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    Race Cars Aerodynamics

    This info is from Josef Katz's book Racecar Aerodynamics. If you are interested to read it you can go there: http://sportcars-history.com/ . You can find this book in "books" category on the right side of main page.

    Also, more info about sportprototypes aero data you can find there: http://www.mulsannescorner.com/data.html

    The most interesting thing there, to my mind, is the comparison of aero efficiency between prototypes and open wheelers:) Lots of people say about F1's leading in aerodynamics, I think it is no so...;)


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    sportcars-history.com


    Re: Race Cars Aerodynamics

    Thanks a lot for the data, especially the links. Have seen them before but it is great to come across them again. Regarding the efficiency of F1 and prototypes, open wheelers are per se less effective because of the aerodynamic difficulties around the wheels. That´s why, in recent years, a lot of effort has been put into the control of airflow around them and has become the most relevant element, being ahead of engine performance or suspension. Given this precondition, the current regulations yet the effort that is put into aerodynamics, F1 is certainly the racing series that extracts the most efficiency out of it. In absolute terms, those prototypes are ahead of them.

    kiss


    Re: Race Cars Aerodynamics

    F1 cars still produce more downforce though, even though their drag is very high. That said. they reach unbelievable speeds when they take less wing on due to their mighty engines (in recent years there ha been a drop of power though - back in 2004 in Monza, top speeds were in excess of 370 kph, now they are some 20 kph lower).


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    FERRARI RULES!!!

    Re: Race Cars Aerodynamics

    REALZEUS:

    F1 cars still produce more downforce though, even though their drag is very high. That said. they reach unbelievable speeds when they take less wing on due to their mighty engines (in recent years there ha been a drop of power though - back in 2004 in Monza, top speeds were in excess of 370 kph, now they are some 20 kph lower).

    The greatest amount of downforce and efficiency (a little less than 5 tons at 200mph with around 800 kg drag, around 5-6 to 1 LD ratio) was seen in sportsprototype championship, especially in IMSA (because of tight tracks and lack of fuel limits) in the end 80's till beginning of 90's. No one is near even today...

    370 kph is a great speed, but if you compare it to CART and Sportprototypes from historical point of view it is low. In 2005 BAR HONDA has shown what speed V10 cars can reach - 413 on straight of aeroport without rear wing and less than 400 on salt. Of course these aero specifications are extreme and not useful during the race. In race specs CART record is 413 kph on oval. Sportprototypes records - 405 kph Mulsanne straight, 413 kph Talladega oval, more than 400 kph Fuji.

    If we will talk about now, speeds are much much lower. I have seen by telemetry that in SPA AUDI r18 reaches 293 kph, F1 car - 303 kph. AUDI has around 0,65 hp per kilo, F1 car has 1,21. So, even with standard diffuser (regulations) LMP1 has a great efficiency aero. Also, in interview Alan McNish has told that their cars reach the same and even larger amount of DF than F1 cars. The main problem of LMP - weight, 920 kg is too much to compare cars dynamics in corners.

    Also, from times you can see that F1 car loses around 8-9 secs on such track as SPA when it is fully loaded by fuel. Diesel LMP1 cars at this moment have around 600 hp (they officially claim around 500, but lets take the higher figure), f1 car has around 750 hp, so with 150 hp difference, much softer tyres compound and more than 150 kg difference between fully loaded f1 car and empty lmp1 the time difference will be 5-6 secs max. 

    Resume: if the lmp1 car will have the same weight as f1 or even 100 kgs more and the same amount of power as today lmp1 has, lmp1 will have the same pace over 1 lap.

     


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    sportcars-history.com


    Re: Race Cars Aerodynamics

    Ferdie:

    Thanks a lot for the data, especially the links. Have seen them before but it is great to come across them again. Regarding the efficiency of F1 and prototypes, open wheelers are per se less effective because of the aerodynamic difficulties around the wheels. That´s why, in recent years, a lot of effort has been put into the control of airflow around them and has become the most relevant element, being ahead of engine performance or suspension. Given this precondition, the current regulations yet the effort that is put into aerodynamics, F1 is certainly the racing series that extracts the most efficiency out of it. In absolute terms, those prototypes are ahead of them.

    kiss

    Not at allSmiley

    The interestiong thing about suspension is also that in open wheeler it is used as aero element))

    As i have read, if i am not wrong, the still (non dynamic) round object like wheel creates + 0,5 of drag. But not only the wheel is a problem. The problem of OW cars that compared to protos the have much less aero effective zones, in other words, in OW car it is much more difficult to calm the turbulented air.


