamic imbalance can be used to your advantage, especially if it's rear-biased. You can set up the car to be mechanically loose with a lot of rear aero, which will make rotating around slow corners easier and add stability for high speed corners. It's not really a matter of balancing out the weight, it's just another way to affect handling.

Another point about weight distribution is exactly where it sits. If a given car has perfect 50/50 weight distribution but has the weight centered over each axle (like a barbell), then there's another with the same distribution but it's centered between the axles (like a bowling ball) the second car will generally handle better at the limit, assuming the suspension is set up properly.

Unless you have AWD or a very low powered RWD, a 50/50 weight distribution is not ideal. Most powerful RWD will benefit from something closer to 40/60 to run larger rear wheels (for traction) while maintaining good handling.

Now for your question, yes, you can change the weight distribution of a car with aero, but it's not something that is usually done. Downforce is usually non-linear, so the car can become hard to drive depending on the setup.

Warren v said: A large aerodynamic imbalance can be used to your advantage, especially if it's rear-biased. You can set up the car to be mechanically loose with a lot of rear aero, which will make rotating around slow corners easier and add stability for high speed corners. It's not really a matter of balancing out the weight, it's just another way to affect handling.

I think Ferrari has been doing that with its roadcars since the 355?

Depends what you are trying to achieve.

The spoiler also is used to counteract lift at high speeds.