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Para
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Group: Forum Members
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+x+xHi Guys, First of all, thank you to everyone for getting back back....much appreciated. I realise that the splitter itself does not actually create downforce (unlike an airfoil). All it does is to increase the surface area over which high pressure can build up. The more high pressure there is above the splitter...and the more low pressure below the splitter, the greater the net downforce. Also, my understanding is that splitter function is also very sensitive to ride height. The lower the car is to the ground the greater suction that will be created by the ground effects, hence the reason why the splitter is located at the lowest possible point. However if the splitter is too close to the ground it will stall, producing less downforce and more drag because air cannot flow through the bottom part of the splitter, so the speed of the flow there will decrease, increasing the pressure. I read somewhere that this sensitivity can be reduced by designing anhedral shaped splitter. The idea being that in the case that the car touches the ground, part of the splitter will continue to function and hence create downforce. So yes, i understand there is no one answer without CFD. The splitter will be unique to the vehicle it is being designed for...as frontal are, stagnation point etc are all different on different vehicle types... But i was quite surprised to read that splitters can generate between 300-400 kg of load....astonishing ! Thanks once again everyone...much appreciated Splitters do create downforce, just not as much as an airfoil. The main function of a splitter is to reduce the amount of air going underneath the car. As with all aero structures, the high pressure zone on top of the structure contributes very little to the negative lift being created, it is all about that low pressure zone on the bottom that does all the work. But the splitters role is much more important than just that; not only does it reduce positive lift by reducing the volume of air underneath the car, but by doing so it improves the performance of other aero components like any canards or front wings, side skirts, rear wing, rear diffuser if there is one, etc. So the net benefit can be huge because not only does the splitter itself produce negative lift, but it also let's the entire aero package produce more negative lift. They can actually produce significantly more than 400kg, mine is a relatively simple design. The splitter/front wing combinations on cars at the pointy end of Time Attack are making more than 800-1000kg of negative lift - to put that in perspective, it means you should be able to park a small car on top of the splitter and not see any deflection... So they can be absolutely massive, and are a hugely structural component. That said, a 20mm lip stuck to the bottom of the front bumper without proper rake or rear extension, is not going to do that and is really only contributing to drag. So most splitters that you see on street cars and the likes are not making any downforce at all. If you cant stand on it, its not doing anything for you!
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
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+xHi Guys, First of all, thank you to everyone for getting back back....much appreciated. I realise that the splitter itself does not actually create downforce (unlike an airfoil). All it does is to increase the surface area over which high pressure can build up. The more high pressure there is above the splitter...and the more low pressure below the splitter, the greater the net downforce. Also, my understanding is that splitter function is also very sensitive to ride height. The lower the car is to the ground the greater suction that will be created by the ground effects, hence the reason why the splitter is located at the lowest possible point. However if the splitter is too close to the ground it will stall, producing less downforce and more drag because air cannot flow through the bottom part of the splitter, so the speed of the flow there will decrease, increasing the pressure. I read somewhere that this sensitivity can be reduced by designing anhedral shaped splitter. The idea being that in the case that the car touches the ground, part of the splitter will continue to function and hence create downforce. So yes, i understand there is no one answer without CFD. The splitter will be unique to the vehicle it is being designed for...as frontal are, stagnation point etc are all different on different vehicle types... But i was quite surprised to read that splitters can generate between 300-400 kg of load....astonishing ! Thanks once again everyone...much appreciated Splitters do create downforce, just not as much as an airfoil. The main function of a splitter is to reduce the amount of air going underneath the car. As with all aero structures, the high pressure zone on top of the structure contributes very little to the negative lift being created, it is all about that low pressure zone on the bottom that does all the work. But the splitters role is much more important than just that; not only does it reduce positive lift by reducing the volume of air underneath the car, but by doing so it improves the performance of other aero components like any canards or front wings, side skirts, rear wing, rear diffuser if there is one, etc. So the net benefit can be huge because not only does the splitter itself produce negative lift, but it also let's the entire aero package produce more negative lift. They can actually produce significantly more than 400kg, mine is a relatively simple design. The splitter/front wing combinations on cars at the pointy end of Time Attack are making more than 800-1000kg of negative lift - to put that in perspective, it means you should be able to park a small car on top of the splitter and not see any deflection... So they can be absolutely massive, and are a hugely structural component. That said, a 20mm lip stuck to the bottom of the front bumper without proper rake or rear extension, is not going to do that and is really only contributing to drag. So most splitters that you see on street cars and the likes are not making any downforce at all. If you cant stand on it, its not doing anything for you!
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Para
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Group: Forum Members
Posts: 8,
Visits: 20
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Hi Guys,
First of all, thank you to everyone for getting back back....much appreciated.
I realise that the splitter itself does not actually create downforce (unlike an airfoil). All it does is to increase the surface area over which high pressure can build up. The more high pressure there is above the splitter...and the more low pressure below the splitter, the greater the net downforce.
Also, my understanding is that splitter function is also very sensitive to ride height.
The lower the car is to the ground the greater suction that will be created by the ground effects, hence the reason why the splitter is located at the lowest possible point. However if the splitter is too close to the ground it will stall, producing less downforce and more drag because air cannot flow through the bottom part of the splitter, so the speed of the flow there will decrease, increasing the pressure.
I read somewhere that this sensitivity can be reduced by designing anhedral shaped splitter. The idea being that in the case that the car touches the ground, part of the splitter will continue to function and hence create downforce.
So yes, i understand there is no one answer without CFD. The splitter will be unique to the vehicle it is being designed for...as frontal are, stagnation point etc are all different on different vehicle types...
But i was quite surprised to read that splitters can generate between 300-400 kg of load....astonishing !
Thanks once again everyone...much appreciated
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Hanaldo
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Group: Forum Members
Posts: 2.5K,
Visits: 28K
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Totally impossible to give a generic value for. The same splitter on one car will perform differently on another car, let alone different splitters. Variables like rake angle, leading edge thickness, ride height, distance forward of the bumper, diffusers if it has any, etc. etc. To calculate that sort of thing you need CFD data on the specific splitter youre using, and even then you can take those values with a pinch of salt without a full 3D scan of your car.
Splitters can generate massive aero loads though, so they do need to be very strong. The universal one I build Ive done free-air CFD analysis on, and in a perfect situation it will make 400kg of downforce at 200km/h. In the real world thats likely closer to 350kg at 200km/h, but still massive loads. So a 2mm thick carbon sheet wont cut it on a splitter that is actually doing anything!
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Warren (Staff)
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Group: Administrators
Posts: 2.5K,
Visits: 8.5K
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I am not aware of any off the shelf data. Do you mean aerodynamic loadings or strength of a typical splitter? both could be quite different and are effected by different variables although one would hope any decent splitter is strong enough to resist the aerodynamic loads it is designed to take!
Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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Para
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Group: Forum Members
Posts: 8,
Visits: 20
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Dear Sir/Madam,
Is there an empirical data available on what the loads (lbs or Newton) are on a typical splitter for an average passenger car at various speeds?....or is there an easy way to calculate/estimate the force for a given splitter size/area ?
Thanks in advance
kindest regards
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