aerodynamic musings
#31
I'm surprised Jean and Geoffrey experience compressing down of the rear windows - would have thought it would be sucked out (like the sun roof that was lost - or did it cave in to the cabin)
#32
Is there some point where decreasing cd - sloped windscreen, loss of gutters - increase lift? I guess it is a compromise? Air flows over a longer distance over the car vs below like a air plane wing. By making the cars slipperier does it increase lift? May be the current windscreen/gutters help down force?
I'm surprised Jean and Geoffrey experience compressing down of the rear windows - would have thought it would be sucked out (like the sun roof that was lost - or did it cave in to the cabin) - longer distance traveled over the car vs below like a wing creating vacuum/lift above? Or is this just a case of me knowing a little about something but not enough to really understand phenomenon that I always get into...
I'm surprised Jean and Geoffrey experience compressing down of the rear windows - would have thought it would be sucked out (like the sun roof that was lost - or did it cave in to the cabin) - longer distance traveled over the car vs below like a wing creating vacuum/lift above? Or is this just a case of me knowing a little about something but not enough to really understand phenomenon that I always get into...
Longer distance over the car seems to improve drag not deteriorate it, at least this is what many of the old race cars, Manthey and Alzen use on their race cars, but also to improve stability with lateral winds, please don't ask why, but it's true
I never have the windows opened when I am driving at high speeds. The rear lexan does bend inwards at highish speeds, I have it flush mounted. My only guess is that the roof flying on MOD's car is as a result of pressure on the cabin by the wind (sideways from lateral wind and frontal from the direction of movement at speed) which expanded the air inside the cabin upwards or sth like that. Poor fitment also most likely.
#33
My only guess is that the roof flying on MOD's car is as a result of pressure on the cabin by the wind (sideways from lateral wind and frontal from the direction of movement at speed) which expanded the air inside the cabin upwards or sth like that. Poor fitment also most likely.
Next Vmax I'll log cabin pressure via the DL1 to see what happens as speed increases.
#34
I was one of the three. Took a piece of advice from Alan McKee (formerly known as Weltmeister) and duct-tape closed the air intake at the back edge of the hood and also taped the leading edge of the sunroof. Don't know if that's why my sunroof didn't suffer the same fate at MOD500's but it did give some piece of mind for the rest of the day.
#35
I checked the air pressure inside the car today; between at rest and at 175 mph there's a drop in air pressure of about 8 millibar.
So sunroofs are getting pulled out by low pressure from outside of the car, presumably coming off the windscreen?
So sunroofs are getting pulled out by low pressure from outside of the car, presumably coming off the windscreen?
#37
#40
Hi Stefan, nothing much new to share. Vmax was 177mph; backing the wastegates off didn't result in any significant change. I'll post some graphs later. Best 60-130 to date is 9.6 seconds.
#45
Probably 10.4 seconds but with a full 90 litre tank and slowish shifts (0.6-0.7 seconds). That's with a factory 430 ECU. I now manage them in about 0.4-0.5 seconds without speed shifting or anything of that sort.