Ian-S wrote:
Nah, it's the design of the cars that is to blame. Back in the CART days the cars were effectively chiselled off bricks with wings attached, meaning the only downforce produced was that from the wings.
Around the turn of the century designers started re-thinking aero and discovered if you shaped the entire car like a plane wing, you create a low pressure zone under the car which sucks it to the ground (let's call this modern day ground effects) the downside of that as we all know is that it's a very thin line between taking advantage of that low pressure zone to "suck" it down, and loosing control of the area and it producing lift and going into an aerodynamic stall like a lot of these cars have done recently. The flat bottom doesn't really come into it (lost of people point to this as a cause) because the aerodynamics are being produced from the top, not the bottom, because the car is shaped like a wing, when equal air goes both over the car and under it, you go for a nice flight solely from the cars shape, the wings cannot counteract that level of lift.
If you look at an Indycar compared to an old CART car from a side on view you'll see what I mean, this years car is an improvement, the sidepods are flatter and don't appear to produce as much downforce, but compare that to the old CART car that has a perfectly flat top to the sidepods, then we'll, there's your answer.
Around the turn of the century designers started re-thinking aero and discovered if you shaped the entire car like a plane wing, you create a low pressure zone under the car which sucks it to the ground (let's call this modern day ground effects) the downside of that as we all know is that it's a very thin line between taking advantage of that low pressure zone to "suck" it down, and loosing control of the area and it producing lift and going into an aerodynamic stall like a lot of these cars have done recently. The flat bottom doesn't really come into it (lost of people point to this as a cause) because the aerodynamics are being produced from the top, not the bottom, because the car is shaped like a wing, when equal air goes both over the car and under it, you go for a nice flight solely from the cars shape, the wings cannot counteract that level of lift.
If you look at an Indycar compared to an old CART car from a side on view you'll see what I mean, this years car is an improvement, the sidepods are flatter and don't appear to produce as much downforce, but compare that to the old CART car that has a perfectly flat top to the sidepods, then we'll, there's your answer.
Are you thinking of IRL maybe? The regulations varied, but CART never had flat floors and always had some level of ground effects. A feature that Motorsport magazine ran on the Reynard 97i (which is a good read) mentions how the height of the tunnels and the freedom aft of the rear wheel centreline was reduced, but some late 90s/early 00s shots show that it wasn't a fundamental change:
Unspecified Lola, looks less sophisticated than the below example so probably late 90s:
2001 Lola:
When the DP01 was launched, they made a big thing about how the height of the tunnels was increased again:
IMHO, the reliance on underbody aero compared to IRL is a key part of why Champ Cars never seemed as prone to taking off. IRL (at least late in the life of the series) had similar tunnels, but much shallower and accompanied by a much bigger tray area on a much bigger floor:
I can't find any earlier pictures, but I'm pretty sure they didn't change much.
