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Para
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+xI believe modern F1 cars are up around 8 lat G's through the high speed corners. But that said, I cant think of many corners in the F1 schedule that are taken at over 300km/h, which the top Time Attack cars are doing. So they could actually be in close territory. Keep in mind that those classes have very little in common with a passenger car other than their exterior body shape, so it isnt totally surprising. Open class is really your more standard high aero passenger race car, and they will be managing around 3G's lat. Indeed.... 300 kph = 83.3 m/s So 8 g cornering at 300 kph would require a corner radius (constant) of: r = v^2/(G.g) = 83.3^2/(8 x 9.81) = 88.4 m. There may be a few circuits meeting this requirement i supposed ....
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Hanaldo
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I believe modern F1 cars are up around 8 lat G's through the high speed corners.
But that said, I cant think of many corners in the F1 schedule that are taken at over 300km/h, which the top Time Attack cars are doing. So they could actually be in close territory.
Keep in mind that those classes have very little in common with a passenger car other than their exterior body shape, so it isnt totally surprising. Open class is really your more standard high aero passenger race car, and they will be managing around 3G's lat.
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Para
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+x+x+xYou won't find any data on the time attack cars as most of them are privately built. The top cars hire an aero engineer to design and cfd/wind tunnel test, which usually done so under a hefty NDA. However you can compare laptimes at the track World Time Attack is held at each year (Sydney Motorsport Park in Australia) Outright Nico Hulkenberg (GER) A1 Lola Zytek 1.19.142 Group 2A James Winslow Radical SR8 1.25.7027 Time Attack Pro Class 1 Barton Mawer Porsche 968 1:19.2770 2 Andre Heimgartner Nissan Silvia S13 1:21.8760 3 Garth Walden Mitsubishi Evo 1:23.8560 You are correct in thinking these cars weigh more than a F1 or Radical. They also run on lower grip tyre, rather than a slick they use a road legal semi slick. Just going off those two facts and comparing the lap times I would assume the aero loads on Time Attack are no joke. Regarding the time posted, I’m not familiar with the Australian circuit....but obviously mind blowingly quick when referenced to an SR8....although I’m just curious if the Time Attack cars are still incapable of pulling high g’s like the SR8....but they make up the time (lost on cornering) on long straights or gentler bends (as downforce is proportional to velocity squared) by making full use of that collosal power.....so that the cornering capabilities of SR8s is swamped in the overall lap times Indeed, it would be good to have a peek inside and find out what sort of lateral loads these things are capable of. Thanks a lot for a great input...much appreciated They wont be anywhere near an F1 cars lateral acceleration, but they will be surpassing an SR8 Radical by quite a bit assuming Googles data on the SR8 is correct. A quick search tells me an SR8 is capable of 2.5 lateral G's. Open class cars in Time Attack are running up around 3 lateral G's, so already more than the SR8. The Pro and Pro Am cars will be significantly more, though I cant find any posted data on that and havent heard back from my mate at Tilton. But I'm sure they will be up around 4-5 lateral G's. OK no problem....perhaps Tilton do not wish to disclose such data...which is understandable.....so Pro Am cars, around 4-5 Gs is F1 territory
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Hanaldo
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+x+xYou won't find any data on the time attack cars as most of them are privately built. The top cars hire an aero engineer to design and cfd/wind tunnel test, which usually done so under a hefty NDA. However you can compare laptimes at the track World Time Attack is held at each year (Sydney Motorsport Park in Australia) Outright Nico Hulkenberg (GER) A1 Lola Zytek 1.19.142 Group 2A James Winslow Radical SR8 1.25.7027 Time Attack Pro Class 1 Barton Mawer Porsche 968 1:19.2770 2 Andre Heimgartner Nissan Silvia S13 1:21.8760 3 Garth Walden Mitsubishi Evo 1:23.8560 You are correct in thinking these cars weigh more than a F1 or Radical. They also run on lower grip tyre, rather than a slick they use a road legal semi slick. Just going off those two facts and comparing the lap times I would assume the aero loads on Time Attack are no joke. Regarding the time posted, I’m not familiar with the Australian circuit....but obviously mind blowingly quick when referenced to an SR8....although I’m just curious if the Time Attack cars are still incapable of pulling high g’s like the SR8....but they make up the time (lost on cornering) on long straights or gentler bends (as downforce is proportional to velocity squared) by making full use of that collosal power.....so that the cornering capabilities of SR8s is swamped in the overall lap times Indeed, it would be good to have a peek inside and find out what sort of lateral loads these things are capable of. Thanks a lot for a great input...much appreciated They wont be anywhere near an F1 cars lateral acceleration, but they will be surpassing an SR8 Radical by quite a bit assuming Googles data on the SR8 is correct. A quick search tells me an SR8 is capable of 2.5 lateral G's. Open class cars in Time Attack are running up around 3 lateral G's, so already more than the SR8. The Pro and Pro Am cars will be significantly more, though I cant find any posted data on that and havent heard back from my mate at Tilton. But I'm sure they will be up around 4-5 lateral G's.
