Whats best valance or splitter?
- Thread starter cococola
- Start date
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Ah but....Doesn't the diffuser at the rear work differently (or differently in part) gaining most advantage from air volume rather than air velocity?
I don't know if this is the case but consider:-
Car runs into the air and, due to the frontal cross section, only so much air can go under the car. If the cross sectional area under the car increases down its length it will need more air under the car to fill that area thus creating a lower air pressure. Lower air pressure = suck.
I assume this is why the banned side skirts on ye olde F1 cars were so effective on Williams cars but not the Renault Turbos. Williams used Cosworth DFV's which are narrow at the bottom allowing the volume under the car to increase toward the rear . The Renault engine was much flatter and so didn't achieve the same change in volume. Because the governing body is French they had the design banned. [:-]
I don't know if this is the case but consider:-
Car runs into the air and, due to the frontal cross section, only so much air can go under the car. If the cross sectional area under the car increases down its length it will need more air under the car to fill that area thus creating a lower air pressure. Lower air pressure = suck.
I assume this is why the banned side skirts on ye olde F1 cars were so effective on Williams cars but not the Renault Turbos. Williams used Cosworth DFV's which are narrow at the bottom allowing the volume under the car to increase toward the rear . The Renault engine was much flatter and so didn't achieve the same change in volume. Because the governing body is French they had the design banned. [:-]
sawood12
New member
That's ground effect and again only works if you have laminar airflow which is why you would need to instal flat panels under the car to make the underside perfectly smooth and increase the volume under the car as you go towards the rear to accellarate the airflow and hence create lower pressure as moving air has a lower pressure than static air or slightly more slowly moving air which is what creates the pressure differential and sucks the car onto the road. The side skirts prevent air from being sucked from under the sides of the car which will equalise the pressure underneath the car and destroy the ground effect. The early ground effect Williams (or was it Lotus) cars actually had skirts that dragged across the surface of the track creating a near perfect seal which moved up and down to allow for the suspension movement. These were so effective they were immediately banned.
If you have turbulent airflow under the car you cannot control the speed or direction of the airflow and therfore where the area of low pressure occurs therefore you get buffeting as the pockets of low and high pressure are constantly moving around under the car and effectively cancel themselves out. Everything aerodynamic relys upon and needs smooth laminar airflow which is predicatable. This is what is ruining F1 as the relyance on aerodynamics means the cars can't travel close to eachother as they are in the turbulent air of the car in front therfore vastly reducing or destroying the efficiency of the cars aerodynamic devices.
Food for thought though - the aerodynamic devices on an F1 car don't really become effective until about 50mph. Given the precision of the design and manufacture of these devices it makes you think about how effective spoilers on road cars really are. These big boot spoilers you see on Scoobys cannot be that effective below about 70mph and even then given the ratio of the spoilers surface area with the weight of the car compared with the same ratio on an F1 car you can't help thinking they are a waste of time and all they are doing is costing you more in fuel. Fair enough, if you are doing high speed runs on a disused airfield then you probably need them, but for the rest of the time they must be a waste of time and fuel.
If you have turbulent airflow under the car you cannot control the speed or direction of the airflow and therfore where the area of low pressure occurs therefore you get buffeting as the pockets of low and high pressure are constantly moving around under the car and effectively cancel themselves out. Everything aerodynamic relys upon and needs smooth laminar airflow which is predicatable. This is what is ruining F1 as the relyance on aerodynamics means the cars can't travel close to eachother as they are in the turbulent air of the car in front therfore vastly reducing or destroying the efficiency of the cars aerodynamic devices.
Food for thought though - the aerodynamic devices on an F1 car don't really become effective until about 50mph. Given the precision of the design and manufacture of these devices it makes you think about how effective spoilers on road cars really are. These big boot spoilers you see on Scoobys cannot be that effective below about 70mph and even then given the ratio of the spoilers surface area with the weight of the car compared with the same ratio on an F1 car you can't help thinking they are a waste of time and all they are doing is costing you more in fuel. Fair enough, if you are doing high speed runs on a disused airfield then you probably need them, but for the rest of the time they must be a waste of time and fuel.
