beef with FWD
Cyberkreig wrote:A FWD car does not work in this way. Enter a corner at high speed uses the rear tires in one way, to follow the front. Where as the front tires are being used in two ways. Too much throttle will break the tires grip and the car will 'nose' or slide in the direction of its momentum. (not around the corner.)
humm... two factors are ignored in this analysis.
1- aerodynamic lift of the chassis, the center of pressure moves aft as speed increases, lifting the tail2- weight transfer forward during braking or throttle liftoff.
Both decreases the avaliable grip of the rear wheels, and affects a FWD same as a RWD. Just because the rear wheels aren't pushing, doesn't mean they are not working.
MrFox wrote:humm... two factors are ignored in this analysis.
1- aerodynamic lift of the chassis, the center of pressure moves aft as speed increases, lifting the tail2- weight transfer forward during braking or throttle liftoff.
Both decreases the avaliable grip of the rear wheels, and affects a FWD same as a RWD. Just because the rear wheels aren't pushing, doesn't mean they are not working.
Non-issue unless you're talking about sanctioned touring car races or the like. Not applicable to the majority of loud mouth teenage kids running their mouths about that tyte areo kit with huge spoiler with the massive angle of attack, yo! These kids can't even pay to have their body kits painted, for cryin out loud!!
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Cyberkreig
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MrFox wrote:humm... two factors are ignored in this analysis.
1- aerodynamic lift of the chassis, the center of pressure moves aft as speed increases, lifting the tail2- weight transfer forward during braking or throttle liftoff.
Both decreases the avaliable grip of the rear wheels, and affects a FWD same as a RWD. Just because the rear wheels aren't pushing, doesn't mean they are not working.
You are correct that i didnt include all of the physics involved. But you will note that i did NOT say the rear wheels not working. Simply pointing out that the rear wheels can give all their tractions to griping the corner, as the traction is not shared with acceleration.
To address the points you make:
1.) lift of the chassy can be countered with canards, another ricer favorite, lowering the vehicle, and a good front lip or 'chin' spoiler. assuming both vehicles had addressed this problem it becomes a non issue.
(I do not mean to say that all bodykits/canards do or don't serve a purpose, but in the theoretical situation we are discussing, the average aftermarket bumper or canard is for looks only)
2.) Weight transfer into a corner is going to be on the outside wheels and to the rear (assuming accleration in the corner). In this way a wing could help to plant the rear of either RWD or FWD more evenly.
Tho i maintain that the RWD car is in more need of the traction as you are making so many demands of just 2 tires.
Couldn't agree with you more on your points, Cyberieg. I'm not even trynig to defend the original argument of the post, as SmithSR already correctly pointed out the real beef I have with FWD wings. But I like where the conversation is going, so I'll continue
Totally daming the underbody airflow is not feasible or practical, so there'll still be lift. This lift will move rearward and increase in magnitude with speed. To maintain high speed stablitiy something like a wing or diffuser has to start forcing down in the back to balance out the lift.
The wing does helps high speed cornering grip by increasing downforce, but is somewhat detrimintal to overall cornering ability of the car by putting all that weight on top, increasing body roll and weight transfer.
If front wheel traction is a limiting factor for wing application in a FWD car, why not place the wing on or ahead the rear axle line. The downforce will no longer pivot on the rear wheels and try to lift the front, although it will not be as effective at pushing the tail down due to the reduced leverage arm it has on the rear wheels.
Totally daming the underbody airflow is not feasible or practical, so there'll still be lift. This lift will move rearward and increase in magnitude with speed. To maintain high speed stablitiy something like a wing or diffuser has to start forcing down in the back to balance out the lift.
The wing does helps high speed cornering grip by increasing downforce, but is somewhat detrimintal to overall cornering ability of the car by putting all that weight on top, increasing body roll and weight transfer.
If front wheel traction is a limiting factor for wing application in a FWD car, why not place the wing on or ahead the rear axle line. The downforce will no longer pivot on the rear wheels and try to lift the front, although it will not be as effective at pushing the tail down due to the reduced leverage arm it has on the rear wheels.
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Cyberkreig
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MrFox wrote:Totally daming the underbody airflow is not feasible or practical, so there'll still be lift. This lift will move rearward and increase in magnitude with speed. To maintain high speed stablitiy something like a wing or diffuser has to start forcing down in the back to balance out the lift.
this is correct, and is the only use of a wing on a fwd car. however a diffuser, or wing, used for moderate downforce could be much smaller, simpler, or OEM than "rice" wings.
Quote »The wing does helps high speed cornering grip by increasing downforce, but is somewhat detrimintal to overall cornering ability of the car by putting all that weight on top, increasing body roll and weight transfer.[/quote]
I dont think this is at all correct. The added (10lbs-20lbs) of a wing on the back of a car helps to place more weight over the back tires. (providing extra rear traction via weight transfer) At the same time it SHOULD be creating lbs in downforce, and have diffusers on each end, smooothing out the flow of air helping to counteract body roll. The additional weight transfer to the rear may be detrimental to FWD, but would definatly be useful in RWD cars.
Quote »If front wheel traction is a limiting factor for wing application in a FWD car, why not place the wing on or ahead the rear axle line. The downforce will no longer pivot on the rear wheels and try to lift the front, although it will not be as effective at pushing the tail down due to the reduced leverage arm it has on the rear wheels. [/quote]
as i agreed with your first statement, the limited use of a wing on a FWD would be to smooth airflow and provide extra rear wheel traction. (all to counteract lift) So now the back is planted. The front will still lift. Like i said in an earlier post, a good front bumber, chin spoiler and canards can be used to counteract this lift. not infinitely, and nto as well as a full wing, but that is the true function of an "aero package". As to putting the wing on the front of a car to counteract downforce, it isnt practical on street cars, but the F1 guys have been doing it for a long time.
Thanks everybody I learned alot from this post.
my beef was the absurd wings on fwd cars for show
I always saw wings as serving a purpose, I never thought of putting one on a car for show purposes. Although looks and fucntionality would play a part in a choice for a wing if i were ever to purchase one (which i doubt).
well maybe some wings on some fwd cars during some situations may serve a purpose but overalli'd have to say that they are not needed on a fwd unless they are in that situation which is probably rare for a fwd driver.
Mark
my beef was the absurd wings on fwd cars for show
I always saw wings as serving a purpose, I never thought of putting one on a car for show purposes. Although looks and fucntionality would play a part in a choice for a wing if i were ever to purchase one (which i doubt).
well maybe some wings on some fwd cars during some situations may serve a purpose but overalli'd have to say that they are not needed on a fwd unless they are in that situation which is probably rare for a fwd driver.
Mark