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Para
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Group: Forum Members
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+xYou won't find any data on the time attack cars as most of them are privately built. The top cars hire an aero engineer to design and cfd/wind tunnel test, which usually done so under a hefty NDA. However you can compare laptimes at the track World Time Attack is held at each year (Sydney Motorsport Park in Australia) Outright Nico Hulkenberg (GER) A1 Lola Zytek 1.19.142 Group 2A James Winslow Radical SR8 1.25.7027 Time Attack Pro Class 1 Barton Mawer Porsche 968 1:19.2770 2 Andre Heimgartner Nissan Silvia S13 1:21.8760 3 Garth Walden Mitsubishi Evo 1:23.8560 You are correct in thinking these cars weigh more than a F1 or Radical. They also run on lower grip tyre, rather than a slick they use a road legal semi slick. Just going off those two facts and comparing the lap times I would assume the aero loads on Time Attack are no joke. Regarding the time posted, I’m not familiar with the Australian circuit....but obviously mind blowingly quick when referenced to an SR8....although I’m just curious if the Time Attack cars are still incapable of pulling high g’s like the SR8....but they make up the time (lost on cornering) on long straights or gentler bends (as downforce is proportional to velocity squared) by making full use of that collosal power.....so that the cornering capabilities of SR8s is swamped in the overall lap times Indeed, it would be good to have a peek inside and find out what sort of lateral loads these things are capable of. Thanks a lot for a great input...much appreciated
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leeks
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You won't find any data on the time attack cars as most of them are privately built. The top cars hire an aero engineer to design and cfd/wind tunnel test, which usually done so under a hefty NDA.
However you can compare laptimes at the track World Time Attack is held at each year (Sydney Motorsport Park in Australia)
Outright Nico Hulkenberg (GER) A1 Lola Zytek 1.19.142
Group 2A James Winslow Radical SR8 1.25.7027
Time Attack Pro Class
1 Barton Mawer Porsche 968 1:19.2770
2 Andre Heimgartner Nissan Silvia S13 1:21.8760
3 Garth Walden Mitsubishi Evo 1:23.8560
You are correct in thinking these cars weigh more than a F1 or Radical. They also run on lower grip tyre, rather than a slick they use a road legal semi slick.
Just going off those two facts and comparing the lap times I would assume the aero loads on Time Attack are no joke.
