Aerodynamic musings
#19
#20
I have read that this rain gutters removal will help Cd by 3%,
so Cd is lowered from 0.34 to 0.33. But it helps even more because Cd x A is main factor in wind resistance and that A (frontal area) will be also lower.
Edited: I calculated that this rain gutters removal will give you 15 horsepowers at max. speed "for free"
But how much this special windscreen mod helps Cd?
It goes 10 cm far from front edge than normal. Can anyone calculate that effect? Jean?
so Cd is lowered from 0.34 to 0.33. But it helps even more because Cd x A is main factor in wind resistance and that A (frontal area) will be also lower.
Edited: I calculated that this rain gutters removal will give you 15 horsepowers at max. speed "for free"
But how much this special windscreen mod helps Cd?
It goes 10 cm far from front edge than normal. Can anyone calculate that effect? Jean?
Last edited by Jussi; 04-11-2008 at 06:01 PM.
#28
Courtesy of the late great Paul Frere:
So basically factory stock airflow through the front spoiler which allows air to expell just in fron of the front wheels was actually measured in the wind tunnel to improve drag - clever stuff !
My Geek question for today is: (Scott -look away )
Those brake cooling inlets which a lot of us have in place of the stock fog light unit, if they are not "wired in" to be functional (ie do not have all the piping to direct air through the spoiler onto the brakes) and the air just sort of enters the inlets and "splats" into whatever is behind there, do we think that:
1) This will aid the above Frere description by producing even more pressure within the spoiler internals at speed forcing air out in front of the front wheels at a greater (more drag beneficial) speed ?
2) The inlet holes just act as a "drag point" and we are better off drag wise having the fog lamps in place.
3) Increased Drag is irrelevant because the inlets just look sooo cool out cruisin'
So basically factory stock airflow through the front spoiler which allows air to expell just in fron of the front wheels was actually measured in the wind tunnel to improve drag - clever stuff !
My Geek question for today is: (Scott -look away )
Those brake cooling inlets which a lot of us have in place of the stock fog light unit, if they are not "wired in" to be functional (ie do not have all the piping to direct air through the spoiler onto the brakes) and the air just sort of enters the inlets and "splats" into whatever is behind there, do we think that:
1) This will aid the above Frere description by producing even more pressure within the spoiler internals at speed forcing air out in front of the front wheels at a greater (more drag beneficial) speed ?
2) The inlet holes just act as a "drag point" and we are better off drag wise having the fog lamps in place.
3) Increased Drag is irrelevant because the inlets just look sooo cool out cruisin'
#29
Can't look away.
You mean people actually have front ducts that are not routed to the brakes?!
I love reading Frere.
I guess it would depend if there is anything to be gained by having extra pressure within the spoiler. There may be a point where extra pressure on the inlet side creates little or no extra volume on the outlet side. If the outlet air's main beneficial purpose is the evacuation of the still air in front of the wheel, is there a benefit to having it done faster?
I would guess the answer is 2) & 3) .
You mean people actually have front ducts that are not routed to the brakes?!
I love reading Frere.
I guess it would depend if there is anything to be gained by having extra pressure within the spoiler. There may be a point where extra pressure on the inlet side creates little or no extra volume on the outlet side. If the outlet air's main beneficial purpose is the evacuation of the still air in front of the wheel, is there a benefit to having it done faster?
I would guess the answer is 2) & 3) .
#30
For Porsche anoraks he was THE man, had a unique access to all sorts of factory data - still he had a good "innings"
I guess it would depend if there is anything to be gained by having extra pressure within the spoiler. There may be a point where extra pressure on the inlet side creates little or no extra volume on the outlet side. If the outlet air's main beneficial purpose is the evacuation of the still air in front of the wheel, is there a benefit to having it done faster?
I would guess the answer is 2) & 3) .
I would guess the answer is 2) & 3) .