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    sportcars-history.com


    Re: Race Cars Aerodynamics

    kudryavchik:

    As i have read, if i am not wrong, the still (non dynamic) round object like wheel creates + 0,5 of drag. But not only the wheel is a problem. The problem of OW cars that compared to protos the have much less aero effective zones, in other words, in OW car it is much more difficult to calm the turbulented air.


    The wheels themselves are a hindrance due to their shape and position but they also make the airflow around the car far more complex and difficult to control. I guess every engineer would prefer to enclose them for those reasons alone.  That´s what I meant above with the efficiency of different race cars. Given the car´s shape and regulations in F1, they are certainly superior. 

    On the other hand, prototypes from Audi, Peugeot as well as Porsche or Acura must have a very good efficiency as well given the parameters.


    Re: Race Cars Aerodynamics

    Ferdie:
    kudryavchik:

    As i have read, if i am not wrong, the still (non dynamic) round object like wheel creates + 0,5 of drag. But not only the wheel is a problem. The problem of OW cars that compared to protos the have much less aero effective zones, in other words, in OW car it is much more difficult to calm the turbulented air.


    The wheels themselves are a hindrance due to their shape and position but they also make the airflow around the car far more complex and difficult to control. I guess every engineer would prefer to enclose them for those reasons alone.  That´s what I meant above with the efficiency of different race cars. Given the car´s shape and regulations in F1, they are certainly superior. 

    On the other hand, prototypes from Audi, Peugeot as well as Porsche or Acura must have a very good efficiency as well given the parameters.

    Unfortunately, by todays regulations LMP1 are very limited on aero. If in F1 constructors are able to go away from limitations, regulations can be interpreted differently, in LMP1 aco strictly regilates diffusers and front part aero... Diffusers must be standard, front part can develop DF only on certain places...


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    sportcars-history.com


    Re: Race Cars Aerodynamics

    kudryavchik:


    The most interesting thing there, to my mind, is the comparison of aero efficiency between prototypes and open wheelers:) Lots of people say about F1's leading in aerodynamics, I think it is no so...;)

    The Coefficient of Drag (Cd) cannot be equated with "aerodynamic efficiency" without consideration of the context.
    F1 cars have high Cd values due to their exposed wheels, as Ferdie mentioned, and because they have highly effective wings to give them very high downforce on the axles.
    This downforce is essential for high speed cornering and is bought at the expense of drag, as can also be seen by comparing the respective figures above for the "high downforce" and "speedway" versions of the Penske and Galmer cars.

    If this combination of high drag with high downforce is what gives the best overall performance in the context of an F1 race car, then those cars' "aerodynamic efficiency" is the optimum in that context. 


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    fritz


    Re: Race Cars Aerodynamics

    fritz:
    kudryavchik:


    The most interesting thing there, to my mind, is the comparison of aero efficiency between prototypes and open wheelers:) Lots of people say about F1's leading in aerodynamics, I think it is no so...;)

    The Coefficient of Drag (Cd) cannot be equated with "aerodynamic efficiency" without consideration of the context.
    F1 cars have high Cd values due to their exposed wheels, as Ferdie mentioned, and because they have highly effective wings to give them very high downforce on the axles.
    This downforce is essential for high speed cornering and is bought at the expense of drag, as can also be seen by comparing the respective figures above for the "high downforce" and "speedway" versions of the Penske and Galmer cars.

    If this combination of high drag with high downforce is what gives the best overall performance in the context of an F1 race car, then those cars' "aerodynamic efficiency" is the optimum in that context. 

    Of course, these amounts are dependable each other and can't be discussed separately, only their ratio. Ratio of Cl and Cd can show the effectiveness of aero. That's why I have put these data here. From this book and mulsannecorner data you can see that the best ration for OW is max 3.5 to 1...Protos ratio can reach 6 to 1...

    And not only open wheels is the problem of OW's.

    Protos have problems too - f.e. they have higher frontal area and they like to fly))) 

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    sportcars-history.com


     
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