what is the affect of this..?

[mike]

seeing alot of open wheeler and le man cars i hav incounter a thing that i dont quiet understand
while cars like f1 and champ cars hav their sidepods build like a coke bottle shape
le man cars doesn't they just hav straight sidepods
what is the affect of the coke bottle shape sidepods?
if it does provide an advantage why doesn't le man cars hav it?
F2007

Audi R10 TDI

why doesn't the number 8 in the audi r10 bend toward the centre of the car?

[flynfrog]

the lemans cars can cover the wheels making them more areo effective. the F1 car cant so they take as much wetted area off the car as possible to become areo effective.

also the lemans cars can run a bigger under body adding to DF

[kimi]

I guess it is due to the fact that,the F1 cars produce a lot more drag due to their tyres.Whereas in the Le man cars the tyres are covered giving a smooth flow of the air over the car.So side pods in a F1 car help reduce the drag,which is a much needed to counteract the drag produced by the tyres.

[mike]

if the design is only used to decrease drag than why can't le man cars hav it
F1 car also hav a big underbody
the mazda taiki have the covered wheels and the coke bottle shape design
so how does all that work out
i think there must be a down side to the coke bottle shape design

[walter]

the coke bottle shape of the sidepods of f1 cars is not suitable for lemans racers because the internal components of say the audi R10 is more complex. there are turbochargers and intercoolers that need space and more air. I believe that the internal components such as the radiators and the wishbones cannot be showing through the body panels. the lemans racers have a different formula for aero efficiency, they use the hot air from the engine bay to reduce the drag behind the car. In addition the tight sidepod shape of F1 cars is risky for cars that are running endurance races.

If F1 cars could close up their wheels, they would probably start looking like the lemans racers.

[mike]

there are turbochargers and intercoolers that need space and more air. I believe that the internal components such as the radiators and the wishbones cannot be showing through the body panels.

what about champcars they have turbocharger and intercooler and yet they still have this coke bottle design.
i was refering to more of a aero effect of this design rather than the mechanical affect of this design i use the R10 as a example of a close wheeler compare to an open wheeler
sorry i didn't phrase what i was asking properly
but anyway thank for your contribution

[Nazario Nuti]

what about the "chicken wings" at the beggining of the sidepods? What do you think they do?

[scarbs]

All these points are accurate, sports prototypes have both a lot of engine ancillaries to house and also rear the wheel and suspension must not be visible from above (and I’m pretty sure from behind too). However it might be possible to still create a coke bottle shape to allow the bodywork to cut in between the rear wheels. This might be beneficial as it would allow a faster flow over the top of the diffuser, working with a gurney flap this actually improves the potential flow through the diffuser.

I am not sure what the aero benefit of enclosed rear bodywork is, I’d imagine there ends up being quite a high pressure region along the flanks of the car. Intuitively this would bleed high pressure air under the floor. Perhaps the teams use the clear run of bodywork between the wheel housings and monocoque\engine cover to keep a good flow to the rear wing\diffuser. Rather than the single seater method of also sending flow around the sidepods.

[checkered]

I was reading the

LMP2 body rules quite a while ago (something to do with the "Vehicle Development Project here) and I've got a vague recollection of a set of rules that forbade depressions deeper than a certain length as viewed from the top and the side. Equally I believe the rules forbade any sort of apertures in the body, including empty spaces framed by solid "bridging" forms as seen from the side. It was all pretty complicated and I'm not up to looking into this in detail right now. Aren't the LMP rules about to change quite a lot soon? Anyway, I pretty much agree with the above comments to the original question.

[Belatti]

What I can´t understand clearly is why some LeMans teams choose to build a roofed car (Peugeot) and other doesn´t (Audi).

Aerodinamicaly the roofed option seems better, cause, even having a bigger cross section, you have got a continous surface that I suppose can manage better the airflow. But LeMans winner is Audi...

Anyway, regarding mikes question, I think first bottleshaped F1 was McLaren MP4/1C from 1983.

A McLaren MP4/1C Formula One car, at the Donington Collection museum.

The differences between the rear bodywork of this car, designed to run without "ground effect", and its predecessor MP4/1B ground effect car (behind) are clear to see.

[mike]

Quote:
The differences between the rear bodywork of this car, designed to run without "ground effect", and its predecessor MP4/1B ground effect car (behind) are clear to see.

i find that quiet unbelievable as f1 cars these day still creates a good deal of downforce from the diffuser area from the bottom of the car about 30%
and the thing is that the coke bottle shap design has no influence on the amount of downforce created by the diffuser it merely speed up the airflow and hence decrease the amount of drag and increase the overall efficiency of the car downforce/drag wise

Nazario Nuti said

what about the "chicken wings" at the beggining of the sidepods? What do you think they do?

the so called "chicken wings" are first develop in the FW26 as they have a very low sidepod and they have to direct the air flow to aid the cooling of the car. than there is the RA-106 the put them on to much the same purpose. i m not sure if the R26 use it after their mass dampers were banned during 2006. than the R27 and the MP4-22 use these wings which creates lift, to speeds up the air flow above the engine cover and increase the pressure difference of the rear wing and hence increase downforce the rear wing. using this design they effectively sacrifice front downforce for rear downforce and since the rear wing creates more downforce than the front wing, the overall efficiency will still increase, this design also serves the purpose of regulating the turbulent air created by the front wing and more angle of attack can be used to create greater downforce in the front, it pushes the air in to the inlets of the sidepods to improve reliablity of the car. the chicken wing shape is more used in this season because it creates a greater area of pressure drop of the air above the engine cover,and i also believe that this is more used this season because of the nature of the bridgestone tyres which favors the front than the rear, and more downforce is needed to stablise the rear of the car.
we have also heard of the shift in weight balance toward the front, which can be the reason why more teams are using the chicken wing design as an aero weight balancing act to suit the 2007 bridgestone tyres

[modbaraban]

the so called "chicken wings" are first develop in the FW26....

Chicken wings? Do you mean podvanes? I'd appreciate any pics of these on FW26. I always thought it was EJ14 which used podvanes first.
Or maybe I just got it wrong

EDIT: oops! propabley you were talking about 'ears'

[MrT]

What I can´t understand clearly is why some LeMans teams choose to build a roofed car (Peugeot) and other doesn´t (Audi).

[/quote]

Well closed roof are theoretically quicker, as i guess has been shown pratically by the bentleys and toyotas and the old jags and porsches... However they do race in a different class than open cockpits.... not sure what implications this has......

[Belatti]

Mike, the quote I posted is from the page where I took the picture, in those times of ground effect cars, maybe 80% of the dowforce was generated by the bottom of the car.

What I can´t understand clearly is why some LeMans teams choose to build a roofed car (Peugeot) and other doesn´t (Audi).

Well closed roof are theoretically quicker, as i guess has been shown pratically by the bentleys and toyotas and the old jags and porsches... However they do race in a different class than open cockpits.... not sure what implications this has......[/quote]

Sorry, I thought Peugeot was fighting Audi in LeMans... I´m really the opposite of an expert in LeMans categories

[Tom]

The open and closed cars are (nowadays) in the same class known as Le Mans Prototype 1 (LMP1) and Le Mans Prototype 2 (LMP2).

There are specific rules for open cars to determin their structural integrity and specific rules for closed cars too, but they're the same class.
I think the open cars are light because of this and don't lose too much in terms of aerodynamics.
However the governing body is making all prototypes closed top in the near future so spectators can relate them to the companys road cars. This is great news for Peugeot who already run a closed car but terrible news for the likes of Pescarolo who don't produce road cars and have to redesign their whole entry.