They all tried it, but the original idea came from Williams. It was very effective, but less so on the Renault Turbo for reasons as noted above. It was for this reason principally that they were banned. The French governing body would have it that it was by virtue of the increased cornering speeds made the cars dangerous. This obviously had bearing but more so as the French cars weren't as fast.
I appreciate that this was an extreme and best example (hence my choice). I further appreciate that the side skirts greatly enhanced this effect by stopping air spilling in from around the side of the car. However, if you look at the rear diffusers of F1 and GT cars these have vertical vanes for, I assume, the very same reason - to stop air spilling in from the sides so as to maintain the low pressure air,
I take your point with regard to the necessity for flat surfaces; so, be this the case, some flat surface must be better than no flat surface at all .'. the splitter must be better than no splitter.
924nutter
PCGB Member
I think the F.I.A. had a point. Jean-Marie Ballestre always seemed to be slightly 'not living in the real world.' Yeah, like Max Mosely does! All, of course, in the best possible taste and IMHO. Getting back to the point, G/A cars were great as long as they maintained their ground effect, by travelling in the desired direction, and could achieve higher cornering speed,
- lose it in a corner,
- start travelling in a less than optimum, I suppose, trajectory would now be more appropriate description,
- lose the G/A
- I want my mum. The car is now in an unstable condtion
- higher speed, higher kenetic energy, loss of control, harder impact.
924nutter
PCGB Member
Not that I approve of all the meddling. As I see it you can't have degrees of fatality. Improving the chances of survivability?
100% improvement, dont race in F1, then you are not likely to be injured, fatally or otherwise.
F1 is supposed to be the pinnacle of motorsport, yet, year on year, in my opinion, it is being smothered by micromanagement by the F.I.A. What's wrong with an engine pulling 20,000 revs plus, exactly?
If we didn't have motor sport, the motor car would never have made the avances it has.
Don't get me started!
I'm not sure that I agree. All design is a matter of balancing compromises. Despite limitations imposed by capacity, tyre size, tread design, wing area and 1001 other issues, cars are lapping as quickly now as they were 10 or 20 years ago. This still demonstrates advancement in design.
The other option is US KART where, on an oval circuit, the cars are almost too fast for a human driver. Once committed to a line, should something happen ahead, the driver is unable to deviate from his set course. This is not because the car can't accommodate a change in direction but the drivers brain isn't fast enough to compute and initiate the change.
924nutter
PCGB Member
Of course you are quite right John. At 200 mph., a good average, a vehicle( presumably, therefore, the driver too) will have covered 58.6 feet in the two tenths of a second reaction time alone.
Further more I agree that advances in technology and design have all but compensated for the so called speed reduction measures. What next from 'Mad Max' I wonder? Personally I would like to see a ban on wings altogether, in stages, and put the speed of a lap back into the hands of the driver.
If I could be allowed to explain. Wing are desinged to work bl***y welll in the designed direction of travel, but get pitched sideways, into a spin, and the loss of downforce exascerbates the out of control condition. If there were no wings, which are a bit artificial anyway, then it really isn't going to make much difference, one "way" or the other.
How I love this forum, especially when compared to the OTHER forum which has had about two new posts this week.
Noted the 'for' and 'against' arguments for "toast rack" rear valances and on aesthetic grounds (ie I like it) chose the toast rack ... now as a forum newbie (and 80K miles of wunderbar 944 driving behind me) and I am most grateful for all the hints and tips already picked up ... but can anyone tell me if there is a rubber finishing strip or infill strip that fits twixt toast rack and the bottom of the rear bumber. There is a profile on the toast rack that, to me, looks like it slots into the rear bumber ... but on my car there is no corresponding profile in the underside of the rear bumber. Grateful for any help - it looks fine but - to be honest - a tad unfinished.
Thanks.
Thanks.
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