Does PD need to take another look at BOP for N300?

  • Thread starter NosOsH
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05XR8
The real cars Cd are:

Ferrari 458: .35
Hyundai Genesis: .32
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To get the CdA you'd need to multiply the Cd by the frontal area. But additionally, the Cd would be affected by the wings, and if the Ferrari generates more downforce as standard, it would need less of a Cd increase to achieve the same downforce. It would be nice if PD provided the CdA for each car in the game, as it's the main parameter affecting straight line performance that isn't currently provided. There's Crr, but if all cars are using the same tyres, that's not going to vary much across the cars we're choosing from for a race (it will depend on tyre width and pressure). The other parameter that would be really nice to have provided in the game is front:rear weight distribution.
 
The Cake
what is cd meaning? Shape of the car?
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Cd is the coefficient of drag. It doesn't determine the amount of drag experienced by a car, that is determined by CdA, the coefficient of drag multiplied by the frontal area. So when you test in a wind tunnel, what you determine from measuring the force on the balance is CdA, and to separate this into Cd and A, you need to know the frontal area, which I guess is easily enough known from the CAD model for a car. I'm not sure why the convention with cars is to quote Cd rather than CdA. In cycling, for example, nobody talks about their Cd, only their CdA.

So yes, you can think of Cd as being determined by the shape, independently of the size, with the drag of an object depending on both Cd and size. It isn't quite as simple as that, as Cd can depend on the Reynolds number, e.g. a sphere has a Cd that significantly varies with Reynolds number:
https://www.grc.nasa.gov/www/k-12/airplane/dragsphere.html
 
05XR8
Could be more than that. I noticed this in the Brand Central car description, the power figure is different to what we're given. If there are more cars like this, how much more does that throw off B0P?
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Yes, because that's generally how BOP works in real life too...
 
Phaceless_Ph
Yes, because that's generally how BOP works in real life too...
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What I'm saying is if the car has an increase in 5 BHP and PD BoP to whatever, should it have that 5BHP increase or the the lesser figure? THe set up with more BHP starts with a performance advantage before even buying the car.
 
breeminator
Cd is the coefficient of drag. It doesn't determine the amount of drag experienced by a car, that is determined by CdA, the coefficient of drag multiplied by the frontal area. So when you test in a wind tunnel, what you determine from measuring the force on the balance is CdA, and to separate this into Cd and A, you need to know the frontal area, which I guess is easily enough known from the CAD model for a car. I'm not sure why the convention with cars is to quote Cd rather than CdA. In cycling, for example, nobody talks about their Cd, only their CdA.

So yes, you can think of Cd as being determined by the shape, independently of the size, with the drag of an object depending on both Cd and size. It isn't quite as simple as that, as Cd can depend on the Reynolds number, e.g. a sphere has a Cd that significantly varies with Reynolds number:
https://www.grc.nasa.gov/www/k-12/airplane/dragsphere.html
Click to expand...
wow, but the bigger the car the bigger the drag? So both shape and size of the car? Cd = only shape of the car, Cda both shape and size of car?
 

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