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Hanaldo
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+x+xI'm not talking about Radicals or the likes, I'm talking about Time Attack cars. Take a look at any of the Pro or Pro Am cars competing at WTAC. These cars are all making more downforce than an F1 car, they're looking at numbers in excess of 3000kg of aero loading. Yes, in those classes the cars are a tube frame chassis with tunnels in the floor, so they are proper aero cars, but they are based on passenger cars. I was sort of more making the point about how open ended your question was - a splitter can quite literally make anywhere from no downforce at all to over 1000kg of downforce. Its simply impossible to estimate a value without knowing anything about the design or the car its going on. Yes, the total aero package needs to be designed so that it is properly balanced. You need a proper weight distribution including aero loading so that the centre of gravity is as close to the centre of the car as you can get it, but this often comes down to class rules and the actual base car you are starting out with. But with good design it is certainly possible to balance the aero loads and produce very high downforce. As for front airfoils, yes I have designed and built these, and yes they can be superior to a splitter. Again, take a look at any cars running at the pointy end of time attack, they will all have front wings (except the Lyfe GTR, but ccompare them to the competition and you can see they would gain a lot by having some better front aero). RP968 and the 1:1 R8 are probably the best examples of a full front airfoil rather than a splitter. Lots of the other cars will have a combination of splitter and front wings, and this is especially more common in the lower Open Class cars, as this category is still a stock chassis design with flat floors and tunnels prohibited. To throw you another design curve ball - attachment points should all be behind the bumper/air dam. Mounting solutions like splitter tie rods and cables are absolutely horrific when they are external and placed in the air flow. These create so much drag and destroy so much lift potential that you would be better off running a much smaller splitter design in order to do wothout them. Any aero car that has been properly designed will not have any mounting points in the air flow. So what sort of lateral acceleration can these Time Attack cars muster? I couldn’t find any data on that, but I suspect no where near an F1 car…or even a Radical ….i guess one of the limiting factors is the mass of the Time Car….. given that the friction forces (tyres/road surface) would need to overcome m.v^2/r….therefore the greater the mass m, the greater the counter force (grip needed) that needs to be generated to negotiate a bend Yeh you won't find that sort of data published, the teams will keep that information pretty close. I know the race engineer for the Tilton Evo, I'll see if I can get it out of him. However these cars are past the limits of the R-Compound control tyre, the Advan A050. Every year there is a tyre failure from aero loading. They could actually generate more downforce and more grip and go faster, but the current tyre regulations are what holds them back. Which for me is great, you play within the rules, but it makes it a little bit incomparable to most other racing series that run on full slicks. But even on R-Compound tyres, these are 1000kg/1500hp+ cars going full throttle (~300km/h) through Turn 1, which is just unheard of in any other racing category that Sydney Motorsport Park hosts. Even our pinnacle motorsport category here, the V8 Supercars, are completely blown out of the water and running 12 seconds a lap slower.
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Para
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+xI'm not talking about Radicals or the likes, I'm talking about Time Attack cars. Take a look at any of the Pro or Pro Am cars competing at WTAC. These cars are all making more downforce than an F1 car, they're looking at numbers in excess of 3000kg of aero loading. Yes, in those classes the cars are a tube frame chassis with tunnels in the floor, so they are proper aero cars, but they are based on passenger cars. I was sort of more making the point about how open ended your question was - a splitter can quite literally make anywhere from no downforce at all to over 1000kg of downforce. Its simply impossible to estimate a value without knowing anything about the design or the car its going on. Yes, the total aero package needs to be designed so that it is properly balanced. You need a proper weight distribution including aero loading so that the centre of gravity is as close to the centre of the car as you can get it, but this often comes down to class rules and the actual base car you are starting out with. But with good design it is certainly possible to balance the aero loads and produce very high downforce. As for front airfoils, yes I have designed and built these, and yes they can be superior to a splitter. Again, take a look at any cars running at the pointy end of time attack, they will all have front wings (except the Lyfe GTR, but ccompare them to the competition and you can see they would gain a lot by having some better front aero). RP968 and the 1:1 R8 are probably the best examples of a full front airfoil rather than a splitter. Lots of the other cars will have a combination of splitter and front wings, and this is especially more common in the lower Open Class cars, as this category is still a stock chassis design with flat floors and tunnels prohibited. To throw you another design curve ball - attachment points should all be behind the bumper/air dam. Mounting solutions like splitter tie rods and cables are absolutely horrific when they are external and placed in the air flow. These create so much drag and destroy so much lift potential that you would be better off running a much smaller splitter design in order to do wothout them. Any aero car that has been properly designed will not have any mounting points in the air flow. So what sort of lateral acceleration can these Time Attack cars muster? I couldn’t find any data on that, but I suspect no where near an F1 car…or even a Radical ….i guess one of the limiting factors is the mass of the Time Car….. given that the friction forces (tyres/road surface) would need to overcome m.v^2/r….therefore the greater the mass m, the greater the counter force (grip needed) that needs to be generated to negotiate a bend
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Hanaldo
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Group: Forum Members
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I'm not talking about Radicals or the likes, I'm talking about Time Attack cars. Take a look at any of the Pro or Pro Am cars competing at WTAC. These cars are all making more downforce than an F1 car, they're looking at numbers in excess of 3000kg of aero loading. Yes, in those classes the cars are a tube frame chassis with tunnels in the floor, so they are proper aero cars, but they are based on passenger cars. I was sort of more making the point about how open ended your question was - a splitter can quite literally make anywhere from no downforce at all to over 1000kg of downforce. Its simply impossible to estimate a value without knowing anything about the design or the car its going on.
