Color0's Micro RC Blog -- A technical brain dump from the mind of yours truly...
Rear Diffuser Aerodynamics, Rd. 2 Pt. 1
Posted 09-26-2011 at 04:51 PM by color0
Recently I've picked up a new F430 body, but instead of choosing the ubiquitous F430GT, I bought the street-version F430 instead for two reasons:
1) The front bumper sits higher off the ground, allowing me to lower the front end of the car more with minimal plastic trimming. I don't like to trim the front bumper horizontally across the front as it's hard to keep it perfectly level. And keeping it perfectly level is the key to obtaining consistent aero properties across the width of the front end.
2) The rear diffuser actually rises off the ground and slopes upward, a good shape to mount a functional Lexan diffuser to as well as test on its own.
So with the lower ride height comes less frontal area and lower CG, as well as a bit of rake towards the front, so we should see a little bit less drag, a little bit more downforce over the body, and less body roll in a corner, which will reduce the F430's pivoting tendencies and smooth out the steady-state cornering. You can see that this F430 actually sits just as low as its rival SC430:
And here is the rear diffuser! Obviously the stock white body does not come like this, I've cut the holes into the rear bumper using a dremel.
You can see that the stock F430 rear diffuser might act somewhat like an underbody wing/spoiler, and that's exactly what I'm expecting it to do -- if I block off this gaping hole in the rear I expect to lose rear traction when I test this body on the track. And, if I add a Lexan rear diffuser to the stock diffuser, I should expect this underbody wing/diffuser/*shrug* effect to increase, and I should gain rear downforce and reduce the amount of rear end "swing" when heading into a corner at high speed.
Track testing will commence whenever I get the body back from Dr. Kustom -- hopefully I can get some time on carpet where the smallest changes in rear downforce can be noticeably felt. Carpet driving is a little bit like drifting, so just a little more or less rear traction will affect turning radius quite a bit.
1) The front bumper sits higher off the ground, allowing me to lower the front end of the car more with minimal plastic trimming. I don't like to trim the front bumper horizontally across the front as it's hard to keep it perfectly level. And keeping it perfectly level is the key to obtaining consistent aero properties across the width of the front end.
2) The rear diffuser actually rises off the ground and slopes upward, a good shape to mount a functional Lexan diffuser to as well as test on its own.
So with the lower ride height comes less frontal area and lower CG, as well as a bit of rake towards the front, so we should see a little bit less drag, a little bit more downforce over the body, and less body roll in a corner, which will reduce the F430's pivoting tendencies and smooth out the steady-state cornering. You can see that this F430 actually sits just as low as its rival SC430:
And here is the rear diffuser! Obviously the stock white body does not come like this, I've cut the holes into the rear bumper using a dremel.
You can see that the stock F430 rear diffuser might act somewhat like an underbody wing/spoiler, and that's exactly what I'm expecting it to do -- if I block off this gaping hole in the rear I expect to lose rear traction when I test this body on the track. And, if I add a Lexan rear diffuser to the stock diffuser, I should expect this underbody wing/diffuser/*shrug* effect to increase, and I should gain rear downforce and reduce the amount of rear end "swing" when heading into a corner at high speed.
Track testing will commence whenever I get the body back from Dr. Kustom -- hopefully I can get some time on carpet where the smallest changes in rear downforce can be noticeably felt. Carpet driving is a little bit like drifting, so just a little more or less rear traction will affect turning radius quite a bit.
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