Yes, the total aero package needs to be designed so that it is properly balanced. You need a proper weight distribution including aero loading so that the centre of gravity is as close to the centre of the car as you can get it, but this often comes down to class rules and the actual base car you are starting out with. But with good design it is certainly possible to balance the aero loads and produce very high downforce.
As for front airfoils, yes I have designed and built these, and yes they can be superior to a splitter. Again, take a look at any cars running at the pointy end of time attack, they will all have front wings (except the Lyfe GTR, but ccompare them to the competition and you can see they would gain a lot by having some better front aero). RP968 and the 1:1 R8 are probably the best examples of a full front airfoil rather than a splitter. Lots of the other cars will have a combination of splitter and front wings, and this is especially more common in the lower Open Class cars, as this category is still a stock chassis design with flat floors and tunnels prohibited.
To throw you another design curve ball - attachment points should all be behind the bumper/air dam. Mounting solutions like splitter tie rods and cables are absolutely horrific when they are external and placed in the air flow. These create so much drag and destroy so much lift potential that you would be better off running a much smaller splitter design in order to do wothout them. Any aero car that has been properly designed will not have any mounting points in the air flow.
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Para
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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! Hi Hanaldo, Thanks for that. Indeed those are huge loads. However if you look at data from passenger cars modified into track cars, you will see that no such vehicle capable of generating more than about 1.4g centripetal acceleration. I can only think this is due to unbalanced load as it difficult to get comparable loads at the back of the car without substantial aero bits such as diffusers and matching rear wings to ensure non turbulent return of the low pressure flow back up to ambient. On the contrary a proper race car generates half of it’s downforce by ground effects alone (flat bottom and diffusers….the Venturi effect) so a passenger car is never going to get into the 2.5g lateral acceleration as in a Radical of similar. Incidentally, has anybody modelled a front splitter with an aerofoil cross-section and noted the effects?...although this may not be work that well… as an aerofoil needs smooth flow over both surfaces to be effective….given that it is mounted on the front of a car where there is a massive stagnation point….so that may be pointless. Anyway the reason for the original post was to gauge what sort of loads we can get from a splitter so that I could work out the loads that the connecting rods and attachments would be subjected to….attached is an example showing a 90 kg downforce and it’s effects on attachments etc For this I have assumed that the 90 kg (198 lb) force will be evenly distributed along the splitter length. We can then model this force acting at a single point at the centre of the splitter and treat the whole set up as a framework that has external forces acting on it. From a framework perspective, the rods and the splitter itself carry out one of two operations: These can stop the framework from collapsing inwards by exerting an outward force, or THRUST….ie acting as a STRUT or prevent the joints from flying apart by exerting an inward pull (TENSION) at each end…acting as a TIE. The calculations show the thrust and tension loads on the rods and the retaining attachments. I solved for the various loads acting through the system simply by taking moments about appropriate points and resolving vertical and horizontal components of all the forces.  
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